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Volume 92-B, Issue SUPP_IV October 2010

L. Borris T. Bandel B. Eriksson M. Gent M. Homering A. Kakkar M. Lassen A. Turpie T. Westermeier

Introduction: Four randomized, double-blind phase III studies (RECORD1–4) investigated the oral, direct Factor Xa inhibitor rivaroxaban for the prevention of venous thromboembolism (VTE) after elective total hip and total knee arthroplasty (THA and TKA). Patients (N=12,729) were randomized to receive oral rivaroxaban 10 mg once daily, or subcutaneous enoxaparin 40 mg once daily (RECORD1–3), or 30 mg twice daily (RECORD4). Those undergoing THA received rivaroxaban or enoxaparin for 31–39 days in RECORD1, and rivaroxaban for 31–39 days or enoxaparin for 10–14 days followed by placebo in RECORD2. In RECORD3 and 4 (TKA), prophylaxis was for 10–14 days.

Methods: A prespecified pooled analysis of all four studies evaluated the effect of rivaroxaban on the composite of symptomatic VTE and all-cause mortality, and bleeding, relative to enoxaparin. The present subgroup analysis investigated potential drug–drug interactions with concomitant non-steroidal anti-inflammatory drugs (NSAIDs) or acetylsalicylic acid (ASA) – commonly used pain medications known to affect bleeding risk. The risk of on-treatment bleeding in the total study duration pool of all four RECORD studies was investigated. These prespecified analyses focused on on-treatment, adjudicated bleeding events, any bleeding, and the composite of major bleeding and clinically relevant non-major bleeding – after the first tablet intake (rivaroxaban or matching placebo). Co-medication use was evaluated over time. Relative bleeding rates with and without co-medication were calculated separately for the rivaroxaban and enoxaparin/placebo groups. Time after surgery (day of surgery was day 1) was stratified into three periods (days 1–3, days 4–7 and day 7 up to 2 days after the last dose), based on the decreasing risk with time of a first bleeding event after surgery and because prevalence of co-medication use can vary over time. Bleeding rates were recorded for each time period over the at-risk period (the day of surgery until the last day of double-blind study medication intake +2 days or until initial event onset). The ratio of the bleeding rate for co-medication exposed vs unexposed patient-days in the rivaroxaban group was compared with the corresponding rate ratio for the enoxaparin/placebo group for bleeding events (Mantel–Haenszel methods).

Results: Concomitant use of ASA in the rivaroxaban groups showed rate ratios similar to those in the enoxaparin/placebo group (1.32 and 1.40, respectively, for any bleeding). Rate ratios were also similar with concomitant use of NSAIDs (1.22 in both groups, for any bleeding).

Conclusion: In the RECORD1–4 subanalysis, there was no indication of increased bleeding associated with the use of these co-medications in patients taking rivaroxaban, compared with enoxaparin.

A. Albayrak H. Akdeniz E. Karakas M. Tacal M. Yagmurlu

Current treatment modalities for chronic non-healing leg ulcers are time consuming, expensive, and only moderately successful. The use of sub-atmospheric pressure dressings, available commercially as the vacuum-assisted closure (VAC) device, has been shown to be an effective way to accelerate healing of various wounds. There is patented computer-controlled system technology available that is established V.A.C.(KCI Concepts, San Antonio, Texas) treatment. Reducing costs associated with wound treatments is therefore becoming an increasingly important issue in health care. This study included 45 patients with open wounds of the lower extremity with exposed tendon, bone, hardware or with osteomyelitis. Fifteen wounds were the result of trauma. Thirty wounds were non-traumatic (twenty dehisced or infected orthopedic surgical wounds, five pressure sores and five miscellaneous wounds). We use the vacuum therapy as a tool to bridge the period between debridement and definite surgical closure in full-thickness wounds. Treatment efficacy was assessed by semi-quantitative scoring of the wound conditions (signs of rubor, calor, exudate and fibrinous slough) and by wound surface area measurements. In our technique, the system consist of a sterilized simple foam sponge, a vacuum drain, two blood infusion kit and a negative pressure aquarium air pump, one liter salin bottle, an steril drape. It’s mean applying time ten minutes and mean cost at the first time 36 dollars consecutive seances 11 dollars (the aquarium air pump 15 dollars – an electrical engineer change it positive to negative air pressure mode). Forty-five patients who needed open wound management before surgical closure were included in this study. Healing was characterized by development of a clean granulating wound bed (“ready for surgical therapy”) and reduction of wound surface area. To quantify bacterial load, cultures were collected. The total quantitative bacterial load was generally stable. However, nonfermentative gram negative bacilli showed a significant decrease in vacuum-assisted closure-treated wounds, whereas Staphylococcus aureus showed a significant increase in vacuum-assisted closure-treated wounds. Succesfull wound closure was obtained 43 of 45 patients. 41 wounds were closed with split-thicknees skin graft. The median time to complete healing was 31 days (27.5 to 34.5) and wound bed preparation was 7 days (5.8 to 8.2) in the non-computerized V.A.C. therapy, similar with the computerized therapy 29 (25.5 to 32.5–7 days 5.7 to 8.3) This study shows a positive effect of vacuum-assisted closure therapy on wound healing, expressed as a significant reduction of wound surface. The costs of computerized wound care were higher than our techique of V.A.C. and similar clinical results at the end.

H. Al Hussainy S. Wong

In modern orthopaedics surgery, the pneumatic tourniquet has become an essential tool that paved the way to many of the advances in trauma and orthopaedic surgery. Tourniquet slippage is one of the challenging disadvantages of it use. This study examines the possibility of reducing tourniquet slippage by comparing two different tourniquet application techniques.

Twenty two patients were included in the study. Thirteen were males and eight were females. The average age was fifty five years. The patients were randomized into two groups, a controlled, and a modified tourniquet application technique groups. There were eleven patients in the control group and ten in the modified group. A standard tourniquet application technique was used as a control by applying Softband (Orthoband) alone to skin prior to application of tourniquet; this was compared to a modified version where a drape (Steridrape) was used as an interval layer.

There was a strong statistical significant difference in tourniquet slippage between the two groups, p< 0.0001 the control group being the better performer.

We concluded that steridrape interval makes tourniquet slippage more likely to occur.

L. Audigé M. Daigl-Cattaneo J. Goldhahn S. Goldhahn B. Hanson

Background: The interpretation of safety data from clinical studies such as complication risks requires clear definition of targeted and documented complication events. In addition a standardized classification of complications is required to allow appropriate comparison of safety data between studies and treatment groups. This presentation highlights a proposal for a standardized management and classification of complication data to initiate and seek consensus among trauma surgeons active in clinical documentation and research.

Methods: Complication events are examined regarding their timing of occurrence as well as their potential causal inter-relationship for any given patient. While independent events are numbered sequentially, directly associated events (e.g. a fracture collapse and implant screw perforation into a joint) receives the same complication number. Complications are described and categorized according to a pre-defined list of anticipated complication types, or as un-anticipated complications. They are further classified as local or general; local complications occur at or directly around the injuries and are further classified as being “Implant/Surgical procedure”, “Bone/Fracture” or “Soft tissue/Wound” events. Information regarding their operative and/or non-operative treatment and their outcome is recorded. Further assessments are made regarding their seriousness, their relation to the implant used. Final classification of complication events is better determined after independent review by a panel of experienced clinicians.

Results: Our classification process was applied successfully to a series of clinical studies at our department. In a study of 185 distal radius fractures treated by LCP, at least one complication occurred in 21 patients, and in seven cases there was a combination of associated events (e.g. one CTS with tendon rupture). Complication risks ranging from 0% to 11.4% were noted depending on which complications and time frames were considered. There was no risk to obtain a LCP implant specific related complication, whereas the risk for a local complication within 6 months after surgery was 6% (95% CI: 3% – 11%).

Conclusions: This management and classification system proved valuable in the documentation and analysis of safety data from clinical studies. It facilitates communication and understanding of definitions between clinicians, as well as allows a prompt, standardised and accurate analysis and reporting of complication events and risks. We encourage other clinical researchers and professionals to participate in the further development and acceptance of a universal classification system for complications in traumatology and orthopaedics.

O. Dahl A. Clemens B. Eriksson A. Kurth H. Noack N. Rosencher J. Schnee

Dabigatran etexilate (Pradaxa®) is an oral direct thrombin inhibitor that was recently approved in Europe and Canada for the prevention of venous thromboembolism (VTE) in patients undergoing elective total knee replacement or total hip replacement surgery. Two pivotal clinical trials, RE-MODEL (Eriksson BI et al. J Thromb Haemost2007; 5: 2178–2185) and RENOVATE (Eriksson BI et al. Lancet2007; 370: 949–956), studied the efficacy and safety of 220 mg and 150 mg dabigatran etexilate once daily compared with 40 mg subcutaneous enoxaparin. A post hoc pooled analysis was performed in elderly patients (> 75 years) since renal function gradually declines with age. The primary efficacy endpoint was total VTE and all cause mortality and the secondary efficacy endpoint was major VTE and VTE-related mortality. The primary safety endpoint was major bleeding events (MBE), including those occurring at the surgical site. All bleeding events were blindly adjudicated. Of the patients treated with 220 mg dabigatran etexilate (n=1825), 150 mg dabigatran etexilate (n=1866) and enoxaparin (n=1848), 883 patients (16%) were over 75 years. 73% of these elderly patients were evaluable for the primary efficacy endpoint and 75% were evaluable for the secondary efficacy endpoint. All patients > 75 years were evaluable for safety outcomes, including bleeding. The incidence of total VTE and all cause mortality was 20.8% (44/212), 22.6% (49/217), and 27.2% (58/213), respectively, in the three groups. A similar trend was observed for major VTE and VTE-related mortality: 220 mg dabigatran etexilate, 1.9% (4/216, p=0.045 vs enoxaparin using Fisher’s exact test); 150 mg dabigatran etexilate, 4.5% (10/221); enoxaparin, 6.0% (13/218). MBE occurred in 11 of the 295 elderly patients receiving 220 mg dabigatran etexilate (3.7%), 4 of the 282 elderly patients receiving 150 mg dabigatran etexilate (1.4%) and in 9 of the 306 elderly patients taking enoxaparin (2.9%). Notably, 6/11 MBE in the dabigatran 220 mg group and 2/4 MBE in the 150 mg group started before the first dose of treatment. We conclude that in elderly patients (> 75 years) undergoing hip or knee replacement surgery, oral 150 mg dabigatran etexilate exhibited a numerically favourable bleeding profile with no difference in efficacy compared with 40 mg enoxaparin. Because safety, particularly bleeding, is of paramount importance in the elderly, the 150 mg once daily dose of dabigatran etexilate is currently recommended by EMEA for this group.

L. Cusick D. Beverland

In response to the recent publication in April 2007 of NICE guidelines on venous thromboembolism, we report our practice and experience of VTE in adult hip and knee arthroplasty. It is generally agreed that the 2 major complications of VTE are sudden death as a result of pulmonary embolism and post thrombotic syndrome. NICE guidelines make 2 assumptions:

That chemical and mechanical prophylaxis can reduce these complications

That Orthopaedic surgery, in particular elective Primary Joint Replacements are particularly high risk procedures with respect to these 2 complications.

We have studied a large cohort of patients who had Aspirin only as chemical prophylaxis to determine the incidence of clinical thromboembolism before and after discharge and the mortality from PE at 90 days. We performed a retrospective analysis of consecutive patients undergoing primary total knee and hip replacement from November 2002 to November 2007. In total 2050 patients had total knee replacement and 2203 patients had total hip replacement. All patients were treated at one specialist centre under the care of one surgeon. Data was complete and accurate for all patients at 90 days post-operatively. Standard practice was the use of 150mg Aspirin from Day 1 post-operatively for a total of six weeks combined with spinal anaesthesia and early mobilisation. The overall rate for Fatal Pulmonary embolism 0.07% (3/4253), overall death rate 0.31%(13/4253), for treated non-fatal PE 0.66% (28/4253) and for treated above knee DVT was 0.33%(14/4253). Our data suggests that fatal pulmonary embolism is not common and does not account for most deaths following total hip and knee arthroplasty. We suggest there is no evidence that chemical/mechanical prophylaxis reduces the risk of sudden death from PE following elective primary joint replacement and with modern surgical practice elective hip and knee replacement should no longer be considered high risk procedures.

O. Dahl A. Clemens B. Eriksson S. Hantel A. Kurth N. Rosencher J. Schnee

Dabigatran etexilate (Pradaxa®) is an oral anticoagulant licensed in multiple countries, Europe and Canada, for the prevention of venous thromboembolic events (VTE) in patients undergoing total hip replacement surgery (THR) or total knee replacement surgery (TKR). The label recommendation for therapy initiation of dabigatran etexilate is a half dose given 1–4 hours after surgery. If this is not possible, then dabigatran etexilate should be started the day following surgery with the full dose. In the European pivotal Phase III clinical trials, this initial dosing was delayed until the day after surgery in 14% of the cases. This prompted a post hoc study to analyze if these patients received adequate thromboprophylaxis. Pooled efficacy data of major VTE events (composite of proximal DVT, symptomatic DVT, pulmonary embolism and VTE-related death) from the two European pivotal trials (RE-MODEL; Eriksson BI et al. J Thromb Haemost2007;5:2178–2185, and RENOVATE; Eriksson BI et al. Lancet2007;370:949–956) where analyzed. The group with delayed dosing was compared to the group that received therapy initiation on the day of surgery to determine if there was any significant effect on clinical outcome. The final decision on the timing of the administration of the first dose required sometimes clinical judgment, and in particular good haemostasis had to be present. Therefore, the bleeding rate and the timing of the first dose are confounded and an analysis of bleeding events was not performed. The major VTE rate in the group with delayed treatment initiation compared with the 1–4 hour post surgery treatment initiation group were 2.2% (95% CI: 0.1–4.4) vs. 3.0% (95% CI: 2.0–3.9) for 220 mg dabigatran etexilate, 8.3% (95% CI: 4.3–12.4) vs. 3.5% (95% CI 2.5–4.5) for 150 mg dabigatran etexilate, and 4.3% (95% CI 1.2–7.4) vs. 3.7% (95% CI 2.7–4.8) for 40 mg enoxaparin. As the confidence intervals overlap markedly, no statistically significant differences where found. In conclusion, no difference in the rates of major VTE and VTE related mortality was seen when the doses of dabigatran etexilate were postponed to the first postoperative day. These data need to be interpreted carefully due to the low number of patients in the delayed treatment group. As recommended in the current labelling of dabigatran etexilate, treatment should be initiated 1–4 hours post-surgery.

J. Brecelj V. Bole

Introduction: Substitution treatment and radiosynoviorthesis has a leading role in preventing irreversible hemophilic arthropaties. Aim: The aim of the study is to evaluate the effects of radiosynovectomy on the length of intervals between subsequent bleedings in patients with hemophilic synovitis.

Materials and Methods: 33 joints were treated with radiosynovectomy in 28 patients with bleeding disorders. 90Y colloid was used in knees and 186Re colloid for elbow, shoulder and ankle. 20 patients were on prophylaxis. X-rays of treated joints were evaluated on Peterson scale between 0 (normal) and 13 (severe joint destruction). In observation period (range 6 – 44 months) bleeding episodes were recorded and data statistically analyzed.

Results: Before RS, the average interval between haemorrhages was 16.4 days. Immediately after RS, the average interval between haemorrhages more than tripled. Namely, the average length of the first non-bleeding interval after RS was almost 60 days. In the period covering the first five bleeding episodes after RS, the average non-bleeding interval increased to 47.1 days. Therapeutic effects of RS considerably depend on location (joint) of bleeding, damage of the joint and of the patient. But controlling for location and damage of the joint and age of the patient, after RS every sub sequent non-bleeding interval was 11% shorter (p=0.05) than previous non-bleeding interval. After more than 10 bleeding episodes had occurred since RS, the non-bleeding intervals were no longer significantly shorter than before RS (at p=0.05). Therapeutic response to RS could be, therefore, observed in the period of more than 430 days after the procedure.

Conclusion: Radiosynovectomy significantly reduces hemorrhages in target joints for the average period of 14 months. It is more efficient in patients with less affected joints and less efficient in younger patients. The therapeutic effect of RS diminished with the elapse of time.

I. Gill A. Malviya S. Muller M. Reed

Aim: To assess the infection rate following Lower Limb Arthroplasty using single dose gentamicin antibiotic prophylaxis compared to a traditional three doses of cephalosporin.

Material and Methods: All patients undergoing Total Hip and Knee joint replacements over 6 months (October 2007 to March 2008) at 3 participating hospitals were prospectively followed up to assess perioperative infection rates. Joint replacements were defined as having infection by the UK Health Protection Agency Surgical Site Surveillance criteria. All patients received single dose antibiotic prophylaxis using intravenous Gentamicin 4.5mg/kg body weight adjusted for body mass index.

This group of patients were compared with previous data collected over a 6 month period (Jan to Mar 2007 and Oct to Dec 2005) from the same hospitals for infection rates in Lower Limb Arthroplasty using 3 doses of Cefuroxime 750mg as antibiotic prophylaxis.

Results: 408 patients underwent Total Hip Replacements (THR) and 458 patients underwent Total Knee Replacements (TKR) during the study period. This was compared with 414 patients who underwent THR and 421 patients who underwent TKR during a 6 month period over 2 years.

Surgical site infection was detected in 9 THRs (2.2%) and 2 TKRs (0.44%) in the study group as compared to infection in 13 THRs (3.1%) and 12 TKRs (2.9%) in the control group.

Using the Fisher Exact test the infection rates in THRs were not significantly different between the 2 groups (p value – 0.52) but the infection rates were significantly reduced in the study group for TKRs (p value – 0.005).

There were no complications with the use of Gentamicin as antibiotic prophylaxis.

Cefuroxime is known to promote Clostridium difficile infection and was removed from the hospital pharmacy to help meet a UK government targets to reduce the incidence. The rate of Clostridium difficile infection was reduced within the hospital with the use of single dose antibiotic prophylaxis although other measures to reduce its incidence were also introduced.

Conclusions: This study shows that the use of single dose antibiotic prophylaxis using Gentamicin is effective for elective Lower Limb Arthroplasty.

This is recommended for routine use in all elective joint replacements as it is safe, effective and easy to administer.

S. Goldhahn L. Audigé J. Goldhahn B. Hanson R. Mundi

Background: The nature and frequency of complications during or after orthopaedic interventions represent critical clinical information for safety evaluations, which are required in the development or improvement of medical procedures and devices. However, neither uniform definitions nor established classifications about the reporting of complications exist. So complication reporting, even in orthopaedic trials is still up to the surgeons perception and understanding. The goal of this systematic review was to check whether essential data are consistently provided by the authors in the assessment of incidence, severity and characteristics of complications related to orthopaedic interventions in randomized controlled trials.

Methods: Five major, peer-reviewed orthopaedic journals were screened for published randomized controlled trials (RCTs) between January 2006 and July 2007. All relevant papers were obtained, anonymized and evaluated by two external reviewers. A checklist consisting of three main parts: definition, evaluation and reporting was developed and applied for the assessment of complication reporting in RCTs. The results were stratified for the main area of the trial.

Results: One hundred and twelve RCTs meeting our inclusion criteria were identified. The majority of RCTs (n = 73) reported on surgical treatment methods, with most of the trials focussing on arthroplasty (38%); surgical fracture treatment and other surgical interventions accounted for 13% each. Although complications were included as trial outcomes in two thirds of the studies, clear definitions of anticipated complications were provided at least partly in only two trials of fracture treatment and six other trials. It remained unclear whether authors considered the specific events “death”, “mal-union”, “impaired function” and “re-operation” as complications; “impaired function” was not considered as a complication in 93% of the trials and “re-operation” events were considered in only 50% of the trials dealing with surgical fracture treatments. In 83% of RCTs, the identity of the person or group assessing the complications was unknown and in a further 8%, this process was implemented by the treating surgeon. This review did not identify any trial involving a Data Safety Review Board for assessment and classification of complications.

Conclusions: Due to the lack of homogeneity among the published trials, improvement in the reporting of complications is necessary. A standardized protocol for assessing and reporting complications should be developed and endorsed by professional organizations and most importantly, clinical investigators.

B. Eriksson J. Caprini A. Clemens R. Friedman A. Kurth H. Noack J. Schnee

Dabigatran etexilate (Pradaxa®) is an oral direct thrombin inhibitor that was recently approved in Europe and Canada for the prevention of venous thromboembolism (VTE) in patients undergoing total knee arthroplasty (TKA) or total hip arthroplasty (THA) surgery. In the phase III studies, concomitant administration of selective nonsteroidal anti-inflammatory drugs (NSAIDs with t½≤12 hours) and acetylsalicylic acid (ASA; < 160 mg/day) was allowed during treatment with dabigatran etexilate or enoxaparin. Due to the potential additional anticoagulant activity of these concomitant therapies a separate post hoc analysis was conducted to investigate the bleeding risk in these patients. We analysed the pooled study population (8,135 patients) from the three phase III trials in THA and TKA surgery (RE-MOBILIZE, RE-MODEL and RE-NOVATE) for major bleeding events (MBE). All MBE, which included surgical site bleeds, were assessed by an independent, expert adjudication committee. We report the rates of MBE and odds ratios (with 95% confidence intervals [CI]) for comparison of the subgroup concomitantly treated with NSAID (or ASA) versus the subgroup of patients without concomitant antithrombotically active medication. The overall rate of MBE (with and without NSAIDs and ASA) was 1.4% [CI 1.0–1.9], 1.1% [0.7–1.5] and 1.4% [1.0–2.0] with dabigatran etexilate 220 mg, 150 mg, and enoxaparin, respectively. Of the total population, 57.4% of patients received concomitant antithrombotic treatment: 54.1% received NSAID and 4.7% received ASA. The MBE rate in patients receiving dabigatran etexilate or enoxaparin plus NSAIDs was similar to the rate in patients taking only dabigatran etexilate or enoxaparin; 1.5% vs. 1.4% [OR 1.05; 0.55–2.01] for dabigatran etexilate 220 mg, 1.1% vs. 1.0% [OR 1.19; 0.55–2.55] for dabigatran etexilate 150 mg, and 1.6% vs. 1.2% [OR 1.32; 0.67–2.57] for enoxaparin. A similar pattern was seen in patients concomitantly receiving ASA; in this small group only a few patients with MBE were observed: 2 (1.6%) in the dabigatran etexilate 220 mg group, 2 (1.6%) in the 150 mg group, and 4 (3.0%) in the enoxaparin group. No relevant differences in risk for MBE were detected between treatments by co-medication subgroup or within treatment groups when comparing patients receiving dabigatran etexilate or enoxaparin only versus those concomitantly receiving NSAIDs or ASA. In conclusion, patients concomitantly receiving dabigatran etexilate and NSAIDs (with t½ ≤12 hours) or ASA (< 160 mg/day) have a similar risk of MBE to patients taking only dabigatran etexilate. These data support the use of dabigatran etexilate for the prevention of VTE in patients after THA or TKA, when concomitant use of NSAIDs or ASA (< 160 mg/day) is required.

G. Friedl R. Aigner R. Windhager

Background: Aseptic loosening of implants is commonly associated with periprosthetic bone loss, and several authors aimed to preserve periprosthetic bone mass by treatment with bisphosphonates (BPs) in THA. While local application of BPs was argued to provide higher concentrations of bioactive drug at the component-bone interface, we hypothesized that a systemically administration of BPs will be sufficient for sustained effects on local bone metabolism due to local accumulation of the drug in freshly exposed bone mineral early after reaming during implantation. The high antiresorptive potential of zoldronic acid (ZOL) on osteoclasts will be sustained locally by re-attachment after release by osteoclast resorption during the remodelling cycle. While we were able to demonstrate beneficial effects of ZOL on early implant fixation, its local effects on bone metabolism is best reflected by monitoring the relative changes of biochemical markers during follow-up after THA. This is an important issue to be addressed, since there are no reliable data available but essential for a prove-of-concept.

Methods: Fifty patients with ON-FH were consecutively enrolled to receive randomly either 4mg of ZOL or saline solution (CTR) in a double-blind fashion one day after THA. The biochemical bone turnover markers C-terminal teleopeptides of collagen type I (ICTP), CrossLaps (CL), osteocalcin (OC), osteoprotegerin (OPG), soluble RANKL, as well as 25-hydroxyvitamin D (25OHD3) were measured from fasting blood samples before surgery and at 7 weeks, 6 months, 1 year, and yearly thereafter. One patient was lost and after excluding three patients with deficiency in renal function 22 and 24 patients were analyzed in ZOL and CTR, respectively, during a median follow-up of 2.8 yrs.

Results: Within the placebo group, the bone resorption markers ICTP and CL peaked at 7 wks, but continuously decreased thereafter beyond baseline levels. The bone formation marker OC also increased, but peaked at 6 months and stayed increased during the follow-up. Although there was only a transient effect of ZOL found in ICTP, CL rapidly decreased within 7 wks and remained depressed during the whole follow-up period (~ − 65% at 2 yrs, P< 0.0001). Similarly, OC was also depressed in ZOL but never reached significance compared to baseline levels (~ − 19%, NS). No differences or changes were apparent in 25OHD3 levels.

Discussion and Conclusion: The findings strongly support a predominant local effect of systemically infused ZOL over a whole-body effect. Furthermore, the data demonstrate the sufficiency of a single infusion of a single infusion of ZOL for a pronounced and sustained antiresorptive effect after THA, which is essential to preserve periprosthetic bone mass in an effort to prevent aseptic loosening.

F. Dettoni F. Castoldi G. Collo N. Lollino A. Marmotti S. Parisi R. Rossi

Aim: Evaluate the incidence of complications related to timing (time between admission ad operation) and oral antiplatelet/anticoagulant therapy in patients treated for a hip fracture.

Materials and Methods: We prospectively evaluated 5 groups of 30 patients each, selected out of 875 consecutive patients admitted at the First Aid Unit of our Hospital with a proximal femoral fracture: group A – patients on Warfarin therapy, treated more than 5 days after admission (in order to allow the wash-out of Warfarin, as advised by many Anaesthesiologist Associations); B – patients treated more than 5 days after admission, not on Warfarin therapy; C – patients treated less than 48 hours after admission, not on Warfarin therapy; D – patients on Aspirin/NSAIDS therapy, treated more than 5 days after admission; E – patients on Ticlopidine/Clopidogrel therapy, treated more than 5 days after admission. The groups were comparable regarding age, gender, pre-trauma walking ability, mental state, fracture type and treatment. Blood loss, number of RBC transfusions, complications during hospitalization and up to 6 months after discharge, duration of hospitalization, degree of functional recovery and 2 years mortality were recorded. Statistical analysis included Kruskall-Wallis, U-Mann-Whitney and Logistic Regression Tests (SPSS 13.0 software).

Results: Group A showed higher preoperative blood loss (p=0.002), and longer hospitalization (p< 0.001), compared to all other groups. Groups D and E showed no higher complication and mortality rate in comparison to group B and C, while group A showed higher complication and mortality rate. Standing alone, timing and Warfarin appear not to be significant risk factors, while taken together they represent a high risk factor for complications ad mortality (p=0.009).

Conclusion: Patients on Warfarin therapy, affected by hip fracture, are at high risk of complications and mortality, if the recommendation of postponing treatment until drug wash-out is accepted. Reversal of anticoagulation using vitamin K and straight-forward treatment should be considered. Antiplatelet therapy appears not to have the same adverse effect as anticoagulant therapy.

T. Lawrence S. Gudipati

Every surgeon needs to audit the quality of his work to ensure that complication rates are low, good function persists for the intermediate term, and patient satisfaction remains high. The use of the 12-point shortened WOMAC score and Orthowave patient satisfaction survey provides enough information for quantitative assessment of most practices. When applied to my hip arthroplasty practice, analysis of data related to 426 consecutive patients at 1–9 years of follow-up (mean 3.5) revealed pain relief was good to excellent in 96%; rate of recommendation of surgery was 97%. Overall satisfaction was good to excellent in 95%. Mean WOMAC scores improved from a preoperative mean value of 32.5 to mean 6.6 at latest follow-up. When the same scoring system was applied to my knee arthroplasty practice, results were surprisingly inferior. Potential areas for technical improvement were then identified and implemented. This study highlights the simplicity and usefulness of the shortened WOMAC score and Orthowave patient satisfaction survey in assessing and improving an arthroplasty practice.

A. Kurth A. Clemens O. Dahl B. Eriksson H. Noack N. Rosencher J. Schnee

The oral direct thrombin inhibitor dabigatran etexilate (Pradaxa®) was recently approved in Europe for the prevention of venous thromboembolism (VTE) in patients undergoing elective total knee or total hip replacement surgery. In the Phase III RE-MODEL (Eriksson BI et al. J Thromb Haemost2007; 5: 2178–2185) and RENOVATE (Eriksson BI et al. Lancet2007; 370: 949–956) clinical trials the safety and efficacy of 220 mg and 150 mg dabigatran etexilate once daily were studied. In both trials these doses were compared with 40 mg subcutaneous enoxaparin. A post hoc pooled analysis was performed in patients with moderate renal impairment (glomerular filtration rate ≥ 30 and < 50 ml/min) who participated in these two trials. The primary efficacy endpoint in both studies and the post hoc analysis was total VTE and all cause mortality; the key pre-specified secondary efficacy endpoint was major VTE and VTE-related mortality. Bleeding events (the primary safety endpoint) were blindly adjudicated and categorised as major bleeding events (MBE), which includes surgical site bleedings. A total of 1825 patients were treated with 220 mg dabigatran etexilate, 1866 with 150 mg dabigatran etexilate and 1848 with 40 mg enoxaparin. Of these, 337 patients had moderate renal impairment. 68% of these patients could be evaluated for the primary efficacy endpoint, 72% for the secondary efficacy endpoint, and all patients were included in the safety and bleeding analyses. The incidence of total VTE and all cause mortality was 17.7% (14/79), 23.5% (16/68) and 27.8% (25/90) in the 220 mg dabigatran etexilate, 150 mg dabigatran etexilate and enoxaparin groups, respectively. When the secondary efficacy endpoint was analysed a similar trend was seen, with a descriptive statistical significance for a lower event rate in the 220 mg group: 1.2% (1/83; p=0.04 vs enoxaparin using Fisher’s exact test), 4.3% (3/70) with 150 mg dabigatran etexilate; and 9.0% (8/89) in the enoxaparin group. MBE occurred in 6/113 patients (5.3%) in the 220 mg dabigatran etexilate-treated group, in none of the patients in the 150 mg dabigatran etexilate-treated group (0/96; p=0.04 vs enoxaparin using Fisher’s exact test), and in 6/128 patients (4.7%) receiving enoxaparin. Of note, 3/6 MBE in the 220 mg group started before oral dabigatran etexilate treatment was initiated. In conclusion, oral 150 mg dabigatran etexilate showed similar efficacy compared with subcutaneous enoxaparin in patients with moderate renal impairment undergoing hip or knee replacement surgery, with an apparently lower rate of major bleeding. As bleeding is a major concern, especially in this population, the 150 mg once daily dose of dabigatran etexilate is currently recommended by EMEA for this group.

T. Lim Chin G. Liu L. Shen K. Wong Hee

Introduction: Fractures are common with well described morbidities. Few small studies have reported in-hospital mortality of patients with fractures. This study aims to describe the distribution of fractures, the incidence of in-hospital fracture mortality and its risk factors.

Materials and Methods: All patients with fractures related to the hip, pelvis, femur, tibia and spine over a 10 year period in a university hospital were identified using the ICD-9 codes upon discharge. Age, gender, race, length of hospital stay and in-hospital mortality data were collected from electronic records. Detailed analysis of the mortality data was performed with statistical analysis using SPSS software.

Results: 8709 fractures were identified, of which 30.3% were hip fractures [1422(54%) NOF and 1216(46%) IT fractures], 24.4% were spinal fractures [144 (7%) cervical; 558(26%) thoracic; 1038(49%) lumbar; 47(2.2%) sacral and 335(16%) unclassified spine fractures], 24.1% were tibial fractures [proximal and shaft], 14.4% were femoral fractures [1037(83%) shaft and 215(17%) supracondylar] and 6.9% were pelvic fractures [265(42%) non rami and 351(58%) rami fractures]. 25% of the fractures occurred between age 21–40 years and 65% fractures occurred in patients older than age 41 years. 53% of the patients were male. 69%, 12% and 11% of the fractures were found in Chinese, Malay and Indian respectively. 90% were closed fractures.

Overall in-hospital fracture mortality was 1.3% (117 fractures). Fracture specific in-hospital mortality was 2.8% (75 fractures) for hip fractures, 5% (13) for non rami pelvic fractures, 1% (20) for spinal fractures, 0.5% (6) for femoral fractures and near 0%(1) for tibial fractures. In-hospital mortality increased with age (0.4% mortality between 21–40 years, 0.6% between 41–60 years, 0.9% between 61–70 years, 1.7% between 71–80 and 4% between 81–90 years). Infection related causes of death were most common. The mean duration from hospital admission until death was 19 days (SD 20, range 1–34). More hip and spine fractures were seen in Chinese and more femoral and tibial fractures were seen in Malay and Indian patients, and this difference was statistically significant. Logistic regression analysis showed only increased patient age, male gender and fracture type as statistically significant risk factors for increased in-hospital mortality. Subgroup analysis showed a 30 and 20 times increased risk of in-hospital mortality for pelvic (p=0.001, 95% CI 4, 241) and hip (p=0.003, 95% CI 3, 159) fractures respectively.

Conclusion: The overall in-hospital fracture mortality was 1.3% (2.8 % for hip and 5% for pelvic fractures). Increased patient age, male gender, hip and pelvic fractures were found to be risk factors for increased mortality.

R. Kakwani P. Banaszkiewicz B. R. White

Aim: Isotope bone scan has become a part of the routine workup for a painful arthroplasty. A retrospective analysis was performed to analyse the significance of isotope bone scan results in the management of painful arthroplasty.

Methods and Materials: The study group included all the 58 consecutive patients who underwent an isotope bone scan for a painful arthroplasty over a one year period. The data collected included: age, sex, date and nature of primary arthroplasty, inflammatory markers, indication, date and result of the bone scan, and the final outcome.

Results: The primary arthroplasty was a TKR (29 patients) and THR (29 patients). The average duration between primary arthroplasty and the bone scan was 44.3 months (Range 5 – 195 months). The duration was less than 1 year for 6 patients. The average age of the patients was 62 years. The male: female ratio was 31:27. 4 of the arthroplasties were uncemented and 54 were cemented. The bone scan results were normal in 32 patients, unclear in 17 patients and abnormal in 9 patients. There was no statistical correlation found between the inflammatory markers and the results of the bone scan.

Discussion: The results of the bone scan made a significant contribution in the management decision of the patient in 8 of the patients and served to reassure the patient/surgeon in most of the rest 50. In 6 patients it was performed within a year of the primary arthroplasty, during which period the results are not very specific. An isotope bone scan involves a significant radiation exposure to the patient as well utilization of time and resources, hence always ask the million dollar question: “Is it going to alter my management plan”

G. Labek S. Frischhut M. Huebl W. Janda M. Liebensteiner W. Pawelka B. Stoeckl M. Thaler A. Williams

Introduction: Clinical follow-up studies are sample based, in contrast to arthroplasty register data, which refer to the entire population treated. Aim of this study is to assess the differences in revision rate to quantify bias-factors in published literature.

Materials and Methods: A structured literature review of Medline-listed peer reviewed journals on examples has been performed concerning implants with sufficient material in both data sources available. Products with inferior outcome were subsumed in a subgroup.

Results: The number of cases presented in peer reviewed journals are relatively low in general and show a high variability.

The average revision rate in peer reviewed literature is significantly lower than in arthroplasty register data-sets.

Studies published by the inventor of an implant tend to show superior outcome compared to independent publications and Arthroplasty Register data. Factors of 4 to more than 10 have been found, which has a significant impact for the results of Metaanalyses.

When an implant is taken from the market or replaced by a successor there is a significant decrease in publications, which limits the detection of failure mechanisms such as PE wear or insufficient locking mechanisms.

The final statement made about the product under investigation seem to follow a certain mainstream.

Discussion and Conclusion: Arthroplasty Register datasets are superior to Metaanalyses of peer reviewed literature concerning revision rate and the detection of failure mechanisms. Combined reviews could reduce bias factors and thereby raise the quality of reports.

L. Nordin Y. Al-Arabi S. Deo S. Vargas-Prada

Introduction: Many papers present results and outcomes of patients undergoing TKR or THR, these are often available to the general population and health care community and health care commissioners. These results are used as a standard to be expected by the interested parties. Patients undergoing lower limb arthroplasty fall into groups that can be broadly divided into standard and complex. Complexity can be further subdivided into local site of surgery problems, general co-morbidity problems or both.

We have come up with a 4-part stratification based on the patient’s primary condition and comorbidities and have evaluated this for a single-surgeon cohort of TKR patients and a multi-surgeon group of THR patients. We present the results and the implications of the findings and highlight the usability of the system.

Methods: Retrospective review of patient’s notes and radiographs recording lenght of stay, early post operative complications, demographic data, medical co-morbidities and local site of surgery issues. This information was used to stratify patients into 4 groups. Complex Primary 0 -standard joint replacement in a fit patient with simple pattern arthritis, Complex Primary I -a fit patient with locally complex arthritis, Complex Primary II -medically unfit patient with simple arthritis and Complex Primary III -medically unfit patient with complex pattern arthritis. We evaluated this for a single-surgeon cohort of TKR patients and a multi-surgeon group of THR patients, a total of 250 patients.

Results: The complication rates between the four groups were analyzed using logistic regression analysis and this revealed a highly significant trend among the four groups (p< 0.0001). Lenght of stay data was analyzed using non-parametric analysis of variance. This revealed a significantly increased lenght of stay in the CI and CII groups compared to the C0 group. Compared to CP0 patients, we found a 3-fold increase in cumulative complication risk in the CPII group, a 4-fold increase in the CPIII group. There were similar trends between CP0 and CPI and between CPI and CPII.

Discussion and Conclusion: This classification system correlates and quantifies increasing primary joint replacement complexity with increasing postoperative complication rates and length of stay. It is of use in stratifying patients for preoperative planning, risk counselling, and surgeon selection. These noted increases mean that this system can identify patient groups likely to incur greater cost during their treatment. It is potentially reproducible and usable for other types of surgery and can be applied to larger patient groups via institutional or national joint registries.

O. Lorbach M. Brockmeyer D. Kohn S. Maas R. Seil P. Wilmes

Purpose: Evaluation of the inter- and intra-observer reliability of a new developed knee laxity measurement device for tibiofemoral rotation.

Methods: 30 healthy subjects (15m, 15w, mean age of 24 years) were examined with the Rotameter knee laxitiy measurement device. The Beigthon score was reported to test the general laxitiy of the subjects.

After fixation of the device on the lower extremity and positioning of the patient in the starting position the device was first externally and then internally rotated at an applied torque of 5,10 and 15 Nm. To decrease the measurement error the procedure was repeated 5 times. Afterwards 5 measurements were performed by a second examiner in the same way to measure the inter-observer reliability. All 30 patients were measured again after a mean of 31 ± 43 days by the same examiners to test the intra-observer reliability. Statistical analysis was performed using the intra class correlation coefficient (ICC). Pearson correlation coefficient were used to compare the measurements of the left and the right knee.

Results: The Beigthon Score showed a mean of 0.8 ± 1.1 (0–4). At an applied torque of 5 Nm the ICC for the intra-observer reliability of was 0.81 for the external rotation and 0.67 for the internal rotation, the ICC for the inter-observer reliability was 0.94 for the external and 0.94 for the internal rotation. At 10 Nm of rotation torque an ICC for the intra-observer reliability of 0.79 was reached for internal and 0.88 for external rotation, the ICC for the inter-observer reliability was 0.97 for internal and 0.95 for external rotation. At the highest applied torque of 15 Nm an ICC for the intra-observer reliability of 0.93 was observed for the external rotation and 0.83 was found for internal rotation. For the inter-tester reliability the ICC was 0.95 for external and 0.98 for internal rotation.

The comparison of the measurements of the left and the right knee showed high Pearson correlation (.90) at all applied torques.

Conclusion: The Rotameter testing device for the measurement of tibiofemoral rotation showed a high inter-observer and intra-observer reliability. It is easy to perform and might be used in a wide field to examine the rotational stability of the knee.

I. Mcnamara M. Parker T. Prevost A. Sharma

Background: Venous thromboembolism (VTE) remains a significant cause of morbidity and mortality of patients following hip fracture. It is not known preoperatively which patients are at greater risk of developing VTE complications following their surgery. This study reports the incidence of VTE following neck of femur fracture, the timing of the diagnosis of VTE and any risk factors associated with VTE development.

Materials and Methods: We analysed the prospectively recorded complications of patients that presented with a neck of femur fracture. Those patients that developed VTE were compared to those with no complications and their risk factors compared.

Results: A total of 5300 patients were analysed. The incidence of VTE was 2% despite thromboprophylaxis. The significant risk factors for VTE were poor pre operative mobility (p< 0.01), those preoperatively living in their own home (p< 0.01), low mental test score (p< 0.01), high postoperative haemoglobin (p< 0.03), intertrochanteric fractures and fixation with a dynamic hip screw (p< 0.01).

Conclusions: This is the largest group of patients to be prospectively analysed for risk factors for developing VTE following surgery for neck of femur fractures. There were a number of groups that were at a significantly higher risk of developing VTE than others. Orthopaedic surgeons should be aware of these groups in the management of these vulnerable patients.

E. Melamed D. Angel Y. Gotfried

Background: Percutaneous compression plating (PCCP) is used for the fixation of intertrochanteric hip fractures by a minimally invasive technique. While offering several advantages compared to classic open reduction and internal fixation, the technique does not allow direct hemostasis. We aimed to assess the effect of regular aspirin use on blood loss, transfusion requirements and wound complications in patients undergoing urgent fixation using this technique.

Methods: The study involved 326 patients who presented to our hospital with an intertrochanteric fracture. Parameters recorded included time to surgery, blood loss (assessed by pre and post operative hemoglobin concentrations), and transfusion requirements. The status of wound healing was evaluated, with specific reference to hematoma formation. The influence of regular pre-operative aspirin use was analyzed with respect to these outcome measures.

Results: 32% of patients were regular aspirin users, and were comparable to the non aspirin group. There was no significant difference between the aspirin and non aspirin groups in terms of preoperative hemoglobin concentrations, perioperative changes in hemoglobin levels, and transfusion requirements. The severity of wound hematoma and the number of drainage procedures was not significantly different between the two groups. In a multivariate logistic regression analysis (composite complications* versus no complications as the dependent variable. R2=0.108, P< 0.001), only delay to surgery was associated with a higher complication rate.

Composite complications defined as transfusion ≥3 units, abnormal wound hematoma and length of stay ≥ 10 days.

Conclusion: Regular aspirin use pre-operatively is not associated with increased blood loss, transfusion requirements and wound complications in patients treated with this percutaneous fixation technique. Rather, it is the delay to surgery that is associated with a composite bad outcome. Our data suggest that patients on aspirin can safely undergo urgent non-delayed fracture fixation using the PCCP.

V. Nikolaou S. Fogerty P. Giannoudis N. Kanakaris A. Papathanasopoulos

Aim: To evaluate the effect of fasciotomies following compartment syndrome on the healing of closed tibia diaphyseal fractures.

Patients and Methods: Between January 2002 and January 2005 165 patients were treated in our institution with closed tibial diaphyseal fractures. Patients were divided in to two groups; Group A (study group) consisted of patients that, after surgery, developed compartment syndrome and were submitted to fasciotomies and group B (control group) of patients who underwent reamed IM nailing and did not require such intervention. Patients with open fractures, pathological fractures, revision surgery, severe brain injuries, prolonged ITU stay and severe co-morbidities were excluded. Fracture pattern, ISS score, smoking habits, drugs intake, mode of mobilization and additional procedures were prospectively documented. Fracture healing more than 24 weeks was defined as delayed union and over 36 weeks as non-union. All patients had been followed-up clinically and radiologically until fracture union.

Results: One hundred twenty five out of 165 patients fulfilled the inclusion criteria for this study. 30 patients were classified in group A and 95 in group B. 18 patients of group A required skin graft coverage after the fasciotomies. There was no difference between the two groups in terms of the studied parameters. 4 patients from group A and 1 from group B, went to non-union and required second procedures to achieve union. These patients were excluded from the final analysis. Delayed union occurred in 11(percentage) patients in group A and in 10 (percentage) patients in group B (P< 0.05). Overall, fracture healing was prolonged in the fasciotomy group but the difference was not statistical significant, 24.27 weeks (10 – 48) versus 22.19 (12 – 40), (P= 0.157) in group A and group B respectively.

Conclusions: Compartment syndrome and fasciotomies is associated with delayed fracture healing. Nevertheless, this delay was not statistically significant different.

R. Rohit Z. Gamie S. Graham N. Manidakis I. Polyzois E. Tsiridis R. Venkatesh

Introduction: Ever since the coding has been introduced in the NHS there has been lot of debate whether the trust is being paid accurately. There is no data available which compares the coding done by the surgeon and the one done by the coding department.

Material and Methods: A prospective study was done on 305 patients in an elective orthopedic hospital over a period of one month. All operations were coded separately by the operating surgeon and the coding department. The procedures included all upper and lower limb procedures other than elective hand, spine and paediatric procedures. The results were compared by an independent assessor in line with the national guidelines and the information originally available to clinical coders.

Results: The results showed a marked difference in reimbursement cost of complex procedures, revisions and co-morbidities as coded by the surgeon who took into consideration additional top ups which were available and these were often missed by the coding department. There was no difference in the primary hip and knee arthroplasty.

Conclusion: There is an increased need for correct coding as this can result in potential income consequences by applied tariffs. With the introduction of acute phase tariffs and marked difference in reimbursement to the trust if correct codes are not applied, there is an increased need for awareness for the coding and the top-ups available for complex procedures.

C. Quah A. Chougle Y. Joshi P. Mcgraw

Introduction: Elective joint replacement patients routinely require transfusion following surgery. Haemoglobin must remain within red blood cells in order to be functional. The process of surgery and collection in the reinfusion drain may disrupt cell membranes resulting in non functional haemoglobin. The filtration and collection process does not eliminate free haemoglobin. This results in intracellular and free haemoglobin being transfused into patients giving false functional haemoglobin levels.

Aim: To determine the proportion of intracellular haemoglobin in autologous blood transfusion drain following joint replacement.

Research Methodology: Research ethical approval was obtained prior to conducting this study. 20 consecutive patients undergoing elective total hip replacement (THR) and 20 consecutive patients undergoing elective knee replacement (TKR) from April 08–July 08 were consented to participate in this study. A standard full blood count sample of 3 mls was taken from the rein-fused blood. Each sample had the total haemoglobin (THb) concentration determined (i.e. free and intra-cellular) from the blood in the specimen tube. The sample was then centrifuged, and the THb of the supernatant was determined. This determined the concentation of ‘free’ haemoglobin. From these two respective values, the proportion of haemolysed haemoglobin was determined from each sample.

Results: There were a total of 35 participants of which 20 were TKR and 15 were THR. The average THb concentration for the THR and TKR were 7.7g/dl and 10.3g/dl respectively. The proportion of haemolysed Hb was 1.46% and 0% respectively. The THb and proportion of haemolysed Hb for all 35 patients were 8.76g/dl and 0.63%.

Conclusion: Autologous blood transfusion is not only safe and economical but remains an effective procedure with a negligible proportion of haemolysis

L. Ryttberg I. Björholt A. Diamantopoulos F. Forster A. Fraschke M. Lees

Introduction: Rivaroxaban is a novel, oral, direct Factor Xa inhibitor for the prevention of venous thromboembolism (VTE) after total hip and knee arthroplasty (THA, TKA). The pivotal RECORD trials showed that 35 days’ rivaroxaban significantly reduced total VTE following THA versus both 35-day and 14-day enoxaparin regimens. Following TKA, 14 days’ rivaroxaban significantly reduced total and symptomatic VTE versus 14 days enoxaparin. Major bleeding was similar for rivaroxaban and enoxaparin. An economic model was developed based on these results to assess the cost-effectiveness of rivaroxaban relative to enoxaparin in Sweden.

Methods: The incidence of clinical events and resulting consequences on resource use and quality of life were modelled for rivaroxaban and enoxaparin over 5 years. VTE incidence during the prophylaxis period was based upon RECORD2 (THA) and RECORD3 (TKA) and extrapolated out to 90 days following surgery based on published epidemiological data. These trials were used because they best reflect the treatment length currently applied in clinical practice in Sweden. Recurrent VTE and post-thrombotic syndrome (PTS) beyond 90 days were modelled from published clinical data. Literature indicates that 10% of enoxaparin patients require visits from a district nurse following hospital discharge to administer subcutaneous (sc) enoxaparin, a cost not incurred with oral rivaroxaban. The cost associated with clinical events (major bleed, VTE and PTS) and home care visit was derived from published Swedish sources and expressed in Swedish kroner (SEK). Rivaroxaban and enoxaparin costs were included.

Results: In THA, 35 days’ rivaroxaban produced an additional cost (SEK 119 [€12.59] per patient) versus 14 days enoxaparin. However, rivaroxaban resulted in a gain of quality-adjusted life years (QALYs) and in fewer symptomatic events per patient relative to enoxaparin. This means an extra cost with rivaroxaban of SEK 29,378 (€3,109) per QALY gained and SEK 3,929 (€416) per symptomatic event avoided. Because the cost for treating a VTE range from SEK 12,000 to 30,000, it is less costly to avoid such an event by using rivaroxaban than treating it once it occurs. In TKA, 14 days’ rivaroxaban produced savings of SEK 873 (€92) per patient versus 14 days’ enoxaparin, as well as an improvement in QALYs and a reduction in symptomatic VTE events. Consequently, rivaroxaban was both more effective and less costly. Extensive sensitivity analyses showed that these results persist in a clear majority of situations.

Conclusion: The economic analysis showed that by reducing VTE, and providing an oral alternative to sc enoxaparin, oral rivaroxaban has the potential to significantly improve health outcomes in Sweden at a slightly higher (in THA) or lower (in TKA) cost than existing VTE prophylaxis.

P. Pavlou J. Gardiner D. Pili E. Tayton

Introduction: The volume of medical waste has increased in line with increasing medical, diagnostic and therapeutic procedures, and large joint arthroplasty is a major contributor. Demand for landfill sites due to increasing household, industrial and hospital waste loads, have made the current situation untenable.

Methods: A prospective observational study of the waste from non contaminated packaging in consecutive joint replacements was undertaken. The total weight and volume of waste, the cost of disposal, and percentage and constituents of recyclable items were recorded for each case.

Current costs and methods of local waste disposal were also investigated.

Results: The average non-contaminated waste from a primary joint replacement is 5.2 kg and less than 1% is non-recyclable. Paper waste constitutes 57%, plastic waste 36%, cardboard waste 16% and metallic waste < 1%. Landfill costs are between £60–70 per tonne with recent and projected increases in landfill taxes.

Revenue generated from recycling paper is between £50–80 per tone and plastic waste between £150–180 per tonne.

Conclusions: Currently all potentially recyclable waste from common orthopaedic procedures is going to landfill. Reduce, Reuse and Recycle are the cornerstones of waste management. Medical organisations and staff need to understand how best to segregate waste and take advantage of opportunities for reuse and recycling.

The introduction of a local or national recycling policy would make a definite impact on the environment, as well as potentially saving money.

A. Sahu D. Johnson P. Turner T. Wilson

Introduction: To train the surgeon adds to the length of procedures and this is currently not accounted for, in the finance received to perform the operation by the hospital.

Objective: Our study focussed on these main questions:

What is the effect on the length of a procedure when a trainee is involved?

What is the effect on the length of a list and the number of procedures performed on the list when a trainee is involved?

What percentage of cases had trainee involvement for anaesthetics and surgery?

Is this is statistically significant?

Method: Data was taken from two different sources, firstly, the ORMIS theatre system and patient operation notes. These were used to determine the length of six different types of orthopaedic procedures and the level of the main surgeon. This was collected in Stepping Hill hospital, Stockport, United Kingdom between June and July 2008. The second source used was a consultant’s logbook comprising 227 primary total knee replacements between 2004 and 2008.

Results: The data collected via the ORMIS system produced trends suggesting trainees took longer to perform procedures than consultants. The data from the consultant logbook statistically proved this. List times appeared unaffected by trainee presence. In Orthopaedic surgeries, 92% times trainees were present during the procedure and out of this 17% cases were performed by trainees. For total hip replacements done by trainees the procedure took significantly longer surgical time than consultant performed procedures (p = 0.0337).

Among these cases, 71% were performed by senior trainees. The consultant’s log book data also suggested the similar trends. In all comparisions, time taken by trainees to perform surgeries were statistically significant. Trainee performed with consultant scrubbed versus consultant performed (P = < 0.0001), trainee performed with consultant in theatre versus consultant performed(P = 0.0318) and trainee performed with consultant scrubbed versus trainee performed with consultant in theatre (P = 0.002)

Discussion and Conclusion: Hospitals are paid a fixed fees per operation due to introduction of payment by results system as they are paid a fixed tariff for a particular procedure. Training increases the length of a procedure and therefore in an efficient structured environment prevents as many cases being done on a list. Therefore, training future surgeons costs the hospital money. To counter this, training hospitals should be given financial incentives to train in surgery, or procedures performed by trainees should be priced differently to account for the time lost by training.

M. Siebelt M. Bhandari R. Bloem P. Pilot R. Poolman T. Siebelt

Background: One of the disadvantages of the Impact Factor (IF) is self-citation. The SCImago Journal Rank (SJR) indicator excludes self-citations and incorporates quality of citations that a journal receives by other journals, rather than absolute numbers. This study re-evaluated self-citation influence on the 2007 IF for 17 major orthopaedic journals and the difference in ranking using IF or SJR was investigated.

Methods: Divided in a general (n = 8) and specialized (n = 9) group, all journals were analysed for self-citation rate, self-cited rate and citation density. Rankings of the 17 journals for IF and SJR were determined and the difference in ranking was calculated.

Results: Specialized journals had higher self-citation rates (p = 0.05), self-cited rates (p = 0.003) and lower citation-densities (p = 0.01). Both groups correlated for self-citation rate and impact factor (general: r = 0.85 ; p = 0.008) (specialized: r = 0.71 ; p = 0.049).

When ranked for SJR instead of IF, five journals maintained rank, six improved their rank and six experienced a decline in rank. Biggest differences were seen for BMC MD (+7 places) and CORR (− 4 places). Group-analyses for the IF (general: 7.50 – 95%CI 3.19 to 11.81) (specialized: 10.33 – 95%CI 6.61 to 14.06) (p = 0.26), SJR (general: 6.63 – 95%CI 2.66 to 10.60) (specialized: 11.11 – 95%CI 7.62 to 14.60) (p = 0.07) and the difference between both rankings (general: 0.88 – 95%CI –1.75 to 3.50) (specialized: − 0.78 – 95%CI –2.20 to 0.65) (p = 0.20), showed an enhanced underestimation of sub-specialist journals.

Conclusion: Citation analysis shows that general journals tend to use more citations per published article and a larger portion of self-citations constitutes citations of sub-specialist journals compared to more general journals. The SJR excludes the influence of self-citation and awarded prestige by the SJR implies a different quality-evaluation for most orthopaedic journals. A disadvantage using this indicator, is an enhanced effect of underestimation of sub-specialist journals.

K. Sharif T. Bagga T. Nunn F. Rehman

The 2007 National Institute for health and Clinical Excellence (NICE) thromboprophylaxis guidelines concerning hip arthroplasty remain contentious. A survey among British Hip Society members was performed to investigate the impact of these guidelines. Information on thromboprophylactic measures before and after guideline publication was gathered in the three categories of Total Hip Replacement (THR), hip fracture and high-risk patients as defined by NICE. The response rate was 185/250 (74%). All responders used thromboprophylaxis, but only 44%, 22% and 7% indicated they were currently acting in accordance with guidance for THR, high risk and hip fracture groups respectively. 19%, 14% and 14% had changed their practice since publication of the guidance in THR, high risk and hip fracture groups respectively. The effects of the NICE guidance in influencing the responders’ thromboprophylactic protocols have been very limited. These results do not appear to endorse the authority of NICE in decisions made in this area.

S. Somoskeoy T. Illés P. Than

Introduction: Degenerative osteoarticular conditions of the lower limb comprise of the most common orthopedic diseases requiring implants surgery. Biomechanical factors have an important role in the development of the degenerative process. Radiological diagnostics prominently rely on bidirectional 2D X-ray images, CT and MRI also being employed in the assessment process. However, these diagnostic tools usually cover a single joint, mostly unilaterally, rarely if ever providing a chance to simultaneously examine each members of the closed kinetic chain of both limbs under normal postural loads in a standing position. Classification and measurements of anatomical conditions are carried out in a 2D environment only and measured values are projected to real-life circumstances.

EOS, a new 2D/3D digital imaging system based on Nobel-prize winning ultra low-dose X-ray radiation detection and a unique 3D toolbox with 3D reconstruction module offers a truly groundbreaking option in this field. We present results obtained during the first year of clinical use of our EOS 2D/3D system.

Methods: 20 patients with coxarthrosis and 20 patients with gonarthrosis have been examined with traditional 2D X-ray and EOS 2D/3D system. Clinical parameters (femoral and tibial length, mechanical angle of the femur and tibia, anatomical and mechanical femorotibial angle, etc.) have been determined for both diagnostic methods and results were compared. 3D measurements available within EOS 3D toolbox were determined including femoral and tibial torsion and femorotibial rotation. For visualization of the lower limbs EOS 3D reconstructions were made.

Results: Using EOS built-in 3D toolbox, comparison of numerical data for 2D and 3D measurements of clinical parameters showed a significant difference whereby 3D measurements always represented more valid, more accurate values. Differences between 2D and 3D measurement values were as much as 5–10 mm in length or 5–8 degrees in angles. This was particularly true for conditions where torsion and rotation of the bones were present.

EOS 3D reconstruction module provided a surface reconstructed 3D model of the examined limbs and automatically displayed every clinically relevant parameters measured in the 3D toolbox. This proved to be an important feature for pre-operative planning and postoperative evaluations.

Conclusion: EOS 2D/3D system provides a ground-breaking new tool for length and angle measurements of the lower limb in 3D, providing distortion-free clinical parameters that are accurate and true-to-life values, avoiding artefactual effects from projection, torsion and rotation and positioning of the patient, which usually concomitantly affect the accuracy and reproducibility of conventional 2D measurements.

M. Tryfonidis N. Anjarwalla A. Cole

A number of studies have looked at the incidence of cervical rib in various ethnic groups, but have a number of limitations. This is the first large scale study looking at the incidence in White British with direct comparison to the Asian population. A total of 1545 consecutive cervical spine radiographs performed for any reason were collected and reviewed. 5.9% of White British and 24.9% of Asian patients had evidence of cervical rib. This was statistically significant (p< 0.0001, χ2 test). Asians are 5 times more likely compared to White British to have cervical rib (OR=5.303, 95% CI=3.825–7.354). An analysis of male Vs female difference as well as incidence of the various subtypes of cervical rib will be presented. We reccomend that the results of this study should

be considered in the assessment of patients with symptoms of thoracic outlet syndrome,

taken into account during review of cervical spine radiographs and

included in anatomy textbooks in the future.

A. Turpie T. Bandel B. Eriksson M. Gent M. Homering A. Kakkar M. Lassen F. Misselwitz T. Westermeier

Introduction: Four randomized, double-blind, phase III studies (RECORD1–4) investigated the oral, direct Factor Xa inhibitor rivaroxaban for the prevention of venous thromboembolism (VTE) after major orthopaedic surgery. Patients (N=12,729) were randomized to receive oral rivaroxaban 10 mg once daily or subcutaneous enoxaparin 40 mg once daily (RECORD1–3), or 30 mg twice daily (RECORD4). In RECORD1 and 2, patients undergoing total hip arthroplasty received rivaroxaban for 31–39 days. Enoxaparin was given for 31–39 days in RECORD1, 10–14 days followed by placebo in RECORD2. In RECORD3 and 4, patients undergoing total knee arthroplasty received prophylaxis for 10–14 days. After prophylaxis, all patients were followed up for a further 30–35 days. Rivaroxaban significantly reduced the incidence of the primary efficacy outcome for the individual studies (total VTE; composite of any deep vein thrombosis, non-fatal pulmonary embolism [PE] and all-cause mortality) compared with the enoxaparin regimens, with similar rates of major bleeding.

Methods: A pre-specified pooled analysis of all four trials was performed on all randomized patients who received at least one dose of double-blind study medication to evaluate the effect of rivaroxaban on the composite of symptomatic VTE and all-cause mortality (primary outcome for pooled analysis), and bleeding. This outcome was analysed at day 12±2 in the active treatment pool (enoxaparin-controlled in all studies) and in the total study duration pool (including follow-up after treatment).

Results: Rivaroxaban significantly reduced the incidence vs enoxaparin of the composite of symptomatic VTE and death (day 12±2: 0.47% vs 0.97%, respectively, p=0.001; total study duration: 0.81% vs 1.6%, respectively, p< 0.001) and the composite of PE and death (day 12±2: 0.19% vs 0.39%, respectively, p=0.049; total study duration: 0.47% vs 0.76%, respectively, p=0.039). The rates of major bleeding with the rivaroxaban and enoxaparin regimens were 0.34% and 0.21%, respectively, p=0.175 at day 12±2 and at total study duration were 0.44% and 0.27%, respectively, p=0.135. Rivaroxaban also reduced the composite of death, infarction, stroke, symptomatic VTE and major bleeding vs enoxaparin (total study duration: 1.6% vs 2.2%, respectively, p=0.006).

Conclusion: Rivaroxaban reduced the composites of major clinical outcomes compared with enoxaparin regimens, with similar rates of major bleeding, in patients undergoing major orthopaedic surgery.

V. Shetty

Background: The worst fear of a joint replacement surgeon is infection. Many factors are known to contribute to the development of infection in a surgical set up. Post-operative wound soakage is one of them. Wet wounds lead to repeated dressings, exposing the wound for contamination, risk of infection and increased length of hospital stay. Therefore, any measure to avoid postoperative wound problems is desirable. We wish to report our experience of the use of occlusive, sterile sanitary napkin dressings in routine total hip and knee replacement wounds.

Method: In a prospective randomized study, we compared the use of occlusive, sterile sanitary napkin dressings with standard ward gauze dressings in routine hip and knee replacement wounds. We studied 27 patients in two groups (standard dressings and sanitary napkin dressings) for the number of dressing changes required due to wound soakage. Our results showed that use of sanitary napkin dressings reduced the number of dressings, significantly, before staples removal (p= 0.0001).

Discussion: Using hydrofibre dressings have been reported to be effective in reducing the number of dressings in patients with lower limb arthroplasty. However, these dressings are expensive and require special manufacturing techniques. The use of sterile, occlusive sanitary napkin dressing in our set up has facilitated us to manage the joint replacement wounds very effectively. This method is simple, inexpensive and reduces the number of man hours and, we believe, reduces the overall cost of the treatment.

Conclusion: Convinced by the impressive performance of this dressing in joint replacement wounds, the authors recommend this method, highly, for routine primary and revision joint replacements.

P. Vavken J. Grohs A. Lunzer

Background: Postoperative thromboses are among the most feared complications in orthopedic surgery, possibly causing life-threatening conditions in otherwise highly successful procedures such as total joint replacement. Body weight is an important risk factor for thromboses and is being used in algorithms to determine dosages in prophylaxis. However, weight patterns among orthopedic populations have changed considerably since the introduction of these algorithms, essentially shifting towards obesity. This study asks whether present-day obese patients are essential under-dosed and would benefit from higher than usual dosages of bemiparin sodium in the prophylaxis of postoperative thrombosis.

Patients and Methods: To ensure sufficient power a sample of 750 patients, allocated into two cohorts receiving either 3,500 IU or 5,00o IU bemiparin sodium were followed postoperatively for 6 weeks and blindly assessed for clinically symptomatic thrombotic events. Differences in rates of thrombotic events were modeled using mulitvariate Poisson regression including potential confounders severity of immobilisation, gender, exact weight, and age as covariates. A p-value of 5% was considered significant.

Results: Information on 723 patients for a total of 66.8 person-years was analysed per intention-to-treat. The adjusted incidence rate ratio was 0.35 (95%CI: 0.03 to 2.91). Thus there was not evidence for a difference in rates between groups. There was, however, a borderline significant association between rates and body weight, suggesting a potential benefit of higher dosages in even heavier patients. There were no complications due to higher dosages of bemiparin sodium.

Conclusion: We did not see a significant reduction of incidence rates of thromboses with higher dosages of bemiparin in this population. However, there was some evidence that higher dosages might prove beneficial as populations further gain weight.

B. Vingerhoeds D. Fick R. Middleton C. Olyslaegers T. Wainwright

Summary: This study of 1000 patients demonstrates how you can dramatically reduce hospital length of stay, improve clinical outcomes, and increase patient satisfaction if a patient-centred pathway approach is adopted.

Introduction: This study evaluates the effect of adopting a patient-centred approach on clinical outcomes, patient satisfaction and operational efficiency. By adopting standardised working practices, dramatic changes can be achieved to reduce patient length of stay (LOS) and consequently surgical capacity.

Methods: We prospectively studied the first 1000 patients who followed the new pathway (549 Total Knee Replacements, 20 Unicondylar Knee Replacements, 384 Total Hip Replacements and 47 Hip resurfacings). The pathway included an enhanced pre-assessment process. Admission dates were mutually agreed and a predicted discharge date of 4 days was provided. All patients attended a pre-operative education session. Patients were admitted on the day of surgery and followed an intensive physiotherapy program. The surgeons, surgical techniques, and discharge criteria all remained unchanged.

Results: The average length of stay was 4.1 days (St Dev 1.8). 80% of patients went home on or before day 4 post-operatively. This was accompanied by a decreased re-admission rate (1.8%), low complication rates for both hip replacement (Dislocation rate = 0.93%) and knee replacement (Knee MUA = 0.87%) and no cases of deep infection. Pre-operative patient reported outcome measures (WOMAC, SF-12 and Oxford) all improved post-operatively (P< 0.0001) and qualitative data from patients was extremely positive towards the new pathway.

Discussion: The decrease in LOS was dramatic and highly clinically significant. The mean LOS for patients prior to commencing this new pathway was 7.5 days (St Dev 5.7). High patient satisfaction rates indicate that by adopting a patient-centred approach, significant decreases to LOS can be achieved alongside improving the quality of care with a low complication and readmission rate.

R. Walls G. Mchugh N. Moyna J. O’Byrne

Introduction: After total knee arthroplasty (TKA) patients develop marked asymmetrical quadriceps femoris (QFM) weakness due to neurological activation deficits and muscle atrophy; this is associated with a slow (type I) to fast (type II) shift in myosin heavy chain (MHC) expression. Preoperative resistance training (prehabilitation) has been shown to improve strength and function after TKA however is considered costly and labour intensive. Neuromuscular electrical stimulation (NMES) offers the potential for unsupervised training, although its role in prehabilitation has not been investigated.

Aims: Determine changes in myosin heavy chain (MHC) mRNA expression following preoperative NMES.

Evaluate the ability of NMES prehabilitation to improve strength and functional recovery post-TKA.

Methods: Randomised control efficacy study applying NMES to the affected QFM for 20 min, 5 days/week, for 8 weeks pre-TKA. Isometric QFM strength was determined dynametrically and muscle cross-sectional area (CSA) calculated from MRI axial images. Function was assessed with a walk test, stair-climb test, and chair-rise test. Real-time PCR analysed MHC mRNA expression. All evaluations were performed at baseline and preoperatively with strength, CSA and function also tested at 6 and 12 weeks post-TKA.

Results: Patients scheduled for TKA were recruited and randomised into control (n=9) or NMES (n=5) groups. Only the NMES group increased strength (27.8%; p=0.05) and CSA (7.4%; p=0.013) preoperatively. MHC type II mRNA decreased by 42% (p=0.078) indicating a fast to slow fibre shift. Function also improved in the NMES group (stair climb [p=0.006]; chair rise [p=0.018]). While all patients deteriorated after surgery, only the NMES group had notable strength gain from 6 to 12 weeks (53%; p=0.011) with associated functional recovery (stair-climb, p=0.017; chair-rise, p=0.01; walking speed, p=0.014). There were differences seen between the groups at 3 months post-TKA: stair climb (61.6%, p=0.04) and chair rise (28.4%, p=0.013). There was greater muscle atrophy seen in the controls than the NMES group post-TKA when compared to baseline (12.1% [p=0.034] versus 3.7% [ns]).

Conclusions: This study has shown that 8 weeks preoperative quadriceps strengthening using home-based NMES can safely and effectively attenuate the extent and duration of QFM weakness and atrophy after primary TKA. This translates into significantly faster functional recovery thereby expediting a return to normal activities.

M. Widemschek T. Benesch R. Germann A. Martin G. Pfanner A. Von Strempel

Background: In the literature are different data about the allogenic blood transfusion rate after total knee replacement. The common intention in orthopedic surgery is to reduce the requirement for allogenic blood transfusions by optimizing the blood management. The aim of this study is to determine the efficacy of the mechanical autotransfusion system OrthoPAT (Haemonetics Corp., MA, USA) to reduce the postoperative allogenic blood transfusion rate.

Method: According to the preliminary performed power analysis we did a prospective controlled study including 104 patients which were randomized in a group A (OrthoPAT for intra- and postoperative blood salvage and retransfusion, n = 52 patients) and a control group B (no retransfusion system was used, n = 52 patients) All patients had a primary osteoarthritis of the knee and were operated on without use of a tourniquet. We implanted in all patients a cemented posterior stabilized total knee prosthesis design (LPS-Flex Mobile, Zimmer, IN, USA). In group A the autotransfusion system was used for 6 hours (intra- and postoperatively) and the collected blood was retransfused. The retransfused blood is anticoagulanted, filtered and centrifuged to separate waste products. Red cells are washed with saline and reconcentrated to a high haematocrit. The preoperative data for cardiopathy, angiopathy, preoperative anemia or anticoagulant treatment showed no significant differences for group A and B. Because of missing data we finally were able to use the results of 98 patients: 48 group A and 50 in group B. The indications for a blood transfusion were influenced by the clinical symptoms of anemia, the hemoglobin value (hemoglobin < 8.0 g/dl) and the anamnesis of cardiovascular diseases. Evaluation was done with the medical history and the pre-/postoperative hemoglobin values, postoperative blood loss and postoperative need of allogenic blood transfusion.

Results: The two groups showed no significant differences relating to the demographic data or the medical history. 16 patients (33 %) of the retransfusion group who in mean received 281 ml of salvaged blood needed allogenic blood transfusion compared with 22 patients (44 %) of the control group B (p = 0,306). The hemoglobin values of group A versus the control group showed after the donation of the salvaged blood a significant difference (p = 0,027) but no longer at the 3rd and 5th day postoperative.

Conclusions: The use of the autotransfusion system seems to reduce the postoperative allogenic blood transfusion rate but not statistical significant. At the 3rd and 5th day postoperatively no significant differences of the hemoglobin values could be stated comparing group A with group B. For us this was a clue showing that the quality of the erythrocytes after the reclamation was reduced.

T. Zweig M. Aebi E. Aghayev S. Domanja M. Melloh C. Röder L. Staub

Introduction: Dural tears are one of the most frequent type of complication in posterior spinal fusion with little known about their predictors.

Method: Prospective consecutive study with an evidence level 2++ of 42 patients in the international spine registry Spine Tango, who had been treated between 05/2005 and 8/2008 with posterior spinal fusion after opening of the spinal canal. Median age was 62.7 yrs (min 12.5, max 90.5 yrs) with a female to male ratio of 2:1. In 42 of 1575 cases a dural tear occurred being the most frequent type of complication in our study sample. Multiple linear regression was performed on potential predictor-variables of the occurrence of dural tears.

Results: Hospital (p=0.02) and number of segments of fusion (p=0.018) were found to be predictors of the occurrence of dural tears in posterior spinal fusion. Number of fusions per hospital (min 25, max 526) and academic status of hospital had no influence on the rate of dural tears. Fusions of four and more segments showed an increase of the rate of dural tears by three compared to fusions of less than four segments.

Conclusion: Predictors of dural tears in posterior spinal fusion are hospital, independent of number of spinal surgeries and academic status of hospital, and number of segments of fusion. In fusions of four and more segments a threefold higher risk of dural tears in comparison to fusions of less than four segments should be taken into consideration.

A. Barnett J. Eldridge V. Mandalia M. Prentice C. Wakeley

A number of measurements of patellar height are in clinical use all of which reference from the tibia. The patellotrochlear index has been proposed recently as a more accurate reflection of the functional height of the patella and described in normal knees.

We compared patellar height measurements in patients with patellofemoral dysplasia.

In a retrospective analysis of the MRI scans of 33 knees in 29 patients with patellofemoral dysplasia we assessed the inter- and intraobserver reliability of four patellar height measurements: the recently described Patellotrochlear Index (PTI), Insall-Salvati (IS), Blackburne-Peel (BP) and Caton-Deschamps (CD) ratios. We also assessed the correlation between the different measurements in predicting patella alta. Three blinded observers on two separate occasions performed the measurements.

There were 21 females and 8 males with a mean age of 21.4 years (13–33).

Statistical analysis revealed good inter-observer reliability for all measurements (0.78 for PTI, 0.78 for IS, 0.73 for BP and 0.77 for CD). Intra-observer reliability was also good (0.80, 0.83, 0.75, 0.78 respectively). There was weak correlation between the PTI and the other ratios for patella alta. There was a strong correlation between the CD and BP ratios (0.96) and a moderate correlation between IS and CD and IS and BP ratios (0.594 and 0.539 respectively).

We propose the PTI as a more clinically relevant measure.

L. Bayliss T. Briggs K. De Silva P. Gikas M. Parratt

Introduction: Initial results for the management of osteochondral defects with both ACI-C and MACI have been encouraging, showing significant clinical improvements. This study set out to report the functional, clinical and histological outcomes in our institution following nine years experience of cartilage-cell transplants.

Aim: Reporting results of nine-year experience of clinical and arthroscopic assessment in the use of ACI and five year experience of MACI in the management of symptomatic, full-thickness chondral and osteochondral defects in the knee.

Method: Following preoperative functional assessments, arthroscopic harvesting of chondrocytes for culture was performed and patients underwent ACI-C or MACI. In ACI-C a covered technique is employed using a porcine-derived type I/III collagen membrane sutured in place; MACI requires cultured autologous chondrocytes to be seeded in a bi-layered type I/III collagen membrane which is glued into position. An arthroscopy was performed between 12 and 24 months post-procedure to assess graft coverage and biopsies taken to determine extent of hyaline, mixed and fibro-cartilage proliferation.

Results: 354 patients underwent either ACI-C (103) or MACI (251) with an average age of 31.3 (15–54). Cincinnati knee rating scores recorded prior to assessment arthroscopy for ACI-C: 58.6 (12 – 92) and MACI: 48.4 (11 – 90) showed improvement at follow up with means of 84.0 for ACI-C, with 78% of patients scoring good or excellent at nine years, and a mean of 82.3% in the MACI group at five years, with 87% of patients recording good or excellent scores; statistically significant improvement was also noted in Bentley Functional score. Biopsies of the transplants taken between 12 and 24 months revealed proliferation of hyaline and mixed cartilage (hyaline and fibro-cartilage) in 47% patients; the later the biopsy was taken post-implantation, it was more likely to reveal hyaline tissue.

Conclusion: Results to date suggest significant clinical and arthroscopic improvement following ACI-C and MACI, with evidence of proliferation of hyaline cartilage at the transplant site and evidence to suggest dynamic improvement in hyaline-nature of cartilage. Limited differences are noted between the outcomes of the two techniques.

E. Witso A. Lium S. Lydersen

Introduction: We have previously reported on an incidence of diabetic amputations of 4, 4 per 1.000 diabetic subjects per year in the city of Trondheim, Norway, 1994–1997. As a consequence of that study, Trondheim Diabetic Foot Team was established January 1st 1996. The Diabetic Foot Team has been an integrated part of the Outpatient clinic, Department of Orthopaedic Surgery, St. Olavs University Hospital. We report on the incidence of diabetic amputations ten years later (2004–2007).

Material and Methods: The University Hospital is the only hospital in Trondheim, and all amputations are performed at the Department of Orthopaedic Surgery. In 2004–2007 we registered consecutively all diabetic amputations. During the two study periods, 1994–1997 and 2004–2007, the population of Trondheim was 143.300 and 159.000 inhabitants, respectively. The total number of diabetic subjects in Trondheim during the two study periods was 3.600 and 4.600, respectively.

Changes in incidence rates were analyzed using Poisson regression with decade as covariate. Two sided p-values < 0.05 were considered significant. Analyses were performed in State version10.0.

Results: During the decade the number of diabetic amputations/1000 diabetics/year decreased 40 percent from 4, 4 to 2, 8 (p= 0.04). In the same period, 779 patients with diabetes were screened at the Diabetic Foot Team, and 5915 consultations due to diabetic foot problems were performed. From 1996 to 2006 the number of invasive and non-invasive vascular intervention per year in patients with diabetes living in Trondheim did not change.

Discussion: Although other factors may be involved, we attribute the decrease in the incidence of diabetic amputations to the activity of the Diabetic Foot Team. Every department of orthopaedic surgery should make priority to the implementation of a multidisciplinary program for prevention and treatment of diabetic foot ulcers.

A. Angoules K. Balakatounis E. Drakoulakis K. Karzis I. Michos P. Papagelopoulos

Purpose: To evaluate knee proprioception following Anterior Cruciate Ligament (ACL) reconstruction using two different autografts.

Materials and methods: Forty patients, (34 male, 6 female), aged between 17–54 years old (mean: 31), with complete ACL tears were subjected to ligamentous reconstruction. Group A (20 patients) underwent reconstruction with 4 strand hamstrings graft whilst in the remaining 20 patients (group B) bone-patellar tendon-bone graft was used. Proprioception was assessed by the Joint Position Sense (JPS) of the knee for predetermined angles (15°, 45° and 75°) as well as by the threshold to detection of passive movement (TTDPM) at 15° and 45° in flexion and extension using an isokinetic dynamometer (Con-Trex, MJ, Switzerland). The examination was performed pre-operatively and 3, 6 and 12 months after surgery, on both knees of all patients.

The t-test was utilised for statistical analysis.

Results: ACL deficient knees presented with significantly poor TTDPM values at a starting angle of 15° moving into flexion and extension. The JPS findings were statistically different between injured and uninjured knees (p< 0.05).

The TTDPM at 15° and JPS findings of the injured leg, before and 6, 12 months after reconstructive surgery, were statistically different (p< 0.05) for both groups.

There was no statistically significant difference for both JPS and TTDPM at 15° in flexion and extension between the findings in reconstructed and uninjured knees, at 6 and 12 months post-operatively in both groups.

No difference was found when comparing proprioceptive improvement following ACL reconstruction between the two different autograft groups.

Conclusions: Both JPS at 15°, 45°, and 75° and TTDPM at 15° in flexion and extension are impaired in ACL deficient knees. There is improvement of these proprioceptive parameters following operative reconstruction of the ACL using both hamstrings and patellar tendon grafts. No particular graft seems to be preferable in terms of proprioceptive improvement as assessed by JPS and TTDPM.

V. Wylde A. Blom P. Dieppe S. Hewlett I. Learmonth

Introduction: Joint replacement has a low mortality rate, few adverse occurrences, excellent survivorship and is considered a cost-effective intervention to reduce disability in the community. However, the assessment of complications and survivorship fail to measure the success of joint replacement in achieving pain relief and restoration of functional ability. The aim of this large cross-sectional postal survey was to provide information on the prevalence of pain, disability, poor quality of life and patient dissatisfaction at 1–3 years after a range of lower limb orthopaedic surgeries in the UK.

Patient and Methods: A questionnaire was posted to all 3,125 consecutive alive patients who underwent a primary THR, hip resurfacing, TKR, UKR or patellar resurfacing at the Avon Orthopaedic Centre between January 2004 – April 2006. The questionnaire included the WOMAC, HOOS/KOOS quality of life scale and a validated satisfaction scale. All questionnaires are scored on a 0–100 scale (worst-best) and a poor outcome was defined as a score of ≤ 50 on the outcome measure.

Results: Completed questionnaires were received from 2,085 patients (response rate of 67%). Patients had a mean age of 67 years and 42% were male. The mean length of follow-up was 28 months (range 14–44 months). 911 patients had a THR, 157 patients had a hip resurfacing, 866 patients had a TKR, 100 patients had a UKR and 51 patients had a patellar resurfacing.

Pain: the prevalence of poor outcomes were 6% of patients with a THR, 4% with a hip resurfacing, 12% with a TKR, 9% with a UKR and 31% with a patellar resurfacing.

Function: the prevalence of poor outcomes were 12% of patients with a THR, 4% with a hip resurfacing, 16% with a TKR, 9% with a UKR and 35% with a patellar resurfacing.

Hip-related quality of life: the prevalence of poor outcomes were 26% of patients with a THR, 12% with a hip resurfacing, 33% with a TKR, 32% with a UKR and 67% with a patellar resurfacing.

Satisfaction: the prevalence of poor outcomes were 13% of patients with a THR, 8% with a hip resurfacing, 17% with a TKR, 11% with a UKR and 45% with a patellar resurfacing.

Conclusion: This survey has provided descriptive data on the prevalence of patient-reported levels of pain, disability, poor joint-related quality of life and dissatisfaction after lower limb arthroplasty. It is important that patient-reported outcomes after joint replacement are rigorously assessed in order to provide information on which patients do poorly after surgery, with the aim of targeting these patients with an intervention to improve their outcome.

North Bristol Trust Small Grants Scheme provided funding for the consumables for this study.

M. Bohnsack F. Almqvist J. Bellemans F. Luyten D. Saris J. Vanlauwe R. Verdonk J. Victor

Purpose: A three-year evaluation of long-term clinical efficacy of Characterized Chondrocyte Implantation (CCI) compared to microfracture (MF), in the repair of symptomatic cartilage defects of the femoral condyles at 36 months post-surgery.

Materials and Methods: In a prospective, randomized, controlled, multicenter trial, CCI was compared to MF in patients aged 18–50 years with a single symptomatic ICRS grade III–IV lesion of the knee. Clinical outcome was measured 36 months after surgery by means of the KOOS, VAS for pain and ARS, with a non-inferiority margin preset at 9 % points for KOOS and VAS. Furthermore, response to treatment and progression of knee symptoms were assessed. Treatment failure was monitored throughout the study.

Results: Improvement from baseline was higher in the CCI group (N = 41) compared to the MF group (N = 49) for all clinical outcome parameters. Mean improvement from baseline for Overall KOOS was 22.14 vs. 14.48, respectively, with VAS and ARS scores revealing a similar trend. Responder analysis showed 83% of the patients treated with CCI improving vs. 61% after MF. Additionally, we observed a shift in the proportion of knee symptoms over time (52% vs. 35% of asymptomatic knees at 36 months compared to 2% vs. 8% at baseline in the CCI and MF group respectively). At 36 months, failure rates were low in both groups (n=2 in CCI vs. n=7 in MF).

Conclusions: Previous data have described a superior structural repair after CCI compared to MF at 1 year post-surgery. Continued clinical improvement as well as a favorable responder analysis was demonstrated for CCI compared to MF at 36 months.

S. Bignozzi M. Lo Presti N. Lopomo M. Marcacci S. Zaffagnini

Introduction: Anterior Cruciate Ligament (ACL) is primary constrain to anterior displacement of tibia with respect to the femur and secondary to internal/external (IE) and varus/valgus (VV) rotations; an ACL reconstruction should thus control not only AP but also IE and VV laxities. For this reasons, more attention has given to residual rotational instability. This study aims to verify if those subjects with high of pre-op knee laxities has also high post-op laxity after an ACL reconstruction.

Material and Methods: The study includes 115 patients, that underwent ACL reconstructions between January 2005 and September 2007. Patients with associated severe ligaments tears or severe chondral defects were excluded. The joint passive kinematics was intra-operatively assessed using the BLU-IGS system (Orthokey, Delaware). We evaluated, before and after the reconstruction, the manual maximum IE rotation at 30° and 90° of flexion, VV rotation at 0° and 30° of flexion and AP displacement at 30° and 90° of flexion. We used the k-means algorithm applied to pre-op values to create two groups among the patients: the GROUP H, with higher pre-op laxity and the GROUP L, with lower pre-op laxity. The pre-op groups were compared for each test using independent Student’s t-test (p=0.01) in order to assess their difference. Student’s t-test (p=0.01) was performed on the corresponding post-op values in order to verify if the difference between H and L was maintained after the reconstruction.

Results: Mean pre-op VV at 0° was 7.1±0.9° for group H and 4.7±0.8° for group L (p< 0.01), post-op was 3.2±0.8° for group H and 2.5±0.8° for group L (p< 0.01). Mean pre-op VV at 30° was 6.2±1.5° for group H and 3.4±0.7° for group L (p< 0.01), post-op was 3.4±1.3° for group H and 2.2± 0.9° for group L (p< 0.01). Mean pre-op IE at 30° was 28.3±3.5° for group H and 19.2±3.1° for group L (p< 0.01), post-op was 21.5±3.8° for group H and 14.7±3.7° for group L (p< 0.01). Mean pre-op IE at 90° was 31.3±2.8° for group H and 22.4±3.5° for group L (p< 0.01), post-op was 22.3±4.0° for group H and 17.0±4.4° for group L (p< 0.01). Mean pre-op AP at 30° was 14.5±2.1mm for group H and 8.9±1.6mm for group L (p< 0.01), post-op was 6.2±1.6mm for group H and 4.2±1.6mm for group L (p< 0.01). Mean pre-op AP at 90° was 11.2±1.7mm for group H and 6.7±1.4mm for group L (p< 0.01), post-op was 5.4±1.8mm for group H and 3.4±1.3mm for group L (p< 0.01).

Discussion: The comparison between group H and group L showed that those patients with higher pre-op laxity had maintained higher post-op values mainly for all the tests. This finding is probably correlated to the possible presence of different tears affecting soft structures of the joint and to the proper and specific anatomy of each patient.

D. Bruni G. Giordano M. Marcacci G. Marcheggiani Muccioli A. Russo S. Zaffagnini

We performed a clinical, instrumental and radiographic study on a highly homogeneous series of 100 consecutive patients with unilateral ACL lesion at 7 years of minimum follow up, alternatively assigned to a single bundle reconstruction using patellar tendon (PT) or to a double bundle reconstruction using hamstrings (DB). Mean Tegner score was 4,8 for PT and 6,5 for DB (p=0,0005). Time for sport resumption was 6,6 months for PT and 3,8 months for DB (p=0,0052). There were no significative differences between the two groups regarding range of motion and functional subjective self-evaluation. Mean anterior displacement at instrumental evaluation performed with KT2000 showed no significative differences between the two groups. Objective clinical evaluation with IKDC was superior for DB group (A=86,5%; B=13,5%) respect to PT group (A=18,7%; B=75%; C=6,3%) (p< 0,0001). We found no differences regarding anterior knee pain between and Ahlback radiographic score the two groups and we have observed no recurrence of instability after surgical treatment. Double bundle ACL reconstruction with hamstrings has showed higher results respect to single bundle ACL reconstruction with patellar tendon in terms of Tegner score, IKDC, time for sport resumption.

L. Canata Gian L. Canata Gian

The conservative treatment of ACL lesions in the adolescent is unfavourable in the long term risking precocious joint deterioration. Nevertheless, literature does not agree on the timing and on the best type of surgery in this age group. The results of ACL repairs with the open technique are evaluated negatively. We present a retrospective evaluation of a case history of adolescents surgically treated with ACL reconstruction with patellar tendon or with arthroscopic reinsertion of the ACL in the case of proximal lesions and of good quality ligamentous tissue.

Materials and methods: From 1990 to 2006, adolescents under 18 were surgically treated for instability as a consequence of ACL rupture. 75 of these were evaluated retrospectively and divided into two groups: 59 cases, mean age 16 years (13–17), 28 males and 31 females were treated with patellar tendon, Group A. 16 cases, mean age 14 years (11–17), 8 males and 8 females, were treated with arthroscopic repair of the ACL (mean time between lesion and surgery 24 days, 2–200, Group B. Mean follow up 120 months (18–204). The evaluation of the results was carried out using the IKDC 2000 score. In all cases a clinical, radiographic and MRI evaluation was performed.

Results: Group A: 50 A, 5 B, 4 C. Group B: 14 A, 1 B, 1 C. Subjective IKDC: Group A mean 97 (80–100). Group B mean 99 (81–100).

Conclusions: The high percentage of good or excellent results (93%) confirms the possibility of a complete functional recovery, after the lesion of the ACL in the adolescent, with surgery. The use of the patellar tendon for the repair does not result as having compromised the functionality of the extensor apparatus. Excellent results are possible both with patellar tendon and with ACL reinsertion in the case of proximal lesions and of a good quality of the ligament. Reinsertion with the arthroscopic technique results efficacious in a high percentage of subjects. Above all, it is indicated when the young biological age of the patient could mean postponing reconstructive surgery with the risk of secondary lesions and of successive unsatisfactory results.

P. Boisrenoult P. Beaufils A. Bouchard O. Charrois P. Hardy P. Neyret N. Pujol H. Robert E. Servien

Introduction: Lateral meniscectomies lead to degenerative arthritis and therefore meniscus transplantation has been considered. In literature, this procedure appears to have good clinical results. The aim of this study was to evaluate our clinical results at mid-term follow-up and to correlate these results to the morphology and position of the transplanted meniscus.

Material and methods: Twenty-eight patients operated in 4 surgical centers, were retrospectively reviewed following lateral meniscal allograft transplantation. The mean age of the patients was 34 years (range, 18 to 50 years). Before surgery, all these patients suffered of permanent lateral femorotibial pain without radiological knee arthritis. The knees were all stable or stabilized, without axial malalignment of the lower limbs or corrected by a concomitant high tibial osteotomy. Arthroscopic procedure was performed for 9 patients and arthrotomy for 19 patients. Different techniques of fixation of the transplant were used, with or without bone plugs. The associated procedures were 2 ACL reconstruction, 3 high tibial varus osteotomies, and 1 mosaicplasty. The IKDC score were used for the analysis of the functional results. An arthroTDM or an arthro MRI was used to analyse the morphology and position of the transplanted meniscus.

Results: The mean follow-up was 35 months (range, 12 months to 6 years). The mean post-operative subjective IKDC score was 65.5 points (range, 19.5 to 89 points). There were 2 failures associated with a fast arthritic evolution and 2 functional bad results. The others 24 patients (85%) were satisfied or very satisfied, with a real improvement of the pain and the function. Seventeen patients (60%) have started again a sportive activity superior than the one pre-operating. At the last follow-up, all transplanted meniscus have healed, but the morphology and position of the transplanted meniscus was not always normal with absence of the middle segment in 3 cases; its extrusion in 9 cases, a posterior segment shortened or partially hurt in 5 cases and its absence in 3 cases. Better results were associated with good meniscus positioning and morphology.

Discussion: Our works confirm that lateral meniscal allograft is a therapeutic option with favourable results in terms of pain reduction and functional improvement in the medium term for symptomatic patients after lateral meniscectomy. Our results are comparable with those of the literature. The allograft is technically reliable, reproducible notably for the methods of fixation. A long term follow-up is necessary to evaluate the benefit of these grafts on the protection of the cartilage.

M. El-Husseiny F. Haddad A. Potty F. Rayan

Background: Medial plica syndrome is the most common symptomatic plica. The size and shape of the plica have an important impact on impingement on the femoral condyle and hence, symptoms. The validity of the classification systems of such injuries is essential for prospective studies. The study was designed to assess the reproducibility and reliability of Iino and Jee classification systems of medial plica syndrome. The agreement among multiple surgeons for medial plica syndrome has not been established before.

Methods: We validated both classification systems independently from the original authors at our institution. Arthroscopic videos from 30 patients were reviewed by 6 consultant surgeons, 6 registrars and 6 house officers. Intra- and inter-observer reliability and reproducibility were assessed. Each observer scored the videos on two separate occasions and classified the medial plica according to its type (A, B, C and D) for Iino classification and (1, 2, 3 and 4) for Jee classification system.

Results: The results were subjected to weighted kappa analysis. Intra-observer agreements were 0.76 for consultants, 0.64 for registrars and 0.60 for house officers for Iino classification system. They were 0.81 for consultants, 0.75 for registrars and 0.71 for house officers for Jee classification system. Total unanimity (18 observers assigned same grade for medial plica) was achieved in 23% (7 of 30) with Iino system and 40%(12 of 30) for Jee system. Inter-observer agreement was 0.63 for the first reading and 0.68 for the second reading for Iino system. They were 0.72 for the first reading and 0.80 for the second reading for Jee system. Validity analysis showed a kappa value of 0.78 (substantial agreement).

Conclusions: Jee classification system showed a better inter and intra-observer agreement compared to Iino’s system. Consultants had a better intra-observer agreement compared to their registrars. We have shown that substantial agreement can be found between individuals with no specialist training. Such reliability is crucial for multi-centre clinical research studies involving arthroscopic knee surgery. Jee’s classification system did not consider femoral condyle impingment which has an important effect on symptoms. Both systems should be used in prospective studies to evaluate the state of the medial plica.

L. Carrera-Calderer E. Diaz-Ferreiro N. Joshi J. Nardi-Vilardaga

Purpose: Our purpose was to study the 10-year results of a proximal soft-tissue procedure combined with a Lateral Patellar Facetectomy technique for an isolated osteoarthritis of patellofemoral joint.

Methods: The study group included 39 knees (30 patients). There were 19 female and 11 male patients. Mean age 52 years old (range 40–65). All patients were evaluated at a mean follow-up of 10 years. The indications for surgery were instability of patellofemoral joint with isolated arthritis. Patient outcome scores, patient demographics, and data from a physical examination, x-Ray and TC were collected before and after surgery. A release of the lateral patellofemoral ligament and a retinacular release were performed, leaving the synovial tissue intact to isolate the joint. The lower fibers of the vastus lateralis were released as well, and the release was carried down to the level of the tubercle. Medially, an imbrication of the medial retinacular tissue from the medial aspect of the quadriceps tendon to the proximal aspect of the tibial tubercle, as Insall described, was performed.

Results: At final follow-up, the results were excellent or good in 89% of the knees, fair in 7%, and poor in 3%. Subjective improvement was reported by 90% of patients. Follow-up radiographs showed slow progression of osteoarthritis in the patellofemoral and tibiofemoral compartments, but radiographic appearance did not always correlate with clinical symptoms. The success of this procedure depends largely on relief of pain.

Conclusions: proximal soft-tissue realignment combined with a Lateral Patellar Facetectomy for a severe isolated osteoarthritis of patellofemoral joint is a powerful way to correct malalignment and offload the lateral and distal parts of the patella. This technique relief pain and improved the activity level. Is an effective surgical treatment for middle-aged to elderly active patients with isolated lateral patellofemoral osteoarthritis who want to maintain activity level.

J. Dargel J. Koebke K. Mader D. Pennig R. Schmidt-Wiethoff T. Schneider

Introduction: Drilling of the femoral bone tunnel in anterior cruciate ligament reconstruction may be performed in a transtibial drilling technique or via the anteromedial portal.

Purpose: To determine the accuracy of the radiographic bone tunnel position using either a transtibial or anteromedial drilling technique.

Materials & methods: The postoperative lateral radiographs of 100 patients after anterior cruciate ligament reconstruction were reviewed. In each patient, the femoral bone tunnel was created either through the tibial tunnel or via the anteromedial standard arthroscopy portal. The resulting position of the femoral tunnel was evaluated according to reference values reported by Aglietti (65 % of the cortical femoral A-P distance along Blumenstaat’s line), Amis (60 % of the A-P diameter of the posterior lateral femoral condyle parallel to Blumensaat’s line), and Harner (80 % of the A-P length of Blumensaat’s line). The mean deviation of the radiographic tunnel position from the referenced values was statistically evaluated.

Results: Radiographic bone tunnel positions with transtibial drilling were 62.42 ± 8.36, %, 54.53 ± 8.43 %, and 75.84 ± 9.56 % according to Aglietti, Amis, and Harner, respectively. Bone tunnel positions with anteromedial drilling were 65.46 ± 5.29 %, 59.59 ± 4.18 %, and 79.93 ± 4.24 %, respectively. The mean deviation from the reference values was significantly higher when comparing transtibial to anteromedial drilling. Transtibial drilling resulted in a significantly more anterior bone tunnel position.

Conclusion: Precise bone tunnel placement is a prerequisite for proper postoperative knee function and stability. The results of this study indicate that the accuracy of femoral bone tunnel placement through the anteromedial arthroscopy portal was superior to transtibial drilling. It may therefrore be concluded that drilling the femoral tunnel through the anteromedial portal is recommended when using fixation techniques not depending upon placement of a transtibial guide.

A. Fechner G. Godolias O. Meyer

Ouery: Matrix-coupled autologous chondrocyte transplantation (MACT) has become increasingly widespread in the therapy of cartilage defects. The objective of this controlled prospective study was to examine the mid-term results of MACT compared to those of Microfracturing (MF) for the treatment of cartilage defects in the knee joint and to determine possible advantages or disadvantages of the two methods.

Method: In order to compare the two treatment methods, 40 patients with discrete cartilage defects were treated with MACT and 40 with MF between 4/01 – 4/03. As inclusion criterion, the patients had a chondral defect of at least 1.5 cm and as exclusion criterion, there could be no additional cartilage damage in the other areas of the knee. MRI examinations were performed preoperative (T2 gew. TSE-Sequence, fetts. FLASH-3D) and could be repeated after 6 and 12 months. Knee joint function, the activity level and the patient’s quality of life were evaluated in both groups pre- and postoperative using the modified Cincinnati Score and the Tegner Activity Index.

Results: There was significant improvement in the scores used for the study in both the MF group and the MACT group. Comparison of the two groups revealed significantly greater clinical improvement in the MACT patients than in the MF patients (3.8 point increase MACT versus 2.6 point increase MF in the Cincinnati Score). Taking the size extent of the treated cartilage damage into account, there was, however, no relevant difference in defects less than 2,5 qcm.

Conclusion: The study could demonstrate that both methods are successful in treating localized cartilage damage in the knee joint. Comparison of the two forms of therapy showed a greater extent of improvement in the MACT group. However, classification by the size of the defect revealed that this effect was relevant only in larger defects, so that the size of the defect should be a decisive criterion for the selection of therapy.

T. Gunes B. Bostan M. Erdem D. Koseoglu Resid A. Sahin Seyyid C. Sen

Coblation is supposed to enhance healing due to increasing vascularity in the degenerated tendon. In the present study the effect of coblation treatment on tendon degeneration was investigated.

A total of 32 New Zealand rabbit were enrolled in the current study. Experimental degeneration was performed by injecting prostaglandin E1 (PGE1) to bilateral achilles tendons of rabbits. Four rabbits were excluded by different reasons. Coblation and control groups were composed of 12 rabbits in each. Coblation device only touched to tendon in the control group whereas in the coblation group coblation treatment was performed through 2 cm segment to form grids with 0.5 mm apart with level four energy lasted for 500 ms. 6 rabbits in control and coblation groups were sacrificed in 6th and 12th weeks. Achilles tendons were evaluated histopathologically by modified Movin scale and immunohistopathologic examination was performed using vascular endothelial growth factor (VEGF) and type 4 collagen.

After injection of PGE1, findings similiar to chronic tendinosis were revealed. Coblation group revealed significant increment in vascularity with histopathological and immunohistochemical examination. However difference regarding healing of tendon degeneration was not significant between control and coblation group.

Coblation treatment increases vascularity in degenerated tendon, but doesn’t increase healing process.

W. Huysse P. Verdonk R. Verdonk

Introduction: Partial and total meniscectomy has been shown to result in cartilage degeneration and osteoarthritis in the long term. Thus, research efforts have focused on tissue regeneration following meniscectomy. A novel device has recently been developed which, when implanted in the meniscus, provides a three-dimensional honeycombed matrix for vascular ingrowth and tissue regeneration to replace lost meniscus tissue. To evaluate this vascular ingrowth and tissue regeneration a Dynamic contrast-enhanced MRI non invasive technique was used.

Methods: A prospective, non-randomised, single-arm, multi-centre, clinical investigation was conducted in 52 patients with an irreparable medial or lateral meniscal tear or partial meniscus loss, with intact rim. Patients were required to have a stable knee joint or be a candidate for knee joint stabilization within 12 weeks of the index procedure, have an International Cartilage Repair Society (ICRS) classification of Grade I or II, and have undergone no more than 3 previous surgeries on the index knee. Following implantation of the novel scaffold, dynamic contrast-enhanced magnetic resonance imaging (DCMRI) using intravenous gadolinium contrast material was performed at 1 week, and at 3 and 12 months post-implantation. Because the scaffold and normal meniscus tissue lack vascularity, the presence of signal enhancement in the device is an appropriate surrogate for the ingrowth of blood vessels and native tissue into the scaffold. All scans were assessed for neovascularization in the scaffold meniscus and integration of the implanted device. To date DCMRI scans at 3 months are available for 48 of the 52 patients. Full data for all available patients will be presented.

Results: Using this non-invasive technique evaluable DCMRI data at 3 months were obtained for 42 of the 48 patients (87.5%), showing vascularity, and therefore the presence of tissue, in 35 of the 48 (72.9%) patients. No enhancement (vascularity) was demonstrated in 6 of the 48 (12.5%) patients.

Conclusions: At 3 months post-implantation, vascularization, and therefore tissue ingrowth, was demonstrated using DCMRI in the vast majority of patients treated with the novel meniscus scaffold.

M. Honl T. Plytwana J. Williams M. Wimmer

Introduction: Autologous osteochondral transfer is an option for the treatment of articular defects. However, there are concerns about graft integration and the nature of the tissue forming the cartilage-cartilage interface. Chondrocyte viability at graft and recipient edges is stated to be an important determinant of the success of repair.

As a tool, water jet (WJ) provides a cold cutting process. The cut is performed using water under high pressure (potential energy) by transforming it into water with high velocity (kinetic energy) using a nozzle.

This study evaluates the feasibility of performing selective cutting on the cortical bone and articular cartilage tissue by the use of plain water jetting.

Materials and Methods: Fresh full thickness cartilage explants were obtained from the stifle joints of 5 young calves (6–8 months old). Full thickness cartilage explants were removed from the femoral condyles using a scalpel. A specially designed water jet system was used for the study. The intensifier pump allowed pressure variations between 100–700 bars. The nozzle (Ø=0.2mm) was mounted on a gantry with two degrees of freedom. The cutting experiments were performed in displacement control mode, with cartilage held stationary and the nozzle moving at a traverse speed of 1mm/s. To calculate the energy typically required for consistent material removal, 40 cartilage samples were cut at various pressure levels using the water jet. Depths of the cut were measured by a Vernier caliper.

Multi- and one-way analyses of variance were computed with cutting depth as dependent variable.

In the second part of the study osteochondral cylinders were obtained from the femoral condyles using:

8 mm diameter Arthrex OATS punch,

8 mm diameter diamond coated drill punch and

the water jet cutting device.

Plugs were then assessed for cell viability along the cut periphery by performing live-dead cell staining and viewing under the confocal laser scanning microscope.

Results: There was a significant correlation between pressure and kerf depth (p< 0.001). At a relatively high transverse speed of 1mm/s cartilage was cut smoothly and easily. The typical material removal energy for bovine cartilage is 7,38.109 J/m3. Using Equation 1, the resultant kerf depths of multiple jet parameter can be calculated easily.

The margin of superficial zone cell death at the curved edge was significantly greater in the OATS punch group (390±18μm) and in the diamond drill group (440±18μm), when compared to the WJ group (10±4 μm).

Discussion: The dead at the cutting edge was greatly for WJ cut samples, making it a promising technology for cartilage repair. The results of the present study suggest that water jet cutting has the potential to be developed as an alternative means to prepare the cartilage for patients undergoing cartilage transplantation.

Y. Joshi Y. Agrawal P. Phaltankar C. Quah

Purpose of Study: To prospectively evaluate the outcome of single surgeon endoscopic anterior cruciate ligament (ACL) reconstruction with quadrupled hamstring tendons drilling femoral tunnel independent of the tibial tunnel.

Methods and Results: 28 patients underwent endoscopic ACL reconstruction by a single surgeon in a DGH setting. All patients had symptomatic ACL deficiency proven by either MRI or previous arthroscopy. All patients were prospectively scored using the International Knee Documentation Committee (IKDC) score, the Lysholm score, Tegner activity score and the SF36 score. In each patient, an ipsilateral four-strand semi-tendinosus/gracilis tendon graft was used. The femoral tunnel was drilled through the anteromedial portal independent of the tibial tunnel as per the technique described by Leo Pinczewski, Sydney, Australia. This technique was used to place the femoral end of the graft in a more lateral position than obtained by the traditional transtibial technique. The ACL graft was fixed using RCI interference screws. All patients underwent standard accelerated rehabilitation program. All patients were reviewed clinically and radiologically at a mean follow-up 9 months. A significant improvement was noted in all the scores at the time of follow-up. Radiologically all femoral and tibial tunnels were satisfactorily placed with the femoral tunnels being in the 10 o’clock or 2 o’clock position with no evidence of tunnel widening. None of the grafts had failed. We feel that this technique may allow better rotational stability following ACL reconstruction.

M. Hantes G. Basdekis G. Karidakis A. Liantsis K. Malizos A. Venouziou

Aim: To determine the quantity and the quality of the bone bridge between the bone tunnels, in both the femoral and tibial side, after double-bundle anterior cruciate ligament (ACL) reconstruction.

Material and methods: Twenty-seven patients undergoing primary double-bundle ACL reconstruction with hamstring tendon autograft were included in this prospective study. Computed tomography (CT) was performed in all patients at a mean of 13 months postoperatively. The amount of the bone bridge between the bone tunnels was measured, in both the femoral and tibial side, on an axial plane at three locations:

at the level of the joint line

at the mid-portion of the bone bridge and

at the base of the bone bridge.

In addition, the bone density of the bone bridge was measured in Hounsfield units (HU) in the same locations. Bone density of the anterior tibial cortex lateral femoral condyle, and adjacent cancellous area, and were measured for comparisons.

Results: CT confirmed that the bone bridge was triangular in shape in all cases in both the femoral and tibial side. On the femoral side, at the level of joint line (apex of the bone bridge) the mean thickness of the bone bridge was 1.7 mm, at the mid-portion the mean thickness of the bone bridge was 3.7 mm and at the base of the bone bridge the mean thickness was 7.1 mm. On the tibal side, at the level of joint line (apex of the bone bridge) the mean thickness of the bone bridge was 1.5 mm, at the mid-portion the mean thickness of the bone bridge was 3.2 mm and at the base of the bone bridge the mean thickness was 6.5 mm. Bone density at the mid-portion and at the base of the bone bridge was similar to the cancellous bone for both the femoral and tibial side. However, the bone density of the bone bridge, at the level of the joint line, for the femoral side was 860 HU and this was not statistically significant in comparison to the density of the lateral femoral cortex (960 HU). Similarly, the bone density of the bone bridge, at the level of the joint line, for the tibial side was 885 HU and this was not statistically significant in comparison to the density of the anterior tibial cortex (970 HU).

Conclusions: Our study demonstrated one year after double-bundle ACL reconstruction the thickness of the triangular bone bridge between the bone tunnels is sufficient at the mid-portion and at the base of the triangle but is thin at the level of the joint line. However, the bone bridge at the apex of the triangle is very strong since its density is similar to that of cortical bone. We believe that the “corticalization” of the bone bridge at the level of the joint line on both the femoral and tibial side is important and contributes significantly to avoid communication of the bone tunnels.

P. Kankanalu M. Hockings R. Veale

Aim: To assess and establish the reason for repeating knee arthroscopies. A retrospective study at Torbay General Hospital.

Methods and results: The sample period was from January-2004 to July 2007 during which 695 knee arthroscopies were done, of which 71 patients (10 %) were coded as having same knee scoped again. A total of 58 out of 71 patients notes were available for review of which 12 were excluded due to coding-error and septic-arthritis. Among the 45 patients included, 67% were males and mean age was 44 years (range 17 to 70 years). The average time from listing the patient to actual scope was 20 weeks (range 0 to 54). At their first scope 24 patients required partial meniscectomies, of which 11 (45%) and 6 (25%) patients had posterior-horn and body of medial meniscal tears respectively, and 7 (29%) had tears in posterior-horn of lateral meniscus. Among the 23 who had chondral defects, 73% had changes on medial femoral condyle, 70% on patella, 52% on medial tibial condyle, 47% over lateral femoral condyle, 43% on trochlear grove, and 39% on lateral tibial condyle. Thirty-three-percent patients had anterior cruciate ligament (ACL) tears and 6% require loose bodies removal.

Average time between re-scopes was 16 months (range 0 to 3.5 years). The numbers of patients requiring repeat knee arthroscopy for similar clinical problems were 16 out of 695 patients (2.3%). During repeat arthroscopies, 10/16 (62%) required procedures on meniscus, 4/16 (25%) for osteochondral lesions 2 patients had same diagnosis as ACL tears. 90% of partial meniscectomies were repeated on the posterior horn of both medial and lateral meniscus, and 20% required trimming of body of the meniscus.

Conclusion: Contrary to general opinion being too many patients knees are been re-scoped, only 16/695 patients (2.3%) had their knees re-scoped for similar problem as found at first arthroscopy. 62% of these patients required partial meniscectomy mainly on the posterior-horns and 25% had chondral defects. We concluded that MR-arthrogram should be considered due to its specificity and sensitivity as detailed in literature, before performing repeated knee arthroscopy.

S. Mayer A. Büttner V. Jansson W. Mayer P. Müller M. Schieker T. Schiergens B. Sievers

Background: In regenerative medicine the autologous cartilage implantation (ACI) has been used for the repair of cartilage defects. As modification of ACI, the matrix assisted ACI is used nowadays with varying results. There is a general discussion about whether supporting scaffolds should be used or whether a scaffold-free cartilage repair is the method of choice. The major problem of scaffold-free regenerates is how to keep the cells in place after transplantation. Aim of this study was to examine a new scaffold-free diffusion-culture model, which uses a mega-congregate of chondrocytes cultured at an air-medium interface. This scaffold-free high-density diffusion culture could be used to repair cartilage defects.

Material and methods: Human chondrocytes from passage 1–7 were expanded in monolayer and transferred to pellet-culture or diffusion-culture. After one week cultures were stained with toluidine blue and safranin-O and evaluated by immunohistochemical staining for type II collagen. Quantitative real time reverse transcriptase polymerase chain reaction (qRT-PCR) was performed for the mRNAs of cartilage markers.

Results: Positive alcian blue staining was detectable in diffusion-culture for human chondrocytes up to passage 7. Within passages the amount of proteoglycan production in relationship to the number of cells increased. There was a positive signal for Collagen type II in diffusion-cultures up to passage 7.

In qRT-PCR a redifferentiation of human chondrocytes was shown by the transfer into diffusion-culture. Within passage 1 to 3 human chondrocytes which were cultured in monolayer lost the ability to express Collagen Type II but could regain it if they were transferred to diffusion-culture. At diffusion-culture chondrocytes showed the highest expression of Collagen type II at passage 1 when compared to monolayer or to pellet-culture.

Conclusion: It could be shown that the cultivation in a scaffold-free diffusion-culture can lead to redifferentiation of human chondrocytes Chondrocytes in diffusion-cultures tend to form their own matrix and produce Collagen type II at higher amounts than in monolayer or in normal pellet-cultures. Therefore diffusion-culture congregates might be an appropriate tool to be used for a new scaffold-free cartilage regeneration approach.

A. Monk D. Beard C. Dodd H. Doll C. Gibbons H. Gill D. Murray S. Ostlere D. Simpson

Patello-femoral instability (PFI) affects 40 individuals per 100,000 population and causes significant morbidity. The causes of patello-femoral instability are multi-factorial, and an isolated anatomical abnormality does not necessarily indicate instability. Patello-femoral subluxation ranges from 0% (stable patella tracking) to 100% (dislocation) and there is an established relationship between the amount of subluxation and anterior knee pain. Traditionally, magnetic resonance (MR) imaging and standard radiographs are used to guide the clinician towards a suitable corrective procedure for PFI. The multi-factorial nature of patello-femoral instability is not addressed with current imaging techniques. This study aims to address which anatomical variables assessed on MR images are most relevant to patello-femoral subluxation. This information will aid surgical decision making, particularly in selecting the most appropriate reconstructive surgery.

A retrospective analysis of MR studies of 60 patients with suspected patello-femoral instability was performed. All patients were graded for degree of subluxation using a dynamic MR scan.

The patient scans were assessed for the presence of a specific range of anatomical variables:

patella alta, (modified Insall-Salvatti)

patella type (Wiberg classification)

trochlea sulcus angles for bone and cartilage surfaces

the distance of the vastus medialis obliquis (VMO) muscle from the patella

trochlea and patella cartilage thickness

the horizontal distance between the tibial tubercle and the midpoint of the femoral trochlea (TTD)

patella engagement – the percentage of the patella height that is captured in the trochlea groove in full extension.

The Wilk’s Lambda test for multi-variate analysis was used to establish whether any relationship was present between the degree of patello-femoral instability and bony or soft tissue anatomical variables. Non-parametric statistical tests were applied across the groups and within the groups to assess their relative significance.

The following variables showed a significant relationship with patellofemoral subluxation; distance of the VMO from the patella (< 0.001), TTD (< 0.001), patella engagement (0.001), sulcus angles (0.004) and patella alta (0.005).

This study agrees with previous work showing a significant correlation between subluxation and trochlea sulcus angle and TTD.

This is the first study to establish a significant correlation between patella engagement and radiological instability. The lower the percentage engagement of the patella in the trochlea, the greater the degree of patello-femoral instability. Patella engagement showed a more significant relationship with subluxation than patella alta.

We report a new method of predicting patello-femoral instability by measuring the overlap of the patella in the trochlea groove.

M. Naveed A. Porteous

We present 10–15 year follow-up of 33 patients who underwent Elmslie-Trillat osteotomy for severe patellar subluxation or dislocation. In the literature it has been reported that tibial tubercle osteotomy predisposes to subsequent patella-femoral arthritis, however it has never been documented if pre existent knee chondral damage has any role in this development. In our group all patients had pre-op knee arthroscopy performed and extant of chondral damage was documented. We pre-formed an evaluation by long-term follow-up to determined weather pre-op chondral damage was the cause of subsequent osteoarthritis of patella-femoral joint.

All patients were invited to attend outpatient clinic for clinical examination and knee radiographs and assessed by an independent research surgeon. Mean age at follow-up was 43 years and average follow-up was 10.5 years (range 10–15 years). 90% follow-up was achieved. Knee function was assessed by clinical scores (Lysholm knee score, American Knee Score, Oxford Knee score, Tegner and Insall knee scores) and three radiographs (AP, Lateral and Merchant views) were performed.

Four patients had developed significant arthritis and underwent joint arthroplasty. Majority of patients reported good results with no further dislocation. However we noticed that extant of pre-op chondral damage was a significant factor in subsequent development of patella-femoral arthritis. We will present our data which is unique as no previous such long-term results have been reported for tibial tubercle transfers followed-up for more than 10 years and have pre-op arthroscopic documented chondral damage.

W. Rodkey K. Briggs J. Lysholm Steadman Y. Tegner

Purpose: The purpose of this study was to determine psychometric properties of the Lysholm score and Tegner activity scale as patient-administered outcomes scores for anterior cruciate ligament injuries of the knee. We hypothesized that these two outcomes measures remain valid by today’s standards twenty-five years after they were originally introduced as physician-administered outcomes instruments.

Methods: One thousand seven hundred eighty-three (1783) patients were included in this study. There were 749 females and 1034 males. Average age was 37 years (range, 18 to 77). Isolated ACL tears were documented in 593 patients, and 1190 patients had concurrent injuries including meniscus pathology and/or cartilage damage. Patients with multiple ligamentous injuries were excluded. All patients in this study were diagnosed with an ACL tear at arthroscopy. For responsiveness, scores were measured preoperatively and at a minimum of two years postoperatively. For test-retest, scores were measured at a minimum of two years postoperatively and again within four weeks of the original postoperative questionnaire. For criterion validity, patients completed the short form (SF-12®) of the health related quality-of-life scale and the IKDC score in addition to Lysholm and Tegner instruments. For all other analyses, preoperative Lysholm score or Tegner activity levels were used.

Results: There was acceptable test-retest reliability for overall Lysholm score (ICC=0.94 [95% confidence interval=0.88 to 0.96]) and Tegner (ICC=0.82 [95% confidence interval=0.66 to 0.89]). The minimum detectable change for Lysholm was 8.9 and for Tegner was 1.4. The Lysholm score demonstrated acceptable internal consistency (Cronbach’s alpha=0.72). The Lysholm score correlated with IKDC (r=0.78) and the physical function domain of SF-12® (r=0.43). The Tegner scale correlated with physical function domain of SF-12® (r=0.2) and IKDC (r=0.22). Both scores had acceptable floor and ceiling effects, and all hypotheses were significant. The Lysholm score and Tegner scale both had a large overall effect size. There were no differences between isolated and combined ACL injuries.

Conclusion: After 25 years of changes in treatment of ACL injuries and postoperative rehabilitation protocols, the Lysholm knee score and Tegner activity scale continue to demonstrate acceptable psychometric parameters. The Lysholm score and Tegner scale both had acceptable test-retest reliability, construct validity, criterion validity, content validity, and responsiveness when patient-administered similar to the physician-administered results when they were originally validated. Our hypothesis was affirmed.

S. Konan F. Haddad S. Rhee N. Tamini T. Zhang

Radiographs are frequently ordered following acute knee injury. However, it is suggested that only 6 % of patients with a knee trauma have a fracture. Decision rules such as the Ottawa rules and the Pittsburgh rules have been developed to reduce the unnecessary use of radiographs following knee injury.

We prospectively reviewed all acute knee injury patients who were referred to our clinic from the emergency department over a 3 month period. The reason for ordering radiographs was analysed. The Ottawa and the Pittsburgh rules were applied to individual patients to evaluate the need for radiographs. In patients with a diagnosis of fracture, the accuracy of the Ottawa and the Pittsburgh rules was studied.

A total, of 106 patients were referred to the acute knee clinic from the emergency department. 95.28 % (101) of these patients had radiographs of their knee in the emergency department. Five (4.72%) patients had a fracture of their knee and all these cases, the Ottawa and the Pittsburgh knee rules for ordering radiographs was fulfilled. In a vast majority of cases without any fracture, the clinical reason for ordering radiographs was not clear. Using the Ottawa rules for knee radiography 25.47% (27) radiographs could be avoided without missing a fracture. Using the Pittsburgh rules, 30.19 % (32) knee radiographs could be avoided without missing a fracture.

The Ottawa and the Pittsburgh rules have a high sensitivity for the detection of knee fractures. Use of these rules can aid efficient clinical evaluation of the knee in an emergency situation without adverse clinical outcome. They may also have an implication on reducing the work load of radiology department and reduction of health costs.

W. Rodkey K. Briggs

Objectives: Partial meniscectomy is the current standard of care for torn menisci not suitable for repair. Arthroscopic partial meniscectomy is the most commonly performed orthopaedic surgical procedure. The purpose of this study was to determine what specific factors influence longevity of improvements in function and activity levels following arthroscopic partial meniscectomy.

Methods: Six hundred forty (640) knees which had undergone isolated partial meniscectomy were identified from a clinical database. One hundred ninety-three (193) knees had partial lateral meniscectomy, 342 had partial medial meniscectomy, and 105 had partial medial and lateral meniscectomy. Average age was 52 years (range, 15 to 79) with 207 females and 433 males. Patients were excluded if they had concurrent ACL reconstructions or microfracture for chondral defects. Lysholm function and Tegner activity scores were collected for a minimum of 8 years after the index partial meniscectomy.

Results: For all knees, Lysholm scores improved significantly from preoperative (54) to 1 year postoperative (76) (p< 0.001). Lysholm scores did not change from year 1 to year 5. At year 6, average Lysholm score decreased to 69, and by year 8, the score decreased further to 63. When comparing degenerative knees to non-degenerative knees, the non-degenerative group had greater improvement and maintained it longer. Medial meniscus patients maintained their improvement at 6 and 7 years while the lateral meniscus group showed less improvement and decreased at years 6 and 7. Anatomic location of meniscus tear (anterior, middle or posterior thirds) was not associated with changes in improvement of Lysholm or Tegner scores. Tegner activity levels improved significantly from preoperative (3.6) to 1 year postoperative (4.7) (p< 0.001). This improvement was maintained at years 2, 3, and 4. There was no significant difference between preoperative Tegner and year-5 Tegner scores (4.0) (p> 0.05). This same finding was also seen at years 6, 7, and 8. In degenerative knees, there was less improvement, and levels declined at years 6, 7, and 8.

Conclusions: Patients who undergo partial meniscectomy can expect 4 to 5 years of improved function and activity levels. Knee function continues to improve up to 5 years, but it decreases as activity levels decrease. Patients who delay treatment or have degenerative changes experience a decrease in function and activity levels sooner. Meniscectomy provides a short term improvement in function and activity levels, but long term improvement seems unlikely. Our findings confirm that specific factors such as which meniscus (medial or lateral) undergoes meniscectomy, chronicity of the tear, and preexisting degenerative changes might be expected to influence longevity of improvements after partial meniscectomy.

W. Rodkey K. Briggs Steadman

Purpose: Meniscus loss leads to decreased clinical function and activity levels and increases rate of knee degeneration, thus leading to additional surgeries or even knee replacement, especially in chronic patients. Chronic patients are more focused on preserving their knees and avoiding additional surgeries. The purpose of this study was to determine if replacement of lost or irreparable meniscus tissue with the Collagen Meniscus Implant (CMI) decreased the need for additional surgeries in multiply operated chronic knee patients compared to meniscectomy only. We hypothesized that patients who gained meniscus tissue with the CMI would require fewer surgeries than meniscectomy only controls through five years.

Methods: In this prospective randomized multicenter clinical trial (Level of Evidence I), patients 18 to 60 years old who had undergone one to three prior partial medial meniscectomies (PMM) and currently had clinical symptoms of meniscus pathology were randomized either to receive the CMI or have an additional PMM (control). Eighty-five CMI were implanted, but one was removed at 3 weeks after an incision wound infection, and two patients died. The remaining 82 CMI patients were compared to 66 controls over 5 years to determine survivorship. Survivorship was defined as not having an additional unplanned surgery outside the experimental protocol on the study knee.

Results: Follow-up rate at 5 years was 96%. Eight CMI patients (9.5%) and 15 control patients (22.7%) required reoperation through 5 years. Survivorship at one year was 90% for control and 95% for CMI patients, 86% for control and 95% for CMI patients at 2 years, 83% and 92% at 3 years, 79% for control patients and 91% for CMI patients at 4 years, and 74% for control patients and 89% for CMI patients at 5 years. CMI patients had a significantly higher survivorship compared to controls (p=0.04). The risk (odds) of reoperation was 2.7 times greater for controls compared to CMI patients at 5 years (95% CI=1.2 to 6.7). Furthermore, the majority of control patient reoperations occurred prior to 24 months, but only four CMI reoperations occurred during the first 24 months.

Conclusion: This study confirms that chronic patients who received the CMI required fewer additional surgeries in their multiply operated knees than PMM only controls through 5 years. The additional tissue regeneration supported by the CMI may decrease progression of degenerative changes and reduce necessity and frequency for additional surgeries. This study further confirms the importance of preserving as much meniscus tissue as possible at time of meniscus surgery, and clearly it supports potential positive benefits of regrowing or regenerating lost meniscus tissue. Our hypothesis was affirmed.

W. Rodkey K. Briggs

Introduction: Meniscus repairs with sutures have become more common as the importance of preserving the meniscus has been established. Studies have shown a high rate of repeat surgery, but it is unclear what factors contribute to failure. The purpose of this study was to determine what factors lead to failure of suture meniscus repair. Failure was operationally defined as repeat surgery on the meniscus within 2 years of the repair.

Methods: Two hundred eighty-three (283) meniscus suture repairs were performed by a single surgeon. The average patient age was 31 years (range, 18 to 71). There were 177 males and 106 females. All repairs were completed with an inside-out suture technique. One hundred thirty-seven (137) had an ACL reconstruction and meniscus repair (93 concurrent reconstructions and 44 two-staged ACL reconstructions). One hundred eighty-one (181) medial menisci and 102 lateral menisci were repaired. Of the medial repairs, 80% were in the posterior third of the meniscus, 11% in the middle third, 1% in the anterior third, and 8% extended to all areas of the meniscus. Of the lateral meniscus repairs, 49% were in the posterior third, 26% in the middle third, 22% in the anterior third, and 3% extended to all areas.

Results: Twenty-eight (28) patients (10%) had required repeat surgery on the repaired meniscus within the first 2 years and were considered failures. The average time to repeat meniscus surgery was 12 months (range, 2.5 to 24 months). There were no differences based on age, gender or location. Thirteen percent (13%) of medial repairs and 4% of lateral repairs failed (p=0.012). Medial meniscus repairs failed significantly earlier (5.6 months) than lateral meniscus repairs (12.9 months) (p=0.001). For patients who had ACL reconstruction and meniscus repair, factors associated with failure included age (failed age=22; non-failure age=29; p=0.013), and concurrent ACL reconstruction (two-staged repair failures=2%; concurrent repair failures=11%; p=0.04).

Conclusion: Failure of suture repair of the meniscus within the first two years following index repair is more likely to occur in medial meniscus repairs and in young patients who had a repair and concurrent ACL reconstruction.

W. Rodkey K. Briggs Steadman

Prospectively, we determined amount of meniscus loss and anatomic location of Collagen Meniscus Implant (CMI) placement after partial medial meniscectomy (PMM). At 1-year relook we determined total meniscus tissue present based on surface area coverage. We correlated percent of meniscus and anatomic location of the original lesion with function and activity levels 6 years after CMI placement. We hypothesized that meniscus amount and anatomic location would influence clinical function and activity levels.

In a prospective randomized controlled multicenter clinical trial (Level of Evidence I), 114 chronic patients (1 to 3 prior PMM on the involved meniscus) 18 to 60 years old underwent partial medial meniscectomy, and then randomly one group received a CMI to fill the meniscus defect. There were 68 PMM only controls and 46 CMI patients. At index surgery, amount and anatomic location of meniscus removed and CMI placement were documented on a standard grid. Locations were categorized as posterior (A), middle (B), or anterior (C) third. A 1-year relook was done on CMI patients, and meniscus surface area coverage was measured. Patients were followed clinically for a minimum of two years and subjectively annually thereafter. Average follow-up was 69 months (range, 24 to 92). All patients completed validated questionnaires including Lysholm and Tegner scores to assess function and activity.

For CMI patients, 29 had lesions which included posterior and middle thirds (AB), and 17 had lesions involving all three zones (ABC). Lysholm scores were significantly higher in patients with AB lesions (81) compared to ABC lesions (71), p=0.046. AB lesion patients also had significantly higher Tegner index (0.70) than ABC lesion patients (0.22), thus AB patients regained more of their lost activity, p=0.049. Comparing all patients with > 60% meniscus surface area coverage, CMI patients had significantly higher Tegner index compared to controls (0.59 vs. 0.30), p=0.036. No differences between treatment groups were seen in patients with < 60% meniscus surface area coverage. When comparing 24 month to final follow-up values, controls had no change for Lysholm (p=0.13) or Tegner (p=0.39) scores, but CMI patients improved significantly over time for both Lysholm (p=0.02) and Tegner (p=0.04) scores.

Zones of meniscus involvement influenced clinical outcomes at 6 years in CMI patients. Those whose lesions extended into all three zones did worse than those with lesions in posterior and middle zones only. Patients with successful CMI procedures yielding > 60% meniscus surface area coverage were significantly better than PMM only controls for both clinical function and activity levels. Noteworthy, CMI patients continue to improve over time for clinical function and activity levels, but PMM controls do not.

M. Sabeti M. Geisler A. Goll A. Ochsner T. Pachtner M. Schmidt M. Serek

Compared to conventional road-cycling, little is known about overuse injuries in mountainbiking. The adjustment of the mountainbike seems to be crucial avoiding these syndromes. No other study has prospectively put overuse injuries into correlation with the mountainbike’s adjustment in a competition setting until now.

Methods: This prospective field study consisted of two phases using preformed questionnaires to interview volunteering athletes in a race. In phase one overused body regions were identified in mountainbikers. In phase two riders were examined before and after the race for overused body regions which were put into correlation with the bike’s adjustments. The statistical analysis comprised a multivariance analysis.

Results: 169 competitors were analyzed of which 87 had after the race. Most injuries inflicted the lower back, the buttocks and the knee. There was a significant correlation between inadequate saddle pedal distance and the incidence of knee pain (p< 0.038), and paraesthetic sensations in the hand (p< 0.023). The inclination of the saddle has also significant impact on the occurrence of pain in the buttocks (p< 0.014)). Symptoms occurred highly statistically in downhill (p< 0.0001) and uphill (p< 0.0007) passages.

Conclusion: Overuse injuries are frequently observed in competitive mountain bikers. More than half of the investigated athletes had pain at any body region immediately after the race. The bike’s adjustment has a significant impact in the occurrence of overuse injuries.

P. Sillanpaa H. Maenpaa V. Mattila H. Pihlajamaki

Background: No studies exist about the long-term correlation of patellofemoral osteoarthrosis to poor outcome after traditional realignment surgery for chronic patellofemoral instability. The objective of this study was to evaluate the recurrent instability and symptomatic osteoarthrosis over a long follow-up period.

Methods: Fifty-two patients underwent distal realignment surgery for chronic patellar instability, 28 with Roux-Goldthwait procedure and 24 with Krogius procedure. A follow-up evaluation was performed at a mean 12 years (range, 8 to 22 years) after surgery, in which 39 of 52 patients participated. Recurrent instability and osteoarthrotic characteristics were evaluated by plain radiographs and magnetic resonance images obtained at follow-up. The original hospital data were reviewed to assess patients’ background. Subjective symptoms were assessed with patellofemoral scores.

Results: Of the 39 controlled patients, 10 had chronic patellar instability, including 4 patients who underwent reoperation during follow-up. The mean patient age at follow-up was 33 years (range, 26 to 43). Patellofemoral full-thickness cartilage lesions were found on MRI in 29 (75%) of patients and all of the patients had mild lesions. A joint space narrowing was present in 6 cases in plain radiographs indicating severe patellofemoral osteoarthrosis. Only 48% of the patients reported satisfaction with the patellar stability and anterior knee symptoms and the unsatisfactory result was associated with patellofemoral osteoarthrosis (P=0.05). The mean Kujala score was 83 (range 52–100) points. The surgical technique employed did not affect the overall outcome.

Conclusion: The long-term outcome of traditional realignment surgery for chronic patellofemoral instability seemed to be strongly associated with patellofemoral osteoarthrosis. Despite the relatively rare occurrence of recurrent instability, less than half of patients achieved a satisfactory result. Patellofemoral osteoarthrosis seems to be the long-term consequence in patients treated with traditional surgical procedures for patellar instability. In future studies focusing on patellar stability, preventive methods against the development of patellofemoral osteoarthrosis should be emphasized.

F. Trouillet J. Chouteau M. Fessy B. Moyen

Introduction: The anterior cruciate ligament (ACL) can be anatomically divided into two bundles: the anteromedial (AM) and the posterolateral (PL). These two bundles have unique contributions to load transfer across the knee joint.

Material and Methods: We retrospectively reviewed the clinical results of a consecutive series of 25 patients who underwent partial ACL reconstruction. In 22 cases AM bundle reconstruction was performed, and in 3 patients isolated PL bundle reconstruction was performed.

The 25 patients included 7 women and 18 men with an average age of 29.2 years at the time of surgery.

Preoperative evaluation was conducted using manual Lachman test, pivot-shift tests, KT-1000, magnetic resonance imaging and passive stress radiographs of both knees. In all cases preoperative clinical evaluation was graded C as per the IKDC scoring system. The preoperative side-to-side anterior laxity measured by means of the KT-1000 was 5.8 mm in case of AM bundle rupture and 4.3 mm in case of PL bundle rupture.

All the patients underwent single-bundle reconstruction of the ACL under arthroscopic assistance (one single incision technique).

In case of AM bundle repair, the type of graft used was all autologous and included bone-patellar tendon-bone in 14 cases, 4-strand hamstring tendons in 5 cases and 2-strand hamstring tendons in 3 cases.

In case of PL bundle repair, 2-strand hamstring tendons transplant was used in the 3 cases.

Results: In all cases, postoperative clinical evaluation was graded A as per the IKDC knee examination scoring system. No abnormal sagittal laxity was found with the Lachman manual test. Postoperative IKDC knee subjective evaluation score averaged 81.3 % [58–95] at an average of 9 months follow-up.

Postoperative side-to-side anterior laxity measured with KT-1000 averaged 0.46 mm in case of AM bundle rupture and 0.5 mm in case of PL bundle rupture.

Postoperatively, all the patients had full extension of the knee. The flexion was the same as contra lateral knee in 92 % of the cases. We had no postoperative complication.

Discussion: Diagnosis of partial ACL rupture is often difficult. If the AM bundle is torn, the Lachman manual test is soft and the pivot-shift test is more often equal or glide. If the Lachman manual test is intermediary between firm and soft and the pivot-shift test is clunk, PL rupture has probably occurred.

The size of the graft was smaller than in one bundle procedures and was matched with the size of the bundle reconstucted. Peroperative technical difficulties were to preserve the healthy bundle and to drill the femoral tunnel in case of posterolateral bundle reconstruction.

Conclusion: This study showed consistent postoperative results. If partial rupture of the ACL can be diagnosed, isolated AM or PL bundle reconstruction should be considered.

M. Tengrootenhuysen G. Meermans K. Pittoors G. Van Damme J. Victor

Introduction: Meniscal injuries are common and a potential source of osteoarthritis of the knee. This has led to the development of techniques to repair meniscal tears. The goal of this study was to look at the independent variables that have an influence on the outcome and identify factors that might improve future clinical results.

Method: A total of 119 meniscal repairs were included in this study and evaluated at minumum 72 months postoperatively (range 72–86). Meniscal repair was done by an arthroscopically assisted technique: inside-out, all-inside or by a combination of both techniques. Patients with menisci repaired were clinically evaluated. We performed examinations using the International Knee Documentation Committee (IKDC) form and the Lysholm score. Radiological analysis of the knees was done by means of the Ahlback classification pre- and postoperatively. Variables that were analyzed were age, gender, type of repair, chronicity of the lesion, zone of injury, morphology of the tear, involvement of the anterior cruciate ligament (ACL), and the compartment involved. Statistical analysis was done by means of logistic regression.

Results: The overall clinical success rate for meniscal repair was 74.0%. In 73.1% of the cases, the mensiscal injury was associated with an injury of the ACL. Patients with an associated ACL injury had a better chance for a successfull outcome, but this was only significantly when the ACL injury was repaired (p< 0.05). There was no difference between the male and female patients regarding outcome. A delay in treatment for 6 weeks or more resulted in significantly worse results (p< 0.001). Younger patients had significantly better outcome results (p< 0.05). Better results were obtained when the inside-out technique was used for meniscal repair (p< 0.05).

Discussion: Our data confirm the good outcome results of meniscal repair. In our hands, a meniscal repair has the highest likelihood of success in young patients, with a concomitant ACL injury that is repaired at the same time. Better outcome scores were observed when the inside-out technique was used and when menisci where repaired within 6 weeks of the initial injury.

M. Ruiz-Iban I. Cebreiro Martinez Del Val N. Comellas Melero M. Del Cura Varas J. Díaz Heredia F. González Lizán D. Jimenez S. Moros Marco

Introduction: tibial plateau fractures are a therapeutic challenge that are increasingly being dealt with arthroscopically assisted surgical treatment. About 40% of cases associate a meniscal lesion. Meniscal repair is a challenging technique in this setting but has an increased importance due to the intrinsic role as cartilage protector of the meniscus. Although suture in the course of the reconstructive procedure is more technically demanding and time consuming the biological surrounding of the repair is optimal (extensive intraarticular bleeding, prolonged non weight-bearing, presence of bone marrow elements, acute repair).

The objective of this study is to determine the outcomes of meniscal suture in this group of patients.

Material and methods: Between 1999 and 2007 sixty one tibial plateau fractures were operated with arthroscopic assistance in our institution. Of these, 25 presented meniscal injuries and 16 of these were repaired. Repair criteria were: no age limit was established and all types of ruptures (even radial or bird-beak lesions) were repaired if technically possible. 14 external menisci and 2 internal menisci were repaired. Morphologically 15 were longitudinal ruptures in the red-red zone and one was a bird beak rupture. Suture was performed using a combination of repair techniques including outside-inside (seven cases), inside-outside (two cases) and all-inside (14 cases). Functional results were evaluated with the following scales: Rasmussen, Honkonen, ICDK, Lysholm, SF-36 and Knee Society scores. Evaluation of the meniscal repair was performed either by M.R.I. of the knee (obtained in six cases) or arthroscopic revision of the meniscal repair (during surgery for implant removal in 9 cases). In one case the patient required a TKA not related to the meniscal lesion and the meniscus was revised during the procedure.

Results: All cases were available for follow up a minimum of 12 months after surgery (mean 2.6 +/−1.4 years). Functional results were excellent or good in 14 of 16 cases. One poor result was related to meniscal symptoms and requiered arthrocopic meniscectomy, the other poor result was due to arhtrofibrosis. Direct visual revision of the suture (either arthroscopically [9 cases] or during open surgery [one case]) allowed for the diagnosis the symptomatic failure of the repair and of complete healing in the rest of cases (9). MRI showed complete repair in four cases, partial repair in one and failure in one; all being asymptomatic.

Conclusions: this technique seems to offer good results with complete healing observed in 81% of cases and partial healing in 6%; symptomatic failure of the repair was observed only in 6% of the cases. In meniscal injuries related to this type of fracture, repair should be always considered as the biological environment seems to facilitate success in the repair.

P. Verdonk A. Mulliez R. Verdonk

Background: There are several surgical options for recurrent lateral dislocations of the patella. As the reconstruction of the medial patellofemoral ligament reconstruction (MPFL) has been proven to restore stability, it has become more accepted by surgeons. No study to date has examined the difference in clinical outcome between patients with a primary MPFL reconstruction (group 1) versus MPFL reconstruction in patients with a previously failed patellar stabilizing operations (transposition of tibial tuberosity, trochleoplasty, medial raphy) (group 2).

Study type: Prospective cohort study

Methods: 30 patients have been treated with an MPFL reconstruction for episodic patellar dislocation between april 2007 and april 2008. 12 of them already had a patellar stabilizing operation in the history (group 2). The clinical follow up was done by the KOOS and KUJULA scores.

Results: For both groups, the KOOS and KUJALA score increased significantly at final follow-up. KOOS pain and ADL subscore had the lowest increase. At final follow-up, the KUJALA and KOOS score were significantly higher for group 1 vs group 2. The net gain for both KOOS and KUJALA was also significantly higher in group 1 compared to group 2.

Conclusions: MPFL reconstruction is a viable treatment option for episodic patellar dislocation both in a primary setting as well as in a secondary setting for failed surgery cases. The net clinical gain is nevertheless significantly higher in primary cases.

R. Verdonk P. Verdonk

Introduction: Currently, partial meniscectomy represents the only viable treatment option for patients with irreparable meniscal tears; however, functional limitations have been reported both in the short- and long-term. Furthermore, over time, removal of knee meniscus tissue leads to degenerative joint changes and osteoarthritis. Given the limited alternatives to meniscus removal, researchers have developed a novel meniscal scaffold. Upon implantation to the vascularized portion of the meniscus, the scaffold allows the ingrowth of blood vessels, facilitating the regeneration of meniscal tissue.

Methods: A total of 52 patients with an irreparable medial or lateral meniscal tear or partial meniscus loss (with intact rim) were recruited into this prospective, non-randomised, single-arm, multi-centre clinical study. Patients were to have a stable knee joint or be a candidate for joint stabilization within 12 weeks of the procedure, an International Cartilage Repair Society (ICRS) classification ≤ 2, and no more than 3 prior surgeries on the index knee. Post-implantation, clinical efficacy was assessed at each follow-up visit based on the following patient-reported outcome scores: Visual Analogue Scale (VAS) score for pain, and both the Knee and Osteoarthritis Outcome Score (KOOS) and International Knee Documentation Committee (IKDC) score for function. Preliminary efficacy data are available for 48/52 patients at 3 months follow-up and 35/52 patients at 6 months follow-up. Full data, including 12 months follow-up for all available patients will be presented.

Results: Compared to the mean baseline values, a statistically significant reduction in post-operative knee pain was reported based on VAS both at 3 and 6 months. Statistically significant improvements compared to baseline were also reported in IKDC scores and all components of the KOOS questionnaire both at 3 and 6 months post implantation.

Conclusions: These promising clinical results clearly illustrate the early efficacy of this novel meniscus implant for partial meniscus tissue loss. Longer follow-up is however needed to establish its full potential.

L. Verlaan B. Grimm I. Heyligers R. Senden

Modern orthopaedics increasingly demands objective functional outcome assessment beyond classic scores and tests suffering from subjectivity, pain dominance and ceiling effects. Inertia based motion analysis (IMA) is a simple method and validated for gait in knee arthroplasty patients. This study investigates whether IMA assessed stair climbing can distinguish between healthy and pathological subjects and is able to diagnose a meniscal tear (MT).

Following standard physical examination (McMurray, rotation pain), 37 patients (18–72yrs) received arthroscopy suspecting a meniscal tear resulting from trauma, degeneration or both. Arthroscopy identified the presence or absence of MT and the osteoarthritis level (Outerbridge).

Prior to arthroscopy, the ascending and descending five stairs twice at preferred speed and without the use of handrails was measured using a triaxial accelerometer (62×41×18mm; m=53g; f=100Hz) taped to the sacrum. Based on peak detection algorithms, temporal motion parameters were derived such as step time up and down (Tup, Tdown), the difference between step time up and down (Tup-down), step irregularity (step time difference of subsequent steps) and step asymmetry (step time difference between affected and non-affected leg).

Patients were compared to a control group of 100 healthy subjects (17–81yrs) without any known orthopaedic pathology. Using the results of arthroscopy, test sensitivity and specificity for differentiating healthy and pathologic subjects and for diagnosing MT were calculated based on threshold values.

Sensitivity and specificity for detecting pathological motion was 0.68 (CI 0.50–0.81) and 0.92 for the most sensitive parameter (Tdown). Sensitivity and specificity to detect MT was 0.74 and 0.25 percent overall compared to 0.53 and 0.50 for the McMurray. Sensitivity increased to 1.00 when MT was combined with a chondropathy scale III or IV (McMurray 0.33).

IMA assessed stair climbing can distinguish healthy and pathological subjects and detect the presence of MT with better sensitivity than classic scores especially when combined with severe chondropathy. IMA is a simple and fast clinical outcome measure suitable for routine follow-up and may support the diagnosis of meniscal tears prior to arthroscopy.

P. Verdonk R. Forsyth R. Verdonk

Introduction: Partial meniscectomy is the preferred treatment option for patients with irreparable meniscal tears. While generally accepted as producing favorable clinical results in the short run, it is widely accepted that meniscectomy induces articular cartilage degeneration in the long run. Thus, tissue regeneration post-meniscectomy is a desirable therapeutic approach in order to restore the function of the meniscus, thereby preventing long-term damage. A novel device, designed to act as a scaffold for blood vessel ingrowth and meniscal tissue regeneration in patients with irreparable meniscus tears and meniscal tissue loss, has recently been developed.

Methods: Fifty-two patients with an irreparable medial or lateral meniscal tear or partial meniscus loss, with intact rim, were treated with the meniscal scaffold in this prospective, non-randomised, single-arm, multi-centre clinical study. To date, biopsy samples 12 months post-implantation harvested from the center of the inner rim of the implanted scaffold meniscus using a standardized biopsy harvest protocol are available from 9 of the 52 patients. Histochemical staining was performed with haematoxylin and eosin, Masson’s trichrome, Sirius Red and combined Periodic Acid Schiff-Alcian Blue (PAS-AB). Immunohistochemistry was performed using the cartilage markers S100, the vessel markers CD31 and CD34, the smooth muscle marker SMA, and the histiocytic marker CD68.

Results: All biopsies showed fully vital material, with no signs of necrosis or cell death. In addition to a fibrous capsule, 3 distinct zones were identified based on the presence or absence of vessel structures, cellular morphology, and composition of extracellular matrix. Zone 1, a vascularized, fibrotic zone, mainly consisting of fibroblasts, was observed in 4/9 biopsies. Zone 2, an avascular and loose collagenized zone, consisting of a mixture of fibroblasts and chondrofibroblast-like cells, and Zone 3, an avascular and fibrin-rich zone, consisting of fibrochondroblast-like cells, were evident in all 9 biopsies.

Conclusions: All biopsies showed complete re-population, and thus can be regarded as vital structures, illustrating the biocompatibility of the meniscal scaffold. Moreover, zonal organisation, each with its own histological characteristics, suggests an ongoing process of regeneration, maturation and integration towards meniscus-like tissue. These data offer a first insight into the complex human healing potential after implantation of a polyurethane meniscus scaffold.

On behalf of the Actifit Study Group: R Verdonk, P Beaufils, J Bellemans, P Colombet, R Cugat, P Djian, H Laprell, P Neyret, H Paessler,

S. Zaffagnini R. Berbig P. Bulgheroni R. Crespo D. Holsten C. Lagae Koen M. Marcacci C. Monllau Juan

Introduction: The Collagen Meniscus Implant (CMI) has been shown to be effective for the replacement of lost medial meniscus tissue; however, no such device has been available for treatment of similar injuries to the lateral meniscus. Loss of the lateral meniscus results in a rapidly increased rate of knee degeneration compared to similar medial injuries. The purpose of this study was to determine if a CMI developed for use in treatment of lateral meniscus deficiencies is as safe and effective as has been reported for the medial CMI.

Methods: Prospectively, 60 patients (12–65 years of age) were enrolled at 7 sites between March 2006 and October 2007. Patients had irreparable lateral meniscus tears requiring partial meniscectomy. The knee had to be ligamentously stable and in neutral alignment and with no untreated Grade IV cartilage damage. Patients gave informed consent and agreed to comply with postoperative assessments and standardized rehabilitation. The surgical technique involved insertion of the dry implant into the lateral compartment of the knee joint. Fixation of the implant to the host meniscus rim was accomplished with either an all-inside suture technique or a hybrid all-inside/inside-out technique. Clinical evaluations and patient self-assessments were conducted preoperatively and at defined intervals through 2 years postoperatively. Procedure specific intraoperative parameters, radiographic evaluations, and adverse events were documented. Data collection was monitored by a third party according to GCP regulations.

Results: 49 patients received a lateral CMI. Currently, 24 patients have 1-year follow-up and 13 patients have been followed approximately 2 years; the mean follow-up is 22 months. Follow-up included assessments of changes in Lysholm, pain, Tegner and patient satisfaction. All patients showed clinical improvement from the preoperative to the 1 year postoperative time points. Four patients experienced adverse events which required an additional arthroscopic procedure between 4 and 16 months and included removal of implant remnants, synovectomy and debridement.

Conclusions: These preliminary results appear to suggest that implantation of lateral CMI leads to improved clinical outcomes in pain, function, self-assessment and activity levels. Frequency and type of adverse events are comparable to those for suture repair reported in the literature. Based on results reported for the medical CMI, we anticipate that these lateral CMI patients will have improved long-term results compared to partial lateral meniscectomy.

J. Walsh G. Byrne D. Fitzpatrick D. Mccormack J. Quinlan R. Stapleton

Hypothesis: Athletes significantly alter their lumbar spinal motion when performing squat lifting at heavy weights. This altered motion effects a change in pressure in the posterior annulus of lumbar discs.

Study Design:

3-D motion analysis of lumbar spinal motion in athletes, during squat weight lifting.

Pressure measurement of the posterior annulus following the motion analysis study.

Methods: 48 athletes performed 6 lifts at 40% maximum, 4 lifts at 60% max and 2 lifts at 80% max. 3-D motion analysis system, measured lumbar spine motion. Exercise performed as a ‘free’ squat and repeated with a weight lifting support belt.

4 cadaveric sheep spinal motion segments mounted in purpose built jig, replicating angulation seen in the in vivo motion study. These samples were then fixed to a tension/compression loading frame, replicating the forces seen in the in vivo study. Pressure measurement was achieved using a Flexiforce single element force sensor strip, positioned at the posterior annulus.

Posterior annulus pressure was measured during axial compression and on compression with the specimen fixed at 3° of extension.


Significant decrease (p< 0.05) in flexion in all groups when lifting at 40% max was compared with lifting at 60% and 80% of max. Flexion from calibrated zero point ranged from 24.7° (40% group), to 6.8° (80% group). A progressively significant increase (p< 0.05) seen in extension in groups studied when lifting at 40% max was compared with lifting at 60% and 80% max lift. Extension from a calibrated zero point ranged from − 1.5° (40% group), to − 20.3° (80% group). No statistically significant difference found between motion seen when performing the exercise as a ‘free’ squat or when lifting using a support belt in any group studied.

Initial uniform rise in measured pressure readings to a pressure of 350–400N, in the axially loaded and extension loaded specimens. Pressure experienced by the axially loaded group then gradually dropped below the pressure exerted by the loading frame, while the pressure experienced in the posterior annulus of the extension loaded specimens progressively increased.

Comparing axially loaded specimens with specimens loaded in extension, there was an average increase in pressure of 36.4% in the posterior annulus, when the spine was loaded in 3° of extension at a pressure equivalent to the 80% lift in the in vivo motion study, in comparison to axial loading.

Conclusions: Squat weight lifting at heavier weights, causes athletes to lift at a progressively greater degree of extension. The use of a weight lifting support belt does not significantly alter spinal motion during lifting. The increased extension at heavier weights results in a stress concentration in the posterior annulus of lumbar discs.

P. Wilmes D. Kohn O. Lorbach R. Seil C. Weth

Purpose: The objective of this investigation was to evaluate the precision of tibial tunnel drilling for anatomic anchoring of meniscus transplants at the tibial insertion area, using previously obtained percentage references.

Methods: In 20 cadaveric tibial heads, anterior and posterior horn insertions of both the lateral and the medial meniscus were dissected and their circumferences outlined. Standardized photographs of the tibial plateau were obtained. Applying previously obtained percentage values for radiographic determination of the meniscus insertion midpoints, tibial tunnels were drilled with the use of a standard ACL-guide. The positioning of the drilling guide was performed by solely using the midpoints as determined on standard ap and lateral radiographs; during the procedure, no position correction related to the anatomic insertions was made. After tibial tunnel drilling, a second set of standardized photographs of the tibial plateau was obtained. Adobe Photo Shop permitted the superposition of pre- and postoperative images. Coincidence between the anatomic insertion areas and the footprint of the tibial tunnel exit was determined, as well as the distance between the borders of the insertion areas and the tunnel footprint.

Results: For the lateral meniscus, the mean coincidence of insertion area and tunnel footprint was 60.5 ± 34.6 % for the anterior horn insertion and 62.4 ± 32.0 % for the posterior horn insertion. The mean distance between the borders of insertion area and tunnel footprint was 1.7 ± 1.5 mm for the anterior horn insertion and 2.3 ± 1.7 mm for the posterior horn insertion.

For the medial meniscus, the mean coincidence of insertion area and tunnel footprint was 88.4 ± 15.5 % for the anterior horn insertion and 60.3 ± 31.6 % for the posterior horn insertion. The mean distance between the borders of insertion area and tunnel footprint was 0.8 ± 0.8 mm for the anterior horn insertion and 2.1 ± 1.4 mm for the posterior horn insertion.

Conclusions: The use of percentage references for tibial meniscus insertion midpoint determination in combination with a radiographic positioned standard ACL-guide permits a precise drilling of tibial tunnels at the anatomic location of the meniscus insertions.

Clinical relevance: Enhancement of the surgical technique for bone plug fixation of lateral and medial meniscus transplants.

P. Aldinger G. Aldinger K. Krahmer G. Omlor H. Ulrich

Introduction: Improved biomechanics and stem fit facilitated by gender adepted dual stems and modularity has the potential to make THA easier and thereby decrease the complication rate. Increased fretting wear at the connecting interfaces may be a drawback. 10 year survival exceeding 90% is required to endorse modular necks and dual stem gender technology.

Materials and Methods: We followed the first 190 consecutive implantations of an uncemented, straight femoral stem with dual stem technology and modular necks (European Hip System (EHS)/Profemur E, Wright Medical Technology Inc., Arlington, TN, USA) and a grit blasted titanium acetabular cup with a ceramic on polyethylene bearing in 178 patients from 1992 to 1997. Mean time of follow-up evaluation was 10 (8–13) years. Titanium serum ion levels were measured to detect fretting in the metal connection.

Results: At follow-up, 21 patients (22 hips, 11.6%) had died, and 13 (14 hips, 7.4%) were lost to follow-up. One hip underwent femoral revision for a periprosthetic fracture. Overall stem survival was 99 (98–100) % at 10 years, survival with femoral revision for aseptic loosening as an end point was 100 (99–100) % at 10 years. Three acetabular components were revised, one for infection and two for aseptic loosening of the titanium shell. There was one fracture of a high offset modular neck at the laser labeling without trauma; the design was changed subsequently. The mean Harris-Hip-Score at follow-up was 88 points. 153 hips were available for radiolographic evaluation. No case of femoral or acetabular osteolysis or loosening was found. Accelerated wear was not detected on radiographs. No dislocation was found during the study period. The results showed no increased titanium serum ion levels compared to an age matched control group.

Conclusions: The complication rate with this uncemented modular gender hip system was extremely low with a high patient (and surgeon) satisfaction. The modular neck system as well as the dual stem technology proved to be reliable. The metal ion analysis revealed no elevated serum ion levels. Modular necks and dual gender stems are a reliable and durable option in primary total hip arthroplasty.

P. Anil Kumar V. Kavarthapu S. Kirmani P. Li

There is little in the literature reporting on the incidence of heterotopic ossification (HO) after hip resurfacing arthroplasty. HO has long been recognized as a complication of THA, with a reported incidence that ranges between 5 – 90 %. We investigated the incidence of HO in a group of hip resurfacing patients, and compared this against the incidence of HO in a comparable group of patients managed with a conventional THA. We retrospectively reviewed patients who had a hip resurfacing procedure from January 2004 to December 2007 carried out by a single surgeon. To act as our comparative group, we selected a closely matched group of patients in terms of age and sex who underwent a THA over the same time period, under the same surgeon. 47 cases of resurfacing, 23 were female and 24 male. The 47 cases of the selected THA group consisted of 24 females and 23 males. Therefore the two groups were of a similar sex make up. Within the resurfacing group of patients, the ages ranged from 31 to 68 years, with the mean being 55.4 years, and the median being 56.5 years. The THA group possessed an age range of from 31 to 68 years, with the mean being 55.4 years, and the median being 56.5 years. The resurfacing group of patients had 5 cases showing HO, giving an overall rate of 10.6 percent. 3 were of the grade I variety, while 2 were grade II. The THA group had 6 cases showing HO, giving an overall rate of 12.8 percent. 5 of these were of the grade I variety, while 1 was of the grade III variety. We used a two tailed Fischer’s Exact test set at the 5th percentile significance level to compare the overall rate of HO occurrence between the 2 groups, namely 10.6 percent versus 12.8 percent. This gave a p value of 0.238. Therefore we can state that there is no significant difference in the rate of HO formation between the resurfacing and THA patients.

N. Baldini G. Ciapetti A. Giunti L. Savarino

Ceramic-on-ceramic bearing is an attractive alternative to metal-on-polyethylene bearing due to the unique tri-bological advantages of alumina. However, despite the long-term satisfactory results obtained so far in the vast majority of patients, failure may occur in a few cases.

Clinical, radiographic, laboratory and microbiological data of 30 consecutive subjects with failed alumina-on-alumina total hip arthroplasties (THA) were analyzed to define if foreign body reaction to wear debris may be responsible for periprosthetic bone resorption, as in conventional metal-to-polyethylene bearings. In all cases, clinical and radiographical material was reviewed, retrieved implants were examined, and histology of periprosthetic tissues was analyzed. Massive osteolysis was never observed. Apart from 5 five patients for which revision surgery was necessary due to the occurrence of late infection, in all other cases failure had occurred due to secondary implant instability (as in the case of screwed sockets, 19 cases) or to malpositioning of the implant (5 cases). One patient suffered from chronic dislocation.

In the vast majority of cases, ceramic wear debris was absent or scarce, and did not induce any tissue reaction. In a few cases with severe wear, debris was evident in clusters of perivascular macrophages, notably in the absence of foreign body multinucleated cells, confirming the excellent biocompatibility of ceramics.

These findings indicate that wear debris and peri-prostetic bone resorption were the effect rather than the cause of failure, differently from revised metal-on-polyethylene bearings, in which foreign body cell reaction is the main pathogenetic mechanism of failure. On the contrary, mechanical problems, due to incorrect surgical technique or to inadequate prosthetic design, may cause instability of the implant, in turn resulting in wear debris production and moderate if any biological reaction.

G. Bhabra L. Cartwright P. Case H. Evans B. Fisher M. Saunders A. Sood S. Thawley

Increasing numbers of young people receive metal on metal (CoCr on CoCr) total hip replacements. These implants generate nano-particles and ions of Co and Cr. Previous studies have shown that micro-particles, nano-particles and ions of CoCr cause DNA damage and chromosomal abberrations in human fibroblasts in tissue culture, and in lymphocytes and bone marrow cells in patients with implants. Several surgeons have used these implants in women of child-bearing age who have subsequently had children. Significantly elevated levels of cobalt and cromium ions have been measured in cord blood of pregnant women with CoCr hip implants. The MHRA (Medicines and Healthcare products Regulatory Agency) subsequently stated that there is a need to determine whether exposure to cobalt and chromium represents a health risk during pregnancy.

In an attempt to investigate this risk, we used a well established in vitro model of the placental barrier comprised of BeWo cells (3 cells in thickness) derived from the chorion and exposed this barrier to nanometer (29nm) and micron (3.4μm) sized CoCr particles, as well as ions of Co2+ and Cr6+ individually or in combination. We monitored DNA damage in BJ fibroblasts beneath the barrier with the alkaline gel electrophoresis comet assay and with γH2AX staining.

The results showed evidence of DNA damage after all types of exposure. The indirect damage (through the barrier) was equal to the direct damage at the concentrations tested. The integrity of the barriers was checked with measurements of electrical resistance (TEER values) and permeability to sodium fluorescein (376Da) and found to be intact.

In light of these results and with the knowledge that BeWo cells express the transmembrane protein Connexin 43, we tested the theory that a damaging signal was being relayed via gap junctions or hemi channels in the BeWo cells to the underlying fibroblasts. We used the connexin mimetic peptides Gap19 and Gap26 (known to selectively block hemichannels and gap junctions respectively) and 18α-glycyrrhetinic acid (non-selective gap junction blocker). All of these compounds completely obliterated the indirect damaging effect seen in our previous experiments.

We conclude that CoCr particles can cause DNA damage through a seemingly intact barrier, and that this damage occurs via a bystander mechanism. It would be of interest to test whether this is simply a tissue culture effect or could be seen in vivo.

G. Babis M. Connor A. Hanssen V. Sakellariou F. Sim

Background: Massive bone loss from the proximal femur is a complex problem, occurring in multiple-revision hip arthroplasties, and malignancy. Allograft prosthetic composites (APCs) are used to restore bone loss and provide better function of the limb.

Material and Methods: Between 1986 and 1999, 94 patients (96 hips) including 31 male and 63 female (mean age 59.5 years), with massive bone loss due to an average of 2 previous revisions, had a revision hip arthroplasty using an allograft-prosthesis composite (APC). A previous history of infection was present in 21 of these cases.

Results: At an average follow-up of 11 years (range, 8 to 20 years), 72 patients were alive, 21 patients died, and 1 patient was lost to follow-up. Major complications occurred in 33 cases: femoral stem loosening (12); dislocation (15); periprosthetic fracture (10); and infection (7). Minor complications occurred in 13 other cases. Further revision surgery was performed in 21 of the 96 cases including revision of the acetabular component (3), femoral APC (16) or both (2). The 10 year survival of the APCs was 68.8% (95% CI 58.6%–79%, 26 cases remaining at risk). There was no statistically significant difference in survival time between gender, age, indication for APC (including infection), surgical approach and APC technique. Statistically significant factors negatively impacting APC survival included two or more prior revisions, severity of preoperative bone loss (Paprosky type IV) and use of plates and screws (p< 0.05). Statistically significant improvement in APC survival was identified in those reconstructions in which cement was used for proximal fixation of the femoral component within the allograft (p< 0.05).

Conclusion: Reconstruction of massive proximal femoral bone loss with an allograft-implant composite is a demanding procedure. Preservation of bone stock is a great advantage of this biologic means of reconstruction. Specific technical issues should be known and followed so to avoid failure and need for early re-revision

S. Bergeron J. Antoniou R. Chakravertty B. Ma J. Rudan

Introduction: Adequate bone in the femoral head and neck is a prerequisite in ensuring the longevity of a surface arthroplasty. The pistol grip deformity is one of the most common bony abnormalities of the femoral head encountered at the time of resurfacing. Severe flattening results in segmental bone loss requiring adjustments in the alignment of the femoral component to achieve optimal orientation. However, very little is known as to how the femoral implant positioning will be affected by increasing deformity. The purpose of this study was to classify the deformity of the femoral head to better understand how it influences the alignment of the femoral component during surface arthroplasty. This classification was then used to determine whether the femoral implant can be safely inserted with optimal alignment despite progressive deformity of the femoral head and neck.

Methods: The classification was developed using plain radiographs and computer tomography scans from 61 patients (66 hips) who presented with primary osteoarthritis prior to hip resurfacing. Surface arthroplasty simulations were generated with three-dimensional computed tomography to quantify the change in femoral component orientation from the neutral position that would allow optimal alignment. The biomechanical parameters were also calculated to determine the influence of the deformity on the final implant position.

Results: There were 47 men and 14 women, with a mean age of 50.3 years (range, 33 to 63 years). Three categories of femoral head deformity were created using a modified femoral head ratio (Normal ≥0.9, Mild = 0.75 – 0.9 and Severe < 0.75). There were a total of 32 normal hips (48%), 23 hips (35%) with mild deformity and 11 hips (17%) with severe deformity of the proximal femur. A severe deformity required significantly more superior translation of the entry point (p=0.027) and greater reaming depth (p=0.012) to allow safe insertion in relative valgus without notching. This could be achieved while preserving length discrepancy (p=0.17) and minimizing the component-head size difference (p=0.16), although femoral offset was significantly reduced (p=0.025).

Conclusion: A classification of femoral head deformity was created to better understand how progressive deformity influences the alignment of the femoral component during surface arthroplasty. This classification is simple and easily measured using standard AP radiographs of the hip. We found that the femoral component can be safely inserted with optimal alignment during surface arthroplasty by modifying the surgical technique in the face of severe deformity.

B. Boesenach R. Nelissen H. Van Der Heide J. Wolkenfelt

Aim: Suction fit is a common phenomenon of metal on metal (MOM) or ceramic on ceramic hip joints, in which the head and the cup can be hold to each other in the presence of lubricant. The aim of this study was to measure the suction force of MOM hip joints with different clearances and fluid viscosities.

Materials and Methods: CoCrMo hip prostheses of Ø50 mm with two diametral clearances of 100 and 200 microns were tested. A range of fluids were made using different ratios of deionized water and carboxy-methyl cellulose (CMC). The fluid viscosities ranged from 0.0011 to 0.3 Pa s determined by a cone-on-plate viscometer (Physica Rheolab MC100). Before the measurement, about 1 ml fluid was placed in the cup and the bearing surfaces of both the head and the cup were fully wetted by rotating the femoral ball in the cup. A pre-loaded 3kN was applied to push the head into the cup by a servohydraulic test machine, the femoral head was then lifted out of the cup at a rate of 2 mm/s and the maximum suction force value was recorded.

Results: Generally, the suction force increased with the increase of viscosity for both 100 and 200 microns clearances. In the lower range of the viscosity, the suction force increased rapidly, but when the viscosity reached a certain value it leveled off to about 190 N for the 100 microns clearance and 150 N for the 200 microns clearance. In the whole range of viscosity, the suction forces of 100 microns clearance were higher than those of 200 microns clearance and the differences were statistically significant (t-test, P< 0.01). In the lower range of viscosity (< 0.04 Pa s), the suction force of 100 microns clearance was more than two times higher than that of 200 microns clearance.

Discussion: For a MOM hip joint, suction force can be explained by the vacuum within the bearings. When the clearance is small and the lubricant viscosity is high, the edge of the bearing surfaces can be easily sealed off so that certain degree of vacuum can be produced between the head and the cup. In this test, the maximum suction force for the Ø50 mm MOM hip joint can be calculated as: F = (projected area) x (atmospheric pressure) = 196 (N). The results confirmed that the suction force of Ø50 mm components can not be higher than 196 N.

Although suction force may have a benefit in reducing the risk of dislocation, it may prevent lubricant recovery between the bearings and will influence the sliding resistance. If the suction force is too high, the head and cup can be held together such that the recovery of synovial fluid is restricted or impossible, even when the hip is not loaded during the swing phase. Both the clearance and the viscosity have a significant effect to determine the suction force and the lubrication of MOM hip joints. It is concluded that suction force is a factor to be considered during the selection of MOM hip joint clearance.

J. Boldt

Femoral stress shielding in cementless THA is a potential complication commonly observed in distally loading press-fit stems. This prospective study describes long-term femoral bone remodeling in cementless THA at a mean of 17 years (range: 15 to 20) in 208 consecutive fully HA-coated stems (Corail, DePuy Int. Ltd, Leeds, UK). All THA were performed by one group of surgeons between 1986 and 1991. The concept of surgical technique included impaction of metaphyseal bone utilizing bland femoral broaches until primary stability was achieved without distal press-fit. Radiographic evaluation revealed a total of five (2.4%) stems with periprosthetic osteolysis, which were associated with eccentric polyethylene wear. They were either revised or awaiting revision surgery. The remaining 97.6% stems revealed biologic load transfer in the metaphysis alone (52%) or in both metaphysis and diaphysis (48%). Stem survival of 97.6% after 15 to 20 years without stress shielding were considered to be related to: impaction of metaphyseal bone, bland broaches, HA coating, and unique prosthetic design.

C. Brockett A. Breckon J. Fisher G. Isaac A. Schepers S. Williams

Ceramic-on-metal (COM) bearings have shown reduced wear and friction compared with metal-on-metal (MOM) bearings in-vitro. Lower wear has been attributed to a reduction in corrosive wear, smoother surfaces, improved lubrication and differential hardness reducing adhesive wear. Clinical studies have also shown reduced metal ion levels in-vivo compared with MOM bearings. The aim of this study was to examine two explanted COM bearings (one head and cup, one head only), and to assess the effect of in-vivo changes on the wear performance of the COM bearings by comparing the wear of the explanted bearings with three new COM implants in a hip wear simulator.

Two 28mm diameter COM bearings were provided for analysis. These were visually examined and surface profilometry was performed using a 2-D contacting profilometer (Form Talysurf, Taylor Hobson, UK). Scanning electron microscopy was used to image the regions of transfer on the ceramic heads, and EDX to assess the transfer composition (Philips XL30 ESEM).

Hip simulator testing was conducted for 2 million cycles (Mc) comparing the explanted bearings with three new 28mm COM bearings. Tests were performed in a Prosim simulator (SimSol, UK), which applied a twin peak loading cycle, with a peak load of 3kN. Flexion-extension of − 15 to 30 degrees was applied to the head and internal-external rotation of +/− 10 degrees was applied to the cup, components were mounted in the anatomical position. The lubricant was 25% (v/v) calf serum supplemented with 0.03% (w/v) sodium azide and was changed approximately every 0.33Mc. Wear was measured gravimetrically at 0.5, 1 and 2 Mc.

Regions of material transfer, identified on both ceramic explant heads, were shown to be CoCr material by EDX analysis, suggesting metallic transfer from the metal cup. Profilometry traces across metallic transfer showed comparable surface roughness measurements compared to unworn material.

The overall mean wear rate for the new COM bearings at 2Mc was 0.047 ± 0.06mm3/Mc. The mean wear rate for the explanted head articulated with a new cup was slightly lower at 0.034mm3/Mc. The mean wear rate for the explanted head and cup was highest at 0.15mm3/Mc. It was noted that the explanted head/cup had higher bedding in wear compared with the other bearings, but still significantly less than a new MOM bearing (mean bedding-in wear rate 2.03 ± 2.59 mm3/Mc). The steady-state wear was comparable with the new bearings. As the orientation of these implants in-vivo was unknown, it is proposed that the elevated wear during bedding-in of the explanted head/cup bearing may be due to the alignment of the components. The wear rates of the explanted ceramic head against a new cup were comparable with the new bearings, suggesting that the presence of metallic transfer on the ceramic head does not adversely affect the wear behaviour of COM bearings.

D. Bosson P. Kägi Kaltenecker P. Massetti M. Rösgen D. Suvà

Introduction: The non-cemented CBC femoral stem has been used in total hip arthroplasty (THA) since 1997. This shaft exists in a standard and a lateralised version. The concept behind the design of the implant focuses on proximal anchoring and load introduction. Migration within the first two years after surgery is confirmed to be a good predictive value for early failure of the femoral component in THA. With respect to the different load transformation of the two stem types clinical outcome and migration were investigated.

Material and Methods: Prospective follow-up study of 170 patients (52% female) who received 172 non-cemented CBC femoral stems. THA was performed in eight European clinics between March 2001 and April 2005. 127 standard and 45 lateral CBC stems were implanted. 106 cases fulfilled the criteria having a series of four X-rays during a minimum period of two years. After a mean follow-up of 32.1 months in 106 patients migration was analysed using the EBRA system. The mean age at surgery was 66.9 years (range, 39.1–85.2 years). Mean body mass index was 27.8 kg/m2 (range, 16.3–42.6 kg/m2).

Results: The average subsidence is − 0.63 mm (− 0.36 mm lateral, − 0.75 mm standard group), 7.6% of the stems showed a subsidence of > 2 mm. None of the lateralised stems migrated > 3 mm, but there is no statistical significance between the groups. There is no evidence of association of high stem migration (> 2 mm) and lower scores. The HHS increased from a preoperative mean of 51 to 96 points after 5 years follow-up. At last follow-up patients with a standard stem had a flexion, external rotation and total ROM value of 105°, 29°, and 220°, respectively. Patients with a lateralised stem reached values of 115°, 36°, and 237°, respectively. Interestingly, 93% of patients with a lateral stem indicated putting on socks “easy”, compared to 81% in the standard group, although the BMI of patients with a lateralised stem was significantly (p=0.014) higher. No thigh pain was reported after 5 years follow-up. No revisions had taken place.

Conclusion: The prism-shaped geometry of the ribs promotes good osteointegration. The standard stems showed higher migration values compared to the lat-eralised stem, statistically not significant. Patients with a lateralised femoral component showed better results for ROM, flexion, external rotation, putting on socks. Putting on socks “easy” was positively correlated with a higher flexion angle. All patients undergoing THA showed significant improvements in postoperative functioning and activity level after the implantation of a CBC stem. None of the stems had to be revised.

C. Bragdon D. Burke A. Ekeledo A. Freiberg M. Greene W. Harris H. Malchau

Highly cross-linked polyethylene (HXLPE) is one of the most widely utilized bearing surfaces for total hip arthroplasty (THA). The first patients to receive XLPE will be 10 years post-op as of December 31, 2008. The purpose of this study is to report the long-term clinical and radiographic outcomes of patients implanted with HXLPE.

A group of 247 primary total hip replacements (224 patients) using HXLPE liners (Longevity or Durasul, Zimmer Inc.) with 22, 26, 28, or 32mm femoral heads were implanted between 1999 and 2001. Clinical evaluation measures included the Harris hip, EQ-5D, SF-36 functional scores, and UCLA activity scores. In addition to plain radiograph assessment, the computerized Martell method was used to measure head penetration over time. A matched group of 241 primary total hip replacements (201 patients) with the same head sizes using conventional polyethylene (PE) with a minimum of 7 years follow-up was used as a Martell method control group. The steady state penetration rate was defined as the slope of the linear regression line of the plot of head penetration from the 1 year film to each subsequent film to discount the early bedding-in process. A student’s t-test was used to compare wear rates between head sizes in each group, and a repeated-measures mixed model ANOVA was used to compare the groups for the 28mm head size.

There were no osteolytic lesions around the cup or stem, and no revisions were performed for polyethylene wear or liner fracture. Clinical outcome scores were averaged: Harris Hip 88.1±11.97, EQ-5D 74.0±27.0, SF-36 physical activity scores 53.3±8.4, SF-36 mental score 46.9±11.1, and UCLA activity 6.4±2.1. The steady state wear of the conventional polyethylene patients increased with time for both 26 and 28mm head sizes (0.144 and 0.127mm/year, respectively). No significant difference was found between the head sizes coupled with conventional polyethylene (p=0.14). Femoral head penetration in the highly cross-linked polyethylene did not increase over time after the first year. The steady state wear rates of HXLPE liners with 28mm or 32mm femoral heads were not significantly different than a slope of zero (p=0.54 for both head sizes).

Clinical follow-up results are typical of a primary THR patient population, and the radiographic results are excellent with no signs of peri-prosthetic osteolysis. Patients with PE show wear rates that are significantly different than zero indicating significant wear of the material. Conversely, patients with HXLPE display no measureable wear at 7–9 years as the wear rates were within the error detection of the Martell method. This long-term clinical and radiographic follow-up study for this new bearing material shows excellent clinical outcomes with very low in vivo wear.

A. Cobb R. Oakeshott T. O’Sullivan

Introduction: The DePuy ASRTM hip resurfacing system has been in clinical use since 2003. Its design features include a diametral clearance of 100–150 microns for optimal wear, and thinner components for improved bone preservation. Three of the six designer surgeons have pooled their clinical experience from three countries.

Methods: 1030 consecutive cases have been studied prospectively at annual intervals,. There were 379 females (average age 56.8 years, 16–71 years) and 579 males (average age 56.9 years, 21–75 years). 86% of patients had a primary diagnosis of Osteoarthritis. Follow up data has been collected by patient questionnaire, radiographs and clinical review. All retrieved specimens have been analysed

Results: The size of implants used varied from 46mm outside diameter acetabular component to 70mm

The Harris Hip Score improved from a pre-operative mean of 56.99 to 97.12 at the latest follow up, and 60% of patients were scored at 100. At the latest follow up, 91% of patients scored 6 or above on the UCLA activity score; indicating at least regular participation in moderate exercise.

There were no dislocations and no clinically evident DVT’s or PE’s

There have been 11 revisions for fracture (1.06%). Five of these were intra-operative fractures, and six of these took place in patients aged over 50years. Fractures occurred in 3.1% of patients 65 years or more and in 0.5% of patients under 65 years(P< 0.05). In addition there were three revisions for cup loosening (0.29%) all in women over 60 years, three for unexplained pain (0.29%), one for impingement and subluxation, and one for infection(0.1%) Five patients have died with the resurfacing in situ (0.51%), for unrelated causes.

The 3-year cumulative survival rate for all patients and all components was 97.4%. For 425 patients under 55 years the cumulative survival rate was 99.4%, aged under 65 years was 98.3%, and aged over 65 yrs was 94.8 %.

Discussion: Clinical results of this all-inclusive cohort of patients using a new resurfacing implant have been typical of other resurfacing systems and confirm excellent relief of pain and rapid return to an active lifestyle. The failures were evident within the first year after implantation, with no revisions occurring after 2 years. Cup loosening has been a rare complication associated with older females and only 0.29% of patients have undergone revision surgery for pain which could not be attributed to implant loosening or infection.

K. Corten W. Bartels J. Bellemans P. Broos G. Meermans J. Simon J. Vander Sloten

Introduction: The Birmingham Hip Resurfacing (BHR) is the most commonly used hip resurfacing for the treatment of hip osteoarthritis. The goal of this study was to evaluate how the surgeon could influence the biomechanical features of the navigated and non-navigated resurfaced proximal femur. METHODS 20 Cadaver hips were resurfaced with a BHR using femoral navigation. The native anteversion and neck shaft angle as indicated by the navigation system were used as a reference. The non-navigated femoral component jig was first placed in the “ideal” position aiming for 10° of valgus and neutral anteversion. The jig was then displaced 5mm in 4 directions. The anteversion and stem shaft angle (SSA) angle were measured for each position using the navigation system. A scaled XR was taken pre- and post-operatively. For statistical analysis, the paired Student’s T-test with a confidence interval of 95% and a significant p-value of p< 0.05 was used.

Results: The centre of rotation (COR) of the navigated resurfaced femur was 3,5 mm significantly (p=0,0006) more distal in the femoral neck than the native COR. This resulted in a 2.1 mm vertical caudal drop (vertical offset) and an average 2.7 mm lateral displacement of the COR (horizontal offset). The same measurements were done with 5° increments of the SSA from 120° to 140°. The vertical offset loss increased non-significantly (1.7 to 2.6 mm). The horizontal offset loss decreased non-significantly (3 to 2.2 mm). The native vertical and horizontal offset could be restored if 5 mm less bone was taken off the femur. The offset loss was significantly increased if 5 mm more bone than the normal reaming had been taken off (p< 0.0001). The “ideal” jig position on the lateral femoral cortex led to an average 137° SSA. Five millimetres of jig displacement on the lateral cortex in either direction did not lead to significant changes in the SSA or anteversion angles relative to the “ideal” position (all p> 0,13). Five millimetres of posterior displacement resulted in an average 139° SSA and 5,8° of anteversion in 95% of hips.

Conclusion: Surgical interventions can significantly change the biomechanics of the hip. Increasing the SSA with a fixed femoral head entry point, as often is done with navigation, does not significantly change the femoral offset. If the surgeon decides to take less bone off the femur, then the offset could be restored and even increased to 1 mm more than the native femur. If due to pathologic changes the bone loss would be increased to 5mm more than the “normal” bone loss, a significant offset loss of > 5 mm could be expected which might lead to detrimental biomechanical effects. The positioning of the jig is subject to surgical errors. The effect of a 5 mm error in either direction does not lead to significant changes in anteversion or SSA. Posterior displacement led to the most reproducible component positioning.

A. Bucknill R. De Steiger

Introduction: Perthes disease often leaves young adults with hip joint incongruency due to femoral head asphericity, (an extra-articular extrusion and a superior flattening). This causes femoroacetabular impingement, a reduced range of movement and early degenerative change. We report a novel method for restoration of femoral head sphericity and femoroacetabular congruency.

Methods: 2 males (21 & 22 years) presented with groin pain and severe hip stiffness after childhood Perthes disease. Imaging confirmed characteristic saddle shaped deformities of the femoral head, with central depression and overlying cartilage loss. A new method of treatment was proposed. Both cases were treated in the same manner.

Results: Using a surgical dislocation with the trochanteric flip osteotomy it was possible to remove the extra-articular bump to reduce femoroacetabular impingement. We found that the sphericity of the femoral head could be restored using a HemiCap partial resurfacing (Arthrosurface, MA, USA). The radius of the implant was selected to match that of the acetabulum.

Restoration of the height of the flattened portion of the weight-bearing surface of the femoral head reduces abnormal loading of the acetabular articular cartilage by improving congruency of the joint.

At a minimum of 3 year follow up both patients had sustained improved range of movement, pain and Oxford hip score. Repeated imaging shows no evidence of joint space narrowing or loosening at this stage.

Conclusion: We conclude that this novel treatment functions well in the short term. Further studies are needed to confirm that after Perthe’s disease this treatment results in improved long term durability of the natural hip joint.

K. Corten W. Bartels J. Bellemans P. Broos G. Meermans J. Simon J. Vander Sloten

Aim: Component positioning may be adversely affected by minimally invasive approach in total hip replacement due to restricted visualization. Problems with proper alignement are suggested to concern anteversion more than inclination and occur particulary in the lateral position.

Method: 53 patients were enrolled prospectively randomised to each group. First group (standard group, n= 30pts) underwent conventional total hip replacement in supine position and transgluteal approach and second group (MIS group, n= 23pts) underwent THR using minimally invasive anterior approach in lateral decubitus position Every group was operated on by two experienced senior surgeons. Desired cup position was 40°–45°inclination and 15–20° anteversion for the MIS group and 45°inclination and 15 ° anteversion for standard group. Postoperatively all patients had pelvic CT scan. Inclination and anteversion were determined by an independent observer using a 3-D model and planning software, the operative definition was used according to Murray.

Results: Mean inclination/anteversion in the MIS group was 39°(26°–50°)/25°(10°–47°), and 44°(29°–57°)/22°(1°–53°) within the standard group. Standard deviation for inclination was 7° for both groups, and 10° (MIS group) vs 14° (standard group) for anteversion.

The difference in the mean values regarding inclination was greater than would be expected by chance; there was a statistically significant difference (P = 0,010).

Discussion: In general cup positioning in both groups was less steep and more anteverted as presumed. The standard deviation for inclination was the same in both groups, but the standard deviation for anteversion was less in MIS group, that means less outliers regarding anteversion. Cup positioning in minimally invasive total hip replacement is safe compared to traditional approach.

Navigation technique was discussed to equalize the drawback of MIS. However, tools like imageless navigation may further improve the cup position even in traditional approach.

J. Bunn N. Bardakos R. Villar

There is a known association between femoroacetabular impingement (FAI) and osteoarthritis of the hip. What is not known is whether arthroscopic excision of an impingement lesion can significantly improve a patient’s symptoms.

This study compares the one-year results of hip arthroscopy for cam-type FAI in two groups of patients. The study (osteoplasty) group comprised 24 patients (24 hips) with cam-type FAI who underwent arthroscopic debridement with excision of their impingement lesion. The control (no osteoplasty) group comprised 47 patients (47 hips) who underwent arthroscopic debridement without excision of their impingement lesion. In both groups, the presence of FAI was confirmed on pre-operative plain radiographs. The modified Harris hip score (MHHS) was used for evaluation pre-operatively and at one year’s follow-up. Non-parametric tests were used for statistical analysis.

A tendency towards higher median post-operative MHHS scores was observed in the study than in the control group (83 vs. 77, p = 0.11). This was supported by a significantly higher portion of patients in the osteoplasty group with excellent/good results (83% vs. 60%, p = 0.043). It appears that even further symptomatic improvement may be obtained after hip arthroscopy for FAI by means of the femoral osteoplasty. When treating cam impingement arthroscopically, both central and peripheral compartments of the hip should always be accessed.

A. Desai T. Board B. Derbyshire A. Karva M. Porter

Introduction: The clinical results of the modular Charnley Elite total hip system have been the subject of some interest in recent years. Some studies have shown significant subsidence and rotational instability in some stems when used with low-viscosity cement. These unstable stems have been shown to fail early. This purpose of this study is to demonstrate our conflicting clinical results.

Materials and Methods: 616 modular Charnley Elite total hip arthroplasties were inserted between 1995 and 2002 at Wrightington Hospital, which is a tertiary referral centre and centre of excellence for joint replacement in United Kingdom. Both Consultants and trainees performed operations and a variety of surgical approaches were used. Normal viscosity bone cement was used in all patients. All patients were followed up prospectively.

Results: At mean follow-up of 8 years (range 5–12), 471 hips were available for review. 87 patients had died and 12 were lost to follow-up. 2.7% (13 cases) of femoral components and 2.9% (14 cases) of acetabular components had been revised for aseptic loosening. 10 hips (2.1%) underwent revision for deep infection and 2 (0.04%) for recurrent dislocation. The overall survival with aseptic loosening as an end point was 97% and for revision for any reason was 94.5%.

Conclusion: Our results show acceptable clinical survivor-ship for this implant when used with standard viscosity cement. This contrasts with the lower survivorship rates published by other centres. Our result should reassure patients and surgeons alike that this prosthesis can be associated with acceptable results in the medium term.

E. Dantonio P. Piciocco F. Santori Termine

Introduction: One of the problems of total hip arthroplasty (THA) is blood loss frequently leading to one or more postoperative blood transfusions. The use of fibrin sealants (Quixil) has already proved to be extremely effective in general surgery. Previous reports have shown remarkable benefits in liver resections, soft tissue tumor resections, adenoidectomy and tonsillectomy. The use of these sealants has been recently extended to total hip and total knee replacement surgey. We present our experience with Quixil in our orthopaedic practice.

Materials and Methods:Seventy-eight patients operated for primary THA between June 2006 and July 2008 were included in this study. Subjects with operative or transfusional risk increased by concomitant cardiovascular, autoimmune and/or metabolic pathologies were excluded from the study. All patients were operated by the same surgeon and received the same implant. Patients were randomly allocated in two groups: in the control group A (n=43) only conventional careful haemostasis was performed at the end of the procedure, whilst in the treatment group B (n=35) Quixil application was added. Postoperative haemoglobin (Hb) levels were measured at 12, 24 and 48 hours. Postoperative transfusions of autologous and/or heterologous blood were required when Hb was lower than 8.2 g/dl. The occurrence of haematomas or other complications was also evaluated.

Results: The use of Quixil in THA was associated with reduced postoperative blood loss, lower incidence of haematomas in the operated region, less pain and faster functional rehabilitation. The decrease of Hb levels measured at 12, 24 and 48 hours after the operation was higher in group A (10.3, 9.4, and 8.6 g/dL respectively) than in group B (10.6, 10.0, and 9.3 g/dL). Group A patients also showed a significant increase of blood loss in the drainages and a higher incidence of haematoma in the operated region. A cost benefit assessment of the use of Quixil in THA was also performed.

Conclusions: This is the first randomized study comparing in THA the results of patients treated with fibrin spray with patients treated with conventional haemostasis. A statistically significant reduction of blood loss was observed following the use of fibrin sealant, as well as a decreased requirement of auto/heterologous transfusions. The same treatment group also showed lower incidence of hematomas, less pain and faster rehabilitation. Based on these results, the possibility to perform THA without the requirement of autologous or heterologous transfusions can be predicted in patients with normal preoperative Hb levels and no concomitant pathologies.

S. Descamps

Introduction: The aim of this prospective, randomized, monocentric study was to compare wear of polyethylene when using a 28 mm diametre ceramic head versus a metallic head.

Material and Method: 226 THR performed between 1988 and 1990 were evaluated in 2005: 111 patients had died, 28 were lost of follow up and in 17 cases radiological assessment was not possible. 74 arthroplasties have been analyzed. In all cases, a straight femoral stem in protasul 10 (Zimmer), and a polyethylene cup sterilized under gamma radiation were used. In 37 cases the bearing surface used a metal head and in 37 cases a ceramic head. Radiolucent lines were analysed on AP x-rays. Aseptic loosening was defined according to Hodgkinson and Harris criteria. The penetration of the femoral head was measured with a special software (M.P.H. Wear) on digitalised x-rays.

Results: The two groups were statistically comparable (p = 0.0857). For metallic heads, linear wear was 0,102 mm/year (62.8 mm3/year volumetric wear). For ceramic heads, linear wear was 0,058 mm/year (volumetric wear 35.7 mm3/year. It represents a significant reduction (p = 0.0004) 44% of penetration. There was a penetration higher than 0.1 mm per year in thirteen cases of metal heads and in only one case of ceramic head. It was noted four aseptic loosening. In these four cases penetration was greater than 0.2 mm per year. In three cases, it was a metal head and in one case, a ceramic head.

Discussion: Our results are comparable to those found in the literature when the follow up is more than ten years as reported by Schuller, Oonichi and Hernigou. For authors with follow up shortest than ten years, it is reported identical outcomes between ceramic head and metal head (as reported Jenni, Devane and Sychterz).

Conclusion: This is the first randomized prospective study with two identical populations, showing a statistical significant difference of wear of polyethylene between ceramic and metallic prosthesis head.

D. De Kam N. Egmond J. Gardeniers W. Schreurs

Introduction: Loosening of acetabular components often lead to excessive bone defects. Managing severe acetabular bone loss in revision arthroplasty is a serious or sometimes even an impossible challenge. Several authors even have published disappointing results. The purpose of this study was to evaluate the long term clinical and radiographic results of acetabular reconstruction with the use of bone impaction grafting and a cemented cup in cases with very large acetabular defects.

Methods: In this historical prospective study, 27 hips (25 patients) with large acetabular defects (AAOS type III and IV, Paprosky type 2B to 3B) were reviewed. In all cases an extensive reconstruction with the use of bone impaction grafting and a large rim wire mesh (Stryker Howmedica, Newbury, UK) was performed. All patients have had a six week bed rest period or 3 weeks of bed rest with 3 weeks of non-weight bearing mobilization. No patient was lost to follow-up. Three patients died during follow-up, the cause of death was in all cases not related to the surgery. All medical files and radiographs were analyzed.

Results: After a mean follow-up of 8.8 years (range 4 to 14.1), 3 hips needed repeat revision and another 2 hips were considered radiographic loose. Reasons for repeat revision were: septic loosening after 4.7 years, aseptic/traumatic loosening after 5.8 years and a broken-out reconstruction after 5 weeks because lack of compliance of the patient.

Kaplan-Meier analysis showed a ten-year survival rate of 87% (95%C.I. 73.1–100%) with end point acetabular revision for any reason and 95% (95%C.I. 86.2–100%) with end point acetabular revision because of aseptic loosening. The mean preoperative HHS was 55 points and improved to 72 points postoperative.

Conclusion: Acetabular reconstruction using impaction bone grafting and a cemented cup can produce favorable long-term results in patients with massive acetabular bone-stock defects. It is the only revision technique which restores massive acetabular bone stock loss. However, in these extensive defects it is a technical demanding procedure and should only be used by surgeons with extensive experience with this technique.

B. Derbyshire B. Derbyshire

Introduction: Although acetabular cup wear is usually reported in terms of penetration (measured from radiographs), true wear – wear volume – depends on several variables. This study examined how these variables affect the calculation of the theoretical wear volume at the low wear penetrations found with highly cross-linked polyethylene (XLPE) cups.

Method: A computerised numerical analysis technique was used to calculate the “exact” theoretical wear volume of an acetabular cup under a variety of circumstances, including: variations in wear direction, head size, and initial radial discrepancy (i.e. initial difference between socket and head sizes). The validity of published wear volume formulae was assessed. The effects of creep and wear measurement error were also assessed.

Results: For a given wear penetration, as the wear direction (relative to the cup base) increased, the wear volume increased – almost doubling as the direction reached 60°. The initial radial discrepancy made a substantial difference to the calculated wear volume at penetrations less than 1 mm. At low penetrations, its neglect caused an overestimation of wear volume of well over 100%. Creep volume was substantially overestimated because of this. An analysis of wear measurement error showed that the calculation of wear direction (an important variable in the calculation of wear volume) was severely affected at low penetrations by the precision of penetration measurements. For a penetration precision of ±0.25 mm (as reported for the Martell Hip Analysis Suite), the maximum wear direction error was ±39° at a penetration of 0.4 mm. When the precision was ±0.1 mm (as with RSA), this reduced to ±14°.

Discussion: Many studies have shown the superior wear performance XLPE acetabular cups compared with standard PE cups. In those studies, comparison in terms of wear penetration was possible because of the large difference in penetrations between the two groups. This study has shown that true wear (wear volume) is significantly affected by wear direction (relative to the cup), the initial radial discrepancy, and the femoral head size. The differences in penetrations when comparing two types of XLPE cups would not be so large and it is therefore necessary to compare the two groups in terms of wear volume. Published formulae for estimating the wear volume of acetabular cups do not take the initial radial discrepancy into account, and they can substantially overestimate the wear volume in the penetration range encountered with XLPE cups. Creep volume is also greatly overestimated. Since wear volume varies with wear direction, the wear measurement technique must be capable of accurately determining the wear direction. This analysis has shown that only RSA might have sufficient precision to determine the wear direction at the medium-term penetrations encountered with XLPE cups.

B. Espehaug B. Engesaeter Lars O. Furnes I. Havelin Leif

Background: Few studies have compared long-term survival for different types of cemented primary total hip arthroplasties, and prostheses are still used without adequate knowledge of their endurance.

Patients and Methods:We compared the 10 most used prosthesis brands cemented with Palacos or Simplex in primary THAs reported to the Norwegian Arthroplasty Register in 1987–2007, totaling 62305 operations. Survival analyses with revision as endpoint (any cause or aseptic loosening) were performed with Kaplan-Meier and multiple Cox regression analyses. Risk estimates were established for different time intervals after the primary operation (0–5 years, 6–10 years, > 10 years).

Results: At 20 years, the Kaplan-Meier estimated revision per cent with any revision as endpoint was 15 % (95 % CI: 14–17), and with revision due to aseptic loosening as endpoint, 11 % (9.8–13). The adjusted revision percentage for aseptic loosening at 10 years could be established for 7 of the prostheses and varied from 0.4 % (0.0–0.8) for the Lubinus SP (I, II) to 6.6 % (4.1–9.0) for the Reflection all poly/Spectron-EF (cup/stem) combination. Only Charnley, Exeter, Titan and Spectron/ITH could be compared beyond 10 years. While long-term results were similar for these stems, Exeter (RRcup = 1.7, p = 0.001) and Spectron (RRcup = 2.4, p = 0.001) cups had higher revision rates due to aseptic loosening than Charnley cups. Comparing Charnley with prostheses with shorter follow-up, we observed an increased revision risk for aseptic loosening in the 6–10 year time interval also for Reflection all poly/Spectron-EF (RRcup = 5.5, p< 0.001; RRstem = 2.4, p< 0.001), Elite/Titan (RRcup = 7.5, p< 0.001; RRstem = 5.4, p< 0.001) and for the cup in the Reflection all poly/ITH combination (RRcup = 2.1, p = 0.03). Only the Lubinus SP had statistically significant better results than the Charnley prosthesis (RRcup = 0.2, p = 0.09; RRstem = 0.1, p = 0.01). Since several of the prostheses were introduced in recent years, analyses were also performed on operations from 1998 and onwards. Except for Lubinus SP that now had results similar to that of Charnley, differences in survivorship as compared with Charnley were enhanced. This was mainly due to a marked improvement in results for the Charnley prosthesis.

Conclusion: We observed in the Norwegian Arthroplasty Register clinically important differences among cemented prosthesis brands and identified inferior results for previously undocumented prostheses. Overall results at 20 years were, however, satisfactory according to international standards.

B. Dilaveroglu O. Erceltik M. Ermis E. Karakas

The adult congenital hip dislocations and dysplasias have been previously classified by Eftekhar, Crowe et al., Hartofilakidis et al., Kerboul et al. and Mendes et al. The most conventient and widely used one is the Hartofilakidis and Crowe classification. Three different types of congenital hip disease in adults have been distinguished by Hartofilakidis and et al. based upon the position of the femoral head relative to the acetabulum: dysplasia; low dislocation; and high dislocation. All these classification systems are only radiological and does not highlight the operative technique in detail and the complications that we can observe perioperatively. Our classification system is also a radiological classification system but more useful for predicting the difficulty of the operative procedure and selecting the right operative method. In our classification system; at type I; dysplasia and less than 25% subluxations, we divided type I in to three subgroups, at type Ia, only dysplastic acetabulums, at type Ib, with elephant’s trunk type osteophyte formation and at type Ic, curtain type osteophytic formations, we included dysplasia and less than 25% subluxations in the same group because of operative technique similarities. At type 2; subluxations between 25% and 75%, we divided type II in two subgroups according to the angle between the inner margin of the teardrop and superior border of the acetabulum, at type IIa, the angle is less than 60°, at type IIb, the angle is greater than 60°, it’s important to show femoral allogreft usage requirement, at type 3; subluxations greater than 75%, at this type there will be no need of femoral allogreft usage but extra-small reamer usage for forming a suitable acetabular bed. At type 4; luxations greater than 100%, we also divided type IV in to two subgroups accordind to the distance between superior margin of true acetabulum and trochanter major line, at type IVa, < 2.5 cm, at type IVb, > 2.5 cm. It’s also important to make the decission of shortening. To form this classification three observers with different levels of training independently classified 412 dysplastic hips (operated between1995 and 2005) on 380 standard anteriorposterior pelvis radiographs, retrospectively according to the criteria defined by us. To assess intraobserver reliability, the measurement was repeated 3 months later. Statistical analysis was performed by calculating the weighted kappa correlation coefficient. System showed good inter- and intraob-server reliability for use in daily practice. Eventually, we determined a significant correlation between the aplied surgical procedures and classification. As a conclusion, we believe that our classification system of osteoarthritis secondary to developmental dysplasia of the hip in adult patients guides the surgical procedure more effectively than the other classification systems.

M. Fehm D. Burke J. Geller J. Huddleston H. Malchau

Background: Abductor failure after total hip arthroplasty is a rare but debilitating problem. The diagnosis is difficult, and when recognized, there are few successful treatment options. The purpose of this study is to review our experience with a new surgical technique using fresh-frozen Achilles tendon allograft with an attached calcaneal bone graft to reconstruct a deficient abductor mechanism after total hip arthroplasty.

Methods: From 2003 to 2006, we performed seven abductor reconstructions with Achilles tendon allograft for patients with abductor deficiency after total hip arthroplasty. Four patients had a prior posterior approach and three had a prior anterolateral approach. At a mean of 29 months from index procedure, all seven patients suffered from symptoms of lateral hip pain and abductor weakness as documented by positive Trendelenburg sign, limp, and limited motor strength with side-lying abduction. Hip arthrograms were obtained in five of seven patients.

Results: The average pre-reconstruction Harris Hip Score was 34.7 and average pain score was 11.4. All five hip arthrograms showed extravasation of dye over the greater trochanter, confirming the diagnosis of a bald greater trochanter and massive abductor loss found at time of surgery. At a minimum 24 month follow-up and an average follow-up of 31 months, the post-reconstruction Harris Hip Score was 85.9 and the average pain score was 38.9.

Conclusions: Abductor reconstruction with Achilles tendon allograft using calcaneal bone block fastened to the greater trochanter has offered significant relief of pain and improvement in function at early follow-up in this series of patients.

G. Flivik U. Kesteris A. Lindstrand C. Olsson

Collarless, polished and tapered cemented stems are nowadays commonly used in hip surgery. Normally, a hollow centralizer is applied to the stem tip to allow the prosthesis to sink in the cement mantel in the event of creep and loosening between stem and cement. It is believed that in this way the stem will stabilize and regain its tight bond with the cement. The prosthesis MS-30 (Zimmer) is collarless, polished and triple tapered and has a hollow centralizer, but was previously used with a solid centralizer. We hypothesised that these types of stems, exemplified by the MS-30, used with a hollow centralizer would sink more but stabilize better, become more stable in the important rotational migration and retrovert less than with a solid centralizer. In a prospective, controlled clinical study we randomised 60 patients with primary coxarthrosis into either hollow or solid centralizer used with the MS-30 stem. The effect was evaluated for a 2-year follow up period by repeated RSA examinations, conventional radiographs and clinical follow-ups with the questionnaires WOMAC, SF-12 and Harris Hip Score.

The RSA results showed small early migration in both groups and almost all of it occurred within the cement mantle, i.e. between stem and cement. The group with hollow centralizers migrated distally significantly more than the group with solid centralizers (p< 0.0001) (1.40 mm vs 0.28 mm). In rotation, however, there was no difference (retroversion 0.99° and 0.94°). Neither was there any difference regarding clinical outcome and questionnaires.

As expected the group with hollow centralizers migrated more distally, in the same magnitude as reported in earlier RSA studies for the conceptually similar prostheses Exeter and C-stem. Interestingly, there was no difference regarding the rotational behaviour, and both groups showed less retroversion than reported in the earlier reports. MS-30 seems to have a design that regardless of centralizer type well withstands rotational motion within the cement mantle. This study cannot fortify the need for a hollow centralizer for this collarless, polished and triple tapered prosthesis.

C. Fraitzl R. Buly L. Castellani L. Moya T. Wright

Introduction: The S-ROM® modular hip system (DePuy, Warsaw, IN) has a cementless femoral component made of titanium alloy with a distally fluted and slotted stem. The stem mates with a sleeve that is implanted in the proximal femur. No reports exist in the literature of intraoperative difficulties in disengaging the sleeve-stem interface. Induced by the impossibility of intraop-eratively disconnecting the sleeve-stem interface in one patient leading to unintended revision of a well-fixed sleeve, we asked whether in vivo evidence for fretting or mechanically-assisted crevice corrosion of the mating surfaces could be found in retrieved components and whether its appearance is influenced by factors such as length of implantation.

Methods: The sleeve-stem combinations were retrieved from 1998 to 2008 as part of our IRB-approved implant retrieval system. Twenty-two sleeve-stem interfaces of S-ROM® femoral components were located in our retrieval collection. Seven sleeve-stem combinations were still mated when retrieved; 2 were disengaged by hammering the sleeve away from the stem, the remaining 5 had to be cut longitudinally with a diamond saw to disengage the sleeve from the stem. All disengaged sleeves were also cut to expose their inner surfaces. The surfaces of the taper region and the corresponding inner surfaces of the split sleeves were inspected macroscopically and assigned to the following groups: severe corrosion; moderate surface changes; and few or no evidence of surface changes. Microscopic examination was used to grade fretting and corrosion using an established subjective scale (Goldberg et al., 2002). The surface of the taper and the sleeve was divided into 12 regions each and every region was evaluated separately. The mean score of all 24 regions was calculated and opposed to the implantation time of the respective femoral component. Statistical analysis of correlation between the mean score and implantation length was performed using the Pearson product moment correlation. Additionally, the surface of the taper regions of 6 specimens underwent detailed analysis with SEM and EDAX.

Results: In 3 of 22 sleeve-stem interfaces severe corrosion accounting for at least 80% of the surface area was detected. Furthermore, ten sleeve-stem interfaces showed moderate surface changes. Nine sleeve-stem interfaces showed few or no surface changes. There was no correlation between presence of corrosion and implantation length (r=0.13; p=0.56).

Conclusion: In 3 of 22 retrieved sleeve-stem interfaces severe corrosion was found at the stem-sleeve interface. Though apparently not the rule, failure to disengage the stem from the sleeve undermines an important advantage of this type of modularity in total hip replacement and suggests that alternative procedures should be anticipated when planning for revision surgery of such (or a similar) modular femoral component.

G. Friedl R. Aigner R. Radl P. Rehak R. Windhager

Despite great progress in implant design, materials and new implantation techniques aseptic loosening is still the most frequent cause of implant failure in THA, which was found to be increased especially in patients with osteonecrosis of the femoral head (ON-FH). While a direct link between aseptic loosening and periprosthetic bone loss still remains elusive, there is plentiful evidence for a close association with early migration of implant components. Although the beneficial effect of bisphonates on periprosthetic bone mass is well established, little is known to date about their effects on implant migration. This is an important issue, because successful prevention of early implant migration would provide strong evidence of a beneficial effect on the survival rate of THA. Previously, Krismer et al. found that a total migration of the cup of ≥ 1mm and a subsidence of ≥ 1.5mm 2 years after surgery was highly predictive for aseptic implant failure of THA within 8 to 10 years.

Fifty patients with end-stage ON-FH were consecutively enrolled to receive either 4mg of ZOL or saline solution (CTR) in a double-blind fashion. Radiographs standardized for EBRA-digital analysis were performed at each follow-up exam at 7 weeks, 6 months, 1 year, and yearly thereafter. The minimum follow-up period was 2 years (median follow-up: 2.8 years). Migration of the acetabular and femoral components was analyzed with the EBRA-digital software (University of Inns-bruck, Austria) independently by 3 investigators fully blinded to randomization.

Within the placebo group, distal migration of the stem (subsidence) steadily increased up to −1.2mm ± 0.6 SD at 2 years after THA without reaching a plateau phase (P< 0.001, Friedman ANOVA). Less but a nearly curvilinear migration pattern was found for the acetabular components, with a transverse migration of 0.6mm ± 1.0 SD and a vertical migration of 0.6mm ± 0.8 SD at 2 years (P< 0.001, Friedman ANOVA). Treatment with ZOL effectively minimized the migration of cups in both the transverse and vertical direction (0.15 mm ± 0.6 SD and 0.06 mm ± 0.6 SD, respectively, P< 0.05, ANOVA), and a trend to a decreased subsidence was also found for stem migration (−0.91 mm ± 0.51 SD; P=0.11, ANOVA). In addition, total cup migration exceeding 1mm at 2 years was significantly reduced by ZOL in 8 patients (12 vs 4 in CTR vs ZOL, respectively) as was also found in 6 patients for subsidence (≥ 1.5mm in 9 vs 3 patients in CTR vs ZOL, respectively) (P< 0.05, Fisher’s exact).

This is the first clinical trial reporting that a single infusion of ZOL suffices to improve initial implant fixation in THA. Based on best evidence available to date, this new concept shows great promise of improving the long-term outcome in THA and should be given attention in long-term trial.

E. Garcia-Cimbrelo A. Cruz-Pardos E. Garcia-Rey

Introduction: Severe stress shielding and radiographic cortical changes in the proximal femur are frequent after extensively porous-coated stem in revision surgery. We have analyzed the evolution of the femoral cortex at different levels and related factors.

Material and Methods: We assessed 95 extensively porous-coated stems in revision surgery with a minimum 5-year follow-up (Mean 10.2 years). 77 hips were revised due to aseptic loosening and 18 due to periprosthetic fractures. Extended osteotomy was used in 29 hips. No cortical struts were used. Preoperative and postoperative osteoporosis was graded according to Moreland and bone defect according to Paprosky. Femoral cortex width was measured at different levels in the immediate postoperative radiograph, at 3, 6 and 12 months and at the last follow-up.

Results: There were 2 re-revisions for aseptic loosening. Radiographic ingrowth fixation was more frequent in minor intraoperative bone defects (p=0.011). Preoperative osteoporosis was related to the width of the medial and lateral cortex. Medial cortical thickness increased at different levels with a mean increase of 13.4% (p< 0.001) and the lateral cortical thickness showed a mean decrease of 2.7% at the proximal level. The femoral medial cortex tended to show a higher slope trend in periprosthetic fractures (p=0.015). The outside femoral diameter increased more rapidaly with an extended trochanteric osteotomy (p=0.007). The slope trend of the lateral and medial cortex was significantly higher at proximal levels in hips with a 10-inch stem (p=0.015).

Conclusions: Although without clinical relevance at the end of follow-up, femoral medial cortical thickness increased while frequently lateral cortical thickness decreased over time after an extensively porous -coated stem in revision hip surgery.

P. Georis P. Gillet

Cross-linked PE theoretically allows the use of thinner inserts and larger diameter heads than UHMWPE. This participates in reducing the risk of dislocation. Durasul® liners have demonstrated improved wear performance over UHMWPE in laboratory testing. This may also result in lower migration and loosening rates of the implants.

Our first aim was the assessment of linear wear of Durasul® inserts associated with Protasul® 36 mm CoCr prosthetic heads. We compared the results with our data on 28 mm CoCr and Biolox heads.

The first hypothesis was that Durasul® inserts combined with a 36 mm CoCr head would not produce more wear than would Durasul® inserts in association with a 28 mm CoCr prosthetic head.

The second hypothesis was that Durasul® inserts combined with a 36 mm head could even produce less wear than a UHMWPE liner in association with a Biolox® 28 mm prosthetic head.

The second aim was to correlate cup migration with polyethylene wear rate.

111 patients (37 men, 74 women) with a median age of 74 years (range: 54–90) received Durasul® liners in an Allofit Ti cup and Protasul® 36 mm heads. They were followed for minimum 5 years.

16 patients with a Durasul® liner received a 28 mm Protasul® head (control A) and 40 received a UHMWPE liner combined with a Biolox® 28 mm head (control B).

Patient outcome was assessed with the HHS. PE wear assessment was performed using a specific analysis model created in the Imagika® software. Cup migration was evaluated using the EBRA-CUP® software.

The preoperative and last follow-up HHS were 50.4+/−10.5 and 97.5+/−5.5 respectively.

The bedding-in penetration of the prosthetic head were 0.054+/−0.009 mm (Durasul®, 36 mm CoCr head), 0.056+/−0.008 mm (Durasul®, 28 mm CoCr head) and 0.057+/−0.010 mm (UHMWPE, Biolox® 28 mm head). There were no significant differences between the different groups.

The annual linear wear rates were 0.029+/−0.003 mm (Durasul®, 36 mm CoCr head), 0.032+/−0.014 mm (Durasul®, 28 mm CoCr head) and 0.087+/−0.056 mm (UHMWPE, Biolox® 28 mm head). There were no significant differences between Durasul® groups, but a P value of 0.00027 was observed between the study group and the control B group.

We didn’t observed cup migration in our patients (0.09 mm medially and 0.13 mm cranially).

Patient satisfaction was high with improvement of quality of life.

Combined with the Durasul® inserts used in this series, 36 mm CoCr prosthetic heads had no unfavourable influence on the wear assessment compared with the use of 28 mm prosthetic heads. The annual linear wear rate of Durasul® liners was 37.84% of that seen with the UHMWPE liner. The absence of cup migration at last follow-up may indicate very low PE wear rates.

A. Fritsche R. Bader W. Kolp W. Mittelmeier I. Tokar

Introduction: To obtain secondary implant stability of acetabular press-fit cups, sufficient primary stability is essential. The aim of this study was to investigate the influence of cup insertion force and bone quality on the primary implant stability.

Materials and Methods: The experiments were carried out using two commercially available press-fit acetabular cups (Trident PSL, Stryker und EP-FIT PLUS, PLUS Ortho-peadics), comparable in design and with identical diameters, which were inserted axially into artificial bone by a female and a male surgeon. Two bone substitute material models were used. To imitate osteoporotic bone, a PMI-model (ROHACELL 110 IG, Gaugler & Lutz oHG) was employed. To simulate sclerotic bone, a composite-model made of a PMI-bloc with a 4 mm thick PVC-layer (AIREX C70.200, Gaugler & Lutz oHG) was used. The cups were inserted using an insertion device, equipped with a force sensor, and an 1100 g surgical hammer. Additionally, all experiments were carried out using a dynamic testing machine (25 kN, Instron) utilising insertion forces of 4.0 kN and 8.0 kN respectively. Primary implant stability was determined via lever-out tests using a static universal testing machine (Z050, Zwick/Roell).

Results: On average an insertion force of 4.8 kN (female) and 7.0 kN (male) using the PMI-model and 6.2 kN (female) and 7.5 kN (male) for the composite-model was assessed for the two different surgeons. The machined forces averaged 3.8 kN and 7.9 kN.

Lever-out-moments of 17 Nm were determined for both the PMI- and composite-model for the female surgeon using the PSL cup, whereas 27 Nm and 70 Nm, respectively, were reached for the EP-FIT shell.

For the male surgeon using the PSL cup, lever-out moments of 15 Nm and 30 Nm for the PMI- and composite-model respectively were determined. Insertion of the EP-FIT cup resulted in lever-out moments of 10 Nm using the PMI-model and 82 Nm using the composite-model.

The low machined insertion force led to average lever-out moments of 34 Nm for the PSL and 71 Nm for the EP-FIT cups using the composite-model. For the high machined force, the highest lever-out moments of 44 Nm and 99 Nm for the PSL and EP-FIT shells respectively were determined.

Conclusion: Using the composite-model (sclerotic bone), higher insertion forces lead to higher lever-out moments and hence higher primary implant stability for both tested cups. However, a high, non axial applied force can result in loss of stability using the PMI-model (osteoprotic bone). Compared to the manually inserted acetabular cups, the machined insertion resulted in higher primary stability for both implants and artificial bone types.

L. Gerdesmeyer H. Gollwitzer R. Gradinger M. Rudert

Background: A total hip arthroplasty system with 3-dimensional interconnecting surface topography was developed for optimum osseous integration and long term stability. The present study was performed to assess long-term implant survival and function.

Methods: We prospectively studied a consecutive series of 100 cementless total hip arthroplasties in 94 patients using the ESKA GHE cementless spongy metal hip replacement. Study end-point was implant revision, and both function as well as satisfaction with treatment outcome was assessed after a mean follow-up of 18 years.

Results: Mean age at the time of operation was 47 years [range 18–65]. Seven patients were lost to follow-up. 11 patients had died for unrelated reasons at 14.1 ± 4.3 years after surgery with all 14 hip replacements in situ. Consequently, at a mean follow-up of 18 years [15.3 – 20.3], 74 patients (74 hips) could be included in the final analysis. Survival with aseptic loosening as the endpoint was 95% for the femoral component and 85% for the acetabular component. Two cups had to be revised for recurrent dislocation, resulting in a total implant survival at follow-up of 95% for the femoral component and 81% for the acetabular component.

Very good functional results were obtained with an improvement of the mean Merle d’Aubigné score from 9.5 ± 2.0 at baseline to 15.0 ± 3.1 at follow-up, and 86% excellent or good results (McNab score). Satisfaction with treatment outcome was high, and 96% of patients would recommend the performed procedure to a friend.

Conclusion: Excellent survival rates were observed in a young patient population after cementless hip arthroplasty with the GHE spongy metal hip replacement at a mean follow-up of eighteen years. Thus, modern cementless hip replacement shows long-term survival and might be favourable in young and active patients.

L. Gomes A. Cervieri S. Griza T. Strohaecker

This experimental study aimed to determine the pattern of load transmission to the cement mantle and to the outer surface of six composite femurs implanted with three different designs of polished, collarless, tapered stems (2 specimens for each type), before and after the removal and reinsertion of the same stem. Strain distribution was measured with uni-axial and tri-axial strain-gauges before, after implantation and after reinsertion of the stems. Additionally, axial and rotational stability of the stem relative to the cement mantle and to the composite were determined by means of one extensometer and two linear variable displacement transducers (LVDT’s). All specimens were loaded simulating single leg stance of 3,25 body weight for a 708N subject. Static load were applied to the intact femurs, after implantation, after cyclic loads of 1Hz up to 3x10 5 cycles followed by 7Hz up to 1million cycles, and after reinsertion. Variation of strain and micro-motion during static loading following reinsertion were determined by the average of 10 cycles, with each cycle being represented by the difference between maximum and minimum values.

Linear regression analysis of the strain values obtained by the sensors in the cement mantle after reinsertion plotted with regard to the strains obtained initially by the same sensors before and after cyclic loading showed coefficients R2= 0.95; 0.91,with slopes of 1.12 and 1.03 respectively. The values of static strain of all sensors plotted with regard to values of initial static strain showed a very strong positive correlation (R2 = 0.98; slope = 0.96).

These findings support the concept that reinsertion of same design and size polished, collarless tapered stems may not alter the pattern of load transmission and stability at the interfaces between stem/cement, and cement/bone to the outer surface of bone. The mechanical conditions at the interfaces are restored with no need for additional cement during reinsertion if the cement envelope is preserved. The same mechanical principle that maintains the stability of the stem during subsidence for ”force-closed” fixation, may keep the stability of the interface following reinsertion. For these reasons this procedure may not be applicable to designs with texturing or pre-coating, and cylindrical-collared designs because in such conditions (“shaped-closed “fixation) the mechanics of stem/cement interface may not be restored.

J. Goosen B. Kollen A. Kums C. Verheyen

Background: The purpose of this systematic review was to determine the clinical and radiologic benefit of hydroxyapatite-coating in uncemented primary total hip arthroplasty.

Methods: A database of Medline articles published up to september 2007 was compiled and relevant references screened. Studies that satisfied the following selection criteria were included:

a proper randomized controlled trial;

based on a total hip prosthesis with or without hydroxyapatite-coating with one identical geometry;

primary uncemented total hip arthroplasty; and

used objective, validated clinical and radiographic outcome measurements.

Results: Eight studies, involving 857 patients, were included in the review. Observer agreement was 94%, while the interobserver reliability was K =.799 (.611 −.987); P < 0.001. Pooled analysis for Harris Hip Score as a clinical outcome measure demonstated no advantage of the hydroxyapatite coating (WMD: 1.49, CI: −2.32 to 5.31, P = 0.44). Radiologically, both groups showed equal presence of endosteal bone ingrowth (RR: 1.04, CI: 0.88 to 1.23, P = 0.66) and radio-active lines (RR: 1.02, CI: 0.90 to 1.16, P = 0.74) in the surface area of the prosthesis. Pooling on stem subsidence was not feasible, because three different measurement techniques were used.

Conclusion: Based on eight randomized controlled trials, this meta-analysis demonstrates no clinical nor radiological benefits to the application of a hydroxy-apatite coating on a femoral component in uncemented primary total hip arthroplasty.

G. Grabmeier C. Berger A. Engel S. Newrkla S. Seidl

Background: Patients with femoral head osteonecrosis usually tend to be younger and more active when compared with osteoarthritis patients. Second generation metal-on-metal THA was reintroduced to reduce poly-ethylene-induced wear debris, and therefore increase longevity of implants.

The aim of this retrospective study was to compare full blood cobalt-chrome levels, patient activity, clinical/radiological outcome and implant survival in patients with osteonecrosis and osteoarthritis after a minimum follow up of 12 years.

Methods: Full blood cobalt-chrome levels of a consecutive series of 125 patients, consisting of 40 patients (38 male, 2 female, average age 35 years, range 28 to 46 years) with osteonecrosis (ON group) and 85 patients (60 male, 25 female, average age 58 years, range 52 to 68 years) with osteoarthritis (OA group) as primary diagnosis were retrospectively compared. Patient activity level was assessed using UCLA Score and clinical outcome was evaluated using HHS. Radiological outcome and implant survival (Kaplan Meyer analysis) was determined in both groups.

Results: Patients with osteonecrosis of the femoral head showed significant higher UCLA scores when compared to OA group (4 versus 7) (p < 0.05). Despite this higher patient activity no significant difference was found between cobalt-chrome full blood levels (2.1/1.6 μg/l, ON group, 1.9/1.8 μg/l OA group, respectively) (p > 0.05). No positive correlation between patient activity, acetabular cup abduction angle and cobalt-chrome levels was found (r2 < 0.01). Clinical and radiological outcome were equal in both groups. Harris hip score was 91 points in the OA and 92 in the ON group (p > 0.05). Average cup inclination angle was 47° (range 32° to 55°) and 44° (range 30° to 56°) respectively (p > 0.05). Implant survival at 12 years follow up was 96% in the OA and 97% in the ON group.

Conclusion: After a minimum follow up of 12 years, we could not find increased metal levels in osteonecrosis patients when compared to the osteoartrithis group. Regarding our clinical and radiological outcome we cannot confirm previously published reports showing suboptimal results of THA in patients with osteonecrosis. Implant survival data did not differ among both group.

Metal on metal THA seems to be an effective and safe treatment option for these patients.

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G. Grabmeier C. Berger A. Engel S. Newrkla S. Seidl

Background: The Duraloc cup is a frequently used metal backed hemispheric porous-coated cementless acetabular cup. Published radiological data on loosening rates remain contradictory. Despite to this contradictory radiological data is the good clinical performance of this cup reported by many authors. The aim of our study was to evaluate radiological outcome (cup migration, acetabular abduction angle, cup anteversion) and possible correlation to clinical data after 12 years.

Methods: Migration analysis of 40 cementless Duraloc 100 cups (38 patients, average age 57 years, range 52 to 68years, 25 male, 13 female) could be retrospectively performed after a 12 year follow up using Einzelbild-Roentgen-Analyse (EBRA) software. An average of 5 standardised anteriorposterior radiographs (range 4 – 8) could be evaluated. Clinical outcome was assessed using HHS score. Cup migration, acetabular abduction angle, cup anteversion, heterotocpic ossification and wear were determined. Statistical evaluation was performed using Mann- Whitney - U test and correlation analysis.

Results: At 12 years follow up the average horizontal migration was 1.51 mm (range 0 to 8.5 mm) and the average vertical migration was 1.44 mm (range 0 to 4.5 mm). The average cup abduction angle was 48° (range 30° to 58°, average cup anteversion was 16° (range 12 to 25°) Average wear of the polyethylene liner at latest follow up was 1.5 mm (range 1.1 to 2.1). Harris hip score improved from average 41 (range 30 – 55) to 90 (range 77 to 95) at latest follow up. We could not find any significance difference between cup migration and gender (p > 0.05). There was no positive correlation between clinical scores and migration data found (r2 = 0.01). The cup diameter however showed positive correlation with cup migration (r2 = 0.8).

Conclusion: Our study shows good radiological and clinical results of the Duraloc cup after 12 years. Radiological migration data did not show any correlation with clinical results. A greater cup diameter however is a risk factor for higher migration.

G. Grammatopoulos D. Beard C. Gibbons H. Gill R. Gundle P. Mclardy-Smith D. Murray H. Pandit D. Whitwell

Metal on Metal Hip Resurfacing Arthroplasty (MoMHRA) has gained popularity due to its perceived advantages of bone conservation and relative ease of revision to a conventional THR if it fails. Known MoMHRA-associated complications include femoral neck fracture, avascular necrosis/collapse of the femoral head/neck, aseptic loosening and soft tissue responses such as ALVAL and pseudotumours. This study’s aim was to assess the functional outcome of failed MoMHRA revised to THR and compare it with a matched cohort of primary THRs.

Method: We have revised 53 MoMHRA cases to THR; the reasons for revision were femoral neck fracture (Fracture Group, n=21), soft tissue reaction (Pseudotumour Group, n=16) and other causes (Other Group, n=16: loosening, AVN and infection). Average followup was 2.9 years. These MoMHRA revisions were compared with 103 matched controls from a primary THR cohort; matched for age, gender and length of followup. We compared, using the MannWhitney U test, operative time (OT, measured in minutes), and Oxford Hip Score (OHS) between the revised MoMHRA groups and their individual controls. We also compared, using the Kruskal Wallis test, UCLA Activity Score in the revised MoMHRA groups.

Results: There were no differences between the Fracture Group (mean OT 99.6, SD: 30.4; mean OHS 19.8, SD:9.2) and its controls (mean OT 95.9, SD: 31.8; mean OHS 17.3, SD: 7.5) nor between the Other Group (mean OT 129.4, SD: 36.7; mean OHS 22.2, SD: 9.4) and its controls (mean OT 104.4, SD: 39.2; mean OHS 20.3, SD: 10.1) in terms of OT and OHS. The Pseudotumour Group had significantly longer OT (mean 161.6, SD: 24.5, p< 0.001) and worse outcome (mean OHS 39.1, SD: 9.3, p< 0.001) than its controls (mean OT 113.1, SD: 51.7; mean OHS 20.0, SD: 9.2). In the Fracture Group, there were 3 infections requiring revisions. For the Pseudotumour Group, there were 3 recurrent dislocations, 1 femoral artery stenosis and 3 femoral nerve palsies. In the Other Group, there were 2 periprosthetic fractures. There was significant difference (p< 0.001) in UCLA scores between the MoMHRA groups. The Pseudotumour Group had the lowest mean UCLA score of 3.8 (SD: 1.89). The Fracture Group (mean: 7.0, S.D. 2.0) and the Other Group (mean: 6.7, S.D. 2.1) had similar UCLA scores.

Discussion: The results demonstrate that outcome after revision of MoMHRA is dependent upon the indication for revision. Patients revised for soft tissue reactions had significantly worse outcome. Patients with soft tissue reactions are more likely to experience complications and require further surgical intervention. The pseudotumour associated revisions were associated with a significantly prolonged OT. The overall complication rate for the study groups was quite high, with 11 (21%) revised MoMHRA cases experiencing a complication. The Pseudotumour Group had a higher complication rate (37%).

B. Grimm I. Heyligers M. Renckens

Polyethylene (PE) wear particle induced osteolysis remains a major cause of failure in total hip arthroplasty (THA), so that routine clinical measurement of wear stays important. Crosslinked PE promises very low wear rates so that measurement accuracy becomes increasingly important to distinguish alternative materials. The rising use of large femoral heads causes lower linear head penetration also requiring improved accuracy. Digital x-rays and wear measurement software have become standard, but during archiving and exchange of x-rays, image format, resolution or compression are often changed without knowing the effects on wear measurement. This study investigates the effect of digital x-ray resolution and compression on the accuracy of two software programs to measure wear.

The 8-year post-op digital x-rays of 24 THA patients (Stryker ABG-II, 28mm metal femoral head against Duration or conventional PE) were taken from the hospital PACS (Philips Diagnost H, AGFA ADC Solo, Siemens Medview) as DICOM at 5.1 MPix resolution. Images were converted to compression-free TIFF format using Irfanview V4.1. Wear (linear head penetration) was measured using Roman V1.7 and Martell Hip Analysis Suite 7.14. The x-rays were smoothened (Irfanview V4.1, Median Filter: 3) as recommended in literature for compatibility with Martell’s edge detection algorithm. Wear was measured twice by two independent observers at original format and resolution and then once by a single observer at three subsequently halved resolutions (2.6, 1.3, 0.65MPix) and three jpeg compressions (90%, 50%, 20%). Intra- and inter-observer reliability (R) was compared to the reliability of measuring manipulated images (Pearson’s r). The mean absolute wear differences (AD) were calculated versus the original x-ray.

The mean total wear was 0.98+/−0.59mm (0.3–2.4mm) equaling an annual of wear rate of 0.11mm/yr. Using Roman, Intra-R (0.97) and Inter-R (0.96) were high and AD low (0.10 and 0.20mm). Reduced image resolution caused the R to drop only slightly to 0.95 (2.6MPix), 0.92 (1.3MPix) and 0.94 (0.65MPix) while AD remained low (< 0.20mm). Also compression hardly affected R (90%:0.96, 50%: 0.94, 20%:0.93) nor AD (< 0.20mm). Using Martell Intra-R (0.99) and Inter-R (0.87) were also high but dropped with reducing resolution (0.82, 0.72, 0.34, AD: 0.4–1.1mm) but hardly with increased compression (0.95, 0.92, 0.94, AD< 0.20mm).

Low resolution and high compression do not have to be critical for wear measurement accuracy and reliability when edge detection is performed by a trained human eye. This way interpolating the ball and cup perimeters and locating their centers can be performed at accuracy below pixel size (ca. 0.40mm at 0.65MPix). Automatic edge detection is less robust to reducing resolution but performs at high compression. If image size needs to be reduced compression is preferable to reducing resolution.

N. Hailer J. Kärrholm S. Lazarinis

Background: Hydroxyapatite (HA) is the main inorganic component of bone, and HA coating is widely used on acetabular cups in hip arthroplasty. It has been suggested that this surface finish improves cup survival, but there is little evidence to support this.

Patients and methods: All patients registered in the Swedish Hip Arthroplasty Register between 1992 and 2007 with an uncemented acetabular implant that was available with or without HA coating were identified. A study population of 8,043 hips with the most common cup types manufactured either with or without HA coating (Harris-Galante, Romanus and Trilogy) was investigated. Kaplan-Meier survival analysis and a Cox regression model including type of coating, age, sex, primary diagnosis, cup type, and type of stem fixation were used to calculate adjusted risk ratios (RR) of the risk for revision.

Results: Kaplan-Meier analysis of all patients indicated a non-significant trend towards inferior performance of the HA-coated cups (p=0.78). When stratified for age, Kaplan-Meier analysis revealed inferior survival of HA-coated cups when compared to non-coated cups in the age group < 50 years (p=0.031). A Cox regression model showed that HA coating was a significant risk factor for cup revision due to aseptic loosening (adjusted RR 1.645; 95% CI 1.315–2.058). Age at primary arthroplasty < 50 years, a diagnosis of paediatric hip disease, a cemented stem, and the Romanus and Harris-Galante cup types were also associated with significantly increased risk for cup revision due to aseptic loosening. There was no difference in the hazard patterns when the risk for revision for any reason was chosen as the endpoint of the analysis. The risk for revision due to infection was not influenced by the type of coating.

Discussion: Our results derived from register data on 8,043 hips indicate that HA coating does not enhance survival of cups when using aseptic loosening as an endpoint. On the contrary, hydroxyapatite coating is a significant risk factor for cup revision due to aseptic loosening when adjusted for other covariates such as age, sex, cup design and primary diagnosis. HA coating cannot be generally recommended as a surface treatment of acetabular cups in younger patients. This conclusion is medically and economically relevant, as many young patients today receive HA-coated cups, and because HA-coated implants are more expensive.

P. Halonen I. Stogiannidis

Sectioned femoral components retrieved from failed hip resurfacing arthroplasties show resorption of proximal femoral bone or formation of a fibrous membrane at the bone cement interface. We hypothesize that both scenarios create a functional discontinuity zone (FDZ), which exacerbates off-loading the proximal bone and promoting resorption. Our study uses Finite Element (FE) modeling to examine the effects of the presence of an FDZ on bone remodeling following hip resurfacing arthroplasty. A radiographic analysis of the proximal femur following hip resurfacing was conducted in order to draw a comparison to clinical findings

The hip resurfacing FE models were oriented in variable angles and a low-modulus (2 MPa) FDZ was simulated beneath the implant head. Femoral joint and muscle loads were applied. Interface stress was compared for the normal and simulated FDZ resurfaced femurs. Bone remodeling stimuli was determined using changes in strain energy. A range of implant orientations were compared to study the affect on bone remodelling. A retrospective radiological analysis was undertaken on 100 hips with a minimum of 5 years follow up. Measurements of femoral neck diameter at 2 and 5 years were undertaken.

The presence of the simulated FDZ in the FE analysis resulted in increased proximal-medial bone resorption and slightly greater bone formation surrounding the stem. Correspondingly, device-bone interface stresses were found to decrease proximally under the loading platform and increase at the stem, particularly adjacent to the stem-head junction. Valgus orientation showed increased resorption underneath the shell. Varus orientation showed increased bone formation at the stem tip. The radiological analysis identified 2 distinct patterns of neck thinning. Slow thinners (76%) had less than 5% reduction in neck diameter at 2 years and less than 10% at 5 years. Rapid thinner (24%) had more than 5% thinning at 2 years and more than 10% at 5 years. The mean reduction in neck diameter was signifanctly different between the two groups at the two time points (p< 0.01). The rapid group had a higher proportion of valgus aligned implants (88%) and a significant decrease in reconstructed offset (p=0.0023).

The FE results support the hypothesis that the presence of a FDZ decreases load transfer to the proximal bone, resulting in increased medial stress shielding and resorption. These results are consistent with the radiological findings. In order to better understand the cause of resurfacing implant failures, additional retrieval studies are necessary.

F. Hirano H. Fujii T. Mori T. Nakamura H. Ohnishi S. Okabe S. Tanaka H. Tsurukami S. Uchida

Purpose: There is no report concerning about long-term comparison result of high placed cementless cup stability with or without screws for developmental dysplasia of the hip. The aim of this study was to ascertain whether or not there are any differences in high placed cementless cup stability with or without screws at the mean 10-year (6–14) follow-up period.

Method: We divided 109 hip-cases who underwent identical cementless total hip arthoplasty system (Mallory – Head : Biomet Inc.) to two groups: 57 cups with screw (screw group) and 52 cups without screw (no screw group). No case in both group underwent bulk bone graft for acetabular roof. Radiographic signs of cup instability were defined as the development of radiolucent line (> 2mm) or migration (> 4mm). Degree of subluxation by Crowe classification, cup size and cup abduction angle were also measured.

Results: In both groups, there was no significant difference in terms of degree of subluxation (each grade’s %) (screw vs no screw = I (68, 73), II (21, 25), III (11,0), IV (0, 2)), age (yrs) (58, 60), cup size (mm) (46, 47) and cup abduction angle (49, 47). In screw group, one case was revised by replacing only polyethylene insert due to excessive ware. No case in both group showed any sign of component instability.

Conclusion: High placed Mallory-Head type cementless cup without screws showed stable radiographic fixation as well as cup with screws at mean 10 years follow-up period.

O. Holubowycz D. Howie R. Middleton

Early revision is an important risk factor for repeated revision and poor results after primary total hip replacement and instability is a major cause of early revision. Larger articulations with cross-linked polyethylene are proposed as a solution, but these are not without risk, including fracture of the thin polyethylene rim of the liner. The aim of our study was to examine implant-related revisions among primary total hip replacement patients with up to six year follow-up in a randomized controlled trial which compared 28 mm and 36 mm metal on highly cross-linked polyethylene articulations in total hip replacement.

557 patients undergoing primary total hip replacement were included in this study. Risk factors for dislocation and wear were controlled by stratification and patients were then randomized intra-operatively to either a 28 or 36 mm articulation.

To date, 10 hips have been revised for implant-related problems following primary total hip replacement. Seven hips with a 28 mm articulation were revised to a larger articulation because of instability. Four of these were for recurrent dislocation, one for an irreduceable first dislocation and two for subluxation. In contrast, only one patient who had undergone total hip replacement with a 36 mm articulation was revised for recurrent dislocation. One hip with a 36 mm articulation in a well-positioned cup was revised to a 32 mm articulation because of elevated lip liner fracture. Another 36 mm articulation hip was revised for acetabular component loosening.

This study shows that a 36 mm metal on highly cross-linked polyethylene articulation reduces the need for early revision for instability after primary total hip replacement. However, these benefits need to be weighed against the potential risks associated with these articulations, including rare fracture of the relatively thin poly-ethylene liner.

O. Holubowycz D. Howie R. Middleton

Large articulations using cross-linked polyethylene and other alternate bearings are increasingly being used to reduce the incidence of dislocation, the most common early complication following total hip replacement. While indirect evidence has suggested the potential benefits of a large articulation in reducing dislocation risk, this has not been proven in a well-controlled clinical trial. The primary objective of our multi-centre international randomized controlled trial was to compare the one-year incidence of dislocation between a 36 mm and 28 mm metal on highly cross-linked polyethylene articulation in primary and revision total hip replacement.

644 patients were entered into the study. Patients were stratified according to a number of factors which may influence dislocation risk, including primary or revision total hip replacement, age, sex, Charnley grade, diagnosis and stem type. Patients were randomized intra-operatively to either a 28 or 36 mm articulation.

The 12-month incidence of dislocation was statistically significantly lower in patients undergoing total hip replacement with a 36 mm articulation than in those with a 28 mm articulation (1.3% vs 5.2%, p< .05). A total of 6 dislocations occurred in the 4 patients who dislocated with a 36 mm articulation, compared to a total of 36 dislocations in the 17 patients who dislocated with a 28 mm articulation. When primary and revision THR were examined separately, the 12-month incidence of dislocation was statistically significantly lower in patients undergoing primary total hip replacement with a 36 mm articulation than in those with a 28 mm articulation (0.7% vs 4.2%, p< .05). A total of 4 dislocations occurred in two patients with a 36 mm articulation, compared to a total of 19 dislocations in 12 patients with a 28 mm articulation. The incidence of dislocation after revision total hip replacement with a 36 mm articulation was 4.8%, compared to 11.1% with a 28 mm articulation.

This large randomized study unequivocally shows for the first time that, compared to a 28 mm articulation, a 36 mm articulation in total hip replacement is efficacious in reducing the incidence of dislocation in the first year following hip replacement.

A. Hommel K. Thorngren

Background and purpose: As hip fracture patients are common and constitute an increasing health problem it is important to use available resources effectively and provide high quality care. Correct treatment can start in the ambulance with administration of oxygen, pain relief and intravenous glucose liquid according to the Lean Production concept. The basis of Lean Production is that the employees themselves develop their work as a natural part of the job. In the case of health care, this involves learning what it are that really benefits the patients, what it is that creates added value. Anything that does not benefit the patients is to be removed.

The aim of this study was to improve the preopera-tive care of hip fracture patients.

Subjects : During the period 2007-04-01 to 2007-12-31 totally 365 hip fracture patients were consecutively admitted to the University Hospital. Of them 117 (mean age 82.8) patients were included in the project and 248 patients (mean age 81.3) were controls.

Method: Patients with a suspected hip fracture (shortened and externally rotated leg) were supposed to be included in the study. Exclusions criteria were medical unfit patients with for example ongoing hearth problems or stroke. Already in the ambulance the patient’s identification was established, blood samples were drawn and electrocardiography was taken. At admission to the hospital the ambulance personnel directly followed the patient to the x-ray unit and further to the orthopaedic ward without passing the acute and emergency unit.

Results: Patients included in the project felt that they were in safe hands and were satisfied with the handling time from the ambulance until they were at the ward. This time has diminished from 4 hours to half a hour. The mean time from admission to surgery was 29 hours for patients in the control group versus 21 hours for patients included in the project. Furthermore, the personnel at the x-ray unit are satisfied with the new organisation since there are more personnel lifting a better pain relieved patient from the trolley to the x-ray table.

Conclusion: When we are working in multi professional and multi functional teams with the LEAN concept, safety and quality of care can be improved if the preop-erative care of hip fracture patients is speeded up.

M. Honl J. Jacobs M. Morlock M. Wimmer

Ludloff’s medial approach has never been used for other hip surgeries especially not for THR.

47 patients (26 men/21 women) provided informed consent to participate in the study. The inclusion criterion for the study was the diagnosis of osteoarthritis of the hip joint. The average age at operation was 53.7±10.4years. All patients were provided with a CUT® prosthesis.

All patients were examined clinically and X-rayed preoperatively as well as postoperatively at three days, two weeks, six weeks and six months. The functional hip scores according to Harris and the Oxford hip score were obtained preoperatively and at the defined intervals postoperatively. The surgical duration and the intraop-erative as well as the postoperative blood loss were measured for each patient. Abductor muscle function and the number of steps a patient was able to walk without walking aids on a treadmill at a velocity of 5km/h (a maximum of 100steps was measured) were assessed.

Multifactorial analyses of variance and Chi-square tests were performed.

Based on the numbers available there were no significant differences between the two groups in the distribution of patient age (p=0.604), gender (p=0.654), weight (p=0.180) and height (p=0.295). No significant differences in the calculated Harris score (p=0.723) were found pre-operatively. The amount of steps the patient was able to walk was not different between the approach groups (p=0.636).

The total amount of blood loss (intra- + post-OP) was even significantly lower in the medial approach group (p=0.009).

Three days post-operatively the leg lengths were assessed. The difference was not statistically significant based on the numbers available (p=0.926). The overall correlation between Harris and Oxford score was significant (r2=0.63, p< 0.001).

Three days post-operatively a slight, but significant better Harris (p< 0.001) and Oxford scores (p=0.001) could be observed in the medial approach group. The number of steps the patient was able to walk without help or crutches was significantly higher in the medial approach group (p=0.001). The Trendelenburg sign (p< 0.001) and the limping criterion (p< 0.001) were significantly less in the medial approach group.

Two weeks post-operatively the Harris (p=0.001) and the Oxford (p=0.046) scores were significantly better for the medial approach group. The number of steps the patient was able to walk without help or crutches was significantly higher in the medial approach group (p< 0,001).

The medial approach is clinically feasible to perform the implantation of a femoral neck prosthesis. The accuracy of the stem implantation reflected in both the leg lengths and the postoperative X-ray alignment was not different between the groups.

After six months there was no significant difference between the conventional anterolateral approach and the medial approach in the presented study.

I. Havelin Leif M. Fenstad Anne O. Furnes G. Garellick P. Herberts J. Kärrholm S. Overgaard A. Pedersen

Introduction: Up to now comparisons and pooling of data between the Scandinavian arthroplasty registers have been restrained by use of separate and incompatible data systems.

Purpose: To create a common Scandinavian database for hip arthroplasties and to compare demographics and results between the Scandinavian countries.

Materials and methods: For this study we selected primary total hip prostheses (THR) from 1995–2006. A common code set was made, and after de-identification of the patients’ identity, including deletion of the national civil registration numbers, Denmark, Sweden, and Norway delivered data. Kaplan-Meier and Cox multiple regression, with adjustment for diagnosis, age, and gender, were used to calculate prosthesis survival, with any revision as end-point.

Results: 280,201 operations were included (Denmark 69,242, Sweden 140,821, Norway 70,138). Female patients constituted 60% in Denmark and Sweden and 70% in Norway. In Denmark, Sweden, and Norway childhood disease constituted 3.1%, 1.8%, and 8.7% respectively. The posterior approach was used in 91% of cases in Denmark, 60% in Sweden, and 24% in Norway. Cemented THRs were applied in 46% of patients in Denmark, 89% in Sweden, and in 79% in Norway. Resurfacing hips constituted 0.5% or less in all countries.

9,596 of the 280,201 primary THRs, had been revised. Ten-years survival was 91.9% (95% CI: 91.5 – 92.3) in Denmark, 93.9% (95% CI: 93.6–94.1) in Sweden, and 92.6% (95% CI: 92.3–93.0) in Norway.

In Sweden and Norway 23% of revisions were due to dislocation, compared to 34% in Denmark. Replacement of only cup or liner constituted 29% of the revisions in Sweden, 33% in Norway, and 44% in Denmark.

Conclusion: This unique database is now functioning, and has showed differences among the countries concerning demographics, prosthesis fixation, prosthesis survival, and reasons for revisions. The large number of THRs in this database significantly enhances our perspectives for future research, especially in diagnostic- and treatment groups with too small numbers in each separate

G. Isaac T. Siebel

Surface replacement is widely used as a treatment for younger patients requiring hip replacement. However the long-term performance of such devices remains unknown. One area of concern is the viability of the bone in the proximal portion of the femur. These concerns are related to the trauma which the proximal femur is exposed to during the operative procedure and the level of vascularity which is subsequently attained. Previous studies have used a single time point and shown reduced loss in bone stock compared to total hip replacement and minimal difference with the contra-lateral unaffected hip. The aim of this study is to report the changes in bone mineral density (BMD) which take place at different time points in the same patients following implantation using DEXA scanning. The effect of component placement and metal ion levels will also be considered

A total of twenty-six patients were recruited (18 male, 5 female; 15 left hip 11 right, mean age at surgery 56 years, range 31–69) who had DEXA measurements at all three time points post-op, 120 and 420 days (4 and 14 months). Measurements were taken in the neck region and Gruen zones 6 and 7. Metal ion levels were measured in whole blood using the high resolution ICP-MS technique.

The BMD in the neck region, zone 7 and 6 post-operatively were 0.945, 1.092 and 1.451g/cm2 respectively. In the neck region BMD reduces at 120 days (96.5%) and then increases to higher than the post-op level at 420 days (103.6%, differences between all three groups: p< 0.008).

In zone 7, BMD drops at 120 days (98.2%, p=0.03) but recovers to higher than post-op levels after 420 days (101.65%)but not significantly so (p=0.13). In zone 6 there are no significant differences at any ime points.

Despite the wide variation in the immediate postoperative bone density (0.70–1.25g/cm2), there is no obvious relationship between this value and the capacity of the bone to recover from the operative trauma

Twenty-three of these patients were also part of a metal ion study previously reported. There was no relationship between the combined metal ion levels (chromium+cobalt) at 12 months and the changes in BMD in the neck region at 4 or 14 months.

There was no significant difference in the response of the male and female patients. There was no significant relationship between changes in BMD and cup abduction angles, femoral component inclination nor acetabular component diameter.

This is a short-term study, however it is reassuring that whilst BMD reduces in the neck and Gruen zone 7, by 420 days (14 months) it has recovered to postop levels and in zone 7 has exceeded the post-op levels. Furthermore this response appears to be unrelated to patient factors and component position.

D. Howie M. Beck K. Costi R. Ganz S. Pannach L. Solomon

Introduction: Periacetabular osteotomy is a complex procedure which is associated with significant complications during the learning period and difficult to maintain such expertise when it is undertaken infrequently. Results were reviewed to determine if this difficult PAO procedure can be safely learnt by a process of mentoring and review.

Methods: A structured mentoring program was adopted by the senior author. A double approach was used in the first 11 cases to enhance exposure and minimise the risk of complications. Fifteen osteotomies have subsequently been undertaken using a single approach. The median patient age was 28 years (13–41 years). The median follow-up was 5 years (2–14 years). The clinical and radiographic results were examined.

Results: Two cases in the double approach series progressed to total hip replacement and there were two other major reoperations. Two cases in the single approach series had an ischial non-union not requiring reoperation. The median Harris hip score at latest review was 82 (35–100) and 80 (26–100) for the double and single approach series respectively. All radiographic indices indicated correction of the acetabulum for both series.

Discussion and Conclusion: A structured program of mentoring and review has allowed a complex surgical procedure to be learnt and surgical expertise maintained at a distant centre while avoiding the complications previously associated with the learning curve and achieving the acetabular correction similar to the originator of the procedure.

D. Howie K. Costi D. Findlay W. Martin M. McGee S. Neale L. Solomon R. Stamenkov D. Taylor

While computed tomography (CT) provides an accurate measure of osteolysis volume, it would be advantageous in general clinical practice if plain radiographs could be used to monitor osteolysis. This study determined the ability of plain radiographs to detect the presence of and determine the progression in size of osteolytic lesions around cementless acetabular components.

Nineteen acetabular components were diagnosed with osteolysis using a high-resolution multi-slice CT scanner with metal artefact suppression. Mean duration since arthroplasty was 14 years (range 10–15 years) at initial CT. Repeat CT scans were undertaken over a five year period to determine osteolysis progression. On anteroposterior pelvis (AP) radiographs and oblique radiographs of the acetabulum seen on the rolled lateral hip view, which were taken at the same time as the CT scans, area of osteolysis was measured manually correcting for magnification.

Osteolysis was detected on the AP radiographs in 8 of 19 hips (42%), on the oblique radiographs in 6 of 19 hips (32%) and on the combined AP and oblique radiographs in 8 of 19 hips (42%). Throughout the study period, osteolysis was detected on 31 of 76 AP radiographs (41%) and 22 of 75 oblique radiographs (29%). Osteolysis was more likely to be detected on plain radiographs if the lesion volume was greater than 10cm3 in size (p=0.005). On CT, osteolysis progressed by more than 1cm3/yr in 10 of 19 hips (55%). In these ten hips, osteolysis progression was detected on AP radiographs in six hips and on oblique radiographs in three hips. No correlation was found between osteolysis progression measured by CT and that measured on AP (r2=0.16, p=0.37) or oblique (r2=0.37, p=0.15) or AP and oblique radiographs (r2=0.34, p=0.17).

Plain radiographs are poor in monitoring progression in size of periacetabular osteolytic lesions. Plain radiographs may detect lesions more than 10cm3 in size, but are unreliable.

A. Hussain J. Daniel A. Kamali C. Li J. Pamu

Introduction: The accepted method of assessing wear following a hip simulator test has been to use a precision balance. As the MoM devices produce significantly less weight loss than hard-on-soft bearings, the measurements of MoM devices are now almost at the detection limit of many balances. There is a need for a method that can be used in conjunction with gravimetric analysis that will provide an accurate assessment of ion concentration levels that will support the gravimetric measurements.

Aim: To develop a method to assess wear using metal ion analysis in order to support gravimetric measurements of metal on metal devices.

Materials and methods: Hip simulator test: Three pairs of 50 mm diameter as cast CoCr MoM devices were tested in a ProSim hip wear simulator (SimSol Stockport/UK) under physiologically relevant conditions. The lubricant was new born calf serum with 0.2 % sodium azide concentration diluted with de-ionised water for protein concentration of 20 g/l. Stop-start motion was implemented every 100 cycles. Lubricant changed every 125 k cycles. The frequency was 0.5 Hz. Wear was assessed gravimetrically at every 0.5 million cycles (Mc) interval.

Ion analysis: Serum was collected from test station and allowed to settle for 12 hours. An aliquot of 20 ml from lubricant was collected. Each sample was centrifuged at 2500 g-force for 10 minutes. A 10 ml aliquot was collected from each sample and was further centrifuged at 2500 g-force for 10 minutes. 1.5 ml aliquot was collected and stored at −20 °C. A high resolution inductively-coupled plasma mass spectrometry instrument (ELEMENT, ThermoFinnigan MAT, Bremen/Germany) was then used for the analysis of metal ions.

Results and Discussion: The average cumulative metal ion levels at 0.5, 1 and 1.5 Mc showed similar trends in wear to that of the average cumulative weight loss assessed gravimetrically. There were similar biphasic wear trends in both metal ion levels and gravimetric weight losses. Other studies have also shown similar correlation between volume loss and ion concentration levels. The percentage distribution of Co, Cr and Mo in the metal ion samples are in close agreement with nominal chemical composition of the material tested.

Conclusion: This study showed that metal ion measurements can help to confirm gravimetrically measured material loss.

D. Howie S. Callary T. Kane M. McGee S. Pannach N. Russell L. Solomon R. Stamenkov

Introduction: In the past, surgeons have found impaction bone grafting technically difficult leading to its limited use. This paper reviews the long term results and developments in instrumentation and techniques aimed at simplifying femoral impaction grafting at revision hip replacement. The expanded indications for this procedure are reviewed and recent results of stem fixation using radiostereometric analysis (RSA) are reported.

Methods: The impaction bone grafting procedure, using a cemented collarless polished double taper stem, has been used in 66 hips (median patient age 63yrs) since 1993. The technique has undergone numerous developments. Modular tamps have been used in the last 29 hips and in the last seven hips, a pneumatic mechanical vibration device has been used in place of manual impaction. Stem subsidence at both the prosthesis-cement and cement-graft/bone interfaces was measured, more recently using radiostereometric analysis.

Results: There was a high early incidence of failure in the initial cases but there have been no further revisions for mechanical failure at up to 15 years. Technique developments have resulted in dramatic improvements in stem fixation achieved. In the modular tamp cases, the mean stem subsidence at the cement-bone interface at 12 months was 0.07mm (0 to 0.7mm) at 12 months. The stem subsidence in the hips where the mechanical vibration device was used was 0.05mm (0 to 0.06mm). Femoral impaction grafting offers special advantages in younger patients include standard femoral stem revision and at the second stage of two stage revision for infection.

Discussion and Conclusion: A stable cement-bone interface is achieved using advanced techniques of femoral impaction grafting that includes the use of modular impaction instruments. Early results of mechanical vibration impaction are encouraging. Femoral impaction grafting restores bone and new techniques simplify the femoral revision procedure.

G. Isaac A. Breckon C. Brockett J. Fisher A. Schepers D. Van Der Jagt S. Williams

The combination of a ceramic head articulating against a metal acetabular liner (CoM) has shown reduced metal ion levels compared with a metal-on-metal bearing (MoM) in hip simulator studies. A randomized prospective clinical trial was undertaken using CoM and MoM bearings in an otherwise identical total hip procedure. The initial clinical results were encouraging. This report comprises a further review of metal ion data.

Patients received identical components with the exception of the bearing surface material but all were 28mm diameter. All components were supplied by DePuy International Ltd. Patients were assessed pre-operatively, 3m, 12m and > 24m (median 32m). Whole blood samples were collected at regular follow-ups, frozen and analysed in batches using high resolution Inductively Coupled Plasma – Mass Spectrometry (ICP-MS). All recruited patients are included irrespective of outcome. However some patients failed to attend specific follow-ups and some contaminated samples had to be discarded. Statistical significance was analyzed using a non-parametric comparison (Mann-Whitney test). After 3m and 12m implantation there were between 21 and 24 patients available for analysis in both the CoM and MoM cohort and after > 24m point 10 and 9 respectively.

There were four outliers (either Cr or Co > 10ug/l) in both the CoM and MoM groups. In common with previous studies (with the exception of two marginal outliers), these were related to component position. They were implanted with either a cup abduction angle of > 55°, an anteversion angle of > 30° or both. Other studies with the same design of component have reported no significant outliers.

The median Cr and the Co levels are lower with the CoM bearing compared with the MoM at all measurements points following implantation. The median background (pre-operative) levels for the combined CoM and MoM group were Cr: 0.22ug/l and Co: 0.49ug/l. These were significantly different (p=0.006).

In the CoM group, the median 12m Cr and Co values were 0.43ug/l and 0.72ug/l respectively. The comparable values for MoM are 0.68ug/l and 0.83ug/l. Increases in metal ion levels from pre-operative levels are used as the primary ion level outcome in this study because the background level will comprise of the order of 30–50% of the overall value. The increase in Cr for CoM and MoM from pre-op levels to 12m significantly different for Cr (p=0.015). It has a lower significance for combined metal ion levels (p=0.029). This difference in not significant for Co (p=0.195).

In agreement with predictions from hip simulator studies, CoM bearings in this study produced lower levels of metal ions than comparable MoM bearings at all time points. However the difference is less than that predicted in the laboratory and is much more pronounced with Cr than with Co.

M. Jäger R. Krauspe S. Kurth K. Stefanovska C. Zilkens

Introduction: Femoroacetabular Impingement (FAI) with more or less subtle abnormality of the hip anatomy and function may contribute to the early development of osteoarthritis (OA). Surgical dislocation as well as arthroscopy of the hip joint are effective and save tools to correct these anatomic deformities. Good clinical results could be achieved predominantly in patients not exceeding grade I OA. The aim of the presented study was to evaluate the clinical and radiological outcome of patients that were treated by open surgical hip dislocation for more advanced OA of the hip joint (> grade I).

Patients and Methods: This is a prospective clinical trial on the outcome of patients after surgical hip dislocation. We report on 45 hip joints (41 patients, 16 m, 25 f) that were treated in our institution by offset-correction (removal of osseous bumps at the femoral head-neck junction) and/or labral surgery for FAI. All patients were evaluated prospectively before and after surgery (Harris Hip Score, radiographic parameters, arthro-MRI).

Results: The mean follow up (FU) was 45 months (range: 12–102 months). 9 hips underwent total hip replacement in the further course of FU for persisting pain. In the remaining hips a significant pain reduction but no amelioration of hip range of motion could be accomplished. In 90% of the cases, a good correlation between preop-erative arthro-MRT findings and intraoperative labrum and cartilage assessment could be demonstrated. Concerning the outcome, no patient or radiographic factors could be identified that were strongly associated with failure after surgical dislocation.

Discussion and Conclusion: Our data suggests that even patients with more advanced osteoarthritis of the hip may benefit from the surgical dislocation approach as a hip salvage procedure. However, the high number of conversion to total hip arthroplasty indicates, that the indication for hip salvage should stay restricted. Patient or radiographic factors indicative of failure could not be identified. In the future and with more sophisticated molecular MRI techniques such as delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC) concrete prediction models could be implemented to preoperatively assess hip cartilage in order to sort out patients who will not profit from salvage surgery for advanced OA due to FAI.

T. John A. Biechteler S. Dix W. Ertel D. Haschtmann M. Ihle M. Reinke

Introduction: We present a clinical and radiology follow-up of the uncemented titanium coated monobloc Robert Mathys (RM) Acetabular Component (Mathys AG Bettlach, Bettlach, Switzerland).

The acetabular component is a monobloc hemispherical cup manufactured from Ultra High Molecular Weight Polyethylene (UHMWPE), with a pure titanium particle coated surface. With heat and pressure, the particles are blasted into the polyethylene surface. The coating promote osseointegration. Stability of the cup is provided by 2 anchoring pegs on the weight bearing part on its outer surface. The inclination of pegs and holes diverge by 5 degrees providing a press-fit effect that increases the rigidity of the primary fixation and this is supplemented by screws inserted through the periphery of the cup. Tow cups designs are available, a full-profile and a bevelled cup. In all cases the bevelled cup was used. The purpose of this study was to assess the clinical performance with 15 years of this cup.

Methods: In this study, the status of the uncemented titanium coated RM cup placed in patients who underwent a primary total hip replacement between January 1, 1988 and December 31, 2001 was determined. A total of 1876 cups (1584 patients) were placed in patients with a permanent residence in Berlin. The femoral component was either an uncemented or a cemented stem in an supine lateral approach with either a 28 or 32mm diameter head. The majority of the heads were ceramic and stainless steel.

The diagnosis was osteoarthritis, rheumatic arthritis, femur neck fracture, developmental dysplasia of the hip (DDH). 1034 patients were contacted by telephone. Out of this patients group 539 patients (678 cups) were evaluated by clinical examination (HHS), radiographic investigation and social evaluation by the WOMAC and NHS score. 451 patients who had died unrelated to the operation. Lost of follow up were 65 patients (69 Cups) and 34 patients (48 cups) had to be revised.

Results: The cumulative survival rate of the RM cup is 98.2 percent at 5 years, 97.5 percent at 10 years and 96.9 percent at 15 years. The survival rate in the ceramic head group is 98.7 at 15 years and by using stainless steel head 91.7 at 15 years. Reseaon for re-opertion was in 34 patients aseptic loosening, 8 patients had infection. Dislocation, malpsition and periprosthetik fracture in 2 patients. In the group with clinical evaluation, the HHS was in 80.2 percent of all patients good and ecellent, 9,7 percent had a moderate result and 10,1 percent had a poor result.

Discussion/Conclusion: The low failure rate for loosening demonstrates that this implant has excellent ongrowth and fixation potential. The RM Cup has been shown to function well at up to 15 years post implantation. Its success may in part be due to the one-piece design.

S. Jibodh C. Bragdon M. Greene A. Kandil H. Malchau

Highly cross-linked polyethylene liners in total hip replacement (THR) have allowed the use of larger diameter femoral heads. Larger heads allow for increased range of motion, decreased implant impingement, and protection against dislocation. The purpose of this study is to report the clinical and radiographic outcomes of patients with large femoral heads with HXLPE at 5 years post-op.

A group of 124 patients (132 THRs) who had a primary THR with a 36mm or larger cobalt-chrome femoral head and a Durasul or Longevity liner (Zimmer; Warsaw, IN) were prospectively enrolled in this study. 93 THRs (88 patients) had minimum 5 year follow-up. All patients received a cementless acetabular shell (Trilogy or Inter-op, Zimmer Inc, Warsaw IN) and a highly cross-linked polyethylene liner with an inner diameter of 36 or 38mm. The median radiographic follow-up was 5.6 years (range 5.0–8.0), and patients were assessed clinically by Harris Hip score, UCLA activity score, EQ-5D, and SF-36 functional scores. Femoral head penetration was measured using the Martell Hip Analysis Suite.

No osteolysis was seen in the pelvis or proximal femur, and no components failed due to aseptic loosening. Four patients have questionable signs of bone changes around the acetabular shell with future CT scans scheduled to help reach a final determination. The median acetabular shell abduction and anteversion were 44° (30–66°) and 13° (3–33°) respectively. There was no evidence of cup migration, screw breakage, or eccentric wear on the liner. Regarding the femoral component, there were no episodes of loosening, migration, osteolysis, or fracture. There was no significant difference in the median penetration rate from post-op to longest follow-up between the 36mm (24 patients) and 38mm (4 patients) femoral head groups (0.056±0.10mm/yr and 0.060±0.05mm/yr respectively). Therefore, the data were pooled into one group. Using every post-op to follow-up comparison, the linear regression penetration rate of this combined group was 0.003 mm/yr which is within the error detection of the Martell method. The median femoral head penetration rate during the first post-op year measured 0.59±1.04 mm/yr. In contrast, the median steady state wear rate from the 1yr film to the longest follow-up measured -0.009±0.15mm/yr. A linear regression steady state wear rate from the 1 year film to every follow-up of −0.031 mm/yr indicated no correlation between the magnitude of polyethylene wear and time.

The mid-term results on this series of patients with THRs with a 36 or 38mm femoral head articulating with highly cross-linked polyethylene showed excellent clinical, radiographic, and wear results. The lack of early signs of osteolysis with the use of these large diameter femoral heads is encouraging. Continued and longer-term follow-up is needed to provide survivorship data.

C. Kerin G. Cheung P. Cool N. Graham

Background: There are no evidence based guidelines on the surveillance of cemented total hip arthroplasty. We reviewed the outcomes of those patients undergoing this procedure in 1996 & 1997.

Methods: The patients were identified from theatre log books. The follow up date was then retrieved from the electronic patient record system used at our institution. From these we recorded the age, sex, side of procedure, evidence of radiological loosening & time of revision surgery. The data with regards to radiological evidence of loosening & revision surgery were then analysed using a XXX statistical software package. From this we were able to plot Kaplan-Meier survival & hazard plots.

Results: We identified 425 primary total hip arthroplasties. Using radiological evidence of loosening as the end point we found that there was a peak initially and a peak at 8 years. There was a 10 year survival rate of 85.8%. Using revision surgery as the end point we found that there was, again, an initial peak & a peak at 8 years. There was a 10 year survival rate of 91.5%.

Conclusions: Once the patient has made it through the first post operative year they do not need to be followed up again until 8 years assuming they remain asymptomatic.

A. Kamali A. Hussain C. Li

Introduction: Based on the clinical success of large head metal-on-metal (MoM) bearings technologies in the resurfacing arena, a multi-bearing acetabular system, known as R3 system, was developed by Smith & Nephew. The novel R3 system utilizes porous coated Ti-6-4 shells in which liners of crosslinked UHMWPE, ceramic, or as-cast CoCr liners can be placed. The as-cast CoCr metallurgy and microstructure is identical to the clinically successful Birmingham Hip Replacement (BHR) resurfacing system. The design and manufacturing aspects such as diametrical clearance, surface roughness, and spherical form are all identical for the two systems.

Aim: to evaluate the tribological performance of R3 devices as compared to that of standard BHR devices.

Materials and Methods: Five pairs of 46 mm MoM R3 devices (Smith & Nephew) and three pairs of 48 mm BHR devices (Smith & Nephew) were tested in a ProSim hip wear Simulator. The lubricant was new born calf serum with 0.2% sodium azide diluted with de-ionized water to achieve protein concentration of 20 g/l. The flexion/extension was 30° and 15° and the internal/external rotation was +/− 10°. The force was Paul-type stance phase loading with a maximum load of 3 kN and a standard ISO swing phase load of 0.3 kN. The frequency was 1 Hz.

One R3 joint and one BHR device were friction tested in a ProSim hip friction simulator at 0, 3 and 5 million cycles of wear testing. The test was conducted in new born calf serum with added carboxy methyl cellulose (CMC) to generate viscosities of 1 to 100 cP. The loading cycle was set at maximum loads of 2 kN and minimum load of 0.1 kN. The flexion/extension was 30° and 15°, and the frequency was 1 Hz.

Results and Discussions:

Friction: The coefficient of friction (COF) of the R3 joint varied from 0.08 to 0.14 depending on the viscosity of the serum and cycles of wear simulation test. Under physiologically relevant lubricant conditions (1, 3 and 10 cP), the COF for the R3 device tested was comparable to that of the standard BHR device.

Wear: The R3 devices generated typical characteristics of wear to the BHR devices, with a higher wear rate during the initial running in period (0 – 0.5 Mc) followed by a low steady state wear rate after 0.5 Mc. The average wear rate at 0.5 Mc was 1.86 mm3/Mc for the R3 and 1.80 mm3/Mc for the BHR devices. The wear rate during the steady state for the R3 and the BHR devices was reduced to 0.09 mm3/Mc and 0.12 mm3/Mc respectively. The difference in average wear rates between the BHR and R3 devices during the running in and steady states were not statistically significant (p > 0.05).

Conclusion: The test results presented in this study show that the tribological performances of the R3 and the BHR devices are comparable.

V. Killampalli F. Chaudhry M. Chowdhry N. Fisher R. Kundra K. Mathur A. Reading

The management of osteoarthritis of the hip in young active patients has always been challenging. This can be made more difficult because of the longevity required of the prostheses used and the level of activity they must endure.

The aim of this study was to compare the functional outcomes and activity levels following hip resurfacing and uncemented THA in young active patients matched for age, gender and activity levels.

A retrospective review of 255 consecutive hip arthroplasties performed in a teaching hospital was carried out. From this series we identified 58 patients who had undergone uncemented THA (Group A) and 58 patients who underwent hip resurfacing (Group B), matched for age, gender and pre-operative activity level.

The mean age of patients within Group A was 58.5 years (34–65) and in Group B was 57.9 years (43–68). Mean pre-operative University of California at Los Angeles (UCLA) score in Group A was 3.4 (1–7) and in Group B was 4.2 (1–8). The mean pre-operative Oxford Hip Score (OHS) was 46.1 (16–60) and 44.4 (31–57) in Groups A and B respectively.

Mean follow-up period was five years (4–7 years). In the hip resurfacing group, the mean UCLA score improved from 4.2 (1–8) to 6.7 (3–10), while in the uncemented THA group this improved from 3.4 (1–7) to 5.8 (3–10). Similarly, the mean OHS improved from 44.4 (31–57) to 16.6 (12–31) in the hip resurfacing group and from 46.1 (16–60) to 18.8 (12–45) in the uncemented THA group.

This study found no statistically significant difference in the levels of function (p= 0.82) or activity pursued (p= 0.60) after surgery between uncemented THA and hip resurfacing in a population of patients matched for age, gender and pre-operative activity levels.

Although there was statistically significant improvement in UCLA and OHS within each group, it was found that no group was better than the other.

This study has shown comparable outcomes with hip resurfacing and uncemented THA in terms of both functional outcomes and activity levels in a group of young active patients. The potential complications unique to hip resurfacing may be avoided by the use of uncemented THA. In addition, uncemented THA has a longer track record.

D. Kendoff F. Boettner C. Mustafa L. Nelson A. Pearle V. Stüber

Background: Arthroscopic femoral osteoplasties might cause prolonged operative times, restricted intraop-erative overview or insufficient localisation of surgical tools. Computer assisted techniques should improve the precision with an overall accuracy is within 1mm/1°. An automated navigated registration process matching preoperative CT data and intraoperative fluoroscopy, should allow for non-invasive registration for FAI surgery. We evaluated the general precision (I) of the CT and fluoroscopic matching process and (II) the precision of identifying the defined osseous lesions in various anatomical areas.

Material and Methods: Three cadavers (6 hip joints) utilizing a conventional navigation system were used. Before preoperative CT scans, defined osseous lesion (0.5x0.5mm) in the femoral neck, head neck junction, head region were created under fluoroscopic control. Following reference marker fixation, two fluoroscopic images (12 inch c-arm) with 30° angle differences of the hip joint were taken. Automated segmentation including CT-fluoro image fusion by the navigation system enabled a noninvasive registration process Precision of registration process was tested with a straight navigated pointer (1mm tip) trough a lateral arthroscopic portal, during virtual contact to the bone, without arthroscopic control After arthroscopic view was enabled the in vivo distance of pointer tip to bone was measured (I). In vivo real distances between inserted navigated shaver and osseous lesions was done over an anterior hip arthrotomy. Under navigated control, blinded to the situ, placement in the lesions should be done. Distances between shaver tip and osseous lesions were measured with a caliper (II).

Results: The precision for registration (I) was within 0.9mm within the femoral neck (SD 0.24mm; 0.6–1.3mm); 1.2 mm (SD 0.33mm; 0.8–2.0mm) (p> 0.05) for the head neck junction; 2.9 mm (SD 0.57mm; 1.8–3.7mm) for the femoral head (p< 0.001 respectively p< 0.001) Mean offset of the navigated shaver to the lesions (II) was 0.93 mm (SD 0.65mm; 0–2mm). Within the femoral neck a mean accuracy of 0.6mm (SD 0.59mm; 0–1.4mm), the head neck junction 0.8 mm (SD 0.78mm; 0.1–1.5mm), the femoral head 1.3 mm (SD 0.50mm; 0.6–1.7mm) was found (p> 0.05; p> 0.05; p> 0.05).

Conclusion: A combined CT-fluoroscopy matching procedure allows for a reproducible noninvasive registration process for navigated FAI surgery. Precision of the registration process itself is more accurate at the femoral neck and head-neck junction than at the femoral head area. However a navigated identification of osseous lesions was possible within 1mm deviations in all regions.

I. Kim Kang J. Cho Yoon A. Ramteke C. Yoo Myung

Introduction: Periacetabular rotational osteotomy is a joint preserving reconstructive surgery indicated in hip dysplasia. However hip dysplasia is frequently accompanied by intraarticular pathology like labral tears. This study was undertaken to ascertain whether:

concomitant hip arthroscopy during osteotomy could identify intra-articular pathology associated with hip dysplasia;

hip arthroscopy combined with our technique of acetabular osteotomy was effective in treatment of intraarticular pathology;

this technique was associated with a favorable outcome over a mid term followup period.

Materials: Between July 2001 and February 2005, 43 dysplastic hips with 40 patients consecutive of periac-etabular rotational osteotomy using modified Ollier’s approach and concomitant hip arthroscopy could be followed up at average 52 months (range, 42–67 months). On arthroscopic examination labral lesion and cartilage condition was evaluated and torn labrum was treated. Two patients underwent simultaneous femoral procedures. Mean age at the time of surgery was 40 years (range, 20–67 years). Pre and postoperative hip function was compared using Harris hip score. Radiographic evaluation consisted of pre and postoperative measurement of CE angle, Sharp angle, acetabular head index, head lateralization index and medialization of femoral head. The degree of osteoarthritis was evaluated and compared by radiographic appearance using Tönnis classification.

Results: Intraoperative arthroscopic examination revealed labral lesion in 38 hips. Twenty-eight (65%) out of 43 cases showed cartilage degeneration on arthros-copy. Mean HHS changed from 72.4 preoperatively to 94 postoperatively. On radiographic evaluation CE angle changed from 6.3o to 32.3o, Sharp angle changed from 47o to 39o, acetabular head index changed from 57% to 92% thus indicating the increase in contact area. Head lateralization index changed from 61.2 to 54.9. At the latest review, the severity of osteoarthritis improved in 12 (28%), remained unchanged in 29 (67.4%), and worsened in 2 cases (4.7%). Complications include intraarticular osteotomy, disruption of posterior column and deep vein thrombosis in 1 case each. No other complications like non-union, nerve injury, avascular necrosis, or infection were seen. No patients underwent a conversion THA indicating a 100% survival for the minimum followup period of 42 months and beyond.

Conclusion: Periacetabular rotational osteotomy showed good results in midterm and in 88% of cases we observed and treated labral lesion through a concomitant hip arthroscopy. Thus we recommend that evaluation and treatment of labral lesion should be considered when the joint-preserving acetabular osteotomy is performing due to dysplastic hip.

S. Konan F. Haddad F. Rayan

Radiographic evaluation of the anterolateral femoral head is an essential tool for the assessment of cam type of femoroacetabular impingement. Computerised tomography (CT), magnetic resonance imaging and frog lateral plain radiograph views have all been suggested as imaging options for this type of lesion. Alpha angle is accepted as a reliable indicator of cam type of impingement and this may also be used as an assessment tool for successful operative correction of the cam lesion.

The aim of our study was to analyse the reliability of frog lateral view plain radiographs to analyse the alpha angle in cam femoroacetabular impingement.

Thirty two patients who presented with femoroac-etabular impingement were studied. Interobserver reliability for assessment of alpha angles on frog lateral radiographic view was analysed using intraclass correlation coefficient. The alpha angles measured on frog lateral views using digital templating tools were compared to those measured on CT scans.

A high interobserver reliability was noted for the assessment of alpha angles on frog lateral views with a correlation coefficient of 0.83. The average alpha angles measured on frog lateral views was 58.71 degrees (range 32 to 83.3). The average alpha angle measured on CT was 65.11 degrees (range 30 to 102). However, a poor correlation (Spearman r of 0.2) was noted between the measurements using the two systems.

Frog lateral plain radiographs are not reliable predictors of alpha angle. Various factors may be responsible for this such as the projection of the radiographs, patient positioning and quality of images. CT imaging may be necessary for accurate prediction of alpha angle.

M. Krause M. Kristensen F. Mehnert S. Overgaard A. Pedersen

Background: A general increase in total number of primary total hip arthroplasty (THA) has been observed in Denmark from 3.828 in 1995 to 7.645 in 2006. During the same period the number of pa-tients treated at private clinics has also increased. To our knowledge no studies, comparing patient characteristics and treatment quality between public and private hospitals, have been published.

We compared patients’ characteristics and outcome following THA in private and public hos-pitals.

Materials and Methods: We used data from the Danish Hip Arthroplasty Registry to identify 69 249 primary THA’ies performed between 1 January 1995 to 31 December 2006.

To detect eventual difference in patient characteristics- age, gender, diagnosis leading to THA, Carlson’s comorbidity score and Charnley category were evaluated.

We matched 3 658 cases operated in private with 3 658 controllers operated in public hospitals on propensity score. Scoring parameters were age, gender, diagnosis leading to THA, Carlson’s comorbidity score, Charnley category, operating time, type of anesthesia and type of prosthesis.

We used multivariate logistic regression on propensity score matched data to assess association between type of hospital and outcome by computing relative risks and 95% Confidence Interval (CI). Outcomes were perioperative complications, readmission within 3 months, re-operation within 2 years, implant failure after 5 years, and mortality within 3 months of surgery.

Results: Private hospitals operated on older females, patients with primary osteoarthritis and low comorbidity and Charnley category 1.

Patients in private and propensity matched controls from public hospitals showed no differences in age, gender, diagnosis leading to THA, Carlson’s comorbidity score, Charnley category, operating time, type of anesthesia and type of prosthesis (p-value < 0,0001).

Based on matched data, private hospitals had lower relative risk for perioperative complications (0.39, 0.26–0.60), reoperations (0.59, 0.41–0.83) and readmissions (0.57, 0.42–0.77) compared with public. There was no difference in mortality or implant failure.

Discussion and Conclusions: We had no data on surgeon, general health and socioeconomic status of the patients. In addition, reported data from private clinics have not been validated in contrast to public hospitals

We found significant difference between patient characteristics operated at public versus private hospitals. No difference was evident regarding mortality and implant failure but for complications, reoperations and readmissions between private and public hospitals.

P. Kjaersgaard-Andersen S. Johnsen S. Overgaard A. Petersen A. Riis

Introduction: NSAID’s are routinely used as either pain-killer or in prevention of heterotopic bone formation (HBF) after total hip replacement (THR). Experimental animal studies have in two decades shown NSAID’s to influence bone remodelling, and thereby also to reduce fixation and bone healing round non-cemented implants. Clinical studies have, however, non been able to demonstrate these observations, too. This may be due a low power in such studies with only few observations. The present study present results from The Danish Hip Arthroplasty Register (DHR) on the effect of NSAID’s to revision of cemented implants due aseptic loosening.

Materials and Methods: DHR was established January 1, 1995 and covers all Danish clinics. All report both primary and revision cases to a central database. Every Danish citizen have an unique civil register number - making it possible to follow both primary and revision cases and to investigate survival due various circumstances. Cox’s regression analysis to estimate the relative risks (RR) of revision and data are presented with 95% confidence intervals.

Results: During the period 1995–2006 total 64.725 primary THR’s were recorded in DHR. Of these 8.531 cases had prophylactic NSAID after surgery in prevention of HBF. Total 409 hips (4.8%) of this population undergoing revision THR had been treated with NSAID’s after surgery. In contrast, 2.536 (4.3%) undergoing revision in the population had no NSAID’s. Overall the risk for revision for any reason was reduced for patients treated with NSAID’s (RR = 0.88 (0.79–0.98) p=0.02). This was even more significant in revision due to aseptic loosening (RR = 0.76 (0.64–0.90) p< 0.01). Subgroup analysis showed that the reduction was in the cemented THR (RR = 0.82 (0.70–0.95) p=0.01) with a further more significant sign in revision due aseptic loosening (RR = 0.69 (0.55–0.87) p< 0.01). In contrast there was no differences in cementless THR neither in revision for any reason (RR = 1.19 (0.86–1.63) p=0.30) nor for aseptic loosening (RR = 1.72 (0.87–3.43) p=0.12).

Discussion and Conclusion: The present investigation from the DHR is a good example of what can be evaluated from a register, and never possibly concluded from standard clinical studies. The results demonstrate that NSAID’s administrated in order to prevent HBF after primary THR surprisingly did not increase the risk of revision in non-cemented implants, but in contrast did reduce the risk for revision in cemented THR. The reason for this reduction is speculated, and be relate to the phenomenon that NSAID’s did not only influence the osteoblastic activity, but also the osteoclasts and thereby prevent early postoperative bone degradation after cemented THR where heat from the bone-cement may impose devascu-larisation of vital bone near the implant.

S. Konan J. Guerts F. Haddad G. Meermans F. Rayan

The aim of our study was to determine the usefulness of preoperative digital templating of cementless total hip arthroplasty (THA).

60 consecutive cementless THA (synergy stem & reflection cup) were templated digitally by two senior hip arthroplasty fellows (GM, YG) independently. A metallic marker ball of known diameter was used in all images to help scale for magnification. A blinded observer then collated information on the actual implant sizes, size of head component, offset, and level of neck cut intraoperatively. This was used to statistically analyse the correlation (Interclass correlation coefficient) between the digitally templated implant sizes and actual implant sizes used and the reliability of digital templating.

A high rate of coincidence between digitally templated estimates and actual implant sizes was noted for both groups of templates. A high intraclass correlation coefficient (ICC) for the acetabular cup, stem and head were noted (ICC of 0.825, 0.794, and 0.884 respectively). Moderate agreement was noted for neck cut (ICC of 0.567) and leg length (ICC of 0.612).

In conclusion, digital templating can reliably estimate implant sizes in cementless total hip arthroplasty. Valuable information on neck cut and leg length can be obtained by preoperative templating.

Y. Kwon H. Gill P. Mclardy-Smith P. Monk D. Murray S. Ostlere B. Summer P. Thomas

Recently, a series of locally destructive soft tissue pseudotumour has been reported in patients following metal-on-metal hip resurfacing arthroplasty (MoMHRA), requiring revision surgery in a high percentage of patients. Based on the histological evidence of lymphocytic infiltration, a delayed hypersensitivity reaction to nickel (Ni), chromium (Cr) or cobalt (Co) has been suggested to play a role in its aetiology. The aim of this study was to investigate the incidence and level of hypersensitivity reaction to metals in patients with pseudotumour.

Materials and Methods: 25 patients were investigated in this Ethics approved study:

Group 1: MoMHRA patients with pseudotumours, detected on the ultrasound and confirmed with MRI (n=6, 5 F:1 M, mean age 53 years);

Group 2: MoMHRA patients without pseudotumours (n=13, 7 F:6 M, mean age 55 years); and

Group 3: age-matched control subjects without metal implants (n=6, 4 F:2 M, mean age 54 years).

Lymphocyte transformation tests (LTT) were used to measure lymphocyte proliferation responses to metals. Peripheral blood mononuclear cells were isolated from heparinized blood samples using standard Ficoll–Hypaque® (Pharmacia). The PBMC were cultured at a cell density of 106 cells/mL. Culture was set up in the presence of either:

medium alone;

nickel chloride (Sigma; 10-4M-10-6M);

cobalt chloride (10-4M-10-6M); and

chromium chloride (10-4M-10-6M).

After 5 days of culture, cells were pulsed with [3H]-thymidine and proliferation was assessed by scintillation counting. The stimulation index (SI) was calculated by the ratio of mean counts per minute of stimulated to unstimulated cultures. A SI value of greater than 2.0 was interpreted as a positive result.

Results: A clinical history of metal allergy was reported in 2/6 in Group 1, 2/13 in Group 2, and none in Group 3. In pseudotumour group, the incidence of reactivity to Ni, Co and Cr was 60%, 17% and 0%, respectively. Within Group 2, the reactivity to Ni, Co and Cr was 69%, 8% and 15%, respectively. One control subject had reactivity to Ni. Inter-group comparisons of mean SI values (Kruskal-Wallis non-parametric analysis of variance) showed no significant differences (p> 0.05).

Discussion: The incidence of enhanced lymphocyte response to metals in patients with MoMHRA was more common than the control group. However, in comparison with non-pseudotumour patients, there was no significant difference in the incidence or the level of lymphocyte reactivity in patients with pseudotumour. We conclude that patients with MoMHRA have an enhanced lymphocyte response to metal ions, reflecting exposure and immune reactivity. However, patients with pseudotumours have a similar proliferative response to those without pseudotumours, which suggests that type IV hypersensitivity may not be the cause of the pseudotumours.

Y. Kwon N. Athanasou H. Gill R. Gundle P. Mclardy-Smith D. Murray S. Ostlere D. Whitwell

Tribological studies of hip arthroplasty suggest that larger diameter metal-on-metal (MOM) articulations would produce less wear than smaller diameter articulations. Other advantages using these large femoral heads implants include better stability with lower dislocation rates and improved range of motion. The aim of the present study was to compare chromium (Cr), cobalt (Co) and titanium (Ti) ion concentrations up to 1-year after implantation of different large diameter MOM total hip arthroplasty (THA).

Methods: Cr, Co and Ti concentrations were measured using a high resolution mass spectrometer (HR-ICP-MS) by an independent laboratory in 110 patients, randomized to receive a large metal-on-metal articulation unce-mented Ti THA from one of the following companies: Zimmer, Smith & Nephew, Biomet or Depuy. Samples of whole blood were collected pre-operatively, and postoperatively at six months and one year.

Summary of Results: At 6 months, whole blood cobalt levels were: (table removed)

Statistical group comparison revealed significant difference for Cr (p=0.006), Co (p=0.047) and Ti (p=< 0.001). With Biomet implants presenting the best results for Cr and Co and Zimmer the highest Ti level.

Discussion: Different implant factors may influence measured metal ion level in whole blood: articular surface wear and implant passive corrosion. Bearing wear may be related to its diameter, quality of the surface finish, component sphericity, radial clearance, manufacturing process (forged vs cast metal) and metal carbon content. Biomet articulation seems to present the best factors selection. Passive corrosion of exposed metallic surfaces is represented by the elevated Ti levels found in all tested systems (Ti was not part of the bearing surfaces). The plasma sprayed acetabular component surface of the Zimmer’s component seems to be responsible for the significant difference in Ti versus the other implants.

J. Lazennec Y. Catonné M. Gorin A. Rousseau Marc

Introduction: Hip dislocation remains a relevant complication of total hip arthroplasty.The implants position plays a major role, especially cup anteversion.It has been demonstrated that anteversion measured on CTscan depends on the pelvic position in a lying patient. This prospective study evaluates the influence of pelvic tilt according to standing and sitting positions.

Material and Methods: The radiological records of 328 consecutive asymptomatic patients with THP were analyzed. These were routine radiological controls of non cemented THP with metal back acetabular implants. All patients had AP and lateral radiographs in standing and sitting position and a “low-dose” CT scan of the pelvis in lying position.Patients were checked for the absence lower limb length discrepancy and lumbosacral junction abnormality.

All the measurements were done by two independent observers and averaged. From the standard radiographs, the sacral slope (SS), the acetabular frontal inclination (AFI), and the acetabular sagittal inclination (ASI) were measured in standing, sitting, and lying positions.

From the CT scan sections, the anatomical ante-version (AA) was measured in lying position on axial images according to Murray. The results were compared to a previously described protocol replicating standing and sitting positions: CTscan sections were oriented according to sacral slope.

Results: We confirmed that the anatomical anteversion (AA), the frontal inclination (FI), and the sagittal inclination (SI) were functional parameter which significantly varied between standing, sitting, and lying positions according to sacral slope variations.The acetabular parameters in lying position highly correlated to the one in standing position, while poorly correlated with sitting position. The difference between the lying and the sitting positions was about 10°, 25°, and 15° for the AA, the AFI, and the ASI respectively.Mean lying anteversion angle was 24.2° (SD6,9°).Posterior pelvic tilt in sitting position, (sacral slope decrease) was linked to anteversion increase (mean value 38,8° - SD 5,4°). Anterior pelvic tilt in standing position (sacral slope increase) was linked to lower anteversion (mean value 31,7° - SD5,6°).

Discussion and Conclusions: Our study confirms the interest CTscan sections oriented according to sacral slope.The strong correlation between lying and standing measurements suggests that classical CTscan protocol is relevant for standing anteversion. According to the poor correlation between lying and sitting positions, it is less contributive for the investigation of dislocations in sitting position.

M. Lavigne M. Ganapathi J. Nantel F. Prince A. Roy M. Therrien P. Vendittoli

Introduction: Better clinical outcome is generally reported after hip resurfacing when compared to conventional 28mmTHA. This may simply be the consequences of biased patient selection, patient perception or the advantageous use of larger diameter femoral heads in HR. The true clinical benefits of HR can only be assessed by comparison with LDH-THA in a blinded randomized study to eliminate/reduce those biases. This was the aim of the study.

Materials and Methods: Charnley class A patients were randomized between HR or LDH-THA and kept blinded for one year. Clinical data, gait analysis, postural balance evaluations and functional tests were performed preoperatively, at 3, 6, 12 and 24 months postoperatively. 14 normal patients served as controls.

Results: 24 patients were assigned to each group. There was no significant difference in WOMAC, SF-36, activity scores, and patient satisfaction. A slight advantage was observed for HR during the functional reach test (postural balance) and for LDH-THA during the step test (speed, strength and balance), all other tests showing no differences. Both groups quickly reached controls value for all tests by 3 months.

Discussion: We have failed to demonstrate a clear difference in outcome between HR and LDH-THA. Both groups fully recovered quickly. The postulated clinical advantages of HR over 28mmTHA most likely result from using a larger head in highly motivated patients. The only clear advantage of HR over LDH-THA remains proximal femoral bone conservation, although with the excellent durability of currently used femoral stems, HR has to demonstrate comparable survivorship before bone conservation is considered a true benefit.

D. Lazovic F. Dunai R. Zigan

An increasing demand for less traumatic THA combined with a faster recovery time has led to minimal invasive surgical approaches and to bone and soft tissue preserving short stem prostheses. Short stem prosthesis should have metaphyseal fixation, primary stability and lesser changes in femoral elasticity which would lead to less stress shielding. The need for a good joint stability and a higher mobility after THA has led to navigated hip surgery together with the use of modular necks to restore the biomechanics.

From November 2004 to July 2008 we implanted 154 Metha prostheses by a modified less invasive Watson-Jones approach. 104 THA were navigated. The indication was primary (32%) or dysplastic coxarthritis (50%) or femoral head necrosis (18%) without affection of the femoral neck, patients age under 50 years and above with good bone density.

Evaluation was done with regard to primary stability, ease of minimal invasive implantation and restoration of the biomechanics. The cup position was aimed at 45° of inclination and 15° of anteversion. The most used modular neck adapter in the non navigated group was standard (135°CCD, 0° antetorsion). In the navigated group more often different variations of neck adapters were used (mainly 135°CCD, 7.5° retrotorsion). Reliable length (+7mm overall) and offset (−3.5mm) measurements could be achieved in the navigated group. The average antetorsion of the stem was 20°.

Bone loss is low with short stem and it is suitable for minimal invasive procedures. A good primary stability seems to be achievable. Modularity leads to a better restoration of the hip biomechanics. In the navigation of the short stem prosthesis the placement of the stem is separated from the restoration of the biomechanics of the hip. The criteria offset, leg length antetorsion, and center of rotation of the head and implant range of motion can be controlled for restoration by navigation. No dislocation was seen in the intraoperative test and in the postoperative follow up.

The short term results show good functional result and a low complication rate without any dislocation. The use of a lesser invasive approach without detaching muscle led to a subjectively faster recovery. The navigation system helps to be precise in cup positioning and to restore biomechanics in term of center of rotation, leg length and offset by advising the best fitting modular neck and reliably predicting the safe range of motion. In our experience the navigated short stem prosthesis offered a good intraoperative handling and good preliminary results.

P. Lewis E. Bogoch M. Olsen E. Schemitsch J. Waddell

The use of metal on polyethylene articulations was a key development in establishing total hip arthroplasty as a successful and reproducible treatment for end stage osteoarthritis. In order to ensure implant durability in relatively younger populations, there is a need for alternative, wear resistant bearing surfaces. Oxidized Zirconium (Oxinium, Smith & Nephew, Inc., Memphis, TN) is a relatively new material that features an oxidized ceramic surface chemically bonded to a tough metallic substrate. This material has demonstrated the reduced polyethylene wear characteristics of a ceramic, without the increased risk of implant fracture. The purpose of the current investigation was to assess early clinical outcomes following primary total hip arthroplasty with Oxinium versus Cobalt Chrome femoral heads.

One-hundred primary THA procedures were prospectively performed in 100 patients. There were 52 males and 48 females. Using a process of sealed envelope randomization, patients were divided into 2 groups. Group 1 consisted of fifty patients, each receiving primary THA implants with an Oxinium femoral head (OX). The mean age of each patient was 51 years (SD 10.8, Range 22–74) with 26 males and 24 females. Group 2 also consisted of 50 patients. Within this group again each patient received primary THA implants however with a cobalt-chrome femoral head (CC). Demographics were similar with mean age 51 years (SD 11.0, Range 19–76) and again 26 males and 24 females.

The current study reports clinical outcome measures for both the OX and CC groups at a minimum follow-up of 2 years postoperatively. At the time of latest follow-up, stem survival for both groups was 98%. There was a significant improvement in all clinical outcome scores between preoperative and 2 year postoperative time periods for both bearing groups (p< 0.003). There were no significant differences between bearing groups for any of the clinical outcome scores at final follow-up (p> 0.159). Mean Harris Hip Scores at 2 years postoperatively were 92 and 92.5 for OX and CC, respectively (range; 65–100 OX, 60–100 CC). For SF-12, both the Physical Component Summary Scale (PCS) and the Mental Component Summary Scale (MCS) are reported. Mean PCS scores at final follow-up were 45.2 and 49.21 for OX and CC (range; 27.1–56.7 OX, 26.3–61.8 CC). Mean MCS scores were 53.8 and 52.57 for OX and CC (range; 39.2–65.5 OX, 34.3–64 CC). Mean final WOMAC scores are reported as 84.9 and 87 for OX and CC, respectively.

The current data suggest that total hip arthroplasty utilizing Oxinium femoral heads is safe and effective. Additional follow-up of the current cohort will be performed in order to fully assess mid- to long-term clinical outcomes.

C. Lohmann S. Junk-Jantsch G. Pflüger W. Rüther

Introduction: Metal-on-metal (MoM) articulations for THA are used successfully from CoCr-alloys. Low or high carbon hydride metals contain less or more than 0.2% carbon in the alloy. The systems show encouraging clinical results and lower rates of aseptic loosening in midterm results. Hypersensitivity reactions to high carbide MoM articulations were reported. The immune response is characterized by a perivascular T-/B-lymphocyte infiltration of the capsular tissue around the hip replacement. The present study examines if lymphocytic reactions are present in low carbide MoM THA and if distinct cytokines are released to joint fluids. Retrieval tissues from 28 patients were used. Joint fluids were aspirated at the time of surgery.

Materials and Methods: Tissues were collected from 25 patients undergoing 26 aseptic revisions of MoM THA (CoCrMo, Sikomet®, Plus Orthopaedics). The patients had following symptoms: Hip and femoral pain; recurrent dislocation and clicking noises. 8 patients had osteolysis, 12 patients showed a metallosis. The peripros-thetic tissues were examined by standard histology and immunohistochemistry. Joint fluids were frozen at the time of surgery. The control groups were patients with osteoarthritis of the hip (n=10), revisions from Al2O3-UHMWPE articulations (n=6), revisions of MoM with hypersensitivity reaction (n=18), and MoM without hypersensitivity reactions (n=8). The fluids were analyzed for various Interleukins, Il-1 receptor antagonist, G-CSF, GM-CSF, IFN gamma, MIP-1ß, and TNF-α.

Results: 18 out of 26 cases showed diffuse and follicular lymphocyte infiltrations in the revision tissues. Perivas-cular T- and B-lymphocytes and few macrophages were also seen. In low and excessive metallosis no lymphocytes were observed. The tissue response in low carbide MoM is similar to high carbide MoM. Analysis of the cytokine profile in the joint fluids showed markers of osteoclast activation (Il-6 and −10) in all MoM articulations. TNF-α increase was increased in all loosening groups but was further increased in MoM. Il-5, IFN gamma, MIP-1ß, and GM-CSF were increased in all fluids from loosening cases but were further increased in MoM with lymphocyte activation.

Discussion: Activation of lymphocytes in failed MoM THA’s is not necessarily related to high carbide MoM. Hypersensitivity also occurred in low carbide MoM THA. The cytokine profiles in the joint fluids showed distinct characteristics. Il-6 and Il-10, markers of osteo-clast activation, were elevated in all cases of bone loss and osteolysis. The increase in TNF-α may account for a regulation of the OPG/RANKL system TNF-a which can induce osteolysis. The elevated levels of Il-5, IFN gamma, MIP-1ß, and GM-CSF in MoM failures with hypersensitivity represent markers of chemotaxis and lymphocyte activation may account for index markers of hypersensitivity reaction.

F. Leiber-Wackenheim B. Brunschweiler A. Gabrion E. Havet P. Mertl

Treatment of recurrent total hip arthroplasty (THA) dislocation is always a surgical challenge. Numerous treatments have been developed, but until now there is no gold standard. The goal of our study was to evaluate the results of a non-constrained tripolar implant (Novae) in this indication.

Material and Methods: The study was retrospective. The inclusion criterion was a dislocated THA which underwent reoperation for changing acetabular stem for a Novae cup. 59 patients were included. Femoral stem was always cemented and was never changed. All patients were reviewed with clinical and radiological examinations. The mean follow up is 8 years (6–11 years). 9 patients died before clinical examination and there was no lost to follow up.

Radiological examination was performed numerically with the software Imagika®

Results: Only one patient had an early dislocation, treated by external reduction. After reduction, no more dislocation occurred. One patient had a femoral fracture below the femoral stem treated by plate. Dislocation rate in our study was 1.7%. The mean Postel Merle d’Aubigné score was 16.5 (12–18) and the mean Harris score was 86.7 (49–99). Radiologically, there wasn’t aseptic loosening neither implant migration, but 19% of the radiographs showed a radiolucent line (less than 1 mm).

Discussion: We compared the results of our study with the results of the other treatments of dislocation. With a dislocation rate of 1.7%, the efficacy of the tripolar non-constrained implant is much better than that of several other treatments, such as external braces, allograft, re-orientation of acetabular shell, change of liner or acetabular augmentation. Constrained implants have also a low dislocation rate, but they have an increased risk of early aseptic loosening. The high rate of radiolucent lines at the last examination is possibly due to the absence of osteointegrating surface of the shell. New implants with osteointegrating surface have been developed.

Conclusion: The efficacy of the studied non-constrained implant is very good with a re-dislocation rate of 1.7%. At 8 years of follow-up, the clinical and radiological results are excellent. We continue to use this implant in the prevention and treatment of dislocation.

A. Lübbeke P. Hoffmeyer T. Perneger D. Suvà

Objective: Dislocation is a well known complication after total hip arthroplasty (THA), and the second cause of revision surgery. Our objective was to assess the effect of a pre-operative patient education session on the occurrence of hip dislocation within 6 months after primary THA.

Methods: Between 1998 and 2007 we conducted a prospective cohort study at the University Hospital Department of Orthopaedic Surgery including all primary THAs performed via a transgluteal approach and with use of a 28mm diameter head. The preoperative education session was introduced in June 2002 and included advice on muscle strengthening exercises and postoperative restrictions of range of motion as means of preventing dislocation. Main outcome was the incidence of dislocation within 6 months of surgery. The following potentially confounding factors were assessed: age, sex, body mass index, number of co-morbidities, presence of a neurological disorder, history of alcohol abuse, American Society of Anaesthesiologists (ASA) score, diagnosis (primary or secondary osteoarthritis), previous surgery of the hip, surgeon experience, preoperative functional status, pain level, and motion (Harris Hip Score), preoperative general health status (SF-12), and private or public health care insurance (as proxy for socioeconomic status). Multivariable logistic regression was used for adjustment.

Results: 597 patients who underwent 656 THAs between June 2002 and June 2007 participated in the education session, while 1641 patients who underwent 1945 procedures did not. Forty-six dislocations occurred over the study period, 5 (0.8%) in participants and 41 (2.1%) in non-participants (risk difference 1.3%; 95% CI 0.4; 2.3), with the time interval between surgery and dislocation being significantly shorter among participants (0.2 vs. 1.2 months, p=0.016). Preoperative counselling of 77 patients allowed for preventing one dislocation (number needed to treat). Non-participants had a 2.8 times higher risk of dislocation than participants (unadjusted odds ratio 2.80, 95% CI 1.10; 7.13). Adjustment for age, sex, co-morbidities and prior surgery did not change the results (adjusted odds ratio 2.79, 95% CI 1.09; 7.15).

Conclusion: Preoperative patient education reduced the dislocation risk within 6 months after THA, and particularly after the patient had returned home. Other peri-operative benefits from patient education have been reported and should be considered in a cost-effectiveness analysis.

A. Maeda I. Hirose S. Kondo Y. Kuroki A. Kusaba K. Nagase H. Noriyuki

Introduction: “Spongiosa metal” this unique implant surface was introduced in 1982 by ESKA implants Germany.

Pore size was between 800 and 1500 microns with an overall porosity of 60%. The pore depth of the interconnecting surface structure reached up to 3000 microns.

The purpose of this retrospective study is to report the long term results of Spongiosa Metal I cement less total hip prosthesis in Japan.

Materials and Methods: Between 1986 and end 1990 total 113 prostheses were implanted and consecutive 106 implants could be evaluated.

The all evaluated prosthesis combined 28mm ceramic head and polyethylene inlay.

Results: Average follow up period was 17 years.

2 cups and 1 stem were revised by aseptic loosening.

2 stem breakage and 7 ceramic head fracture were seen while following up.

85% of the patients had retained the original prostheses (cup, stem, ceramic head, and inlay).

Survival rate was investigated by Kaplan-Meier method.

Survival rate for the cup component was 95%, and for the stem component was 93%.

Discussion: Main reason of the revision surgery was the ceramic head fracture (7 implants 6%)

We thought that beating with the hammer when we install the ceramic head to the taper was one problem.

On the other hand, few aseptic loosening was seen while following up.

These results suggest that spongiosa metal system can bear for long term of use.

Conclusion: 85% of the patients had retained the original prostheses average 17years following up period.

Main reason for the revision surgery is ceramic head fracture.

We are convinced with this spongiosa metal surface can bear long term of use.

D. Mainard E. Choufani J. Diligent L. Galois S. Valentin Y. Vincelet

Navigation technology is a new tool which can help surgeons to a more accurate hip component implantation and a better reproducibility of the procedure.

The purpose of this study was to compare conventional and navigated technique and a new developed straight hip stem for uncemented primary total hip replacement.

The results of two consecutive implantation series of 42 patients (non navigated) and 42 patients (navigated) were analysed for implant positioning and short term complications. Non navigated components were implanted through conventional incision (15 cm), navigated component by minimal invasive surgery (5 cm). All surgeries were performed through Hardinge approach and by a single senior surgeon.

Radiographic analysis of cup position showed a significant improvement with reduced radiological inclination (53° non navigated/44° navigated, p< 0.001) and higher anteversion (7° non navigated/12° navigated, p< 0.001). The mean postoperative limb length difference was 6.2 mm (SD 9.0, non navigated) and 4.4 mm (SD 6.4, navigated). Intraoperative and early postoperative complications were not different. No dislocation occurred in both groups. There was one intraoperative trochanter fracture which was not revised (non navigated) and one revision because of a periprosthetic fracture caused by fall down during rehabilitation (navigated).

We conclude that acetabular implant positioning can be significantly improved by the use of navigated surgery technique even in minimal invasive surgery condition. The data for postoperative limb length difference was still similar but within the expected range in both groups. Navigation technology seems essential for minimal invasive surgical procedure yielding help and security to the surgeon. The effect of improved cup positioning on mid and long term results for both groups have to be further investigated.

G. Meermans F. Haddad J. Witt

Background: Cam-type femoroacetabular impingement (FAI) is becoming more recognized. Cartilage lesions of the acetabulum and labral tears are frequently encountered. The goal of this study was to accurately describe and communicate these injuries and thus providing a standard for reporting injury, management, and outcome.

Methods: We evaluated acetabular cartilage lesions and labral tears found during hip arthroscopy in 52 patients with radiological signs of cam-type FAI. They were graded according to the morphology and extent of the lesion. The labral tears were described according to the classification by Lage.

Results: Eleven patients (21.2%) had normal cartilage, 14 (26.9%) had a grade 1, 17 (32.7%) a grade 2, 6 (11.5%) a grade 3, and 4 (7.7%) a grade 4 lesion. Labral tears were found in 31 patients (59.6%). There was a high correlation between age and the presence and extent of acetabular cartilage and labral lesions (r=0.70; p< 0.0001 and r=0.45; p< 0.001 respectively). There was also a high correlation between the extent of the acetabular cartilage lesion and the presence of labral lesions (r=0.62; p< 0.0001).

Conclusion: In our study there was a high prevalence of associated injuries (86.5%) in cam-type FAI. Despite the recognized consequences of associated lesions on treatment and outcome, no classification system includes this aspect of FAI. Based on our findings, we developed a system to grade acetabular cartilage lesions according to their morphology and extent. This should provide the surgeon with a standardized tool to better describe the full extent of the injury and treat it accordingly.

A. Lübbeke C. Barea G. Garavaglia P. Hoffmeyer R. Peter C. Roussos

Objective: The Morscher press-fit cup is a cementless, porous-coated acetabular component. The objective of this study was to assess clinical and radiological outcomes, patient satisfaction and complications at 10 years.

Methods: Prospective cohort study including all consecutive primary THAs with the Morscher cup operated by multiple surgeons of a University hospital between March 1996 and April 1998. Patients were evaluated at 120 months (±7.2 months) with clinical and radiological follow-up, patient satisfaction and questionnaire assessment, using the Harris Hip Score (HHS), WOMAC and SF-12. Follow-up examination was done by two physicians who had not performed the operations.

Results: 421 THAs were performed in 389 patients (54.6% women; mean age 69.3, range 28–98). In 80% the diagnosis was primary osteoarthritis. All stems were cemented except for 18 patients (4.3%). One-hundred-twenty-two patients (29.0%) had died, 27 (6.4%) were lost-to follow-up, 24 (5.7%) were unable to attend because of poor general health and 27 (6.4%) refused, thus leaving 221 hips, for which 176 x-rays were available.

None of the patients required cup revision for aseptic loosening. Complications included 12 dislocations and 3 deep infections resulting in 2 total revisions. In 3 patients the stem was revised for aseptic loosening at a mean of 63 months. At 10-years the survivorship was 98.6% (95% CI 96.7; 99.4) with endpoint revision for any cause.

Mean total wear was 0.89 mm (±0.5). 32 cups (18.8%) with a cup inclination > 45° had a mean wear of 1.06 mm (±0.5), whereas 138 cups (81.2%) with inclination < 45° had a mean wear of 0.86 mm (±0.5), p=0.036. In 16 cases osteolytic defects around the stem were present. The outcome scores at 10 years were: HHS 85.9 (±14.1), WOMAC pain 70.7 (±24.7), WOMAC function 68.8 (±24.5), SF-12 physical score 40.3 (±9.2) and mental score 47.0 (±10.4). Ninety-four percent of the patients were satisfied or very satisfied.

Conclusions: The Morscher acetabular replacement cup provides excellent results at 10 years. None of the patients had to be revised for aseptic loosening of the cup, patient satisfaction was high, and clinical results were very good.

K. Mannan G. Scott

The proximally hydroxyapatite coated neck retaining Freeman hip stem (Finsbury Orthopaedics, Leather-head, United Kingdom.) was first implanted in 1989. The outcome of the first 100 stems, in 52 men (6 bilateral) and 40 women (2 bilateral) has been reported to ten years, we have extended the follow-up of this series to 17 years.

The mean age was 58.9 years (19 to 84). The diagnosis was osteoarthritis for 70 hips, rheumatoid arthritis for seven hips, post-traumatic arthritis for 14 hips and either avascular necrosis, septic arthritis or developmental hip disorder in nine hips.

The total hip replacements implanted during the period of study (January 1989 to March 1992) were all secured without cement for either component. The acetabular components comprised press-fitted screw-in Rotalok implants (Corin Medical, Cirencester, United Kingdom) or SLF components (Finsbury). All operations were performed using an anterolateral approach with retention of the femoral neck. Three patients have been lost to follow-up, but are included up to their last clinical follow-up.

There have been 40 re-operations for revision of the acetabular component due to aseptic loosening. However, in all but four of these cases the stem was not revised. In two of these the stem revisions were for damage to the trunion following fracture of the modular ceramic head producing fretting against the ceramic debris and acetabular component. In the other two, revision was due to surgeon preference and in both cases well fixed femoral components were extracted at the time of acetabular revision. Osteointegration of these two stems was evidenced by the adherent bone at the time of removal. There has been only one case of aseptic loosening occurring at 14 years. This was found to be rotationally loose at revision and in hindsight was undersized having migrated distally 7.6mm in the first year before stabilising. The survivorship for the stem at 17 years is 98.5% (95% CI; 94.6% to 100%) with 52 patients at risk, all of whom have satisfactory clinical and radiological outcomes. The Freeman uncemented neck retaining proximally hydroxyapatite coated stem has excellent survival results to 17 years.

C. Mella J. Lara L. Moya A. Nunez D. Parodi

Objective: To evaluate if the complete resection of the femoral bump, in cam-type FAI increases the postoperative flexion and internal rotation.

Material and Method: We reviewed 24 consecutive pre-operative and postoperative hip CT scans in 24 patients with FAI (22 male and 2 female, mean age 36.9 years) who underwent arthroscopic hip surgery for the removal of a bony prominence on the femoral neck-head junction. We measured the alpha angle in two places: in the classical location, in the mid plane of the femoral neck axis and proximally, in the same plane but in first quarter of the femoral neck height. Then we compared these results with the presence of a residual prominence diagnosed in the 3 dimensionally reconstructed images of the postoperative CT scan and the virtual range of motion of the 3D models using impaction detection software.

Results: We found 7 cases with a residual bony prominence at the femoral neck-head junction in the 3D model of the proximal femur after the surgery. In this group the mean mid femoral neck alpha angle was significantly improved from 69.7° before the surgery to 48.3° (p=0.028), however the proximal alpha angle was not significantly improved 71.1° preoperative versus 62.7 (p=0.176) after the surgery. In the 17 patients without a residual bump, both alpha angles were improved, the mid alpha angle from 64.9° before the surgery to 40.76° (p=0.000) after the surgery and the proximal alpha angle from 65.8° to 38.4° (p=0.000). The range of motion of hip in the impaction detection software was also significantly improved in both groups, from flexion of 103° to 116° (p=0.001) in the group without a residual bump and from 102 to 118 (p=0.046) in the group with a residual bony prominence after the surgery. The internal rotation at 90° of flexion was also improved in both groups with a statistically significant difference (p=0.001 versus p=0.028 respectively).

Conclusion: The complete arthroscopic resection of the femoral bump improves significantly the ranges of flex-ion and internal rotation in patients with cam-type FAI.

F. Naal F. Impellizzeri M. Leunig A. Mannion U. Munzinger M. Sieverding

During the last decade, outcome assessment in orthopaedic surgery has increasingly focused on patient self-report questionnaires. The Oxford Hip and Knee Scores (OHS and OKS) were developed for the self-assessment of pain and function in patients undergoing joint replacement surgery. These scores proved to be reliable, valid, and responsive to clinical change, however, no German version of these useful measures exists. We therefore cross-culturally adapted the OHS and OKS according to the recommended forward/backward translation protocol and assessed the following metric properties of the questionnaires in 105 (OHS) and 100 (OKS) consecutive patients undergoing total hip or knee replacement in our clinic: feasibility (percentage of fully completed questionnaires), reliability (intraclass correlation coefficients (ICC) and Bland and Altman’s limits of agreement), construct validity (correlation with the Western Ontario and McMaster Universities Index (WOMAC), Harris Hip Score (HHS), Knee Society Score (KSS), Activities of Daily Living Scale (ADLS), and Short Form (SF-)12), floor and ceiling effects, and internal consistency (Cronbach’s alpha, CA). We received 96.6% (OHS) and 91.9% (OKS) fully completed questionnaires. Reliability of both questionnaires was excellent (ICC > 0.90). Bland and Altman’s limits of agreement revealed no significant bias. Correlation coefficients with the other questionnaires ranged from −0.30 (SF-12 Mental Component Scale) to 0.82 (WOMAC) for the OHS, and from −0.22 (SF-12 Mental Component Scale) to −0.77 (ADLS) for the OKS. For both questionnaires, we observed no floor or ceiling effects. The internal consistency was good with a CA of 0.87 for the OHS and 0.83 for the OKS. In conclusion, the German versions of the OHS and OKS are reliable and valid questionnaires for the self-assessment of pain and function in German-speaking patients with hip or knee osteoarthritis. Considering the present results and the brevity of the measures, we recommend their use in the clinical routine.

F. Naal F. Impellizzeri M. Leunig A. Mannion

The goal of this study was to develop and validate a short, evaluative self-report questionnaire for the clinical self-assessment of patients with hip osteoarthritis (OA). If used together with other self-report outcome tools (e.g. generic or physical activity measures), such a short joint-specific questionnaire could avoid an increased burden to the patients and decrease the risk of data loss. All items of the new score (Schulthess Hip Score, SHS) were generated solely on patient perceptions, for item removal we used the clinical severity-importance rating and inter-item correlation methods. The final score consisted of only five items. We then assessed the following metric properties of the SHS in 105 consecutive patients with symptomatic hip OA (mean age, 63.4 ± 11 years, 48 women) undergoing total hip arthroplasty (THA) in our clinic: proportion of evaluable questionnaires, reproducibility, internal consistency, concurrent validity, and responsiveness. 97% of the questionnaires were evaluable. Reproducibility of the SHS was excellent (intraclass correlation coefficient (ICC) 0.90; standard error of the measure (SEM) 6.4). Exploratory factor analysis indicated that all items loaded on only 1 factor which accounted for 69.4% of the total variance. Cronbach’s alpha was 0.88. Evidence of convergent validity was provided by moderate to high correlations with scores and subscales of the WOMAC (r = 0.58–0.78), Oxford Hip Score (r = 0.78), Harris Hip Score (r = 0.37), SF-12 physical component scale (r = 0.57), UCLA activity scale (r = 0.48), and Tegner score (r = 0.53). Evidence of divergent validity was provided by a lower correlation with the SF-12 mental component scale (r = 0.37). The SHS proved to be responsive with an effect size (ES) of 2.15 and a standard response mean (SRM) of 1.74 six months after THA. Taken together, the results of this study provide evidence to support the use of the five-item self-report SHS in patients with hip osteoarthritis. Considering the brevity of this score, it could be easily used together with other measures such as generic and physical activity assessment tools, without overburdening patients with an inordinate number of items and questions.

L. Moya R. Buly F. Henn B. Kelly Y. Ma D. Molisani

Introduction: Femoroacetabular impingement (FAI) is one of the main causes of hip osteoarthritis. Femoral retroversion has been reported as a cause of FAI and it is well established that a retroverted femur produces hip pain and alterations in the external and internal rotation balance. However, no studies of femoral retroversion in patients with FAI have been reported. Furthermore, since the lack of internal rotation is a common feature in patients with FAI, it could be possible that femoral version abnormalities are present in these patients. The purpose of this study is to describe the femoral version in a group of patients with FAI and to assess its relation in the development of hip osteoarthritis.

Methods: The history, x-rays and hip CT scans of 142 patients with FAI were reviewed. All patients presented persistent hip pain and were evaluated clinically between January 2006 and July 2008. We defined FAI when at least one of the following features were present:

an abnormal alpha angle (> 49°) measured on the elongated femoral neck x-ray,

a positive cross-over sign or pro-trusio acetabuli in the AP pelvis x-ray,

the presence of diminished anteversion in the femur (< 10°) or a retroverted femur (< 0°) in the CT scan, associated with a positive hip impingement test and lack of internal rotation at 90 degrees of flexion.

We documented the type of FAI, the presence of acetabular dysplasia, coxa valga, coxa vara and the femoral version measured on the CT scan. The degree of osteoarthritis of the hip using the Tönnis classification was documented as well.

Results: Two hundred and sixty-five FAI hips from 142 patients (73 females and 69 males) were analyzed. The average age was 36.7 years. The mean femoral version was 11.4 ° (−14.1° to 47°). We found 43 hips (16.6%) of the femora were retroverted and 133 hips (50%) had either diminished anteversion (< 10°) or were retroverted. In 12 hips (0.05%) the only cause of FAI was the presence of a diminished anteversion or retroverted femur. The statistical analysis using the generalized estimating equations method including the right and left hips, shown that among these six predictors, both femoral retroversion (p=0.046) and coxa vara (p< 0.001) were statistically significant for the presence of osteoarthritis.

Conclusion: The presence of a retroverted femur seems to be a cofactor in the development of hip osteoarthritis in patients with FAI. The orthopedic surgeons should be aware of the high frequency of femoral retroversion when evaluating patients with hip impingement, in order to make the right diagnosis and treatment. It might be possible that this association between FAI and femoral retroversion is due to a common hip disease during skeletal maturation (i.e. SCFE) leading to two anatomical alterations at the proximal femur: reduced head-neck offset and retroverted femur.

V. Murakibhavi N. Ahmed V. Raj J. Richardson

Introduction: Autologous chondrocyte implantation (ACI) has been used most commonly as a treatment for cartilage defects in the knee and there are few studies of its use in other joints. There is only one published report of its use in the hip. Is there a role for ACI of the hip?

Materials and Methods: We describe fourteen consecutive patients studied prospectively with chondral or osteochondral lesions of the femoral head that underwent ACI and were prospectively reviewed with a follow up of 5 years (mean 30 months).

Three patients presented with Perthes and five with AVN. Four had chondral loss following trauma and one presented with an area of bone loss in a hip with congenital dysplasia. Defect size was a mean 6.2 cm2.

Pre-operatively hip function was assessed by the patient using the Harris Hip Score and MRI. Postoperatively these were repeated at 1 year and hip scores repeated annually.

Hip arthroscopy and cartilage biopsy provided Cells for culture in a GMP laboratory where passage numbers were limited to two. Three weeks later by open surgery, all unstable cartilage was excised, the base was debrided or excised and bone graft applied, and suture of a membrane of periosteum or collagen membrane over the defect undertaken. A mean 5.2 million chon-drocytes were inserted beneath this patch following a test of the seal.

Results: Ten of the fourteen patients improved at one year, with a mean rise in Harris Hip score from 57 to 63 points. Five patients underwent arthroscopic examination at one year and in four there was evidence of good integration of the new cartilage. In one patient arthros-copy was difficult due to previous trauma. One patient developed AVN as a post-operative complication following a posterior approach. Four patients have progressed to hip replacement or resurfacing but it is of note that all these patients had cyst formation pre-operatively.

Conclusion: The short-term results of ACI for osteo-chondral lesions of the hip suggest that if good early results are obtained they are observed to continue out to 5 years. There is a high failure rate in those with pre-operative cyst formation in the hip