Introduction. After total hip arthroplasty, dislocation is one of the most frequent serious early complications. This occurs in part due to impingement (catching and leverage of the neck-cup on the inlay/cup border). Impingement may also negatively impact long-term outcomes. Materials and Methods. A preliminary model for an optimised hip endoprosthesis system was developed to offer a mechanical solution to avoid impingement and dislocation. A computer-supported range of motion simulation using parameters of cup anteversion and inclination as well as torsion and CCD shaft angle was then performed to localise areas of anterior and posterior impingement of typical acetabular cups. Results. Through isolation of the two main trajectories of motion, and modifications with corresponding gaps to the inlay/cup areas as well as oppositional banking in the abduction/adduction plane, the combination of a snap-fit acetabular cup with reduced cup profile was the result: the “bidirectional total hip prosthesis.”. Under standardised parameters, the ranges of impingement for typical implants are not directly opposite one another (at 180°), but are found instead at an angle of 108.3°. Conclusion. Complications such as dislocation and impingement may possibly be avoided with the bidirectional total hip prosthesis. Typical implantation parameters yield an implant design with rotational asymmetry. [Fig. 1, 2]

Aims: The authors report oncological and functional results after 15 acetabular reconstructions, followed tumor resection, with an original technique using homo-lateral proximal femoral autograft and total hip prosthesis. Material and method: The modiþed Musculoskeletal Tumor Society Score (MSTS) and the Toronto Extremity Salvage Score (TESS) were used for functional analysis. Functional results were available for only 10 patients who presented with a minimal of 2 years follow-up. Results: Fifteen consecutive patients, 9 men and 6 women with a median age of 50 years, were managed in our department for acetabular bone malignant tumor. The tumors involved the zones II in 5 patients, the zones II and III in 5 patients. The tumors included 10 chon-drosarcomas, 1 malignant þbrous histiocytoma, 1 radio-induced sarcoma, 1 myeloma and 2 metastasis. The mean follow-up was 31 months (Range, 12 to 50 months). Local recurrence occurred in 1 case and metastases in 3 cases. Three patients died of tumoral disease and one of intercurrent disease. Eight complications were observed: aseptic failure (n=1), obturator nerve damage (n=1), deep infection (n=4), skin necrosis (n=2), pros-thesis dislocations (n=1) and deep venous thrombosis (n=1). Five revision were performed. The mean MTS was 72% (range, 40 to 96%) and the mean TESS was 82.5% (range, 56 to 86%). Fusion occurred in all reconstructions and all patients recovered an active hip abduction and ßexion. Discussion: This original technique, using an autograft and a standard total hip prosthesis, is available for zone II and III acetabular reconstructions

Because we encountered a high failure rate of the acetabular component of the uncemented, hydroxy-apatite coated, Omnifit total hip prosthesis (Osteonics corporation, Allendale, NJ, USA), we conducted a retrospective study of 418 consecutive total hip arthroplasties with a mean follow up of 60 months. The results of 418 hydroxy-apatite coated, uncemented Omnifit total hip arthroplasties, conducted between 1989 and 1996 were evaluated. Two different acetabulum cups were used: 145 screwcups with one central screwhole, and 273 press fit (PF) cups with several screwholes. The internal geometry of these cups and the fixation of the polyethylene insert in the metal cups were identical. In 339 arthroplasties a 32-mm femur-head was used, in 79 a 28-mm head. Patients’ records and x-rays were evaluated for clinical findings, polyethylene (PE) wear, acetabular and femoral osteolysis and findings during revision surgery. Revision surgery was performed in 73 patients, mainly because of symptomatic acetabular osteolysis (79%). Mean PE wear was 0.16 mm/year (0.19 mm in PF cups, 0.11 mm in screwcups). Acetabular osteolysis was found to be present in178 hips (70 screwcups and 108 PF cups). In both cupdesigns the osteolysis was mainly found around the screwholes of the metal cups. During revision surgery these osteolytic defects were a lot larger than suggested by x-ray imaging. In 22.6% of the hips osteolysis was also present in the proximal femur. Kaplan-Meier survival analysis showed, after 6 year follow up, a better survival for of the screwcup (96%, confidence interval 93–99%) than the PF cup (66%, 95%CI 56–77%). We hypothesized that this specific combination of metal cup and polyethylene insert -possibly due to an insufficient fitting- is responsible for the migration of polythylene wear particles through the screwholes in the metal cup, causing acetabular osteolysis and neces-satating revision surgery. For this reason we abandonned the use of this type of uncemented acetabular component

The ABG total hip prosthesis had been studied to prevent any kind of stress shielding and to allow the localization of the loads in the metaphiseal region of the femur. The aim of this study was to analize the effective behaviour of the loads in long-term implants and the possible correlations of those findings with the clinical situation of the patients. We considered 87 total hip arthroplasty implants executed from 1989 to 1995 and performed by using Anatomique Benoist Girard I uncemented prosthesis. The radiographical findings have been classified observing Engh’s stability criteria according to Gruen’s subdivision of the periprosthetic femoral zones. The radiographical analysis shows a higher presence of can cellous densification in Gruen’s zones 3 and 5 than the one found in zones 2 and 6. Furthermore the presence of a cortical reaction is more relevant in the distal zones.> Radiolucent lines are present in 16% of the cases in zone 4; their percentage in zones 3 and 5 decreases to 7.14% and 10.71%. Our study shows the certain presence of the stress shielding mechanism in long-term analysis and documents that the main region of late anchorage is the distal, not hydroxyapatite-coated, one.> The comparison with other similar studies shows the decrease of the presence of radiolucent lines in proximal femoral zones with the rise of the follow-up: it can be interpreted as the lesser presence of micro movements of the tip of the prosthesis due to the distalization of the anchorage

Purpose: The surgical approach is an essential element for precise reduction and rigid fixation of fractures of the acetabulum. In cases where the anterior column is mainly involved and total hip arthroplasty (THA) is indicated, classical approaches do not allow double assess to the anterior column necessary for reduction and fixation and to the femoral canal for insertion of the prosthesis. Combining Heuter’s anterior approach and Letournel’s ilio-femoral approach provides access to the anterior column and to the often associated posterior hemi-transverse fracture, while allowing insertion of the total hip prosthesis. Material and method: This combined approach was used for ten among 60 THA performed for fracture of the acetabulum. Seven were primary procedures and three were differed reconstruction procedures. Mean patient age was 60.6 years (range 50 – 85 years). Fracture types were: acetabular wall and anterior column (n=8), anterior column and posterior hemi-transverse (n=2). All fresh fractures exhibited major acetabular damage associated with fracture of the femoral neck. A hybrid THA was used for all cases after fixation of the fracture. The femoral heads were used as graft material for deficient anterior columns in two patients and as “piecemeal” grafts for the others. Results: Mean follow-up was 36 months (range 24–35 months). At last follow-up all fractures had healed and all acetabular components exhibited solid fixation with no sign of migration. The mean outer diameter of the ace-tabular components inserted was 56 mm (52–64) using a 2 mm press-fit and one screw. The only complication was one postoperative anterior dislocation. Pain relief and function were satisfactory in all patients at last follow-up with a Postel Merle d’Aubigné score of 16 (13–18). Discussion: This anterior surgical approach enables good access to the acetabular walls and anterior columns, allowing solid fixation and relatively easy THA. The Kocher-Langenbech approach is still better in case of posterior deficiency or when posterior fixation requires space for inserting an acetabular component. We reserve it for THA used to treat fresh fractures of the acetabulum with major damage to the acetabulum and/or the femoral head, with or without neck fracture in patients aged 55 years or more. For differed reconstruction, we also use this approach if the acetabular damage involves the anterior column

Introduction. Total hip arthroplasty in young patients is still associated with high failure rates, especially at the acetabular side. Purpose of this study was to evaluate the long-term results of the Alloclassic cementless Zweymüller total hip prosthesis in patients younger than 50 years at the time of surgery. Methods. Between 1987 and 1994, 73 Zweymüller total hip arthroplasties with a titanium threaded cup were placed in 67 patients younger than 50 years. Mean age at surgery was 43 years (23–49 years). Patients were followed clinically with use of the HHS, revisions were determined and radiographs were analyzed. Kaplan-meier analysis was used to determine survival for different endpoints. Results. Three hips were revised for septic loosening, 3 cups for aseptic loosening and 1 hip because of periprosthetic fracture. Four patients (4 hips) died and 8 patients (9 hips) were lost to follow-up without any revision. 48 patients with 53 prostheses could be evaluated after a mean follow-up of 208 (170–253) months and the mean HHS was 90 (52–100). Cumulative survival analysis with endpoint revision for any reason was 89% (C.I. 85–93) at 17 years. With endpoint aseptic loosening, survival was 95% (C.I. 91–98) at 17 years. Conclusion. Alloclassic Zweymüller total hip arthroplasty with a titanium threaded cup showed good long-term results, even in this group of patients younger than 50 years

Purpose: Wear of prosthetic implants, especially the metal-polyethylene head-cup couple, and dissemination of wear particles throughout the organisms the dominant long-term complication of total hip arthroplasty. We determined serum concentrations of chromium, cobalt, nickel, and molybdenum in patients bearing a total hip prosthesis with a chromium-cobalt metal-poly-ethylene head-cup couple. The purpose of our work was first to compare the levels observed with those found in a control population and then to study variations in these levels as a function of clinical and radiological signs commonly searched for during the follow-up of patients with a total hip arthroplasty. Material and methods: During a period of 30 months, a total hip arthroplasty (PVL®) was implanted in 53 patients suffering from degenerative hip disease. Forty-eight patients were assessed at a minimum follow-up of 32 months with physical examination and standard x-rays as well as serum assay of the specified metals using mass spectrometry on whole blood samples. The control group was composed of 56 patients scheduled for total hip arthroplasty. Results: At a mean follow-up of 44 months, 17% of the patients had a fair or poor functional score and 37% had radiological signs suggestive of femoral stem loosening. There was a significant increase in the serum level of cobalt compared with the control group. This increase was greater in patients with radiological signs of loosening. Discussion: The metal-on-metal couple does not appear to be the only couple which increases serum metal levels. Serum metal assay could be a diagnostic tool useful for following patients with total hip prostheses

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

Purpose: A spacer can be used for two-phase replacement of an infected total hip prosthesis. The goal is to facilitate reimplantation by avoiding soft tissue retraction. Several types of spacers can be used. We searched for a spacer which avoids wear debris due to methacrylate friction against bone, delivers a local antibiotic, is easily removed, and does not worsen bone damage. Since 1995, we have used a Charnley Kerboull type prosthesis as a spacer. The purpose of the present study was to 1) verify the absence of spacer-related complications, 2) assess outcome in terms of cure of infection and improved function. Material and methods: We used 14 articulated spacers for two-phasee prosthesis replacement in nine men and five women, mean age 64 years. Erythrocyte sedimentation rate was 32 and C-reactive protein was 17. The mean Postel-Merle d’Aubigné (PMA) score was 3+5+2. All patients were reviewed at a minimum 37 months follow-up. Technique: The approach was generally a digastric trochanterotomy, associated with a more or less extensive femoral procedure (depending on the length of the plug to remove) to achieve removal of all implants and cement. A small-size polyethylene cup was inserted with cement delivering at least one antibiotic on a Surgicel bed to facilitate later extraction. A long small-diameter femoral stem was then inserted (bridging the femoral window) and blocked with cement, also on a Surgicel bed. Partial then total weight bearing was authorised between the phases. Results: There were no dislocations. All patients achieved total weight bearing between the two phases. The same germ identified at the first operation was also identified at the second in two patients, requiring prolonged antibiotic therapy. There was one septic failure, in a different patient. The mean PMA score was 5.7+5.8+5.2. Conclusion: This technique avoids methacrylate wear induced by classical spacers and does not modify polymorphonuclear chemotactism, facilitating the efficacy of medical treatment. Patient comfort is also improved between the two phases and muscle atrophy, which could compromise long-term function, is avoided

SL-PLUS MIA stem (Smith & Nephew Orthopaedics AG) is a modified implant of Zweymuller type SL-PLUS standard stem (Smith & Nephew Orthopaedics AG). We constructed finite element (FE) models and analysed equivalent stresses in the femur. In addition, we measured bone mineral density (BMD) in the femur by dual-energy X-ray absorptiometry (DEXA) after THA. The purpose of this study was to investigate the equivalent stress and to compare the results of the FE analyses with changes in BMD after THA. Twenty-one patients (18 women and 3 men) who underwent primary cementless THA with SL-PLUS MIA or SL-PLUS formed the basis of this study. Eleven patients received SL-PLUS MIA and ten patients received SL-PLUS. Zones were defined according to Gruen's system (zones 1∼7). Computed-tomography (CT) images of the femur were taken before and at 1 week after THA. FE models of the femur and prosthesis were obtained from CT data by Mechanical Finder (Research Center of Computational Mechanics Inc., Tokyo, Japan), software that creates FE models showing individual bone shape and density distribution. Equivalent stresses were analysed in zones 1 to 7 and compared to the DEXA data. FE studies revealed that there was no significant difference in equivalent stress between SL-PLUS MIA and SL-PLUS. BMD was maintained after THA in zones 3, 4, and 5, whereas BMD decreased in zones 2, 6, and 7. In zone 1, BMD decreased in SL-PLUS MIA stem group by 14%, while BMD was maintained in SL-PLUS standard stem.

Introduction: Unique spongiosa like surface structure was introduced in 1982 by ESKA implants Germany. It is called “Spongiosa-Metal I surface” The purpose of this retrospective study is to report and compare long term results of Spongiosa Metal I total hip prosthesis in Japan and Germany. Method: In Japan, between June 1986 and August 1990 total 113 prostheses were implanted and consecutive 106 implants could be evaluated. In Germany, between May 1983 and December 1985 total 209 prostheses were implanted and consecutive 165 implants could be evaluated. The all evaluated prosthesis combined ceramic head and polyethylene inlay. Results: In Japan, average follow up period was 17 years. 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%. In Germany, average follow up period was 21.8 years. 88.5% of the patients had retained the original prosthesis. Survival rate for the cup component was 95%, and for the stem component was 85%. Discussion: Main reason of the revision surgery was the ceramic head fracture (7 implants 6%) in Japan and the stem component loosening (14 implants 8%) in Germany. There was no ceramic head fracture in Germany. We thought that beating with the hammer when we install the ceramic head to the taper was one problem. Stem loosening was seen in undersized stem component. On the other hand, survival rate for the cup component was 95% in Japan and Germany. This was good result in comparison with other reports about long term survival. Conclusion 85% of the patients had retained the original prostheses average 17years in Japan and 88.5% average 21.8 years in Germany. Main reason for the revision surgery is stem loosening and ceramic head fracture. Survival rate for the cup component was 95% in Japan and Germany. We are convinced with this spongiosa metal surface can bear long term use

INTRODUCTION. Cementless Total Hip Replacement surgery is a well established procedure for relative young patients with severe hip disease. Excellent long term clinical results have been published on the performance of the femoral component. With growing clinical experience, our concern focused on excessive wear of the Ultra High Molecular Weight Polyethylene (UHMWPE) ringloc liner of the Mallory Head cementless Total Hip Prosthesis. After its introduction in our clinic in 1997, this implant is still in use without any modification. We were concerned that due to premature liner wear, the performance of this implant would not be compliant with the international guideline on implant survival (NICE guidelines: at 10 year follow up, 90% of all implants should still be in situ). Our objective was to establish the amount of liner wear in our first 200 MH implants. METHODS. Our first 200 patients consecutively treated with Mallory Head prostheses were followed up to obtain a recent digital image. Follow up was complete for 181 (90.5%) of our 200 patients. Ten had died and nine were not able or willing to come for follow up. The mean duration of follow up was 8.3 years (range: 8–13). The 181 recent digital images were classified as either excessive wear or no excessive wear by two independent orthopedic surgeons. Next, liner wear was measured in the 2D frontal plane using PolyWare Pro/3D Digital Version Rev 5.1 software (Draftware Developers, Conway, USA). A threshold for excessive liner wear was set at 0.2mm/year, according to literature. RESULTS. Using software for measuring PE wear, 46.7% of all patients had excessive UHMWPE wear (> 0.2mm/yr). There was no relation between the amount of wear and BMI, gender, component size or the acetabular inclination angle. Thirteen patients (6.5%) were revised. Nine of these revisions were for excessive liner wear or aseptic loosening (4.5%). For now, our series of cementless Mallory Head prostheses is compliant with the NICE guideline on implant survival. However, with the measured amount of wear we expect to see a significant increase in the number of revisions for liner wear in the near future. DISCUSSION. Our clinical observation of premature UHMWPE wear proved correct. The measured amount of UHMWPE wear is consistent with the few other studies published on this subject. Although we present a retrospective study, limiting the strength of our results, we have included a large group of patients with acceptable loss to follow up. It is unclear if the observed wear will lead to a sharp increase in the number of revisions within the next few years. Possibly, future revisions will be complicated by loss of acetabular bone stock following the pathofysiological reaction to wear particles. Our results can probably be generalised for any district hospital

Total Hip Arthroplasty (THA) is a well-established, cost-effective treatment for improving function and alleviating pain in patients who have disabling hip disease with excellent long-term results. Based on the excellent results, there is an ongoing trend for THA to be performed in younger and more active patients, having higher physical demands on their new total joints.

Polyethylene (PE) wear and its biological consequences are one of the main causes of implant failure in THA. Macrophages phagocytise PE wear particles and this will result in osteolysis and loss of periprosthetic bone. The risk of these complications can be estimated in relation to the amount of volumetric wear based on two assumptions: that the number of PE particles dispersed in the peri-prosthetic tissues is controlled by the amount of PE wear; and that the development of osteolysis and the resulting aseptic loosening is triggered by these PE particles. Based on these assumptions, a model was developed to estimate the osteolysis-free life of a THA, depending on the Linear Wear Rate (LWR) and femoral head size of the PE bearing.

A review of the literature was conducted to provide an estimate of the radiologic osteolysis threshold based on the volumetric wear of the PE bearing. This review demonstrates that this radiologic osteolysis threshold is approximated 670 mm3 for conventional PE. The osteolysis-free life of the THA was estimated by simply dividing this threshold volume by the annual Volumetric Wear Rate (VWR) of the bearing. The annual VWR is basically controlled by two parameters: (1) annual LWR and (2) head size, and was calculated by using published formulae.

For 28 mm heads, following osteolysis-free life was determined in function of the annual LWR. LWR: 10 µm/y => 116.6 years / LWR: 25 µm/y => 46.6 years / LWR: 50 µm/y => 23.3 years / LWR: 100 µm/y => 11.6 years. For 40 mm heads, following osteolysis-free life was determined in function of the annual LWR. LWR: 10 µm/y => 57.1 years / LWR: 25 µm/y => 22.9 years / LWR: 50 µm/y => 11.4 years / LWR: 100 µm/y => 5.7 years.

The osteolysis-free life determined by this model is in good agreement with the clinical results of PE bearings having a 28 mm head size and demonstrates that extreme low LWRs are mandatory to assure a descent osteolysis-free life for THA (PE bearings) using large heads, such as 40 mm. For such head sizes, small variations of the LWR may have large impacts on the osteolysis-free life of the THA.

Between January 1984 and January 1986, 131 porous-coated anatomic total hip replacements were performed in 119 consecutive patients. Of these, 100 patients (110 hips) who were alive at a minimum of 18 years after replacement were included in the study. The mean age of the patients at surgery was 48.4 years and that of surviving patients at the latest follow-up was 67.8 years. The mean duration of the clinical and radiological follow-up was 19.4 years (18 to 20).

The mean Harris hip score initially improved from 55 points before to 95 points at two years after operation, but subsequently decreased to 91 points after six years, 87 points after 11.2 years, and 85 points after 19.4 years. At the final follow-up, 23 hips (18%) of the entire cohort and 21% of survivors had undergone revision because of loosening or osteolysis of the acetabular component and eight hips (6%) of the entire cohort and 7% of survivors for loosening or osteolysis of the femoral component. Only four femoral components (4%) were revised for isolated aseptic loosening without osteolysis and two (2%) for recurrent dislocation. On the basis of these long-term results, the porous-coated anatomic femoral component survived for a minimum of 18 years after operation while the acetabular component was less durable. The findings identify the principles of uncemented joint replacement which can be applied to current practice.

Customization makes it possible to fulfill design requirements during MIS-THA procedures, and has helped define the parameters of fit and fill. This study describes the results of using customization techniques to develop a femoral implant for utilization.

CT-based design criteria for femoral implants has-been developed and used for primary, cement-less, non-minimally invasive THA surgery. Over 1000 procedures performed with these devices have been associated with displaced femoral fractures, and have been revised for septic loosening. This study has 2 parts:

20 implants were designed and implanted with CT-based criteria that utilized the identical fit and fill standards of the custom implants previously established, but had short (< 115 mm), tapered stems;

The stem of these implants was shortened (95–115 mm) and tapered. Implants in both groups were inserted using a single incision, posterior-lateral MIS approach. Patients were followed clinically and radiographically for six months. Immediate full weightbearing and use of a single cane were encouraged.

The use of CT-based customization techniques is helpful for defining design criteria of femoral implants, but the instrumentation for inserting these implants must be adapted to the specific surgery. Customization also facilitates the design and evaluation of CAOS applications for inserting these MIS implants.

Early reports on revision total hip arthroplasty (RTHA) suggested that outcomes of this procedure are as good as those of primary total hip arthroplasty (THA). However, RTHA is associated with longer surgery time, greater blood loss and increased risk of complications (thromboembolism, nerve injury, periprosthetic fractures, recurrent hip dislocations and infections). Aseptic loosening after RTHA was reported in 36% of patients aged over 55 years within 4 years after revision. Infections were reported in 32% and complications during surgery in 23% of patients respectively. Unsatisfactory results of RTHA stimulate the search for alternative procedures. Girdlestone excision arthroplasty (GA) seems to be a good solution for older patients with high risk of complications related to a poor general condition.

Material and method Between 2000 and 2003 we operated 39 patients, 10 for septic (26%) and 29 aseptic (74%) loosening of their THA. All patients complained of painful limb aggravated by weight bearing and the severity of pain was the main indication for the surgery. Average survival time of previous THA was 9 year (range: 1 to 20). We assessed pain, walking distance and the need to use walking aids. The outcomes were measured according to the Harris Hip Scale. The patients had the GA performed. The procedure involved removing implant and bone cement and placing the major trochanter into bone acetabulum. If an infection was present, an antibiotic irrigation system was introduced. No cast or braces were used and walking was started 2–7 days after surgery, depending on patients general condition.

Results Good pain control was reported by 33 (85%) patients. The average Harris Hip Score changed from 25 points preoperatively to 53 at latest follow-up. Average limb shortening was 4 centimetres (range: 2 to 8). Walking aids (one or two crutches) were required by all patients. Eighteen (46%) patients walked more than 500 m, 12 (31%) patients walked 200–500 m and 9 (23%) patients walked less than 200 m, of whom one patient was wheelchair bound.

Infection ceased in 9 cases, 1 patient died because of complications related to chronic infection.

Discussion GA yields satisfactory results in patients who have to have their prostheses removed. It provides a mobile, painless joint. The disadvantages of GA are: limb shortening and unstable gait which requires the use of crutches. This procedure should be indicated for patients with high risk of complications due to poor general health, infection and/or massive loss of bone stock which render more invasive procedures impossible. GA is also advisable in patients with weak hip abductor muscles, when RTHA is associated with a high risk of recurrent hip dislocation. The Girdlestone arthroplasty is a satisfactory salvage procedure in most cases of failed THA, when the choice of reimplantation exposes the patient to a high risk of further failure.

We report the clinical outcome and survival of 100 total hip arthroplasties with Link RS cementless hip prostheses after a mean of 63 months (51 to 93). The average preoperative Merle d'Aubigne hip score was 9.4 points and the average score at the latest follow-up was 15.3 points. Thirteen prostheses have been revised and seven await revision. Survivorship analysis based on intention to revise showed only 68% survival at seven years (95% CI 53% to 81%). The survivals of femoral and acetabular components verified to be loose at surgery were 78% and 89% respectively at seven years. A number of other patients have pain and it seems likely that there will be substantial reduction in these survival figures in the future.

Sixty-five total hip arthroplastics were reinserted after sepsis around the hip, positive cultures being obtained from fifty-six. Although 65 per cent of patients still have their implant in position, only sixteen of sixty-five (25 per cent) show an excellent or good result on a Harris rating. Twenty-three of sixty-five (35 per cent) subsequently required an excision arthroplasty. The indications and contraindications for this procedure are given.

Introduction

Post op cup anatomical and functional orientation is a key point in THP patients regarding instability and wear. Recently literature has been focused on the consequences of the transition from standing to sitting regarding anteversion, frontal and sagittal inclination. Pelvic incidence (PI) is now considered as a key parameter for the analysis of sagittal balance and sacral slope (SS) orientation. It's influence on THP biomechanics has been suggested. Interestingly, the potential impact of this morphological angle on cup implantation during surgery and the side effects on post op functional orientation have not been studied.

Our study explores this topic from a series of standing and sitting post-op EOS images

We enrolled 98 patients (107 hips) with a mean age of 47 years (SD 8.6) into a prospective study of the Madreporic Lord THR; 34 hips had primary and 73 secondary osteoarthritis.

After ten years, the survival rate using revision as the endpoint for failure was 70% (±9) for the cup and 98% (±0.3) for the stem. The combined clinical and radiological survival rates were 46% (±11) and 81% (±10), respectively. Osteoporosis due to stress-shielding was observed in the proximal femur. Hips with radiologically dense bone postoperatively showed the most pronounced bone loss.

We recommend continued radiological follow-up of patients with this type of implant to allow revision to be performed before there is severe bony destruction of the pelvis.

Twenty-nine patients with thirty pseudarthroses after removal of infected total hip prostheses have been reviewed one to six years later. Six hips still had a discharging sinus. Complete removal of all cement was found to be essential for healing, and various points in the technique of its clearance have been made. In this respect radio-opaque cement was a great advantage, and lateral guttering of the femur was most effective. Compared with the situation before replacement considerable relief of pain was obtained in most patients but there was much less improvement in function.

The aim of this study is to review the relation of polyethylene wear in patients underwent Anatomic Medullary Locking total hip replacement with respect to the types of acetabulum used.

85 cementless primary AML joint replacements were performed in the 10 years period from 1988 to 1998. The average age at operation was 46.6 with a range from 22 to 63. Two different types of acetabulum design namely the Acetabulum Cup System (ACS) and Duraloc were used. 39 of them were followed up from 2 to 10 years with an average of 69 months. Xrays were performed at the review visit and the thickness of the insert was calculated. The cup abduction angle was measured and the size of the cup and initial insert thickness was also recorded. The findings were correlated and subjected to statistical analysis.

Our findings suggested that the wear of the ACS cup was significantly higher than that of the Duraloc cup. The size of the cup but not the age of the patient at the time of operation also affects the wear rate. It appears that wear rate started to accelerate from year 8 onwards. The risk is higher with cups of less than 50mm diameter

We conclude that it is advisable to review closely those patients with the ACS cup implanted. Revision surgery should be considered if eccentric wear started to be seen on Xray to avoid complicated procedure.

The shape of the femoral canal is variable, infact more variable than most contemporary designs of femoral components would suggest or accommodate. Clinical and experimental studies of total hip replacement have demonstrated the need for a close geometric fit between the femoral component and the supporting bone for a durable implant fixation. In order to provide a basis for design and selection of femoral components in future, we undertook an anthropometric study of proximal femoral geometry on Indian specimens.

74 cadaveric femorae were studied to analyze the difference in the endosteal and periosteal geometry between Indian and Western population. Standard extra-cortical and endosteal dimensions were determined by direct measurements of radiographs. To enable comparison standard horizontal and vertical axis were established using the geometric center of lesser trochanter and the bisecting axis of the medullary canal at the level of the isthmus. Statistically significant differences were found for the following measurements: Femoral head offset, Width at lesser trochanter, Width at lesser trochanter-20mm, Proximal border of isthmus, Neck shaft angle.

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.

Introduction

Revision surgery is generally recommended for recurrent dislocation following Total hip arthroplasty (THA). However, dislocation following revision THA continues to remain a problem with further dislocation rates upto 28% quoted in literature.

We present early results of one of the largest series in U.K. using dual mobility cemented acetabular cup for recurrent hip dislocation.

Purpose: Fracture of the neck of the femur in elderly subjects is generally treated by arthroplasty, either using a total or intermediary hip prosthesis, but with a high risk of dislocation, estimated at about 10% in the literature. We investigated the contribution of a double mobile cup to lower this risk.

Material and methods: This prospective study was conducted by several operators in the same university unit between 1998 and 2001. A total of 177 mobile prostheses were implanted in patients with fracture of the anatomic neck of the femur (n=145), the neck and trochanter (n=22), or pathologic fracture (n=4). For six patients, the prosthesis was implanted after failed osteosynthesis of a trochanteric fracture. The postero-lateral approach was used for 136 women and 41 men (age range 61 – 92 years) living at home (n=124), or in an institution with a high degree of independence (n=53). The femoral stem was cemented (n=115) or impacted (n=62). A double mobile cup was used in all cases. A chromium-cobalt/ polyethylene couple was used and head diameters were 28 mm (n=150) or 22.2 mm (n=27). We studied outcome and risk of dislocation one year after implantation.

Results: There were six deaths during the postoperative period. Among the 171 patients, 134 were seen at two months, 108 at six months and 89 at one year: 39 were questioned to ascertain outcome. During the first postoperative year, there were 37 deaths; these patients were followed. Six patients were lost to follow-up. We had two cases of intraprosthetic dislocation related to a defect in the chromium-cobalt head retention of the polyethylene insert. These two cases required revision and were reported to material surveillance with corrective measures for the manufacturer.

There were three true dislocations (2%): 1) a posterior dislocation on day 24 in a female patient presenting a fracture with impaction of the femoral stem; 2) a posterior dislocation on day 22 in a female patient in very poor general condition (severe cardiorespiratory failure, death at 48 hr); 3) one recurrent posterior dislocation related to major acetabular retroversion, revised at four months.

Discussion and conclusion: The double-mobile cup appears to be a simple reproducible method for preventing dislocation of prostheses implanted for fracture of the neck of the femur.

Purpose of the study: The purpose of this work was to compare the subjective and functional outcomes of patients with a large diameter total hip arthroplasty (LD-THA) or hip resurfacing (HR).

Material and methods: Forty-eight persons were assessed and double blind randomised to receive either LD-THA (n=24) or HR (n=24). The clinical and radiographic assessment and gait analysis were performed preoperatively and at three, six and 12 months postoperatively. Gait analysis was performed once in a third group of healthy adults (n=14) who served as controls.

Results: The two groups were comparable preoperatively regarding demongraphic and functional characteristics. Postoperatively, the two groups with prostheses exhibited very rapid recovery with normalization of test results compared with controls within three to six months. The clinical assessment, the analysis of postural balance, gait analysis and most of the specific tests were not different between the two groups with prostheses.

Conclusion: There was no remarkable difference in subjective or objective assessments between subjects with a LD-THA or HR. This suggests that the only potential advantage of HR is the preservation of femoral bone stock. Long-term HR implant survival will determine the reality of this benefit.

Purpose: Several studies have shown elevated levels of metal ions in blood of patients with metal-on-metal (MM) total hip arthroplasty (THA). To minimize wear, the elastohydrodynamic theory suggests wear reduction for larger diameter head bearings. This significant reduction in wear has been demonstrated in hip simulators for the 36 mm-head compared to the 28 mm-head prosthesis. However, the survival of larger head MM THAs and the levels of metal ions in the blood of patients having these implants are still to be determined.

Method: Fifty (50) patients (56 hips) who received a DePuy Ultamet™ MM hip bearing (40/44 mm-head) at our Institution between July 1st 2007 and August 31st 2008 were included in the study. Clinical and radiologic data were collected pre-operatively as well as at 6–8 weeks, 4–6 months, and 1 year postoperatively. Results were compared to those of subjects (65 patients, 71 hips) who received a 36 mm-head prosthesis. Cobalt (Co) and chromium (Cr) concentrations were measured at 1 year post-operatively in the blood of patients by ICP-MS. Since Co and Cr ions have the potential to induce irreversible biochemical damage to macromolecules, the levels of oxidative stress markers (total antioxidants and lipid peroxides) were measured in the plasma of these patients.

Results: At their 1-year post-operatively follow-ups, all patients were doing well and no sign of osteolysis was observed on X-rays. Harris Hip Score increased in both groups with a tendency to higher score in the 40–44 mm group compared to the 36 mm group. Activity score also increased in both groups after 1 year without statistical significant differences. Results also show that the levels of Co and Cr ions increased significantly in both groups compared to the Pre-OP control group. The levels of Co were also significantly higher in patients with large head arthroplasty (40 and 44 mm-head) compared to those of the 36 mm-head group (p=0.012). The levels of Cr were similar in both the large head and the 36 mm-head group (p=0.41). Finally, results show that there were no differences in the levels of total antioxidants and peroxides between the 40–44 mm group and the 36 mm group. Moreover, there was no increase in the level of these markers of oxidative stress compared to the Pre-OP control group.

Conclusion: The present study shows that at 1-year postoperatively, patients with large 40–44 mm-head THA had comparable clinical outcomes than those with 36 mm-head prosthesis. However, the levels of Co ions were significantly higher in these patients compared to patients with 36 mm-head THA. This suggests a higher health risk for these patients due to the presence of these ions. However, there were no effects on the levels of oxidative stress markers in the blood of these patients, suggesting that there is no increased risk at short-term. In conclusion, due to the high level of Co ions, longer follow-ups are required to conclusively determine the outcomes of the patients and the survivorship of these new bearings.

Introduction: The goal of the study was to determine the precision of a three-dimensional pre-operative planning tool using a specific software (HIP-PLAN^®) and an anatomic cementless neck-modular stem.

Method: 223 patients who underwent a primary total hip replacement had a CT Scan before and after surgery. A pre-operative three-dimensional planning based on the CT-scan was performed. A cementless cup and a neck-modular stem were used. A computational matching of the pre-operative and the post-operative CT-scans was performed in order to compare the values of the planned anteversions and the planned displacement of the hip rotation center to the post-operative values.

Results: The implanted component was the same as the one planned in 89% for the cup and 94% for the stem. For the mean femoral anteversion, there was no significant difference between the planned value (26.1° +/−11.8) and the post-operative value (26.9° +/−14.1). There was a poor correlation between the planned values and the actual ones for the acetabular cup anteversion (coefficient 0.17). The hip rotation center was restored with a precision of 0.73 mm +/3.5 horizontally and 1.2 mm +/−2 laterally. Limb length was restored with a precision of 0.3 mm +/−3.3 and the femoral off-set with a precision of 0.8 mm +/−3.1. There was no significant modification of the femoral off-set (0.07 p=0.7) which was restored or slightly increased in 93% of cases. Almost all the surgical difficulties were predicted

Conclusion: HIP-PLAN^® software is a reliable three-dimensional pre-operative planning tool which allows acurate prediction of components and hip anatomy.

Purpose of the study: Implantation of a total hip arthroplasty (THA) for major misalignment is a difficult procedure and few results have been published. In the 1950s to 1970s, supra-trochanteric osteotomy was proposed for sequelar osteoarthritis of congenital hip dislocation. Subsequent degradation 20 to 30 years later can lead to neo-osteoarthritis of the joint with an effect on hip alignment and overall balance between the knee and the spine. We present a prospective consecutive series of 60 THA performed from 1991 to 2003on hips with Milch and Schanz osteotomies.

Material and methods: The objective was to reconstruct an anatomic hip joint by femoral re-alignment de-osteotomy, inferior displacement of the hip joint to enable insertion of an implant with a correctly position center of rotation and normal muscle lever arms. The technique was novel because of the direct approach to the subtrochanteric angle. The step by step procedure enabled insertion of the prosthesis without trochanterotomy. Overall recovery was long, often 12 to 18 months. There were 47 patients 60 hips) with at least 18 months follow-up. None of the patients were lost to follow-up.

Results: Results were available for 54 hips (three deaths, six hips). Mean follow-up was eight years. Outcome was good (patient satisfaction, normal x-ray) for 77%. Twelve hips presented poor clinical and radiological results due to loosening and mobilization of the femoral implant with or without nonunion of the deosteotomy. Ten hips were revised at mean five years via a femoral access for insertion of a press-fit distally locked prosthesis with graft of the nonunion (with acetabular replacement in one hip). The outcome was good at last follow-up for nine of these hips. One repeated revision gave satisfactory results.

Discussion: The only factors of risk of failure were related to femoral re-alignment and absence of trochanterotomy. A lesser risk of nonunion was related to the technique used for osteotomy, osteosynthesis and grafting. The use of a non-cemented implant with a solid primary stability and in certain cases a custom-made implant can be discussed for selected patients.

Purpose: The purpose of this study was to evaluate ten year outcome of the 28-mm head self-locking cemented Müller THA.

Material and methods: From May 1988 to May 1990, 187 second generation cemented prostheses were implanted via the transgluteal approach for osteoarthritis. The femoral implant was a straight Prostasul 10 implant with a 28-mm modular head and a gamma ray sterilised poly-ethylene cup. At ten years, for the 187 implants: 64 patients had died, 24 patients were contacted by telephone (all with implants in place) nine were lost to follow-up, and 90 implants in 82 patients were reviewed. The reviewed series included 42 women and 49 mean, mean age 65 years. Clinical outcome was noted with the Postel Merle d’Aubigné score (PMA). Radiographical assessment noted lucent lines, granulomas, migrations, wear, and ossification.

Results: Among the 187 implants, two patients required revision: one for infection and the other for posttraumatic dislocation. Among the 82 patients reviewed at ten years, the PMA score was 16.85 (92% good and very good results). Radiographically, the acetabulum showed nine lucent lines measuring greater than 1 mm and progressing between five and ten years, one migration, and two cases of migration as well as three cases of wear greater than 2 mm. Evaluation of the femur showed osteolysis in zone 3 and 4 in one hip and rarified bone in zone 7 in four. Linear penetration of the head in the cup was 0.08 mm/yr. Brooker stage 3 ossifications were found in 27% of the men and 14% of the women.

Discussion: The clinical results were comparable to other series of cemented prostheses. At ten years, potential loosenings were more frequent at the acetabular level with progressive lines always present at five years; and polyethylene wear that was not always associated with osteolysis or granuloma, while osteolysis and granulomas were always associated with wear greater than 2 mm. Furthermore, there was no anatomoclinical relationship and radiographic anomalies did not always have an effect on function. Prevention of ossifications appears to be important, particularly in men.

Total hip arthroplasty in adult patients with congenital high dislocation of the hip (DDH, Crowe type IV) presents many challenges. Various reconstruction methods including iliofemoral distraction lenghtening and custom made prosthesis have been reported but the standard technique for dealing with this problem is femoral shortening with a subtrochanteric osteotomy. There are many reports of different subtrochanteric osteotomy techniques with satisfactory results.

Since 1999, we have been using the same anatomic reconstruction principles with a proximally hydroxyapatite coated cementless stem. Surgical technique on the femoral side comprises a short oblique subtrochanteric osteotomy and excision of a segment as indicated for a safe reduction. This usually requires extensive soft tissue releases of the pelvifemoral muscles. Gluteus maximus, tensor fascia latae and adductors are routinely released. However, we don’t want to do any more release until it is absolutely necessary. Preserving the attachment of the abductors and iliopsoas are important for eventual functional outcome. They help stabilizing the joint, avoid limping and promote hip flexion during the initial swing phase of the gait and stair climbing. We never resect neither osteotomize the trochanters and, if a release is unavoidable, it is performed proximally. Thus, it is possible to preserve a complete segment of the proximal femur with a soft tissue envelope. This segment allows for better bone stock, prompt healing, reliable proximal fixation through the intact medial calcar and, avoids the complications of trochanteric osteotomy. With this technique we have not observed a femoral revision for any reason in 101 high dislocated hips (in 84 patents), since 1999. Compared with other techniques for arthroplasty in patients with developmental hip dysplasia, this surgical technique has a better functional outcome and a low prevalence of revision.

To evaluate the effect of this reconstruction on gait parameters we analyzed the gait cycle in 17 hips in 10 patients before and after the the total hip arthroplasty and compared it with the patients with hip arthroplasty due to primary osteoarthritis. Our aim is to determine the restoration of normal anatomy in DDH patients compared to the patients with total hip arthroplasty but a normal hip anatomy. As a result we have demon-strated that our technique restores normal gait parameters by improving walking speed, lengthening step-stride length, correcting hip and knee flexion and ankle equinus, improving hip and knee stiffness during gait and helps to restore normal gait parameters

We report the long-term radiographic results of the total hip arthroplasty with use of the cementless porous coated Harris-Galante (H-G) stem. Seventy-five consecutive patients, eighty-eight hips formed the basis of this study. Fifty patients were male, twenty-five patients were female, and thirteen patients were bilateral. The mean age of patients at operation was 42 years. They were followed up for an average of thirteen years four months (ten years two months to fourteen years four months). The diagnosis was avascular necrosis of the femoral head in 49 cases, degenerative osteoarthritis in 32 cases. Clinical results were estimated by modified Harris hip score and thigh pain, and radiographic results by periodically checked plain X-ray film. The average Harris hip score increased from 60 points preoperatively to 83 points at the most recent follow-up examination. The hip pain score increased from 31 points to 41 points. Clinically severe thigh pain was observed in 3 cases (4%). In radiographic evaluation, subsidence more than 5mm was seen in 2 cases (2%). Periprosthetic osteolytic lesion was observed in 15 cases (17%), but the lesions do not influence stability of the stem. Femoral stem stability by Engh was stable in 72 cases, fibrous stable in 12 cases, unstable in 4 cases. Pedestal formation, cortical hypertrophy of the distal femur, and stress shielding was observed more than 40%. Subcollar resorption was identified in 29% and ectopic ossification in 15%. Revision of the femoral stem was needed in 4 cases for aseptic loosening. At 10 years probability of survival of the stem using Kaplan-Meyer method was 95.5%. Use of the cementless H-G stem yielded the excellent long-term outcome, but osteolysis and stress shielding would be the main problems to solve.

BACKGROUND CONTEXT

Ceramic bearings are widely used in total hip arthroplasty (THR) along with metal and polyethylene bearings. There were several studies in past few years evaluating the advantage of one over the other. The young population with high activity levels has an increased risk of wear debris production at bearing surface and subsequent implant failure. Recently, interest and use of a ceramics with high wear resistance has been growing. Early reports on ceramic on ceramic THR have demonstrated excellent clinical and radiological results.

Purpose: In young active subjects, total hip arthroplasty (THA) raises the risk of early polyethylene wear eventually warranting the use of alternative bearings. The purpose of this study was to analyze outcome in subjects aged less than 50 years implanted with a primary metal-on-metal prosthesis.

Material and methods: Between 1995 and 1998, thirty-nine THA with a metal-on-metal bearing were implanted without cement in 30 consecutive patients aged less than 50 years, mean age 23–50). There were nine bilateral implantations. The cementless implants had surface treatment without hydroxyapatite and 28 mm heads. The indication for THA was necrosis in twenty cases, osteoarthritis in nineteen, most in patients with hip dysplasia. The Devane classification placed 84% of the patients in levels 4 or 5, indicating heavy work and/or sports activities. Inclusion criteria were: 1) age less than 50 years, 2) significant activity (occupation and/or sports), 3) osteoarthritis or necrosis. Patients were included and followed prospectively. Serum cobalt level was measured at last follow-up. None of the patients were lost to follow-up.

Results: The Postel-Merle-d’Aubigné score (PMA) improved from 12.8±2.2 (7–15) before surgery to 17.2±1 (14–18) at 5.1 years (5–6.3). None of the patients complained of hip pain. Two patients has moderate inguinal pain related to a cupiliopsoas conflict. All patients achieved complete weight bearing on the fourth postoperative day excepting three who resumed weight bearing at six weeks due to an acetabular augmentation graft. There were no cases of implant migration and all implants exhibited signs of osteointegration on the radiograms. There were no postoperative dislocations and no cases of osteolysis could be identified, particularly in the eight patients who had increased serum cobalt (four bilateral implants) and who had no other statistically significant favouring factor.

Conclusion: The results at five years suggest that the second-generation metal-on-metal bearing is a reliable alternative when THA is proposed for young active subjects. Long-term follow-up of this cohort of subjects at high risk of wear is necessary to confirm these encouraging results.

Aims

The aim of this study was to investigate the association between fracture displacement and survivorship of the native hip joint without conversion to a total hip arthroplasty (THA), and to determine predictors for conversion to THA in patients treated nonoperatively for acetabular fractures.

Orientation of the acetabular component influences wear, range of movement and the incidence of dislocation after total hip replacement (THR). During surgery, such orientation is often referenced to the anterior pelvic plane (APP), but APP inclination relative to the coronal plane (pelvic tilt) varies substantially between individuals. In contrast, the change in pelvic tilt from supine to standing (dPT) is small for nearly all individuals. Therefore, in THR performed with the patient supine and the patient’s coronal plane parallel to the operating table, we propose that freehand placement of the acetabular component placement is reliable and reflects standing (functional) cup position. We examined this hypothesis in 56 hips in 56 patients (19 men) with a mean age of 61 years (29 to 80) using three-dimensional CT pelvic reconstructions and standing lateral pelvic radiographs. We found a low variability of acetabular component placement, with 46 implants (82%) placed within a combined range of 30° to 50° inclination and 5° to 25° anteversion. Changing from the supine to the standing position (analysed in 47 patients) was associated with an anteversion change < 10° in 45 patients (96%). dPT was < 10° in 41 patients (87%). In conclusion, supine THR appears to provide reliable freehand acetabular component placement. In most patients a small reclination of the pelvis going from supine to standing causes a small increase in anteversion of the acetabular component.

Cite this article: Bone Joint J 2013;95-B:1326–31.

Progressive retroversion of a cemented stem is predictive of early loosening and failure. We assessed the relationship between direct post-operative stem anteversion, measured with CT, and the resulting rotational stability, measured with repeated radiostereometric analysis over ten years. The study comprised 60 cemented total hip replacements using one of two types of matt collared stem with a rounded cross-section. The patients were divided into three groups depending on their measured post-operative anteversion (< 10°, 10° to 25°, >  25°). There was a strong correlation between direct post-operative anteversion and later posterior rotation. At one year the < 10° group showed significantly more progressive retroversion together with distal migration, and this persisted to the ten-year follow-up. In the < 10° group four of ten stems (40%) had been revised at ten years, and an additional two stems (20%) were radiologically loose. In the ‘normal’ (10° to 25°) anteversion group there was one revised (3%) and one loose stem (3%) of a total of 30 stems, and in the > 25° group one stem (5%) was revised and another loose (5%) out of 20 stems. This poor outcome is partly dependent on the design of this prosthesis, but the results strongly suggest that the initial rotational position of cemented stems during surgery affects the subsequent progressive retroversion, subsidence and eventual loosening. The degree of retroversion may be sensitive to prosthetic design and stem size, but < 10° of anteversion appears deleterious to the long-term outcome for cemented hip prosthetic stems.

Cite this article: Bone Joint J 2013;95-B:23–30.

Purpose: The ABG Total Hip Joint Replacement is a cementless, hydroxyapatite coated prosthesis designed to be metaphyseal loading. The aim of our study was to analyze the changes in proximal femoral bone mineral density (BMD) following implantation of this prosthesis.

Method: Dual energy x-ray absorptiometry (DEXA) scanning has been shown to be an accurate and reliable method of assessing BMD following total hip arthroplasty. 14 patients undergoing primary ABG Total Hip Joint Replacement were recruited into the study following informed consent. BMD was determined for each of the seven periprosthetic zones of Gruen from DEXA scans, which were performed serially at preoperative,, 3 months, 6 months, 1 year and 2 years.

Results: 8 patients have now completed their scans. The most dramatic change in BMD was found in zone 7 which is the femoral calcar. In this region there was a progressive decrease in average BMD to 75% of the preoperative value at 2 years. In zones 2 and 3 representing the femoral cortex lateral to the prosthesis there was an increase in BMD to approximately 114.5% at 3 months and this was maintained at 2 years. In the remaining zones BMD was reasonably stable between 97.5 and 101%.

Conclusion: We have found that in the 2 years following ABG hip arthroplasty there is a dramatic decrease in BMD to 75% within the region of the femoral calcar. Further scans are required to determine if this is progressive. In the remaining regions BMD is either increased or relatively well preserved.

Introduction. The metal-on-metal (MoM) total hip prosthesis is widely used. However, the adverse reactions such as pseudotumor around the total hip prosthesis are observed. This is considered the effect of the corrosion of alloy which includes metal ion release and the wear particle generation. As materials for total hip prostheses, cobalt chromium (Co-Cr) alloy is used because of the wear resistance and corrosion resistance. The passive film on the surface of alloy contributes to corrosion resistance. The passive film is removed easily with friction. Therefore, metal ion is released from bare metal. However, this removal of passive film can be restored because of oxidation reaction with neighboring environment. The modular MoM total hip prosthesis such as acetabular component-femoral head or taper junction which connect femoral head and stem have friction interfaces. The friction amplitudes must be different among these interfaces. However, how sliding amplitude affects on removal of a passive film is unclear. The main purpose of this study was to investigate the effect of the sliding amplitude of the reciplocating micromotion on removal and reformation of the passive film of Co-Cr alloy. Methods. The behavior of the passive film was observed by measuring the electric potential of the alloy. Co-Cr alloy (ASTM F75) pin specimen and common tablet specimen were immersed in simulated body fluid PBS(−) and abraded with friction testing machine. The electronic potential between the pin and the Ag/AgCl reference electrode (RE-1C, ALS, Tokyo, Japan) were measured using a high impedance electrometer (HE-104E, HOKUTO DENKO, Tokyo, Japan). The friction amplitude was chosen from 0.2–2 mm. The reciprocating cycle was 1 Hz. The load of 10 N applied on the pin by a weight. Results and discussion. The electric potential neared equilibrium before the friction, and the passive film was stable. Electric potential dropped with the onset of friction and gradually increased with the cessation of friction. The potential difference ΔV and a time constant τ of the rise in electric potential after the friction were estimated. Those ΔV and τ were used as the indicator of the passive film destruction and restoration, respectively. At the friction amplitude of 0.2 mm, ΔV was lowest among at the other amplitudes. On the other hand, τ tended to be longer (Fig. 2). It showed that the reformation of passive film was delayed. When the removal of the passive film was repeated on local area of the friction interfaces, it was presumed similar to a phenomenon of the crevice corrosion. To view tables/figures, please contact authors directly

Orthopaedic implants, such as femoral heads, sockets and stems, are manufactured with a high degree of smoothness and very low form error in order to function as low wear bearings. The surfaces are subject to both wear and damage during in vivo use. Articulating surfaces naturally wear during normal use. Aseptic loosening associated with osteolysis and release of wear particles is the main reason for revision of total hip arthroplasty (THA). Damage of femoral heads is well known to increase the wear rate at the articulating surface and is vulnerable to scratching during the maneuver of positioning the femoral component into the acetabulum component either in primary as in revision total hip arthroplasties. The findings emphasize the importance of achieving and maintaining good surface finish of the femoral head component. The author presents a very simple and “zero cost” method of preventing scratching of the femoral head of any kind of total hip prosthesis (ceramic on ceramic, ceramic on poly, metal on metal, metal on poly and even metal on ceramic) when the reduction of the femoral head prosthesis is done inside the new acetabular component with metal, ceramic liner or poly liner with metal back (where the scratching can also occur) as one of the final stages of the surgical procedure which can be crucial to the long survival of the hip prosthesis. A short one minute video on an e-poster will show how this can be done being an easy, reproducible, safe and reliable technique to prevent femoral head scratching

Backgrounds. The authors present an analysis of 30 cases of total hip prosthesis performed with minimally invasive surgical earlier compares with 30 cases of total hip prosthesis performed surgically with direct side. The intent is to demonstrate the immediate and clear advantages especially in the postoperative surgical minimally invasive front. Methods. The authors present a randomized study of thirty cases of patients undergoing surgery for osteoarthritis of the hip prosthesis with primary surgical minimally invasive front compared to a group of 30 patients undergoing surgery with direct surgical side. All patients had the same cementless implants and instruments with the same surgeon. Patients were then evaluated in four different times: before surgery, immediate postoperative, after 1 week and 4 months after surgery. Results and conclusions. The experience of the authors on the surgical front shows the immediate and clear advantages in postoperative species by saving the muscle tissues, little pain, little bleeding, more quick and easy re-education and rehabilitation

Introduction. A 68 year old female patient underwent a left total hip replacement for primary osteoarthritis in March 2004. She was referred back by her GP 5 years as she was struggling with mobility and felt there were mice in her hip. It was squeking so loudly that it could be hear at a distance of 25 metres. There was no history of any falls or dislocation in the last 5 years. The implant used was an Exeter/ABG ceramic total hip prosthesis with Palacos cement. This ladies discomfort in her hip had been always there. She never described herself as being satisfied with the THR. However, her discomfort had worsened terribly over the last year. On examination. The slightest movement around her hip caused her severe pain. Tremendous squeaking could be heard when she was made to walk. She had significantly limb length discrepancy of 2.5cms. The radiographs revealed that she had probably broken the ceramic head as pieces could be seen around the neck area. On table. When the hip was exposed through standard lateral approach it was found that the ceramic head was intact. There was a large amount of blackish debris around the entire area and the shell of the ABG cup had a huge defect in it. It was a strartling revelation as it was initially thought that the ceramic head was broken. Revision surgery was carried out with a C stem total hip prosthesis with an orthodynamic socket. Discussion. Ceramic bearing surfaces have been introduced to reduce friction and prevent bone loss. There has been a problem with squeaky hips following ceramic implant insertion. However there has been no report of cup wear and an intact ceramic head till date in literature. To our knowledge this is the first case being reported and the images are quite startling

Postoperative dislocation following total hip arthroplasty (THA) remains a significant concern with a reported incidence of 1% to 10%. The risk of dislocation is multifactorial and includes both surgeon-related (i.e. implant position, component size, surgical approach) and patient-related factors (i.e. gender, age, preoperative diagnosis, neurologic disorders). While the majority of prior investigations have focused on the importance of acetabular component positioning, recent studies have shown that approximately 60% of “dislocators” following primary THA have an acceptably aligned acetabular component. Therefore, the importance of the relationship between the spine and pelvis, and its impact on functional component position has gained increased attention. Kanawade and Dorr et al. have shown patients can be categorised into having a stiff, normal, or hypermobile pelvis based on their change in pelvic tilt when moving from the standing to seated position. The degree of change in functional position of both the acetabular and femoral components is impacted by the degree of pelvic motion each patient possesses. In the “normal” pelvis, as a patient moves from the standing to seated position the pelvis typically tilts posteriorly, thus increasing the functional anteversion of the acetabular component. However, patients with lumbar degeneration or spine pathology often have a decrease in posterior pelvic tilt in the seated position, thus potentially increasing their risk of dislocation. Bedard et al. noted an 8.3% dislocation risk in patients with a spinopelvic fusion after THA vs. 2.9% in those without. There is the potential that preoperative, dynamic imaging can be used to predict the ideal component position for each individual patient undergoing THA. However, this assumes that a patient's preoperative pelvic motion will be the same following implantation of a total hip prosthesis, and that a patient's pelvic motion will remain consistent over time postoperatively. A recent study has shown that the impact of THA on pelvic motion can be highly variable, thus potentially limiting the utility of preoperative dynamic imaging in predicting a patient's ideal component position. Future investigations must focus on preoperative factors that can be used to predict postoperative pelvic motion and how pelvic motion changes over time following implantation of a total hip arthroplasty

Introduction. Computer navigation is a highly sophisticated tool in orthopedic surgery for component placement in total hip arthroplasty (THA). In order to apply it adequately it is of upmost importance that the targets the surgeon is trying to hit are well-defined. This concept considers all four component orientations: cup inclination (cIncl) and anteversion (cAV), stem antetorsion and neck-to-shaft angle. The optimising goal in this concept is maximising the size of the cSafe-Zone. Methods. A computerised 3D- model of a total hip prosthesis was used to systematically analyse all combinations of component orientations in automatised batch runs. Component orientations were varied for cup inclination, cup anteversion, neck antetorsion and neck inclination. Results. The combined Safe-Zone outlines spaces in a 3D-diagram that show the relationship between cup inclination, cup anteversion and neck anteversion, while the neck inclination is used as a curves parameter. These spaces include all component orientation that allow the predefined iROM without prosthetic impingement. In order to compare these results to Lewinnek's recommendation cross-sections were taken at distinct neck antetorsions in 5° intervals. Conclusion. The new combined Safe-Zone (cSafe-Zone) includes all orientation parameters of both total hip components and such gives well-defined recommendations for combined positioning of both components. Ideally it can be introduced into a smart computer navigation system in order to compute in real-time the best combined orientation of both components

Aims

The aims of this study were to determine if an increasing serum cobalt (Co) and/or chromium (Cr) concentration is correlated with a decreasing Harris Hip Score (HHS) and Hip disability and Osteoarthritis Outcome Score (HOOS) in patients who received the Articular Surface Replacement (ASR) hip resurfacing arthroplasty (HRA), and to evaluate the ten-year revision rate and show if sex, inclination angle, and Co level influenced the revision rate.

Literature surrounding artificial intelligence (AI)-related applications for hip and knee arthroplasty has proliferated. However, meaningful advances that fundamentally transform the practice and delivery of joint arthroplasty are yet to be realized, despite the broad range of applications as we continue to search for meaningful and appropriate use of AI. AI literature in hip and knee arthroplasty between 2018 and 2021 regarding image-based analyses, value-based care, remote patient monitoring, and augmented reality was reviewed. Concerns surrounding meaningful use and appropriate methodological approaches of AI in joint arthroplasty research are summarized. Of the 233 AI-related orthopaedics articles published, 178 (76%) constituted original research, while the rest consisted of editorials or reviews. A total of 52% of original AI-related research concerns hip and knee arthroplasty (n = 92), and a narrative review is described. Three studies were externally validated. Pitfalls surrounding present-day research include conflating vernacular (“AI/machine learning”), repackaging limited registry data, prematurely releasing internally validated prediction models, appraising model architecture instead of inputted data, withholding code, and evaluating studies using antiquated regression-based guidelines. While AI has been applied to a variety of hip and knee arthroplasty applications with limited clinical impact, the future remains promising if the question is meaningful, the methodology is rigorous and transparent, the data are rich, and the model is externally validated. Simple checkpoints for meaningful AI adoption include ensuring applications focus on: administrative support over clinical evaluation and management; necessity of the advanced model; and the novelty of the question being answered.

Cite this article: Bone Joint J 2022;104-B(12):1292–1303.

Objectives. The cytotoxicity induced by cobalt ions (Co. 2+. ) and cobalt nanoparticles (Co-NPs) which released following the insertion of a total hip prosthesis, has been reported. However, little is known about the underlying mechanisms. In this study, we investigate the toxic effect of Co. 2+. and Co-NPs on liver cells, and explain further the potential mechanisms. Methods. Co-NPs were characterised for size, shape, elemental analysis, and hydrodynamic diameter, and were assessed by Transmission Electron Microscope, Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy and Dynamic Light Scattering. BRL-3A cells were used in this study. Cytotoxicity was evaluated by MTT and lactate dehydrogenase release assay. In order to clarify the potential mechanisms, reactive oxygen species, Bax/Bcl-2 mRNA expression, IL-8 mRNA expression and DNA damage were assessed on BRL-3A cells after Co. 2+. or Co-NPs treatment. Results. Results showed cytotoxic effects of Co. 2+. and Co-NPs were dependent upon time and dosage, and the cytotoxicity of Co-NPs was greater than that of Co. 2+. In addition, Co-NPs elicited a significant (p < 0.05) reduction in cell viability with a concomitant increase in lactic dehydrogenase release, reactive oxygen species generation, IL-8 mRNA expression, Bax/Bcl-2 mRNA expression and DNA damage after 24 hours of exposure. Conclusion. Co-NPs induced greater cytotoxicity and genotoxicity in BRL-3A cells than Co. 2+. Cell membrane damage, oxidative stress, immune inflammation and DNA damage may play an important role in the effects of Co-NPs on liver cells. Cite this article: Y. K. Liu, X. X. Deng, H.L. Yang. Cytotoxicity and genotoxicity in liver cells induced by cobalt nanoparticles and ions. Bone Joint Res 2016;5:461–469. DOI: 10.1302/2046-3758.510.BJR-2016-0016.R1

Aims

Factors associated with high mortality rates in geriatric hip fracture patients are frequently unmodifiable. Time to surgery, however, might be a modifiable factor of interest to optimize clinical outcomes after hip fracture surgery. This study aims to determine the influence of postponement of surgery due to non-medical reasons on clinical outcomes in acute hip fracture surgery.

Introduction. The purpose of this study was to experimentally evaluate impingement and dislocation of total hip replacements while performing dynamic movements under physiological-like conditions. Therefore, a hardware-in-the-loop setup has been developed, in which a physical hip prosthesis actuated by an industrial robot interacts with an in situ-like environment mimicked by a musculoskeletal multibody simulation-model of the lower extremity. Methods. The multibody model of the musculoskeletal system comprised rigid bone segments of the lower right extremity, which were mutually linked by ideal joints, and a trunk. All bone geometries were reconstructed from a computed tomography set preserving anatomical landmarks. Inertia properties were identified based on anthropometric data and by correlating bone density to Hounsfield units. Relevant muscles were modeled as Hill-type elements, passive forces due to capsular tissue have been neglected. Motion data were captured from a healthy subject performing dislocation-associated movements and were fed to the musculoskeletal multibody model. Subsequently, the robot moved and loaded a commercially available total hip prosthesis and closed the loop by feeding the physical contact information back to the simulation model. In this manner, a comprehensive parameter study analyzing the impact of implant position and design, joint loading, soft tissue damage and bone resection was implemented. Results. The parameter study revealed a generally high dislocation risk for the seating-to-rising with adduction scenarios. Improper implant positioning or design could be compensated by adjusting prosthesis components correspondingly. Gluteal insufficiency or lower joint loading did not result in higher impingement or dislocation risk. However, severe malfunction of the artificial joint was found for proximal bone resection. Discussion. Previous testing setups ignored the impact of active muscles or relied on simplified contact mechanics. Herein, total hip replacement stability has been investigated experimentally by using a hardware-in-the-loop simulation. Thereby, several influencing factors such as implant position and design as well as soft tissue insufficiency and imbalance could be systematically evaluated with the goal to enhance joint stability

Introduction. Lewinnek's Safe-Zone gives recommendations only for cup placement in total hip arthroplasty while the orientation of the neck isn't considered. Furthermore the criteria for cup placement are not clearly defined and the ranges for cup orientation are considerably large. This study introduces new recommandations for the combined placement of both total hip components, when both, cup and stem, are considered. This defines the new dynamic combined safe-zone (cSafe-Zone) which gives clear directions for the optimal combined orientation of both components in order to maximize the intended range of movement (iROM) while reducing the risk for prosthetic impingement and dislocation. Material and Methods. The combined safe-zone outlines the area that encloses all component orientations that achieve the predefined iROM without prosthetic impingement. A computerized 3D-model of a total hip prosthesis was established that does systematically test all design parameters semi-automatically in order to identify those component positions that fulfill the predefined conditions. The analysis was carried out for straight stems, anatomic stems and short stems. The iROM is composed of basic movements like flexion/extension, internal/external rotation, ab/adduction and combination of these movements that the patient should reach and that are commonly accepted as physiologic hip movements. The orientation of the cup was varied between 20° and 70° of inclination and −10° of retro- to 40° anteversion. Stem antetorsion was tested from −10° retro- to 40°-antetorsion and CCD-angle from 110° to 150°. Head-size and head/neck ratio were additional parameters. Results. The new combined safe-zone has a dynamic location and has a polygonal outer boundary. It is smaller than Lewinnek's safe-zone. Its size and location within the cup inclination/anteversion diagram depends on the antetorsion and the CCD-angle of the stem. It can be demonstrated that a low-anteverted stem should be combined with a high-anteverted cup and vice versa, i.e. cup anteversion and stem antetorsion are linearly but inversely correlated. This is true for a straight stem as well as for anatomic and for short stems. The size of the cSafe-Zone is largest when the socket is radiographically anteverted between 20° and 25°. The neck/shaft-angle (CCD-angle) and the anatomic design do have a high impact on the preferred antetorsion of the stem. A straight 130°-CCD-stem is best implanted in about 15°+/−4degree of antetorsion while an anatomic 127°-CCD-stem can be implanted in a lower degree of antetorsion. Increasing the head/neck ratio increases the cSafe-Zone too and gives room for a lower cup inclination which increases the jumping distance. The optimal CCD-angle of a straight stem is 127°+/−3 degree. Conclusion. The new combined safe-zone (cSafe-zone) gives well-defined recommendations for cup and stem placement taking into account the dynamic interrelationship between cup and stem. In extending Lewinnek's recommendations it defines how both the cup and the stem should be oriented relative to each other and how the component's orientations are optimized in order to achieve the highest safety against prosthetic impingement while reaching the highest range of movement which is especially important for high-performance materials and in young and active patients

Several risk factors can and should be addressed during first stage or spacer implantation surgery in order to minimize complications. Technical aspects as well as practical tips and pearls to overcome common nuisances such as spacer instability or femoral and acetabular bone loss will be discussed and shown with pictures. Total joint arthroplasty (TJA) is one of the most successful procedures in orthopaedics and excellent results are expected in virtually all cases. Periprosthetic joint infection (PJI) though unusual, is one of the most frequent and challenging complications after TJA. It is the third most common cause of revision in total hip replacement, responsible for up to 15% of all cases. In the past few years several improvements have been made in the management of an infected total hip prosthesis. Nevertheless it remains a challenging problem for the orthopaedic surgeon. Although numerous studies report favourable outcomes after one-stage revision surgery, two-stage has traditionally been considered as the gold standard for management of chronic infection. Two-stage exchange consists of debridement, resection of infected implants and usually temporary placement of an antibiotic-impregnated cement spacer before reimplantation of a new prosthesis. Spacers can be classified as static or articulating. The goals of using an articulating antibiotic loaded cement spacer are two-fold: to enhance the clearance of infection by local antibiotic therapy and dead-space management while maintaining joint function during treatment thus improving the functional outcome at reimplantation. Still, hip spacer implantation is not innocuous and there are several possible complications. Going forward, one must consider not just eradicating infection but also the importance of restoring function. In this regard using a mobile spacer adds an element of physiologic motion that both increases patient comfort between stages and facilitates re-implantation surgery. Conversely, mechanical complications are one of the major consequences of this preference. Be that as it may there are ways to minimize these problems. It is the surgeon responsibility to optimize mechanical circumstances as much as possible. I would like to thank Dr. Ricardo Sousa for his help with this work

Aims

Two-stage exchange revision total hip arthroplasty (THA) performed in case of periprosthetic joint infection (PJI) has been considered for many years as being the gold standard for the treatment of chronic infection. However, over the past decade, there have been concerns about its safety and its effectiveness. The purposes of our study were to investigate our practice, collecting the overall spacer complications, and then to analyze their risk factors.

Introduction. In a recent study we evaluated the clinical and radiographic long-term results as well as the serum metal concentrations of 105 cementless primary total hip prosthesis, performed between November 1992 and May 1994 with a 28-mm high-carbide-concentration metal-on-metal articulating surfaces. Forty-one patients who had had a total of forty-four arthroplasties were available for follow-up evaluation at a minimum of seventeen years postoperatively. The median serum cobalt concentration of the patients with their hip replacement as the only source of cobalt was 0.7 µg/L (range 0.4–5.1µg/L), showing no significant difference to the previous study after a minimum of 10 years follow-up. We were investigating the systemic dissemination, which in turn, did not show more severe effects, such as carcinogenicity or renal failure. There are many complex issues associated with the analysis of metal ions, including collecting technique, analysis and reporting of the results. At the AAOS in March 2013, the Hip Society mentioned, that systemic ion levels are just one factor in the evaluation and should not be relied upon solely to determine the need for revision surgery. Furthermore, the correlation between cobalt or chromium serum, urin or synovial fluid levels and adverse local tissue reactions is incompletely understood. Patients and Methods. In our present study we evaluated the serum, urin as well as the joint aspirate metal concentrations, of cementless total hip arthroplasties with a high-carbon, metal-on-metal bearing (Metasul®) at a mean of eighteen-years follow-up. We performed a correlation analysis to evaluate the relationship between these values and to determine whether elevated serum metal concentrations are associated with elevated and local metal concentrations and with early failure of metal-on-metal articulations. Results. Spearman correlations evaluated that there was no significant relationship between the serum cobalt or chromium level and the joint aspirate cobalt (r= 0.60, p=0.15) or chromium (r=0.39, p=0.38) concentration, and the urin cobalt (r=0.21, p=0.62) or chromium (r=0.27, p=0.51) level. Additionally we evaluated a positive correlation between the local chromium concentration and the BMI (r=0.53, p= 0.21) and the cup inclination (r=0.24, p=0.64), a negative correlation between the local chrom concentration and the UCLA (r=0.25, p=0.59) and the Harris hip score (r=0.16, p= 0.73), but without a significance. Conclusion. We evaluated the regional dissemination and the local determination in the synovial fluid, which offers better information about wear and local reactions at the components level prior to the occurrence of marked adverse local tissue and therefore is the best predictor for wear related tissue reaction in MOM articulations, even in asymptomatic patients

Introduction. Total hip replacement is an established surgical procedure done to alleviate hip pain due to joint diseases. However, this procedure is avoided in yonger patients with higher functional demands due to the potential for early failure. An ideal prosthesis will have have a high endurance against impact loading, with minimal micromotion at the bone cement interface, and a reduced risk of fatigue failure, with a favourable stress distribution pattern in the femur. We study the effect of varying the material properties and design element in a standard cemented total hip using Finite Element Analysis. Methods. A patient-specific 3D model of femur will be constructed from CT scan data, while a Summit® Cemented Hip System (DePuy Orthopedic) will be used to as a control for comparative evaluation. We vary the material stiffness of different parts of the prosthesis(see Fig.1) to formulate a design concept for a new total hip prosthesis design; and use Finite Element Method to predict the micromotion of the hip prosthesis at the bone cement interface, as well as the stress distribution in the the femur. Result. Validation of computational protocol was being done by comparing the principal maximum strain of the femoral cortex along the diaphysis, and the amount of deflection, with published literature, similarly, contact modelling validation was also done. Model 1–4 induced lower peak Von Mises stress in the cement, which takes a much lower value than any of the cement mechanical limits postulated. Therefore, the risk of cement failure is greatly reduced in Model 1–4. However, the effect of varying stiffness in different regions is not significant in terms of load transmission to the cement. Micromotion at the bone-cement interface was studied via two approaches: Peak micromotion at the bone cement interface; and the micromotion data at 12 Regions of Interest (ROI)s. Both results showed that model 2 and 3 are capable of reducing micromotion at bone-cement interface, in comparison with the Summit® Cemented Hip System. By comparing the Von Mises Stress distribution in the proximal femur; model 1 is found to result in a significantly reduced stress shielding effect, while model 2–4 are also favourable in comparison to the standard Summit® prosthesis in terms of stress distribution in the femur. Figure 2 shows the effects of the performance of model 1–4, presented as percentage difference from the Summit® prosthesis. Model 1 is unfavourable, despite its favourable stress distribution, because its peak and overall micromotion at the bone-cement interface is greatly increased. Conclusion. Model 2 and 3 have favourable design elements. They both have reduced micromotion at the bone-cement interface; and a favourable stress distribution in the femur. Further refining and testing of model 2 and 3 should done, as these models may provide information which may be useful in improving the performance of the current range of total hip replacement prostheses

Introduction. Relative motion at the modular head-neck junction of hip prostheses can lead to severe surface damage through mechanically-assisted corrosion. One factor affecting the mechanical performance of modular junctions is the frictional resistance of the mating surfaces to relative motion. Low friction increasing forces normal to the head-neck interface, leading to a lower threshold for slipping during weight-bearing. Conversely, a high friction coefficient is expected to limit interface stresses but may also allow uncoupling of the interface in service. This study was performed to examine this trade-off using finite element models of the modular head-neck junction. Methods. A finite element model (FEM) of the trunnion/ head assembly of a total hip prosthesis was initially created and experimentally validated. CAD models of a stem trunnion (taper size: 12/14mm) and a prosthetic femoral head (diameter: 28mm) were discretized into elements for finite element analysis (FEA). The trunnion (Ti6Al4V) was modelled with a hexahedral mesh (33,648 elements) and the femoral head (CoCrMo) with a tetrahedral mesh (51,182 elements). A friction-based sliding contact interface was defined between the mating surfaces. The model was loaded in 2 stages: (i) an assembly load of 4000N applied along the trunnion axis, and (ii) 500N applied along the trunnion axis in combination with a torque of 10Nm. A linear static solution was set up using Siemens NX-Nastran solver. Multiple simulations were executed by modulating the frictional coefficient at the taper-bore interface from 0.05 to 0.15 in increments of 0.01, the coefficient of 0.1 serving as the control case (Swaminathan and Gilbert, 2012). Results. The vertical and tangential displacements of the nodes on the taper of the trunnion relative to the femoral head demonstrated a strong inverse dependence upon the coefficient of friction at the interface (Fig. 1). A similar trend was observed with respect to the peak interface pressure (Fig. 2). The peak von Mises stress, however, increases with increasing coefficient of friction (Fig. 2). A Fisher's R to Z correlation test was performed on each output variable to determine its correlation with coefficient of friction. The coefficient of friction correlated significantly (p<0.0001) with both tangential displacement (r = −0.990) and vertical displacement (r = −0.974). Peak von Mises stress (r = 0.995) and peak contact pressure (r = −0.984) were also found to be significantly (p<0.0001) correlated to the coefficient of friction. Discussion. A higher coefficient of friction at the taper-bore interface led to lower contact pressure and sliding at the modular junction. However, higher coefficients of friction also led to increased von Mises stresses within the bore and the trunnion increasing the risk of yielding and fatigue failure. The current results strongly indicate that factors affecting the frictional coefficient at the interface likely influence the occurrence of and severity of mechanically-assisted corrosion in THA. Significance. The results from this study will help us set tolerances for the interlocking mechanism, identifying the minimum frictional coefficient required to obtain stable implant mechanics

Introduction. Total hip arthroplasty (THA) is the most common surgery performed for complications of bipolar arthroplasty. The present study evaluated the functional results and complications associated with this surgery. Patients and Methods. Forty eight hips (48 patients) who had conversion of bipolar arthroplasty to THA between 1998 June and 2013 June, and who were followed-up for more than one year were evaluated. Twenty one hips had conversion surgery to THA using a Fitmore cup with metal-on-metal articulation (28 mm head). Six hips had surgery using the SecurFit cup and three hips, using the Lima LTO cup with ceramic-on-ceramic articulation (28 mm or 32 mm head). Eighteen hips had surgery using a large head metal-on-metal bearing: –MMC (seven hips), ACCIS (six hips) and Magnum (five hips). The average time of follow-up duration was 3.9 years (range, 1.0–11.3). There were 22 men and 26 women between the ages of 28 and 80 years (average, 68.9 years) at the time of conversion surgery. Conversion arthroplasty was performed for acetabular erosion without femoral stem loosening in 19 hips, acetabular cartilage erosion with femoral stem loosening in 13 hips, periprosthetic fracture in 12 hips, and recurrent dislocation in four hips. Results were evaluated using Harris hip score (HHS) and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) score. The radiographs were analyzed for evidence of acetabular and femoral osteolysis or loosening. The complications were evaluated. Results. The time interval between hemiarthroplasty and conversion total hip prosthesis was 6.7 years on average (range, 5 months to 12 years). Pain was the leading sign in all patients. Average HHS improved from 42 preoperatively (range, 34–67) to 86 (range, 65 – 97) postoperatively. The average total WOMAC score improved from 47 (range, 32–67) to 22 (range, 9–44) postoperatively. All the patients operated for groin pain reported significant improvement in their symptoms. Radiological evaluation showed good bony ingrowth and stability of all the femoral components. None of the acetabular component showed migration, loosening, wear, or osteolysis at last follow-up. Complications occurred in five hips. One dislocation and one recurrent dislocation were encountered in isolated acetabular revision hips; whereas one single dislocation, one recurrent dislocation, and one trochanteric nonunion occurred in the hips with revision of both components. All dislocations were occurred in hips with a femoral head size of 28 mm. Dislocations were managed by closed reduction, and none of the patients required revision for dislocation. Conclusions. Conversion THA after symptomatic bipolar arthroplasty can offer reliable pain relief and functional improvement. The perioperative complications approximate those of revision THAs

Developmental hip displasia (DHD) still presents as an important problem in our country. Latency in diagnosis and inaccurate treatment causes seconder osteoarthritis in young adults and elder patients. Variable reconstructive surgical procedures as proximal femoral and acetabular osteotomies can be performed, but the most satisfactory functional results are achieved by total hip arthroplasty (THA). In this study, we analyzed the results of the cementless total hip arthroplasties performed in coxarthrosis secondary to developmental hip displasia. Between January 2006 and October 2009, 53 patients diagnosed with hip osteoarthritis secondary to DHD, whom performed 59 total hip arthroplasties in GATA Orthopaedics and Traumatology Clinic were included in the study. 10 of the patients were male (%19), and 43 of them were female (%81). Age of the patients varied between 29 and 78 years and the mean age was 48,7. In 23 patients (%44), THA procedure was performed at the right hip and in 24 patients (%45) at the left hip. 6 patients operadted bilaterally. All patients were followed up 8–38 months (mean 20, 6 months) with clinical and radiological evaluation. The hospitalization period varied between 7–14 days, mean 8,3 days. Posterolateral incision was used at all of the patients. Totally 10 (%17) complications were observed. 5 (%8,5) of them was intraoperative and 5(%8,5) was postoperative. Patients evaluated preoperatively and postoperatively with modified Harris Hip Score. While preoperative mean Harris score was 39,1, the postoperative mean score measured as 90,3. The results were excellent in 52 cases (%88,1), and very good in 7 cases (%11,9). Appropriate implementation of cementless total hip prosthesis in patients with hip osteoarthritis secondary to DHD, who have good bone quality and surgical indicaton; clinical and radiological short term results were satisfactory

We report a patient with a peri-acetabular chondrosarcoma which was treated by resection of part of the pelvis and the femoral head. This was followed by replacement with a custom-made titanium alloy pelvic portion and a conventional total hip prosthesis. The operation was carried out in two stages, and yielded a good functional and cosmetic result

The goal of this study was to determine which of two techniques for the treatment of peri-prosthetic femoral shaft fractures has the greatest torsional integrity. The study designed was a laboratory study, using 13 matched pairs of embalmed femurs. The femurs were implanted with a cemented total hip prosthesis, with a transverse osteotomy distal to the stem. These fractures were fixed either with a metal plate with three proximal unicortical screws and three distal bicortical screws or with three proximal cables and three distal bicortical screws. The fracture fixation was tested to failure in torsion. The pattern of failure and torsional limits were recorded. There was no significant difference to failure level between the two constructs. Failure with the proximal unicortical screws was usually catastrophic versus non-catastrophic with proximal cables. The femurs were significantly more likely to fracture in internal rotation. Treatment with proximal cables has the same load to failure in torsion but significantly less complications than with unicortical screws, in agreement with the literature. The findings of the construct being weaker in internal rotation, appears to be a new finding and an area of possible new research

Four en-bloc resections for malignant tumours of the hip, the peri-acetabular region and the iliac wing were reconstructed using an irradiated hemipelvic allograft together with a total hip prosthesis. Technical aspects include the use of an anterior Enneking approach which excises the previous biopsy site, division and re-attachment of the iliac crest and fixation of the prosthesis using a modified acetabular cup and three polypropylene artificial ligaments to increase the stability of the joint. Weight-bearing was allowed at three months. The oncological and clinical results were satisfactory after a mean follow-up of 19 months, with walking distances of 500 metres to two kilometres without pain

Fluid film lubricating ability of a total hip prosthesis depends on the profile accuracies including surface-roughness or the sphericity of a head or a cup. Therefore, surface polishing is important. It was, however, difficult to polish the central portion of a cup or head using the conventional rotating machine. In the present study, we developed a polishing method combining a pendulum machine and a robotic arm. The effect of the accuracy improvement by this method was evaluated by the friction measurements on some test specimens. Nine balls and a cup of Co-Cr-Mo alloy that were polished by a conventional process using a rotating machine were prepared for the prototype. The average diameter of the balls was 31.9648 mm with the sphericity of 0.0028 μm. The inside diameter of the cup was 31.9850 mm with the sphericity of 0.0044 μm. We combined a robotic arm and a pendulum apparatus to enable the further polishing. The ability of both automatic centering and change in the sliding direction was accomplished by this system. The sliding direction has been changed 180 times every ten degrees. The total distance of polishing was 120 m under vertical load of 100 N in a bath of saline solution containing abrasive grains of silicate of the diameter of 2μm. The surface roughness of the central portion of the cup, which is important area for the fluid film lubrication decreased from Ra 20.2 μm before the polishing to Ra 18.7 μm after the polishing. A pendulum type friction tester was used for the assessment of the improvement of the lubricating ability by the polishing. The measurement was run over at 10 times under the conditions of the load of 600 N in a bath of saline solution. As the result, the frictional coefficients decreased from 0.1456–0.1720 before polishing to 0.1250–0.1300 after polishing. The polishing effect was, however, observed only at the specimens that radial clearances did not exceed the value of 50 μm. The present results indicated that the surface polishing of the central portion of hip prostheses must improve the lubrication ability and the radial clearance before the finishing process should be chinked as possible

Total hip arthroplasty (THA) is a commonly performed surgical procedure for various arthritic conditions that affect the hip joint, and it has proven to be highly effective for the relief of pain and improvement in the quality of life. Despite many recent advances in THA, dislocation continues to be a frequent complication, and the incidence of dislocation ranges from 1% to 5% in primary THAs. The literature abounds with options for the treatment of recurrent dislocation after THA. However, to the best of our knowledge, successful treatment with open reduction of a chronic proximal dislocation after THA has not been reported previously in the literature. We report an unusual case of a chronic prosthetic dislocation that was caused by the buttonholing of a prosthetic femoral head by anterior soft tissue, which impeded reduction. A surprisingly good functional result was achieved by an open reduction and revision operation on a 56-year-old man, who had a chronic dislocation of a total hip prosthesis. 5 years after the surgery, the patient has no clinical or radiographic evidence of recurrence of dislocation of THA. We believe that a chronic irreducible dislocation may hamper operations by adhesion and scar tissues. Especially soft tissue buttonholing makes it impossible to perform a closed reduction. We restored a much higher level of function by a single operation in a short time, and made the patient to be able to ambulate with fast recovery from the surgery. Equal limb lengths were restored and no neurologic compromise occurred

Deep infection, the most serious local complication of total hip replacement, prompted a study of the records of 135 patients (137 hips) thus afflicted in a nationwide survey of Canada. Particular attention has been paid to the natural history of the infection, and the problems of diagnosis are described. Twenty-one patients died after the insertion, or removal, of the prosthesis, and of the survivors of the original 135 patients only eighteen have been able to retain the prosthesis without further problems with the wound. The remaining patients had the prosthesis removed, and most dry wounds. Certain suggestions are made on management. The advice that a second total hip prosthesis should be inserted after a deep infection of the first implant is not supported

In acetabular dysplasia, fixation of the acetabular component of a cemented total hip prosthesis may be insecure and superolateral bone grafts are often used to augment the acetabular roof. We used finite element analysis to study the mechanical importance of the lateral acetabular roof and found that the lateral acetabular rim plays an important role in the load transfer of the pelvic bone. When the superlateral rim was lacking, the load shifted to the posterosuperior rim and to the area of pubic support, and the stresses in all materials, especially in the cement and in the trabecular bone, increased greatly. At the cement-bone interface the tilting component of the shear stress increased threefold. In a model in which the dysplastic acetabulum was augmented by a rigidly fixed, load-transmitting bone graft, the stresses were considerably diminished

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

The purpose of this paper is to review the early results of Prostalac system under licence from Therapeutic Goods Administration for Professor Howie in the management of two stage exchange hip arthroplasty for infection (restricted to Royal Adelaide Hospital) and the addition of vancomycin and teicoplanin powder to tobramycin cement without additional tobramycin. Thirteen patients were treated for an infected THR with the Prostalac system. Preoperative and intra-operative cultures were taken to identify the infective organisms. Vancomycin 3 gm was added to the Prostalac cement mantle per 40 gm packet of antibiotic bone cement containing tobramycin 1 gm. Teicoplanin 2.4 gm was used in one case where the patient had a known vancomycin allergy. Postoperatively patients underwent six weeks of IV antibiotics followed by four to six weeks of oral. A short term successful clinical outcome was determined by implantation of a total hip prosthesis at the time of second stage operation and no reoperations resulting from recurrent infection and off antibiotics for â□¥ 6 months with normal clinical and CRP lab values. Thirteen patients received the Prostalac system. No patient was lost to follow-up. Nine have progressed to second stage revision, eight of which had femoral impaction grafting. Two deaths occurred not attributed to the Prostalac system. Three superficial wound infections and two required washout and debridement. One Prostalac stem subsidence. There has been no recurrence of deep joint infection. Retention of the second stage prosthesis has been 100% at 17 months. The PROSTALAC system with the addition of vancomycin or teicoplanin to the tobramycin antibiotic cement has encouraging short-term results for treatment of deep joint infection. Complication rate has been well within the range reported in literature. Successful early outcomes are encouraging with all patients in the Prostalac study having retained their permanent hip prosthesis following second stage surgery

A rotationplasty is a unique surgical procedure used to reconstruct after resection of a tumor of the leg or a congenital defect. This procedure avoids phantom pain, limb length discrepancy and infections or implant related complications. The outcome is unusual for cosmesis but very functional. Background: Borggreve first described a rotationplasty in Germany in 1930 for a 12 year old patient whose knee was destroyed by tuberculosis. In 1950 Van Nes modified the procedure. Kotz and Saltzer described in 1982 the use of a modified version of a rotationplasty to treat malignant tumors of the distal femur. Case studies of two such patients will be presented. A 27 year old man had a non-metastic osteosarcoma of his distal femur at the age of five. He underwent chemotherapy and a rotationplasty. Six years after his operation a correction osteotomy was done. He is doing very well physically and mentally. He graduated business studies, went yearly on Alpine skiing on two legs, likes jogging and perceives no limitations in his life (MSTS, TESS, SF-36). A 24 year old man, 14 years after a Ewing-sarcoma of his hip. He underwent chemotherapy and radiation therapy. Thirteen years later he had a pathological fracture after playing soccer. He was treated with a total hip prosthesis without screening the malignancy. However the pathology of the specimen showed a postradiation sarcoma. He underwent a modified Van Nes rotationplasty (knee for hip and ankle for knee). Although is said that rotationplasty had a poor cosmesis and poor psychosocial acceptance, this is not our experience

Introduction. As population grows older, and patients receive primary joint replacements at younger age, more and more patients receive a total hip prosthesis nowadays. Ten-year failure rates of revision hip replacements are estimated at 25.6%. The acetabular component is involved in over 58% of those failures. From the second revision on, the pelvic bone stock is significantly reduced and any standard device proves inadequate in the long term [Villanueva et al. 2008]. To deal with these challenges, a custom approach could prove valuable [Deboer et al. 2007]. Materials and methods. A new and innovative CT-based methodology allows creating a biomechanically justified and defect-filling personalized implant for acetabular revision surgery [Figure 1]. Bone defects are filled with patient-specific porous structures, while thin porous layers at the implant-bone interface facilitate long-term fixation. Pre-operative planning of screw positions and lengths according to patient-specific bone quality allow for optimal fixation and accurate transfer to surgery using jigs. Implant cup orientation is anatomically analyzed for required inclination and anteversion angles. The implant is patient-specifically analyzed for mechanical integrity and interaction with the bone based upon fully individualized muscle modeling and finite element simulation. Results. Ten clinical severe pelvic bone defects, classified Parosky IIIb, have benefited from this methodology so far. Implant outline, thickness, fixation and cup orientation was adapted to the anatomical situation. Stress shielding of the bone was eliminated by taking into account personalized muscle anatomy, bone quality and patient weight while evaluating the design performance. All implants were applied smoothly intra-operatively because of personalized case documentation provided and jig technology for accurate pre-drilling of screw holes. Postoperative imaging showed excellent results. Short term follow-up indicates good outcome for the patients treated, restoring mobility and functionality, and showing solid anchorage to the bone. Conclusion. Complex acetabular bone defects can be treated adequately and efficiently, using a personalized solution which addresses both patient's and surgeon's needs

Purpose of the study: Implants with multidirectional locking screws theoretically have many advantages for the treatment of periprosthetic fractures. In the event of osteoporotic bone, this system of plate fixation ensures stability and better bone fixation. Using screws anchored in the different angles, we proposed rigid fixation around the prosthesis. We conducted a retrospective analysis of outcomes obtained after treatment of perprosthetic femoral fractures, Vancouver B1 and C, comparing two types of implants with angular stability (straight plate and folded plate). Material and methods: From June 1999 to December 2007, we treated 58 patients with periprothetic fractures of the femur using locking plates. Mean age was 72.4 years, 40 patients were female. Thirty-two patients (55.2%) had a total hip prosthesis, 21 a total knee prosthesis and 5 both types of prosthesis (8.6%). We noted: peri- and postoperative complications, degree of bone healing, degree of mobility (Barthel Mobility index and stand up and go test) as well as the social status of the patients. Results: Bone healing was obtained in 56 cases (96.5%). In two patients, the implant was dislocated and in four others there were general complications. The mean time necessary to obtain total weight-bearing two-leg stance was 8.6 weeks. Forty-six patients (78%) had the same social status as before the fracture. For mobility, 52 patients (89%) achieved the same level as before fracture. Four other patients required a crutch for walking and two needed a walker. Mean Barthel index was 85 points (max 100) and improved 35 points at onset of rehabilitation. Mean stand up and go was 22 s. Conclusion: According to the review of the literature, 35% of plates dislocate after osteosynthesis of periprosthetic fractures. In our study, the rate was 3.5%, with 7% general complications. We can thus conclude that the methods presented here enable good bone healing in the majority of cases

Introduction: The use of hard-on-hard hip prostheses has highlighted specific problems like the “stripe-wear” and the squeaking. Many authors have related these phenomena to a micro-separation between the cup and the head. The goal of the study was to model the hip kinematics under micro-separation regime in order to develop a computational simulator for total hip prosthesis including a joint laxity, and to use it to perform a sound analysis. Method: A three-dimensional model of the Leeds II hip simulator was developed on ADAMS. ®. software. A spring was used to introduce a controlled micro-separation (less than 500 microns) during the swing phase of the walking cycle. The increase of the load during the stance phase induced a relocation of the head in the cup. Values of the medial-lateral separation predicted from the model were compared to experimental data measured using a LVDT of less than 5 microns precision. Theoretical wear path predicted from the model was compared to the literature data. The frequencies of the vibratory phenomena were determined, using the Fourier transformation. Results: There was an excellent correlation between the theoretical prediction and the experimental measurement of the medial-lateral separation during the walking cycle (0.92). Edge-loading contact occurred during 57% of the cycle according to the model and 47% according to the experimental data. Velocity and acceleration were increased during the relocation phase in a chaotic manner, leading to vibration. The contact force according to the model had also a chaotic variation during the micro-separation phase, suggesting a chattering movement. Fourier transformation showed many frequencies in the audible area. Discussion: A three-dimensional computational model of the kinematics of the hip after total replacement was developed and validated with an excellent precision under microseparation. It highlighted possible explanations for the squeaking that may occur during either relocation phase or edge loading

Femoral off-set is the perpendicular distance between femur longitudinal axle and the femoral head’s rotation’s centre. Femoral off-set influences following yardsticks: stability of the joint, range of movement (ROM), muscular forcibleness, solicitations on the femoral component and acetabular component’s usury. From numerous radiographies studies, is shown as off-set is not an indefeasible measure, but an average with a range of variability. Offset is one of the most important yardsticks to consider during the pre-operating planning since, as is broadly documented, it has a positive effect on the functionality of the prosthesis; difficulty remains to individualize the optimal offset value in patient with bilateral coxofemural pathology or carriers of opposite side total hip prosthesis. Modular necks act indipendently in three spatial variables allowing to reach 27 points in the space, disposing of heads with three lenghts the real disponibility become of 81 points. Usually we estimate the sizes and the orientation of the components manually and through a radiographic intra-operative control in order to choose the best match head-neck. If we make a minimum mistake in cup position, the use of modular necks allow to correct this failure to obtain the most correct anatomic position producing negligible debris and the reduction of the mechanic stress. Basing on our experience we think that the possibility to change length and version independently and sequentially is the unique technique avaible to correct the implant’s orientation, even if in our series we have choose neutral neck in most cases. To obtain better functional outcome we are studing a device based on gait analysis and superficial electromyography to calculate pre and post operative off-set. The data that we have achieved are still too few to be able to produce results; if there is possible, presenting them in future editions

Introduction: Primary bone lymphoma is a rare neoplastic disease of bone. Treatment consists predominantly of chemotherapy and radiotherapy. Surgery can be considered for large lytic lesions with impending pathological fractures. This study was performed to find the functional and oncological outcome of patients who underwent limb salvage surgery and custom mega prosthesis for lymphoma of bone. Materials and Methods: Eight patients with lymphoma of bone underwent limb salvage surgery and reconstruction with custom made prosthesis. Males predominated in the study with the average age of 30 years. Lower limb was commonly involved: 6 patients had tumour involving the femur. Five patients had pathological fracture. Resection and reconstruction was done using custom mega prosthesis. Proximal humeral prosthesis was used for proximal humeral tumour and proximal femoral or total hip prosthesis for proximal femoral lesion. One patient each had total femoral prosthesis and total knee prosthesis. Results: With an average follow-up of 78.6 months, two patients died of disease and one patient was alive with disease. The patient with femoral shaft lesion had intra-operative vascular injury requiring vascular repair. The patient with total knee prosthesis had superficial skin necrosis which required skin cover. The functional outcome was satisfactory in 5 patients. Discussion: Primary bone lymphoma accounts for 7% of all bone tumours. There is a male predominance and femur is the most common site of involvement. Five patients in our series had pathological fractures warranting surgical stabilisation. Limb salvage surgery with custom mega prosthesis appears to be a feasible option as more than 65% of our patients had satisfactory functional outcome. They were able to mobilise early with good pain relief and a useful functional limb

Aims: Research was preformed including evaluation of early functional and radiographic results, six months after operative treatment of femoral neck fracture, using hemiarthroplasty and osteosynthesis, and late results, two years and more after operation. Methods: Clinical material comprehended two groups of hundred unselected patients each. Control exams included anamnestic data, and radiographic studies of treated hip. Data were stored in previously prepared research protocol according to applied functional and radiographic scoring systems. Results: Data were analized and compared between groups. Results of hip hemiarthroplasty showed direct influence of age, general state of health, size of prosthesis, use of cement and mode of rehabilitation on outcome of patients. Sex, social state, intercurrent diseases and length of operation showed no influence on outcome. Conclusions: According to this analysis hip hemiarthroplasty is a method of choice in cases of elder cathegory of patients, poor general health state, low mental capacity, short mobility and short life expectancy. In a younger patient group method of choice is ostheosynthesis or total hip prosthesis TKA – general

The use of hard-on-hard hip prostheses has highlighted specific problems like the “stripe-wear” and the squeaking. Many authors have related these phenomena to a micro-separation between the cup and the head. The goal of the study was to model the hip kinematics under micro-separation regime in order to develop a computational simulator for total hip prosthesis including a joint laxity, and to use it to perform a sound analysis. A three-dimensional model of the Leeds II hip simulator was developed on ADAMS® software. A spring was used to introduce a controlled micro-separation (less than 500 microns) during the swing phase of the walking cycle. The increase of the load during the stance phase induced a relocation of the head in the cup. Values of the medial-lateral separation predicted from the model were compared to experimental data measured using a LVDT of less than 5 microns precision. Theoretical wear path predicted from the model was compared to the literature data. The frequencies of the vibratory phenomena were determined, using the Fourier transformation. There was an excellent correlation between the theoretical prediction and the experimental measurement of the medial-lateral separation during the walking cycle (0.92). Edge-loading contact occurred during 57% of the cycle according to the model and 47% according to the experimental data. Velocity and acceleration were increased during the relocation phase in a chaotic manner, leading to vibration. The contact force according to the model had also a chaotic variation during the micro-separation phase, suggesting a chattering movement. Fourier transformation showed many frequencies in the audible area. A three-dimensional computational model of the kinematics of the hip after total replacement was developed and validated with an excellent precision under micro separation. It highlighted possible explanations for the squeaking that may occur during either relocation phase or edge loading

Introduction: Maximum effort should be taken during surgical debridement of an infected hip arthroplasty to remove all implants and cement, as also granulation, devitalized and necrotic tissue. Nevertheless, this process is sometimes technically demanding, risky for bone stock and prolongs the procedure. Residual unremoved polymethylmethacrylate (PMMA) after the resection of infected prosthetic components constitutes a controversial issue. Material and Methods: We analyzed 10 patients with infected total hip prosthesis that had been previously treated with resection arthroplasty and antibiotics who presented persistent infection with residual cement. In 9 patients, surgical debridement with resection of all the PMMA was performed, and adequate intravenous antibiotics were administered. One patient refused surgical treatment, but accepted antibiotics. Results: At an average 4 (1–18) years follow-up, 8 patients evolved with no signs or symptoms of recurrent infection. One severely immunodeficient patient died 2 years after the removal of residual cement for reasons other than his hip with an intermitent fistula. The patient who refused surgical treatment continues to have an active sinus 4 years after first consultation. Conclusions: Residual cement could be responsible for chronic infection. Resection arthroplasty as part of the treatment of an infected hip arthroplasty must be precise and thorough, and all devitalized or foreign material must be removed

We have studied the effect of hydroxyapatite (HA) coating in 15 ovariectomised and 15 normal rats which had had a sham procedure. Twenty-four weeks after operation, HA-coated implants were inserted into the intramedullary canal of the right femur and uncoated implants into the left femur. The prostheses were removed four weeks after implantation. Twelve specimens in each group had mechanical push-out tests. Sagittal sections of the other three were evaluated by SEM. The bone mineral density (BMD) of the dissected left tibia was measured by dual-energy x-ray absorptiometry. The difference in BMD between the control and ovariectomised tibiae was 35.01 mg/cm. 2. (95% CI, 26.60 to 43.42). The push-out strength of the HA-coated implants was higher than that of the uncoated implants in both groups (p < 0.0001), but the HA-coated implants of the ovariectomised group had a reduction in push-out strength of 40.3% compared with the control group (p < 0.0001). Our findings suggest that HA-coated implants may improve the fixation of a cementless total hip prosthesis but that the presence of osteoporosis may limit the magnitude of this benefit

Objectives: Dislocation is one of the common complications of total hip Arthroplasty. Posterolateral approach and small femoral heads have been shown to be high-risk factors for dislocation of the implanted total hip prosthesis. The use of a posterior capsulorraphy has also shown to decrease the rate of dislocation with a posterolateral approach. The objective of this study was to evaluate the early dislocation rate using size 22 mm head and a Posterolateral approach augmented with a posterior capsulorraphy. Methods: Questionnaire and case notes review of 148 patients operated at one institution by 3 different senior surgeons from Aug’03 to Jan’05. A posterior capsulorraphy was performed in all the patients. The primary outcome measure was the dislocation of the prosthetic hip within the first year of surgery. Results: 4 of the 148 patients (2.7%) had an episode of dislocation during the first year of surgery. 3 patients were treated conservatively and 1 required operative intervention in the form of PLAD. Radiographic analysis of this patient showed excessive anteversion of the socket(28. 0). . Conclusions: Studies have consistently shown an increased rate of dislocation with a Posterolateral approach and use of a size 22mm head. A recently published study by Berry et.al has shown a 12.1% dislocation rate with the use of this approach and size 22mm head. However posterior capsulorraphy was not performed in patients in this study group. Our study shows that performing a posterior capsulorraphy can reduce early dislocation rates using Posterolateral approach and size 22 mm head. The dislocation rate (2.7%) is comparable to any other approach and the use of a larger head size. These patients continue to be monitored to evaluate long term outcomes with this approach. (301 words)

Purpose: Using the finite element analysis, the authors analyze the effect of the articulating material properties of the total hip arthroplasty to stress and micro-motion of the proximal femur and the femoral stem. Material and methods: The head (28mm) and the acetabular component (outer diameter = 54mm, liner thickness = 11.4mm) were considered as ceramic on ceramic, cramic on polyethylene, metal on metal, metal on polyethylene and metal on metal-polyethylene. The femur was modeled with different friction coefficients according to the different contact portion of the femoral stem, which was modeled after Omni fit HA #9(Osteonics, Allendale, NJ). Non-linear contact analysis was proceeded in human with body weight 70Kg at one leg standing and stair climbing. Result: The maximal yield strength was always higher in hard-hard coupling. In one leg standing, the site of maximal yield strength was represented at the contact point of articulation. In stair climbing, the site of maximal yield strength was represented at the same site in hand on hard coupling but at the lateral aspect of the neck in hard-soft couplings. There were no changes in the patterns of stress distribution but the micro-motions were up to the limit of bone in growth in hard-hard coouplings. Conclusion: The maximal yield strength and the micro-motions revealed different values according to the articulating materials. These findings were considered valuable information to postoperative management and longavity of the total hip prosthesis but requiring the following experimental and clinical study

Objectives: Critical analysis of the results of 1124 patients over 70 years of age treated with an endoprothesis between 1987 and 2000. Patients: Patients over 70 years of age presenting a non-pathological unstable fracture of the femoral neck. Intervention: Depending on age and functional status preinjury, 715 times a hemi-arthroplasty; 409 times a total hip prosthesis. Main outcome and measurements: Evaluation of the functional status of the patients preinjury based on walking capacity and ability to perform some activities of daily life. Prospective follow-up of all surviving patients during the first postoperative year. Special attention to the local complications needing reintervention. The final functional evaluation in 708 surviving patients preoperatively classified as “independent”. Estimation of the revision arthroplasty rate and functional status of patients operated before 1995. Results: The overall mortality rate after 1 year: 20%. Complications after prosthetic replacement are not harmless: dislocation (2%) needing an early revision arthroplasty in about 50% of the cases; deep infection (< 1%) leading to a Girdlestone situation and sometimes even death. In 32% of the surviving patients preoperatively classified as “independent” the femoral neck fracture had caused an important additional impairment. Failure rate of prosthetic replacement for fractures much higher than after replacement for arthritis: at least 14% within five years. Conclusion: In patients younger than 70 years of age with a good life expectancy, prosthetic replacement has to be avoided whenever possible

Model-based Roentgen Stereophotogrammetric Analysis (RSA) measures micromotion of an orthopaedic implant with respect to its surrounding bone, without the use of markers on the implant. In previous studies with a total knee prosthesis, Model-based RSA showed to be very accurate. In this study, Model-based RSA is validated in a phantom experiment of a total hip prosthesis. A metal backed, elliptical shaped EP-FIT PLUS ®cup was used in combination with a SL-PLUS ® hip-stem from PLUS Endoprothetik AG. In vivo conditions were simulated by using sawbones and perspex plates to mimic the bones and soft tissue. Virtual projections of the CAD models of the implant were fitted on the automatically detected contours in nine RSA radiographs and the error inmigration calculation was determined. The standard deviations of the error in translation for the cup were: 0.03, 0.05, and 0.21 mm. (x, y, z-direction) The standard deviations of the error in orientation were respectively 0.56, 0.48, and 0.18 degrees (n = 10). For the stem, the standard deviations of the error in translation are: 0.09, 0.11, and 0.29 mm and for the orientation: 0.63, 2.03, and 0.24 degrees (n = 0). The results for the cup are satisfactory, and make Model-based RSA a good alternative for conventional RSA. Especially for this type of metal backed, non hemispherical cup for which no markerless alternative is available. The error in orientation around the y-axis of the stem is of concern. Experiments with models from Reversed Engineering had similar low accuracy. We expect that the cause of these inaccuracies is the rectangular cross sectional shape of this specific hip stem, and we expect better results from experiments with differently shaped stems. The results of this study make very clear that Model-based RSA is avaluable and accurate technique, but phantom studies are always necessary to validate the accuracy for a specific implant shape

Introduction: The Gemini stem (DePuy) is a titanium femoral stem with a modular cobalt chrome femoral head. It has a roughened proximal surface finish to enhance cement bonding and a distal centraliser. Purpose of the study: A retrospective assessment of the performance of the titanium cemented Gemini femoral component. Patients and Methods: 196 patients underwent a 204 total hip replacements using a titanium cemented Gemini stem and an uncemented cup. All the operations were performed by a lateral approach using modern cementing technique. Patients were assessed clinically (Harris hip score) and radiologically (standard AP and lateral x-rays). Results: 11 patients with incomplete clinical and radiological follow-up were excluded from the study, leaving 185 patients (193 hips). 36 patients died with their total hip prosthesis in situ. The average age was 71 years and primary diagnosis was OA in the majority. The average follow-up was 70 months (range 35– 121). 29 of the hips have been revised. A further 11 were recognized as radiological failures. In 24, aseptic loosening or a broken stem was an indication for the revision. Mean time to revision was 3.1 years (range 1.5 to 7). Discussion: Our results indicate that there is a high incidence of early failure associated with these titanium cemented stems, a cumulative failure of approximately 20%. The rough surface finish, titanium alloy and a fixed distal centraliser may all contribute to the early failure by increasing the stresses in the cement. Based on our experience, the continued use of this cemented stem is no longer justified

Our aim was to determine if the serum levels of bone-resorbing cytokines (IL-1β, TNF-α, IL-6, GM-CSF) are altered in patients with aseptic loosening of a total hip prosthesis, and if such levels are influenced by the type of implant. We determined cytokine levels in sera from 35 patients before revision for failed total hip arthroplasty and compared them with those in 25 healthy donors. We also assessed the soluble receptor of interleukin-2 (sIL-2r) in serum as an indication of a specific immune reaction against the implant. Our findings showed that the sIL-2r and TNF-α serum level did not change. The IL-6 level was not significantly altered, but was higher in patients with TiAlV prostheses than in those with a CrCoMo implant and in patients with cemented prostheses. The IL-1β level was found to be higher in those with a TiAlV cemented prosthesis than in the control group (p = 0.0001) and other groups of patients (p = 0.003 v uncemented TiAlV, p = 0.01 v cemented CrCoMo, p = 0.001 v uncemented CrCoMo). The GM-CSF level significantly increased in patients compared with healthy subjects (p = 0.008), and it was higher in those with cemented than with uncemented implants (p = 0.01). Only patients with cementless CrCoMo prostheses had levels of GM-CSF similar to those of the control group. The highest GM-CSF concentrations were observed in patients treated with non-steroidal anti-inflammatory drugs (NSAIDs) in the last months before revision (p = 0.04). In addition, when massive osteolysis was observed, the level of GM-CSF tended to decrease to that of the control group

Aims: To investigate the potential of biological þxation of cementless total hip prosthesis in patients over 75 years old, with diagnosed osteoporosis. Methods: Between 1994Ð2000, 30 patients (mean age 77.3 years) underwent total hip arthroplasty (THA). Twenty-two (22) patients, 10 male and 12 female, were found at the last follow-up, which ranged from 1.5–7 years (mean follow-up, 3 years). THA was performed due to primary osteoarthritis (n=16), subcapital fracture (n=4), or dysplastic hip (n=2). Eight (8) smooth, tapered design (CLS) and 14 proximally porous coated prostheses were implanted. Singh index was used for the evaluation of osteoporosis and modiþed Harris Hip Score was used for the clinical evaluation of each patient. Modiþed Wixon score was used for the evaluation of stability probability of the tapered stem. Engh score was calculated for the evaluation of osseointe-gration of the porous coated implants. Results: Pre and post-operative mean Singh index was grade 4. Mean modiþed Harris Hip Score at the last follow-up was 88.6. For the CLS-Spotorno stem a stable þxation probability was calculated at 74.8%, while possible instability was calculated at 48.17%. Porous coated stems provided +13.45 mean Engh score, implying satisfactory þxation of the implant. Post-operative systematic complications are not reported, in contrast to 3 dislocations in the þrst post-operative period, which were treated by closed reduction. Conclusions: In patients over 75 years old, with possible cardiopulmonary disease, cementless total hip arthroplasty offers a reliable treatment, regardless the presence of osteoporosis. Satisfactory osseointegration and absence of systematic complications is compromised by the high cost of titanium implants

Introduction and Objectives: This is a prospective analysis of clinical and radiographic outcomes of total hip prosthesis with alumina-on-alumina friction coupling implants performed at two hospitals. Materials and Methods: This study analyzes 60 prostheses with alumina-on-alumina friction coupling (Ceraver-Osteal) (May 1999-May 2002). The Cerafit cup was used in association with 32 Multicone-HAC stems and 28 Anatomic-HAC. Of these cases, 36 were male, and 24 were female, with average age being 47.05+/−12.60 years. Mean follow-up time was 2.3 years. There were no lost or revised cases. Radiographic analysis was done according to Johnston et al., and wear was assessed using the Sychterz method in a special computer program (Auto-CAD R14). Results: All cases had good clinical and radiographic outcomes. There were no revisions or loosening of the implants. There was one dislocation and one intraoperative fracture, which were both treated by conservative means. There were no infections. The distance between the centres of the femoral head and the cup on the initial radiograph (position zero) was 2.49+/−0.70mm. This measurement stayed constant with time, and no changes were observed associated with so-called early wear or initial seating. Mean wear with respect to a reference of position zero was 0.0184+/−0.0187. This figure is below the error level of the measuring system and thus is not measurable. Discussion and Conclusions: The alumina-on-alumina prosthesis (Ceraver) yields positive clinical and radiographic results at 4 years. Even though the alumina partially distorts the radiographic image, no evidence of early wear due to seating of the components was observed at four years of follow up using the Sychterz digitalized method

To investigate the potential of biological fixation of cementless total hip prosthesis in patients over 75 years old, with diagnosed osteoporosis. Between 1994–2000, 30 patients (mean age 77.3 years) underwent total hip arthroplasty (THA). Twenty-two (22) patients, 10 male and 12 female, were found at the last follow-up, which ranged from 1, 5–7 years (mean follow-up, 3 years). THA was performed due to primary osteoarthritis (n=16), subcapital fracture (n=4), or dysplastic hip (n=2). Eight (8) smooth, tapered design (CLS) and 14 proximally porous coated prostheses were implanted. Smgh index was used for the evaluation of osteoporosis and modified Harris Hip Score was used for the clinical evaluation of each patient. Modified Wixon score was used for the evaluation of stability probability of the tapered stem. Engh score was calculated for the evaluation of osseointegration of the porous coated implants. Pre and post-operative mean Singh index was grade 4. Mean modified Harris Hip Score at the last follow-up was 88.6. For the CLS-Spotomo stem a stable fixation probability was calculated at 74.8%, while possible instability was calculated at 48.17%. Porous coated stems provided +13.45 mean. Engh score, implying satisfactory fixation of the implant. Post-operative systematic complications are not reported, in contrast to 3 dislocations in the first post-operative period, which were treated by closed reduction. In patients over 75 years old, with possible cardiopulmonary disease, cementless total bip arthroplasty offers a reliable treatment, regardless the presence of osteoporosis. Satisfactory osseointegration and absence of systematic complications is compromised by the high cost of titanium implants

This is a retrospective assessment of the performance of the titanium cemented Gemini femoral component. The Gemini stem (DePuy) is a modular titanium femoral stem with a cobalt chrome femoral head. It has a roughened proximal surface finish to enhance cement bonding and a fixed distal centraliser. 205 total hip replacements were performed using a titanium cemented Gemini stem and an uncemented cup. All the operations were performed by a lateral approach using modern cementing technique. Patients were assessed clinically (Harris hip score) and radiologically. Kaplan Meier Survivorship analysis was used to assess survival. 8 patients were lost and 36 patients died with their total hip prosthesis in situ. The average follow-up in the remaining 161 hips was 70 months (range 37–124 months). The average age was 70 years (range 35–91). Osteoarthritis was the commonest diagnosis and majority of the patients was female. Using the Barrack’s criteria for cementing quality, more than 85% of the hips belonged either to grade A or B with an adequate proximal cement mantle. 28 hips have been revised (26 of which for aseptic loosening) and a further ten have been recognized as radiological failures. A small sized stem was used in over 85% of the failures. Mean time to revision was 3.1 years. Survival according to Kaplan-Meier Survivor curves at 6 years was 72%. There is a high incidence of early failure associated with these cemented titanium stems (28%). The possible mechanism of failure is as follows. The rough surface finish and the flexible titanium alloy are likely to produce large amounts of wear debris and the centraliser which is fixed to the stem probably acts as an area of stress concentration causing accelerated destruction of the distal cement mantle. Based on our experience, the continued use of this cemented stem is no longer justified

The aim of this study was to compare the results of resection arthroplasty with two-stage re-implantation procedure performed for peri-prosthetic infection of the hip. Patients who have had a resection arthroplasty can expect to have less pain, but their functional recovery is inferior to that which can be obtained after a two-stage re-implantation. Resection arthroplasty is usually unacceptable as a definitive solution for relatively young and active patients. Possible options for the operative treatment of a periprosthetic infection include debridement with retention of the prosthesis, immediate one-stage exchange arthroplasty, and excision arthroplasty – either as a definitive procedure or as the first of a two-stage reconstructive procedure. The choice of a particular treatment is influenced by a number of factors. At the Department of Orthopaedic Surgery in Hradec Králové we performed resection arthoplasty of the hip in 67 patients between 1984 and 1998. Mean age was 67 years (range 44–91). We were able to follow-up 33 of these patients in 1999. At follow-up, replacement of the total hip prosthesis in two stages had been carried out in 10 of the 33 patients. In 23 patients (11 male, 12 female) the resection arthroplasty had been present for an average of five years. In the remaining ten patients (3 male, 7 female) a total hip reimplantation had been performed after an average of 17 months (range 3 to 63). Mean follow-up after reimplantation was four years. The Harris hip score was calculated for the individual patients during follow-up. The Harris hip score was 66 in the re-implantation group compared to 57.5 in the patients with resection arthroplasty. Personal satisfaction and hip function were better after the two-stage re-implantation procedure

The aim of this study is to compare the results of resection arthroplasty with two-stage re-implantation procedure performed for peri-prosthetic infection of the hip. Patients who have had a resection arthroplasty can expect to have less pain, but their functional recovery is inferior to that which can be obtained after a two-stage re-implantation. Resection arthroplasty is usually unacceptable as a definitive solution for relatively young and active patients. Possible options for the operative treatment of a periprosthetic infection include debridement with retention of the prosthesis, immediate one-stage exchange arthroplasty, and excision arthroplasty – either as a definitive procedure or as the first of a two-stage reconstructive procedure. The choice of a particular treatment is influenced by a number of factors. At the Department of Orthopaedic Surgery in Hradec Králové we performed resection arthoplasty of the hip in 67 patients between 1984 and 1998. Mean age was 67 years (range 44–91). We were able to follow-up 33 of these patients in 1999. At follow-up, replacement of the total hip prosthesis in two stages had been carried out in 10 of the 33 patients. In 23 patients (11male, 12 female) the resection arthroplasty had been present for an average of five years. In the remaining ten patients (3 male, 7 female) a total hip reimplantation had been performed after an average of 17 months (range 3 to 63). Mean follow-up after reimplantation was four years. The Harris hip score was calculated for the individual patients during follow-up. The Harris hip score was 66 in the re-implantation group compared to 57.5 in the patients with resection arthroplasty. Personal satisfaction and hip function were better after the two-stage re-implantation procedure

Ceramic-on-ceramic was shown to have advantageous tribologic properties (low wear and friction). For medical applications two ceramics, alumina and zircona, are available. This case study shows that the combination of different ceramics for hard-hard pairings can be critical. A 57 year old patient received a total hip prosthesis (cementless stem with a ceramic head and a monolithic ceramic cup). Thirty-five months postoperatively the patient complained about squeaking noises during walking and stair climbing. Clinical diagnoses showed a good range of motion and no signs of loosening. Conventional rehabilitation did not improve the situation and 43 months after primary surgery the cup and the head had to be revised on the patients request. Intraoperatively no loosening indications were found. The explanted components were analysed using a 3D co-ordinate measuring machine. The head and the cup were made of different ceramics. The zirconia (ZrO2) head occurred rather white whereas the alumina (Al2O3) cup was yellow-reddish. The inner articulating surface of the cup showed no decoloration or wear. The surface of the head contained mated areas with surface defects in equatorial regions (maximum wear depth 9μm). The head and the cup were combined from different manufacturers. The distinct surface changes and wear marks of the zirconia head probably caused the squeaking noise after 3 years in situ. Zirconia for medical applications is generally Y-TZP ceramic. Pressure, heating, and water can cause severe surface embrittlement. Pre-damaging due to the manufacturing process or friction in the joint might be the mechanism leading to pre-mature wear and failure. Joint components from different manufacturers should only be implanted with proper official authorisation

We have been using a Charnley type hip prosthesis with an alumina ceramic head. Three sizes of alumina head, 28, 26 and 22mm, were employed and the Ortron 90 Charnley total hip prosthesis was used at the same period. The objective of this study was to compare the survival rate and the wear rate of those four groups. There were 90, 62, 322 and 88 hips in 28, 26, 22mm alumina head and 0rtron 90 head group. Average age at operation was 49.5, 57.8, 58.0 and 60.6, respectively. A 28 mm prosthesis was indicated for relatively young patients. The mean duration of follow-up was 156, 97, 49 and 110 months, respectively. Twenty patients were chosen at random for each of four groups and the linear wear as seen on X-ray film was measured every two years with a computer and scanner. Results: The average linear wear rate (mm/yr) was 0.179 for the 28mm, 0.112 for the 26mm, 0.115 for the 22mm alumina head and 0.075 for the Ortron 90 head. The difference between the 28mm group and the other three groups was analyzed statistically. The Kaplan-Meier survivorship analysis, with revision for aseptic loosening as the endpoint, showed the survival rate of the 28mm group appeared to be inferior to that of the other three groups. Discussion: Our study showed that the wear rate of the 28mm alumina group was highest because low grade alumina was used. In addition, the polyethylene socket used for the 28mm group was thinner than that for the other groups. No clinical superiority of ceramics to metal in terms of polyethylene wear can be shown in this study. A randomized prospective study should be carried out to determine whether an alumina ceramic head is clinically superior to a metallic head in terms of polyethylene wear

Introduction and Objectives: The coating of implants with biomaterials seems to be a step further toward the ideal biological integration of an inert implant in live recipient bone where it will be subjected to load and movement. The goal of this study is to present results from 70 hip prostheses with implantation of a bioglass-coated stem. Materials and Methods: The “Grupo para el Estudio del Biovidrio” [Group for the Study of Bioglass] and the Stazione del Vetro de Murano experimented with a biocompatible, osteoconductive bioglass in 1992, creating the Biovetro patent as the first bioglass used for the coating of the CRM total hip prosthesis (Seipi-Bio-implant). In 1992, implantation of this prosthesis was begun in Italy and Spain. In 1994 and 1995, we implanted 70 TiAlva CRM stem total hip prostheses with the proximal two-thirds coated with an 80-micron thick layer of Biovetro. A Ceraver-Osteal impacted cup covered with a titanium mesh was used in all cases. Results: Of the 70 CRM prostheses implanted, adequate clinical and radiographic examination was possible in 62 cases, with an 8-year follow-up time. Clinical evaluation was done using the Merle D’Aubigne Postel criteria: pain, mobility, and gait. In 77% of patients, results were excellent or good, while 23% had fair or poor results. Radiographic evaluation according to Engh’s criteria for cementless stems showed 56 (90%) stable stems, 1 (1.6%) unstable stem, and 5 (8%) stem revisions, in one case due to infection. Survival rate for this stem at 8 years was 91.4%. Discussion and Conclusions: Based on these results, we believe Biovetro coating produces worse osteointegration than HA due to: 1) Appearance of a fibrous interface with a macrophage foreign body reaction. 2) Less new bone formation activity and a significant delay in maturation. 3) Insufficient mineralization of newly-formed bone

Introduction: A potential cause of premature loosening of the total hip prosthesis in patients with osteonecrosis is abnormal cancellous bone in the acetabulum and proximal femur. The purpose of this prospective study was to investigate the hypothesis that osteonecrosis is not confined to the femoral head but may extend proximally into acetabulum and distally into the proximal femoral bone. Also, the clinical and radiographic results of total hip arthroplasty with so-called third-generation cementless total hip prostheses were evaluated in sixty-three consecutive patients with osteonecrosis of the femoral head. Materials and Methods: Twenty-five patients who had simultaneous bilateral total hip arthroplasty, and thirty-eight patients who had a unilateral total hip arthroplasty were included in the study. A cementless acetabular and femoral component were used in all hips. There were fifty-five men and eight women. The mean age at the time of the arthroplasty was 47 years (range, twenty-five to sixty-four years). We performed histological examination of the femoral heads and cancellous bone biopsies from five regions of the hip in patients undergoing total hip arthroplasty. Clinical and radiographic evaluations were performed preoperatively; at six weeks; at three, six, and twelve months; and yearly thereafter. The average duration of follow-up was 4.9 years. Results: The majority of patients with idiopathic or alcohol induced osteonecrosis had normal bone in the acetabulum and proximal femur. The average Harris hip scores in the group treated with unilateral arthroplasty (96 points) and the group treated with bilateral arthroplasty (94 points) were similar at the time of final follow-up. No component had aseptic loosening. In one hip (1%), an acetabular component and a femoral component were revised because of infection. No hip had detectable wear or osteolysis in the acetabulum or in the proximal femur. Conclusions: Normal or nearly normal cancellous bone in the acetabulum and proximal femur and advancements in surgical technique and better designs have greatly improved the intermediate-term survival of cementless total hip implants in young patients with osteonecrosis of the femoral head. An absence of osteolysis in these high-risk young patients is partly related to use of ceramic-on-ceramic bearing; solid fixation of the component; and short-term follow-up

We hypothesise that the stiffness of the acetabular component influences the stresses transmitted to bone. Thus stress shielding or stress overload of the underlying host bone may be influenced by the choice of fixation method. In addition, we believe that the so called “brake drum effect” plays a significant role in the development of rim stresses and subsequent failure of fixation. We have constructed a jig which allows the direct comparison, under controlled conditions, of contact stresses measured behind the acetabular component of polyethylene controls, uncemented metal backe cups and cemented all polyethylene cups, under physiological load. The design of the jig also allows measurement of stresses transmitted to the acetabular rim of the same three prostheses in order to confirm the presence and magnitude of the brake drum effect. The contact stresses are measured by miniature pressure transducers which are inserted through specially drilled holes in the shell of the jig so that the transducer is flush with the prosthesis under test. A total of 6 transducers are arranged in concentric circles radiating away from the prosthetic dome, so that contact stresses may be directly measured in various parts of the acetabular bed under conditions that reproduce as closely as possible the situation in a total hip prosthesis in vivo. Thus our method can be compared to other laboratory and theorectical techniques for investigation into stress transmission around acetabular components. The transducers were callibrated prior to each test to ensure parity of test results. The transducers were prestressed to ensure contact prior to each test. 6 polyethylene uncemented liners were tested alone in the jig to act as a control. In the same fashion, the same 6 polyethylene components were tested firstly in an uncemented, metal back acetabular component, and then as a cemented, all polyethylene component. The results indicate that significantly less stress is transmitted to bone when metal back components are used as compared to cemented components and controls. The data confirms that the brake drum effect occurs in both cemented and uncemented prostheses, leading to at least the absence of compressive forces at the prosthetic rim and in some circumstances tensile forces

Purpose: Periprosthetic ossification is a frequent complication of total hip arthroplasty and can have a major functional impact. Non-steroidal anti-inflammatory drugs (NSAID) can provide effective prevention but with a risk of morbidity. The purpose of this work was to evaluate the efficacy of an anti-Cox2 agent, cele-coxib, for this indication. Material and methods: Total hip arthroplasty was performed in 42 patients with a relative (gastrointestinal) contraindication for the use of NSAID. These patients were given celecoxib (Celebrxy(r)) 200 mg bid starting the day before the operation and continuing for at least five days. A control group of 42 age- (±3 yr) and sex-matched patients who underwent surgery for the same indication performed by a surgeon with equivalent experience was also established. The control patients were given ketoprofen (Profénidy(r)) 50 mg qid for two days then 150 mg bid for five days. The approach, implant, and other adjuvant treatments were equivalent between the two groups. Ossifications were analysed on the follow-up films taken at least three months after surgery. The Brooker classification was used. The exact Fisher test was used for the statistical analysis. Results: The two groups each included 31 women and eleven men, mean age being the same in the two groups (67.12 yrs). Mean follow-up was very similar (8.44 vs 8.6 months). Aetiologies were: primary degenerative hip (n=30), degenerative hip disease after dysplasia (n=9), sequela of infantile arthritis (n=1), revision total hip prosthesis (n=2). Two patients in each group interrupted their treatment between day 2 and 4 because of intolerance. There were no cases of significant haematoma in either group. No ossification > grade 2 was observed. The overall rate of ossification was 42.5% in the control group versus 48.6% in the celecoxib group. The rate of grade 2 ossifications was 8% in the cele-coxib group versus 12% in the control group. These rates were not significantly different (Fisher’s exact test= 0.6). Discussion: In this study, celecoxib and ketoprofen were found to have equivalent efficacy for the prevention periprosthetic ossification. This is an interesting perspective in the probable hypothesis of less morbidity with anti-Cox 2 antiinflammatory drugs used in combination with an antalgesia protocol

Introduction and Objectives: The purpose of this study is to analyse the clinical and radiographic results of revision total hip prosthesis using femoral stems with diaph-yseal fixation. Materials and Methods: We assessed failure of the primary prosthesis based on Paprosky’s classification to identify the femoral defect and determine the optimal component for revision, keeping in mind the difficulty of classifying bone defects based on radiographic parameters. The most commonly-used replacement models were KAR revision stems (wide, straight, long necks and hydroxyapatite-coated along the entire length) and Restoration-T3 stems (diaphyseal fixation, modular, fits different necks, Wagner model progression, particularly indicated to facilitate extraction of cement using a buried diaphyseal osteotomy). Clinical evaluation was done using the Merle D’Aubigné and Postel scales modified by Charnley. Radiographic evaluation of prosthetic stability and osseointegration was done using Engh’s criteria, checking for presence or absence of radiolucency, migration, pedestal, and increase or decrease of endosteal and periprosthetic density (calcar, diaphysis, and greater trochanter). Results: We examined 47 KAR stems and 16 Restoration-T3 stems, with an average follow-up period of 4.1 years (range: 1–9 years) and an average patient age of 69.4 years (range: 40–79 years). Of these, 6 were Paprosky type 1, 36 were type II, 14 were type IIIA, 5 were type IIIB, and 2 were type IV. Average preoperative clinical score was 9.76 points. Aetiology in all cases was aseptic loosening of a primary prosthesis, with the exception of one case of a delayed Corynebacterium infection. There were 2 partial Monk prosthesis revisions and 3 periprosthetic fractures. Average postoperative clinical score was 15.83 points. There were no deep infections or dislocations. Radiolucency was noted in only one case, and no migrations of more than 2 mm were seen. No further stem revisions were required in this series, though we believe a future revision will be necessary in at least one case. Discussion and Conclusions: The use of femoral stems with diaphyseal fixation is an acceptable alternative in revision surgery of the hip, even in cases of major bone deficit. Modular stems have the added advantage of versatility to adapt to a great variety of prosthetic salvage procedures

Purpose: Exposure to polyethylene debris and bearing wear is a common feature of total hip prosthesis inserted with or without cement. Osteolysis depends on the number of particles involved and their size. This continuous series of total hip arthroplasties using a Corail prosthesis with 12 years follow-up was studied to assess the course of osteolysis around the prosthesis and the resistance of hydroxyapatite coated implants to the aggression of wear debris. Material and methods: One hundred fifteen patients underwent total hip arthroplasty in 1989 with a Corail prosthesis implanted by the same operator with a metal backed cup and a polyethylene insert. Mean age at implantation was 65 years. Review radiograms were available for 80 patients (38 women and 42 men). Twenty-seven patients had died, five answered a phone interview and three were lost to follow-up. The follow-up was 12 years and analysis was performed on the population with review data and x-rays. Results: There was no case with a loosened stem and none of the patients underwent revision. Twelve cups were however revised for loosening with granuloma. Polyethylene insert wear was seen in 62% of the cases. There was a relationship between the amount of wear debris and the extent of the gramulomas on the femur. These granulomas were basically observed in zones I and VII. Bone defects were curetted and filled with grafts for the 12 cup revisions. The cup bearing was changed in young patients. Good bone healing was a constant finding on follow-up x-rays. Discussion: Hydroxyapatite coated prostheses exhibit good long-term resistance to wear debris which causes osteolysis since none of the Corail femoral stems were destabilised. The granulomas remain localised in the proximal zone and do not descend along the stem or the cement as seen in cemented prostheses. The intimate contact between the recipient bone and the implant appears to form a barrier against migration of wear debris. It thus appears important to achieve good contact all along the stem and to use a totally hydroxyapatite coated implant. Conclusion: Total hip arthroplasty without cement is spared the problem of polyethylene wear debris, but debris must be limited to prevent osteolysis. This observation questions the long-term appropriateness of metal-backed cups with polyethylene inserts and suggests that low friction arthroplasty or use of a hard bearing couple (Cr-Co-Cr-Co or alumina-alumina) should be preferred

We present our experience with HA-coated total hip prosthesis in a minimum follow-up of eight years. From 1989 to 1991 we performed 92 THRs in 83 patients. The mean age was 62 years (range 32–75). The preoperative diagnosis was: O.A. 68, AVN 12, CDH 8, and post-traumatic arthropathy 4. Pre-operative mean was HHS 43. A posterior approach was used. The ARC 2F Cup, an HA coated spherical cup with thread around the equator, was used. Initial stabilisation is achieved by screwing the cup into the acetabulum. If necessary, a secondary fixation is enhanced by one or two bone screws to the ilium. The Omnifit stem is HA-coated in the proximal third and gives good immediate metaphysical fixation and optimal filling of the metaphysis. Three doses of Cefuroxime for prophylaxis and low molecular weight heparine were used in all cases. All patients had non-weight-bearing on the second postoperative day, partial weight-bearing in six weeks and full weight-bearing in 12 weeks. Four patients were lost to follow-up. Mean H.H.S. was 91 in the first six months, 93 in the first year, and 95 in the second and third year. In the fifth year 97.93% were symptom-free in the first six months and 97% from the third to the fifth post-operative year. 3.7% of the patients complained of mild or moderate activity related to hip pain. No patients suffered marked or disabling pain. Four patients complained of thigh pain six and eight months post-operatively. There were no major complications except for two superficial and two symptomatic deep vein thromboses. All patients returned to their prior activities within four to six months post-operatively. Radiographic evaluation of acetabular components revealed bone condensation in all three Charnley zones. We had no component migration or screw breakage. Calcar resorption was detected on the femoral side in seven patients. During the first post-operative year, AP radiographs of eleven patients indicated cortical hypertrophy in zones 3 and 5. There was no subsidence of the femoral stem. We believe our results are encouraging although the follow-up period is short. We have had no revisions and the functional results are quite good. All patients are asymptomatic and satisfied with the result

Background: Total Hip Replacements in younger active patients continues to pose a major challenge. Surface replacement techniques, designed to preserve bone stock do not yet have proven long term results. Early cemented designs in this population had high failure rates. Concept of fixation of total hip prosthesis by bony in-growth rather than by cement is an attempt to decrease the incidence of loosening. Ceramic joint surfaces produce minimal wear debris. Objectives: A medium term follow-up of clinical and radiological results of the JRI Furlong hydroxyapatite coated prosthesis with ceramic bearing surfaces in young active patients. Methods: A retrospective analysis of 43 JRI Furlong Hip Replacements (mean age 32 Yrs) in 33 patients is presented. The minimum follow-up was 60 months. Functional assessment was done using the Harris Hip Score. Radiolucency around the femoral stem according to Gruen (zone 1-7) and the acetabulum as described by Charnly and De Lee (zone 1–3) is documented. A fully coated femoral component along with the press –fit HA coated CSF cup with a 28mm ceramic insert was used. All cups were routinely augmented with screws. Results: The mean Harris Hip score was 90 (46–96). 4 patients had a score less than 80. 84.2% were completely pain free. Acetabular radioleucencies were noted in 32 hips (72 %).28 cups had radiolucent lines (RLL) in zone 2, 2 cups in zone 1 and 1 cup in zone 3. In 10 patients (23%) the lucent area measured > 2mm at the cup bone interface. No hips had RLL in more than two zones. 4 stems had RLL > 2 mm involving the Gruen zone 7. 90 % showed a distinct osteoblastic reaction at the tip of the femoral component. There was no calcar resorption, endosteal cavitation or ectopic ossification. There were no instances of ceramic fractures and no hips were revised. Discussion: The JRI Furlong hip gives good functional results in young patients in the medium term. Although of concern, there was no co-relation between the presence of acetabular RLL and functional outcome. The RLLs were not thought to be progressive. The RLLs can be explained by backside wear or by fretting of the screws by the ceramic liner. Long term follow up of the CSF cup will be required to determine if these radio-lucent lines are an early sign of failure at the interface or whether they simply represent stable in- growth of fibrous tissue in this highly stressed region