In revision total hip arthroplasty (THA), acetabular reconstruction while dealing with severe bone loss is a challenge. The porous tantalum revision acetabular shells have been in use for the past decade. Several reports have documented successful use at early to mid-term follow up. There is, however, very little literature around the long-term survival and quality of life outcome with the use of these shells.

We reviewed the results of 46 acetabular revisions with Paprosky 2 and 3 acetabular bone defects reconstructed with a hemispheric, tantalum acetabular shell and multiple supplementary screws. There were 31 females. Average age at revision was 64 years (range 23–85 years). The mean and median follow up was 11 years (range 10–12 years, SD 1). Morselised femoral allograft was used in 34 hips to fill contained cavitary defectes. Bulk femoral allografting was performed in 2 hips.

At a minimum follow-up of 10 (range 10–12) years, the survivorship of the porous tantalum acetabular shell, with revision of the shell as end point was 96%. The minimum 10-year survivorship with hip revision for any reason as end point was 92%. We noted excellent pain relief (mean WOMAC pain 92.6) and good functional outcome (mean WOMAC function 90.3, mean UCLA 5); and generic quality of life measures (mean SF-12 physical component 48.3; mean SF-12 mental component 56.7). Patient satisfaction with pain relief, function and return to recreational activities were noted to be excellent.

Cementless acetabular revision with the tantalum acetabular shell demonstrated excellent clinical and quality of life outcomes at minimum 10-year follow-up. As far as we are aware this is the first report of minimum 10-year follow up of use of this technique for revision hip arthroplasty.

Revision surgery for pelvic discontinuity in the presence of bone loss is challenging. The cup-cage reconstruction option has become popular for the management of pelvic discontinuity in the recent years. The aim of this study was to review the clinical, radiological and patient reported outcomes with the use of cup cage construct for pelvic discontinuity at our institution.

Twenty-seven patients (27 cup-cage reconstructions) were identified at median 6-year (minimum 2 year, maximum 10 years) follow up. Eight were female patients. The median age was 77 years [mean 72, range 37–90, SD 13.6]. There were 5 deaths and 2 were lost to follow up.

Two patients were converted to excision arthroplasty; one for infection and one for failure of the construct. A further 3 patients required revision for instability but the cup cage construct was not revised (2 revisions of cemented cups to a constrained cup and one revision of proximal modular component of the femoral prosthesis). Revision of the cup cage construct was not necessary in any of these cases. We noted excellent pain relief (mean WOMAC pain 85.6) and good functional outcome (mean WOMAC function 78.2, mean UCLA 5, mean OHS 78.6). Patient satisfaction with regards pain relief; function and return to activities were noted to be excellent. Radiological changes were noted in further 4 patients (cup migration in one case; fracture of ischial spike in one case and breakage of the cage screws in 2 patients). No migration of the construct was noted in any of the cases.

In conclusion, the cup cage construct is an excellent method of dealing with complex pelvic discontinuity. Our study suggests a low failure rate; high patient satisfaction and pain relief and moderate functional outcome at median 6 year follow up.

Introduction

Despite advances in surgical technique and prosthetics there continues to be a number of patients who are dissatisfied with the results of their knee replacement procedure. The outcome after total knee arthroplasty (TKA) has been reported frequently with use of condition-specific measures, but patient satisfaction has not been well studied.

This single incision, anterolateral intermuscular approach (AL-IM) utilises the interval between gluteus medius and tensor fascia lata. The aims of the study were to compare the quality of life, satisfaction and complications of this approach with two of the most commonly used limited incision transmuscular (TM) approaches, namely the mini-posterior (P-TM) and the mini-direct lateral (L-TM).

One hundred and ninety-nine patients receiving MIS THA surgical procedures were evaluated prospectively (63 AL-IM, 68 P-TM and 68 L-TM). The outcome variables were WOMAC function, pain, stiffness, SF-12 (physical & mental), Oxford-12, satisfaction and radiological outcome. Parametric and non-parametric analyses were performed.

There were no significant differences between groups in baseline characteristics including age, sex, BMI, co-morbidity, or pre-op WOMAC, SF-12, Oxford-12 (p> 0.05). However, the AL-IM group was associated with superior outcomes (p< 0.05) in WOMAC function, WOMAC pain, global WOMAC, Oxford-12 and SF-12 physical component.

In the short term the AL-IM approach provides significant improvements in quality of life scores over other limited incision approaches. It provides minimal soft tissue disruption and maintains the abductor musculature and posterior soft tissue envelope, with similar complications and radiological outcomes.

Revision surgery is an important outcome of hip and knee arthroplasty among patients with osteoarthritis (OA). The objective of this study was to determine the risk of revision over time in a large, geographically defined population in North America, and to assess the effects of age, sex, and socioeconomic status (SES) on knee and hip revision rates in this population.

We used data on admissions to all acute care hospitals in British Columbia (BC), Canada (population of four million people) from 1986 until 2004 (eighteen years of follow-up). Primary knee and hip replacement surgery for OA and revision procedures were identified using diagnostic (ICD-9, ICD-10) codes and surgical procedure codes. We excluded cases admitted due to injury or neoplasm. SES was assigned based on residential address linked to census data at the level of enumeration area (ecological variable), and analyzed according to quintiles or deciles of the distribution. In the analysis, we used Kaplan-Meier survival curves to describe the risk of first revision following first primary replacement surgery over time and parametric (Weibull) survival regression models to analyze the effects of joint (hip vs. knee) age, sex, and SES on revision rates. Death, emigration, and another primary joint replacement were treated as censoring events.

Between 1986 and 2004, we observed 24,169 first primary hip replacements and 22,875 first primary knee replacements. In these patients, there were 1,313 hip revisions and 914 knee revisions following a primary replacement. The risk of revision at five, ten and fifteen years after primary replacement according to joint and sex were identified The overall risks were 10.1% for the hip and 8.7% for the knee at ten years, and 15.5% and 14.7%, respectively, at fifteen years. Risk of revision (%) following first primary joint replacement surgery Hip Knee Years Men Women Men Women 5 5.0 3.9 4.6 3.8 10 11.0 9.4 9.7 8.0 15 17.8 14.1 18.5 12.4 In a multivariate survival regression model including joint, age, sex, and SES, only age and sex were significantly associated with revisions. The hazard ratio was 1.2 for men compared with women (p< 0.0001). Revision rates were higher in younger persons, with hazard ratios increasing from 1.7 for age 70–79 (p< 0.0001) to 3.9 for age < 49 (p< 0.0001) compared with age 80+. After adjusting for age and sex, SES was not significantly associated with revision risk following primary hip or knee replacement surgery in this population (p=0.75).

This is one of the largest and longest cohort studies in North America to look at the epidemiology of revision procedures following hip and knee replacement for OA. Higher rates in men and in younger persons are consistent with previous reports. The lack of association between revision risk and SES in BC is an important finding given current concerns about socioeconomic disparities in access to and outcomes of treatment for OA.

Purpose of the study: Hip resurfacing with a metal-on-metal bearing gives good mid-term clinical results. The design of the femoral piece has an effect on implant longevity, as does the vitality of the underlying cephalic bone. Computer-assisted surgery has been helpful in position the implant but the choice of the best position is still empirical. Prosthesis designers recommend valgus, but with too much there is a risk of a superolaterl notch which would weaken the neck. This leads the surgeon to use a larger femoral implant, and consequently to resect more acetabular bone. Anteversion is not evaluated. The purpose of this study was test mechanically different valgus/varus, anteversion/retroversion positions of the femoral implant.

Material and methods: We implanted 15 femurs made of resin which were geometrically and mechanically identical. The following angles were tested: varus/valgus (−10°, neutral, +10°, +20°) and ante/retroversion (−10°, neutram, +10). A valgus notch (+20° and +10°) and a varus notch (−10°) were simulated. The femurs thus prepared were tested with Instron 8874. Load at failure was noted as well as the type of fracture: distance from the fracture line to the greater trochanter (FGT). Student’s t test was applied.

Results: All of the femurs fractured at the neck. The fracture was closer to the implant (FGT: 11.0 mm) for the 20° valgus implantation (p< 0.05). The displacement was lesser with a valgus notch (mean 2.2 mm) then without a notch (mean 3.3 mm (p< 0.05). The varus notch had no effect. The failure load was lower for 20° valgus (1236 N, range 1117–1356N) then for the other angles (1664N, range 1142–2113 N) with near statistical significance (p=0.08). Retroversion had no effect. Anteversion allowed greater displacement (4.1 mm) and supported greater loading (1879 N) before failure.

Discussion: This study, unlike clinical studies, did not demonstrate any static mechanical superiority of the valgus position for the femoral piece. Another study on cadaver bones is planned for confirmation. Clinical studies reflect the vitality of the trabecular bone supporting the implant, a vitality which could be stimulated by the valgus position.

We have evaluated the function of a trabecular metal augmentation patella to restore knee kinetics and kinematics after revision total knee arthroplasty. An “Oxford type” rig was used with fresh frozen cadaveric knees, for an active model that maximally retained the soft tissue envelope.

Investigating the force through the extensor mechanism, we found a statistically significant difference between the TKA before and after patelloplasty, which was abolished by the insertion of the augmentation patella.

Investigation patella tracking, we found a statistically significant difference between the TKA before and after patelloplasty, that was rectified by the insertion of the augmentation patella.

The purpose of this study is to evaluate the kinetic and kinematic function of a new trabecular metal augmentation patella.

Investigating the force through the extensor mechanism, we found a statistically significant difference between the TKA before and after patelloplasty, which was abolished by the insertion of the augmentation patella.

Investigation patella tracking, we found a statistically significant difference between the TKA before and after patelloplasty, that was rectified by the insertion of the augmentation patella.

This study demonstrates that the augmentation patella restorers the abnormal tracking and higher extensor mechanism forces seen after patelloplasty in revision TKA to those normal after a TKA.

The mean, maximum extensor mechanism force in extension for the TKA group as compared to the patelloplasty group (p=0.0000032), reduced to near normal with the augmentation patella (p=0.198).

The mean, maximum patella maltracking in extension for the TKA group as compared to the patelloplasty group (p=0.025), reduced to near normal with the augmentation patella (p=0.301).

Eight frozen human cadaveric knees (mean age sixty-eight years) were prepared for an “Oxford type” knee rig. Alignment ands offset were addressed and the soft tissue envelope kept as intact as possible. A load cell was introduced into the extensor mechanism. Femoral, patella and tibial motion were assessed using the Optotrak system.

Patella bone loss at revision TKA remains an unsolved problem, with the patella often too thin to accept a new prosthesis. Leaving the patella shell to articulate against the femoral component can lead to disappointing results.

Funding - Zimmer

We compare two applications of minimally invasive hip arthroplasty (MISTHA) with regards to early complication rate and consumption of health care resources. Complications are associated with both manifestations of MIS surgical technique. Two- incision MIS THA is associated with fewer days in hospital in comparison with one incision MIS THA, however requires a greater amount of operating room resources. This paper is among the first to compare two- incision with one incision MISTHA. Two- incision MISTHA may benefit efforts to reduce health resource utilization associated with hip arthroplasty procedures providing that operating room resource consumption and complication rates are not excessive.

A comparative cohort study to evaluate two-incision versus single-incision minimally invasive hip arthroplasty: assessment of early complication rate and health care resource utilization

To evaluate and compare two applications of minimally invasive hip arthroplasty (MISTHA) with regards to early complication rate and consumption of health care resources

One hundred and sixty-five patients received MISTHA from 2002–2004 at a tertiary referral hospital. Patients received two incision (sixty-six patients) or one incision surgery (ninety-nine patients) which was performed according to standard technique. T-test, chi square, fisher’s exact test were used to compare cohorts of MISTHA patients with regards to early complications and consumption of health care resources while in hospital.

At baseline the two cohorts were not different with regards to age, gender, comorbid status, BMI, and pre-operative WOMAC, Oxford-12, SF-12 (p> .05). Major and minor complication rates were similar in the two cohorts (p> .05). Utilization of operating room resources was greater with the two incision group (mean twentyfive minutes more OR time) however length of stay (mean two days less in hospital) and post-operative analgesic use was significantly reduced (p< .05). Complications and operating room resource consumption were highest early in the surgeons’ experience with these procedures.

Complications are associated with both manifestations of MIS surgical technique. Two- incision MISTHA is associated with fewer days in hospital, however requires a greater amount of operating room resources.

This paper is among the first to compare two- incision with one incision MISTHA. Two- incision MISTHA may benefit efforts to reduce health resource utilization associated with hip arthroplasty procedures providing that operating room resource consumption and complication rates are not excessive.

This study evaluated the effect of prosthetic patellar resurfacing on outcome of revision total knee arthroplasty. One hundred and twenty-six patients who underwent consecutive revision of total knee arthroplasty were identified. The status of the patella was ascertained post revision as to the presence or absence of patellar prosthesis. WOMAC, Oxford-12, SF-12 and patient satisfaction data were obtained at a minimum of two years follow-up. Follow-up was obtained in one hundred and ten patients. There was no significant difference between the two cohorts with regards to outcomes. A patellar prosthesis does not appear to significantly affect pain, function, or satisfaction outcomes following revision total knee arthroplasty.

The purpose of this study is to evaluate the effect of prosthetic patellar resurfacing on outcome of revision total knee arthroplasty in a matched cohort study.

The presence or absence of a patellar prosthesis does not appear to significantly affect pain, function, or satisfaction outcomes following revision total knee arthroplasty.

Attempting to resurface the patella in revision cases may not be worthwhile.

Follow-up was obtained in one hundred and ten patients (fifty-two with patellar component, fifty-eight bony shell), matched for age, sex and co-morbidity scores and followed for a minimum of two years. There was no significant difference between the two cohorts with regards to outcomes of WOMAC pain (mean seventy-two and sixty-five, p=0.17), WOMAC function (mean sixty-four and fifty-nine, p=0.26) scores, Oxford −12 (mean sixty-three and sixty-seven, p=0.2), SF-12 (mean forty and thirty-six, p=0.27) and satisfaction outcomes (mean eight and nine, p=0.07), (power of 0.8, beta=0.2).

From January 1997 to December 1999 one hundred and twenty-six patients who underwent consecutive revision total knee arthroplasty were identified. The status of the patella was ascertained post revision as to the presence or absence of patellar prosthesis. At a minimum of two years follow-up, pain and function were assessed by questionnaire for WOMAC, Oxford-12, SF-12 and patient satisfaction data. Co-morbidity, surgical exposure, HSS knee scores and ROM were also collected. Univariate and multivariate analyses were performed.

It is questionable whether patient’s pain, function and satisfaction are affected in revision total knee arthroplasty by patellar prosthetic resurfacing.

Funding: One or more of the authors has received funding from a commercial party. This was DePuy, Inc, Warsaw, IN.

A concern with diaphyseal-fitting cementless stems in revision total hip arthroplasty is intra-operative fractures. Two hundred and eleven patients consecutively underwent revision hip arthroplasty using Solution stems (DePuy, Warsaw, IN). Intra-operative fractures or perforations occurred in sixty-four patients (30% prevalence), with diaphyseal splits in thirty-nine patients (18% prevalence). Risk factors were pre-operative osteolysis, cortex to canal ratio, under-reaming the cortex and large diameter stems. The majority of diaphyseal linear cracks occurred at the distal end of extended trochanteric osteotomies during stem insertion. Intra-operative fracture is associated with an average two days longer length of stay (p< 0.05).

The purpose of this study was to determine the identification of the risk factors and outcomes of intra-operative fractures using a diaphyseal fitting revision stem.

There is an association of intra-operative fracture associated using a diaphyseal-fitting stem in revision total hip arthroplasty with a longer length of stay in hospital.

Identifying preoperative risk factors will allow avoidance of such fractures and prolonged hospital stay.

Intra-operative fractures or perforations occurred in sixty-four patients (30% prevalence) and thirty-nine patients (18% prevalence) sustained diaphyseal splits. Risk factors associated with intra-operative fracture were pre-operative osteolysis, a low cortex to canal ratio, under-reaming the cortex and the use of a large diameter stem. Surgical approach was not directly related to fracture occurrence but the majority of diaphyseal undisplaced linear cracks occurred at the distal end of extended trochanteric osteotomies during stem insertion. Cortical perforation occurred most often with cement removal. Duration of stay was on average two days longer (p< 0.05) for patients with an intraoperative fracture.

Two hundred and eleven patients who had undergone revision hip arthroplasty using the Solution stem (DePuy, Warsaw, IN) between December 1998 and March 2002 were identified. Patients who sustained an intra-operative fracture were compared to controls patients who underwent hip revision at the same time frame but with no fracture. Multiple factors were analyzed to see which were risk factors for intra-operative fractures.

There is a surprisingly high incidence of intra-operative fracture associated with using a diaphyseal-fitting stem in revision total hip arthroplasty. This was associated with a longer length of stay

Purpose: To examine whether neutral or valgus placement results in greater fracture strength ex vivo, when the femoral neck is notched superolaterally as sometimes occurs during hip resurfacing arthroplasty.

Methods: We loaded 10 paired fresh-frozen notched proximal cadaveric femora (8F/2M, 66 to 80 years) to failure. In each case, the right femur was implanted, using bone cement, with a machined resurfacing component aligned neutrally with respect to the femoral neck whereas the left femur was implanted at 10° valgus. The superolateral notch was 3 mm wide by 2 mm deep directly beside the component. Potted femurs were loaded to failure using an Instron materials testing machine. All 20 femora were scanned using Dual-Energy X-Ray Absorptiometry.

Results: The effect of neutral versus valgus placement was complex. (1) Two pairs slowly crushed; the remaining femurs exhibited a clear fracture. When only the fracture-type failures were analyzed, valgus placement resulted in fracture loads on average 22% higher than for neutral placement (paired t-test, p< 0.05). All femurs failed within the notch, as occurs clinically. (2) Femurs with high bone density (BMD> 0.65 g/cm2) showed a significant increase in fracture load (p< 0.05) whereas femurs with low BMD (< 0.65 g/cm2) were unaffected by component placement. BMD was highly correlated with fracture load (Pearson r=0.87, p=0.0003). (3) The greatest improvements occurred when the neck-shaft angle was relatively low, 128°–132°. (4) Two of ten femurs required larger head sizes at 10° valgus.

Conclusions: (1) Fracture load was primarily controlled by bone quality (BMD); (2) nevertheless, varus/valgus placement did affect the fracture load; (3) the magnitude and direction of this effect depended on fracture type, bone mineral density and the original neck-shaft angle; (4) for the level of bone quality typical of patients undergoing hip resurfacing, and for low-to-average neck-shaft angles (up to 132°), the fracture load for 10° valgus placement was significantly higher than for neutral placement. Funding: Other Education Grant

The purpose of this study is to evaluate the effect of prosthetic patellar resurfacing on outcome of revision total knee arthroplasty in a matched cohort study.

From January 1997 to December 1999 126 patients who underwent revision of total knee arthroplasty were identified. The status of the patella was ascertained post revision as to the presence or absence of patellar prosthesis. At a minimum of two years follow-up, pain and function were assessed by questionnaire for WOMAC, Oxford-12, SF-12 and patient satisfaction data. Co-morbidity, surgical exposure, HSS knee scores and ROM were also collected. Univariate and multivariate analysis were performed. Follow-up was obtained in 110 patients (52 with patellar component, 58 bony shell), matched for age (mean 70 and 67 years), sex and co-morbidity scores and followed for a minimum of two years. There was no significant difference between the two cohorts with regards to outcomes of WOMAC pain scores (mean 66 and 74, p=0.14), WOMAC function scores (mean 59 and 65, p=0.22), Oxford- 12 scores (mean 57 and 64, p=0.17), and satisfaction score outcomes (57 and 68, p=0.14). It remains controversial whether the patient’s pain, function and satisfaction are affected in revision total knee arthroplasty by patellar prosthetic resurfacing. Insufficient patellar bone stock may preclude prosthetic resurfacing in which case patel-loplasty is performed. From this series, the presence or absence of a patellar prosthesis does not appear to sig-nificantly affect pain, function, or satisfaction outcomes following revision total knee arthroplasty.

The prospective evaluation of two hundred and seven symptomatic total knee arthroplasties presenting for revision total knee arthroplasty is reported. On univariate analysis patients who had infection differed significantly (p< .001) from those without infection with regards to: elevated ESR, CRP, positive aspiration, and history of; revision procedure less than two years since last surgery, early wound problems, ongoing pain since index procedure, and discharging wound. On multivariate analysis elevated ESR or CRP, positive aspiration, pain since index procedure and early wound complications were significant predictors of infection (p< .05). These variables were then used to formulate an evidence-based multivariate predictive algorithm to assist the clinician in decision making prior to surgery.

Differentiating septic from aseptic failure of total knee arthroplasty on the basis of clinical features and diagnostic tests can be troublesome for the clinician. The purpose of this paper is to describe significant differences between cases of septic and aseptic failure of total knee arthroplasty. The incorporation of these variables into a practical multivariate clinical prediction algorithm can provide assistance in establishing the diagnosis of infection prior to revision knee arthroplasty.

A simple clinical prediction algorithm can assist in the diagnosis of infection in patients with painful total knee arthroplasty. Patients with five of five criteria have a 99% probability of infection whereas patients with zero of five criteria have a 1% probability of infection.

This is the first multivariate evidence-based clinical prediction algorithm presented for use in decision making prior to revision total knee arthroplasty. The surgeon can use the information derived from clinical and laboratory assessment to compute an approximate pre-operative probability of infection prior to surgery (see table).

On multivariate analysis elevated ESR or CRP, positive aspiration, pain since index procedure and early wound complications were significant predictors of infection (p< .05). These variables were then used to formulate an evidence-based multivariate predictive algorithm to assist in clinical decision making.

Prospective data was collected on two hundred and seven symptomatic knee arthroplasties presenting for revision arthroplasty. A multivariate logistic regression model was used to determine the probability of infection using five significant variables. Combinations of these five variables can provide the clinician with an estimate of the probability of infection prior to revision knee arthroplasty.

Please contact author for tables and/or charts.

Patient satisfaction is not uniform or consistent following revision total knee arthroplasty. This study evaluates ninety-nine patients with a self-administered patient satisfaction questionnaire at a minimum of two years following the revision procedure (1997–99) to determine differences between satisfied (sixty-six patients) and dissatisfied patients (thirty-three patients). Univariate analysis revealed that patients satisfied with their results were significantly different (p< .05) than dissatisfied patients with regards to post op scores including those of the WOMAC pain and function, oxford, and SF-12. Patients were not different with regards to (p> .05) age, comorbidity score, surgical approach, or sepsis as a reason for the revision procedure. Regression analysis demonstrated that gender, post-op WOMAC score, and pre-op arc of motion were significant determinants of satisfaction.

The purpose of this study is to evaluate determinants of patient satisfaction following revision total knee arthroplasty.

Patient satisfaction with revision knee surgery is most strongly associated with both pre and post-operative descriptors of knee function as well as gender.

Understanding the variables associated with satisfaction/dissatisfaction following revision knee arthroplasty may further assist ongoing research efforts to improve the outcomes of this procedure.

Univariate analysis revealed that patients satisfied with their results were significantly different (p< .05) than dissatisfied patients with regards to WOMAC pain and function score, oxford knee score, and SF-12. Patients were not different with regards to (p> .05) age, comorbidity score, surgical approach, or presence of sepsis as a reason for the revision procedure. Regression analysis demonstrated that gender, post-op WOMAC score, and pre-op arc of motion were significant determinants of satisfaction (p< .05).

A self-administered patient satisfaction survey was completed by ninety-nine patients at a minimum of two years following revision total knee arthroplasty. Fifty-nine patients were females and forty were males. Sixty-six patients were satisfied and thirty-three patients were dissatisfied with the outcome of their surgery at two years post-op. Univariate analysis and multivariate regression suggest that pre and post-operative joint function and gender are the most significant determinants of patient satisfaction

Purpose: Hip resurfacing techniques utilize mechanical jigs to align a femoral guide-pin that directs implant placement. Errors in alignment may lead to premature failure. The purpose of this study was to compare femoral guide-pin placement using a computer-assisted surgical (CAS) navigation system to a currently available manual alignment device.

Methods: A computer-assisted navigation system was developed by our group. Target guide-pin position was determined for each cadaveric hip from radiographs. A guide-pin was driven into each hip using either the CAS method or a manual alignment jig (Durom; Zimmer) by a novice or expert surgeon respectively. Radiographic pin position was compared to the target and accuracy was compared between the two techniques.

Results: Guide-pin insertion trajectory using the CAS system was significantly less variable in varus/valgus alignment than the mechanical jig (2.0° SD vs. 5.5° SD; p < 0.05). Ante/retroversion variability was also lower using CAS (4.4° SD vs. 7.7° SD) as was alignment error (CAS: 2.0° ± 2.2° SD valgus vs. Durom: 3.3° ± 5.5° SD varus, p=0.17; CAS: 0.1° ± 4.6° SD anteverted; Durom 3.2° ± 7.7° SD retroverted, p=0.48) but not significantly. Both methods proved accurate in placing the pin within 2 mm from the centre of the neck axis. Procedure time was similar between the two methods

Conclusions: Computer-assisted surgical navigation significantly improves reliability of guide-pin placement. This technique may help achieve better femoral implant alignment regardless of experience and contribute to improving hip resurfacing outcomes.

Funding : Other Education Grant

Funding Parties : Zimmer/UBC Research Fund

We have evaluated the function of a trabecular metal augmentation patella to restore knee kinetics and kinematics after revision total knee arthroplasty. An “Oxford type” rig was used with fresh frozen cadaveric knees, for an active model that maximally retained the soft tissue envelope.

Investigating the force through the extensor mechanism, we found a statistically significant difference between the TKA before and after patelloplasty, which was abolished by the insertion of the augmentation patella.

Investigation patella tracking, we found a statistically significant difference between the TKA before and after patelloplasty, that was rectified by the insertion of the augmentation patella.

The purpose of this study is to evaluate the kinetic and kinematic function of a new trabecular metal augmentation patella.

Investigating the force through the extensor mechanism, we found a statistically significant difference between the TKA before and after patelloplasty, which was abolished by the insertion of the augmentation patella.

Investigation patella tracking, we found a statistically significant difference between the TKA before and after patelloplasty, that was rectified by the insertion of the augmentation patella.

This study demonstrates that the augmentation patella restorers the abnormal tracking and higher extensor mechanism forces seen after patelloplasty in revision TKA to those normal after a TKA.

The mean, maximum extensor mechanism force in extension for the TKA group as compared to the patelloplasty group (p=0.0000032), reduced to near normal with the augmentation patella (p=0.198).

The mean, maximum patella maltracking in extension for the TKA group as compared to the patelloplasty group (p=0.025), reduced to near normal with the augmentation patella (p=0.301).

Eight frozen human cadaveric knees (mean age sixty-eight years) were prepared for an “Oxford type” knee rig. Alignment ands offset were addressed and the soft tissue envelope kept as intact as possible. A load cell was introduced into the extensor mechanism. Femoral, patella and tibial motion were assessed using the Optotrak system.

Patella bone loss at revision TKA remains an unsolved problem, with the patella often too thin to accept a new prosthesis. Leaving the patella shell to articulate against the femoral component can lead to disappointing results.

Funding - Zimmer

Purpose: To evaluate and compare patient reported quality of life and satisfaction following metal on metal hip resurfacing and total hip arthroplasty procedures.

Methods: Patients receiving metal-on-metal hip resurfacing and primary total hip arthroplasty were assessed at baseline and followed prospectively with regards to outcomes of quality of life (WOMAC, Oxford-12, SF-12) and satisfaction. Patients receiving resurfacing were matched (1:3) to a cohort of THA on characteristics of age, gender, and comorbidity status. Sample size was selected to evaluate superiority using WOMAC function score with effect size of 0.5, alpha .05, power 80%. Univariate and multivariate analyses were performed.

Results: 222 patients were evaluated with regards to baseline socio-demographic characteristics and quality of life scores(56 resurfacing, 166 THR). Patient cohorts were not different at baseline pre-operatively with regards to age, gender, comorbidity status, WOMAC, Oxford-12, and SF-12 (p> .05). At minimum one year post-op both cohorts reported excellent outcomes. Patients receiving hip resurfacing had superior outcomes with regards to WOMAC function, WOMAC pain, and Oxford-12 hip scores (p< .05). However patients were similar with regards to outcomes of SF-12 mental status and patient-reported satisfaction.

Conclusions: Hip resurfacing and THA patients report excellent outcomes, however, patients receiving hip resurfacing report superior quality of life compared to a matched cohort of THA.

Purpose: To evaluate the effect of outpatient physiotherapy versus a self-adminstered home exercise program on recovery following primary total hip arthroplasty.

Methods: Subjects awaiting primary total hip arthroplasty consented to participate in this prospective randomized clinical trial. Patients were assigned to participate in either an outpatient physiotherapy program or self-administered/self-directed home exercise program following discharge home from hospital. Multiple longitudinal measures were performed to adequately assess recovery over time. Primary outcome for comparison was WOMAC function at 4 months postoperatively, additional outcomes of timed-up-and-go, SF-36, HUI3, FSI. Primary outcome was evaluated using repeated measures analyses and regression models for longitudinal data.

Results: 100 patients were randomized to their respective interventions. The two cohorts were similar with regards to baseline characteristics of age, gender, and pre-op quality of life measures (p> .05). At 4 months post-op both groups demonstrated significant change from baseline function and were similar with regards to recovery and rate of recovery (p> .05).

Conclusions: While all patients demonstrated excellent recovery, patients receiving self-adminstered home exercise program did not demonstrate inferior outcome at the interval(s) assessed. Self-adminstered home exercise program may be an effective alternative rehabilitation program where physiotherapy services are limited or in specific subgroups of patients.

Funding : Educational Grant from the Canadian Orthopaedic Foundation

Purpose: To evaluate the benefits of standardization on the reliability of the physical examination of the hip by rheumatologists and orthopaedic surgeons

Methods: Six subjects with mild to severe hip osteoarthritis (OA) were examined by 6 examiners (4 rheumatologists, 2 orthopedic surgeons) experienced in the assessment of hip OA using a 6x6 Latin square design. Subjects were examined, followed by a standardization meeting and, a day later, by post-standardization examinations. 33 hip examination maneuvers were evaluated, including range of motion, pain, tenderness, muscle strength, leg length and gait. The order of examinations was randomized for each examiner. For dichotomous signs, agreement was calculated as the prevalence-adjusted bias-adjusted kappa (PABAK). Ordinal and continuous variables were analyzed by ANOVA, using the proportion of variance due to rheumatologists to calculate a reliability coefficient (Rc).

Results: Subjects’ mean age was 61 years (range 49–65), mean BMI was 24 (range 21–30), mean WOMAC pain on walking was 52 mm (range 21–81mm). 23/33 (70%) hip examinations were reliable after standardization. Two new items resulted from the standardization meeting. Pre-/post-standardization reliability for select hip examinations using PABAK were as follows: Gait 0.06/0.52; pain on internal rotation 0.60/0.52; pain on external rotation 0.24/0.72; pain on flexion 0.46/0.82; Patrick test for hip pain 0.78/0.80; Thomas test 0.60/0.88; Trendelenburg test 0.36/0.06. Pre-/post-standardization reliability for select hip examinations using Rc were as follows: hip flexion strength 0.83/0.95; hip abduction strength 0.90/0.86; hip adduction strength 0.87/0.86; ROM internal rotation (supine) 0.87/0.94; ROM external rotation (supine) 0.87/0.80.

Conclusions: Moderate to very good agreement was present for many hip examinations prior to standardization. Improved reliability was achieved after standardization for many but not all hip assessments. This will be important for improved outcome studies of early hip OA.

The two most common surgical approaches used in primary hip arthroplasty are the anterolateral and posterolateral approach. While both approaches have potential advantages and disadvantages in comparison to the other, there are no reports with sufficient power to compare their effect on post-operative function and quality of life. This prospective cohort study evaluates and compares the independent effect of surgical approach on function and quality of life among patients who have received their total hip arthroplasty through one of these techniques. Results suggest that there is no significant difference in function or quality of life among these respective cohorts.

The purpose of this study was to evaluate and compare the effect of anterolateral versus posterolateral approach on function and quality of life following primary total hip arthroplasty.

There is no significant difference in outcome as a result of surgical approach. Significance: This is the first report with sufficient power to evaluate and compare outcomes of these two approaches among high volume hip surgeons. This study suggests that surgeons need not worry that the anterolateral or posterolateral approach may compromise patient function or generic quality of life more-so than the alternative approach.

Univariate and regression analyses demonstrate similar outcomes on WOMAC, Oxford-12, SF-12 and satisfaction among cohorts of patients receiving the anterolateral or posterolateral approach for primary total hip arthroplasty.

A prospective evaluation of function and quality of life outcomes was performed on patients receiving the anterolateral or posterolateral approach for primary hip arthroplasty. All participating surgeons were considered to be high volume arthroplasty surgeons. One hundred and sixty procedures were followed and provided complete outcomes data including WOMAC, Oxford, SF-12, and satisfaction scores. Univariate analyses demonstrated no differences among the two cohorts with regards to baseline variables. Regression analyses were performed for the outcome measures with surgical approach treated as an independent covariate while controlling for other potential confounders. The results suggest that there is no independent effect of surgical approach on patient reported outcomes. This suggests that the surgeon should continue to employ the approach which is the most familiar and most likely to result in consistent results in their clinical environment.

Purpose To evaluate the kinetic and kinematic function of a new trabecular metal augmentation patella.

Method Eight frozen human cadaveric knees (mean age 68 years) were prepared for an “Oxford type” knee rig. Alignment ands offset were addressed and the soft tissue envelope kept as intact as possible. A load cell was introduced into the extensor mechanism. Femoral, patella and tibial motion were assessed using the Optotrak system.

Summary of Results The mean, maximum extensor mechanism force in extension for the TKA group as compared to the patelloplasty group (p=0.0000032), reduced to near normal with the augmentation patella (p=0.198).

The mean, maximum patella maltracking in extension for the TKA group as compared to the patelloplasty group (p=0.025), reduced to near normal with the augmentation patella (p=0.301).

Conclusion Investigating the force through the extensor mechanism, we found a statistically significant difference between the TKA before and after patelloplasty, which was abolished by the insertion of the augmentation patella.

Investigation patella tracking, we found a statistically significant difference between the TKA before and after patelloplasty, that was rectified by the insertion of the augmentation patella.