Reports of improved functional outcome of Metal on Metal Hip Resurfacing Arthroplasty (mHRA) to Total Hip Replacement needs to be balanced with concerns of metal ion release. By removing cobalt-chrome, cHRA reduces these risks. To the author's knowledge, there is no data available on functional outcomes of cHRA, therefore the aim of the study was to compare the function between cHRA patients and mHRA patients. 24 patients received a unilateral cHRA (H1, Embody) and was compared to 24 age and gender matched patients with a unilateral mHRA (BHR, Smith and Nephew). All patients completed the Oxford Hip Score (OHS)[T2] and underwent gait analysis on an instrumented treadmill before and at a mean of 74wks (+/− 10) for mHRA and 53wks (+/− 2) for cHRA post op. Walking trials started at 4km/h and increased in 0.5km/h increments until a top walking speed (TWS) was achieved. Vertical ground reaction forces (GRF) were recorded along with the symmetry index (SI). Spatiotemporal measures of gait were also recorded. Vertical GRF were captured for the entire normalised stance phase using statistical parametric mapping (SPM; CI = 95%). The gain in OHS was similar: H1 (25-46), BHR(27-47). TWS increased by 19% with H1 (6.02 – 8.0km/hr), and 20% with BHR (6.02 – 7.37km/hr). SPM of the entire gait cycle illustrated the restoration of symmetry in both groups with no difference in GRF across the stance phase between groups at 5km/hr pre-op and post-op. At faster speeds (6.5km/hr), H1 patients had a mid-support GRF slightly closer to normal compared to BHR. Both groups increased step length similar from pre to post op (H1:0.76 – 0.85cm, BHR:0.77-0.86cm). In this study, subjective and objective functional outcome measures suggest that short term functional outcomes of ceramic resurfacing is not inferior to metal resurfacing

Purpose. This study was performed to evaluate clinical and radiographic outcomes of Hip Resurfacing Arthroplasty for treatment of haemophilic hip arthropathy. Material & Method. Between 2002 and 2013, 17 cases of hip resurfacing arthroplasties were performed in 16 haemophilic patients (13 cases of haemophilia A, 2 cases of haemophilia B, 2 cases of von Willebrand disease). The average age of the patients was 32.5(range: 18∼52) years. The average follow up period from the operation was 6.3 (range: 2∼13) years. In this study, the subjects that completed follow-up were composed of 5 cases composed of patients who were treated with Conserve plus. ®. hip resurfacing system, 5 cases composed of patients who were treated with Durom. ®. hip resurfacing system, 4 cases who were treated with ASR. ®. hip resurfacing system, and 3 cases who were treated with Birmingham. ®. hip resurfacing system. The Modified Harris hip score, the range of motion of the hip joint, perioperative coagulation factor requirements and complications associated with bleeding were evaluated as part of the clinical assessment. For the radiographic assessment, fixation of component, presence of femoral neck fracture, osteolysis, loosening and other complications were evaluated. Results. The modified Harris hip score improved from 65.4(47–80) points before surgery to 97.8(90–100) points at the last follow-up. The average further flexion improved from 103° (70–135) to 110°(80–130) after surgery. The average abduction improved from 22.4° (0–45) to 41.3° (20–50) after surgery. All the patients showed a significant reduction in pain. The mean requirement of factor VIII reduced from 2470 units per month before surgery to 1125 units per month at the time of the last follow-up. However, in the case of high-titer inhibitor to factor VIII, haemophilia B, von Willebrand disease, the average monthly factor requirement was not changed due to bleeding episode of other joints. There was two cases of re-bleeding. There were no femoral neck fracture, no osteolysis, and no implant loosening in last follow up. Conclusion. Hip resurfacing arthroplasty for haemophilic hip arthropathy in patients with mild deformity or relatively preserved range of the hip joint motion can bring reliable pain relief, functional improvement, and reduction of factor requirement for over two years follow-up study. However, bleeding-associated complications are a cause for concern, especially for patients with antibodies against coagulation factors

Humeral resurfacing arthroplasty has been advocated as an alternative to stemmed humeral component designs given its ability to preserve proximal bone stock. Further, these implants have become more attractive given the possibility of stem-related complications including humeral fracture, stress shielding, and osteolysis; complications that may necessitate fixation, revision to long stem components, or reverse total shoulder arthroplasty. As more total shoulder arthroplasties are performed in younger patient populations, the likelihood of increased revision procedures is inevitable. Maintaining proximal bone stock in these cases with use of a resurfacing arthroplasty not only facilitates explant during revision arthroplasty, but preservation of proximal metaphyseal bone facilitates reimplantation of components. Clinical results of these resurfacing components have demonstrated favorable results similar to stemmed designs. Unfortunately, resurfacing arthroplasty may not be as ideal as was hoped with regard to recreating native humeral anatomy. Further, resurfacing arthroplasty may increase the risk of peri-prosthetic humeral fracture, and lack of a formal humeral head cut makes glenoid exposure more difficult, which may be associated with a higher degree of neurovascular injury. Stemless humeral components are designed for strong metaphyseal fixation and avoid the difficulty with glenoid exposure seen in resurfacing designs, as these components require a formal humeral head cut. Early clinical outcomes of a single stemless design demonstrated significant improvements in clinical outcome scores, without evidence of component migration, subsidence or loosening. The only mid-term clinical results of stemless design implants are seen with the Arthrex Eclipse system (Arthrex, Naples, FL). In a prospective study involving 78 patients at 5-year follow-up, significant improvements were observed in clinical outcome scores. While there was evidence of proximal stress shielding in an older population, this did not influence shoulder function. The overall revision rate was 9% at 5 years, with no component necessitating revision as a result of humeral component loosening. Resurfacing arthroplasty and stemless humeral components in total shoulder arthroplasty remain attractive options to preserve proximal metaphyseal bone stock, avoiding stem-related complications. Early and mid-term clinical outcomes are comparable to stemmed designs and demonstrate no evidence of humeral component loosening

Aim: The aim of this study was to assess the role of Hip Arthroscopy in the patient with a symptomatic Resurfacing arthroplasty of the hip. Patients and Methods: Twelve consecutive patients who presented to our clinic with a painful resurfacing and indeterminate or normal investigations underwent an arthroscopy of their resurfacing were prospectively enrolled into the study following appropriate consent. The pre-operative investigations included haematological indices and acute phase reactants to rule out infection along with plain radiographs and an isotope bone scan. Results: (table deleted). Conclusions: Assessment of a symptomatic resurfacing is usually difficult and becomes more challenging in the background of normal or indeterminate investigations. However, in this situation, we found that in experienced hands, hip arthroscopy can be utilised as an effective tool for aiding diagnosis and offering therapeutic interventions in these patients

Introduction: The suitability of third generation metal-on-metal hip resurfacing for patients with a primary diagnosis of osteonecrosis (ON) has been debated. The preservation of femoral head bone stock for femoral prosthetic support is essential for long term stability of the implant. We hypothesized that the Kaplan-Meier survival estimates for resurfacing patients with a primary diagnosis of ON would be significantly lower than the survival estimates for resurfacing patients with a primary diagnosis of osteoarthritis (OA). Methods: One thousand one hundred and forty-eight patients were implanted with a modern hip resurfacing system as part of a United States multi-center investigational device exemption (IDE) study. Of these, 116 subjects had a preoperative diagnosis of ON. A multivariate analysis of variance was performed to identify risk factors for component revision for any reason. Results: A diagnosis other than OA was found to be one significant risk factor for revision. However, the survival estimates were not significantly different (95.9% and 95.8% at 24 months for OA and ON, respectively, p=0.46) when comparing the OA group to the ON group. Comparing only the Ficat stage III and IV to the OA population also did not show a significant difference in implant survival (95.9% OA and 96.1% ON III/IV at 24 months, p=0.57). Discussion: Resurfacing arthroplasty for patients with ON appears to be a reasonable alternative using judgments of implant size, patient gender, and size of proximal femoral deficiency. Further characterization will be needed to identify those specific patients with ON for whom resurfacing arthroplasty is not appropriate. For most patients, however, it appears to be a safe and reasonable option

The Birmingham reSurfacing Arthroplasty (BSA) is a metal on metal prosthesis with no published independent clinical studies. Despite this, it is increasing in popularity, especially as an alternative to stemmed prostheses in younger patients. This study presents the 1year migration results of the BSA femoral component using Roentgen Stereophotogrammteric Analysis (RSA). Twenty six subjects underwent a BSA, through the postero-lateral approach using CMW3G cement, with RSA marker balls placed intra-operatively. The femoral component migration was measured at intervals of 3, 6 and 12 months using the Oxford RSA system. Geometric algorhythms were used to identify the femoral component. The data was examined for distribution prior to analysis. All statistical analysis was performed using the t-test. The data was normally distributed. The 1 year migration results of the BSA femoral component are displayed below. All cemented implants migrate in vivo. The majority of cemented stemmed implant migration occurs within the first post-operative year. High rates of migration within the first post-operative year correlate with premature component failure in some instances. The BSA is a fundamentally different design to most cemented prostheses, despite this we know that very large migrations, those in excess of 2mm/year in any direction are generally regarded as poor indicators of long term outcome. These results suggest that the BSA femoral component is an inherently stable device as it does not migrate significantly within the first post-operative year. Only long-term independent clinical studies and continued RSA follow-up will enable a comprehensive evaluation of the device

Resurfacing arthroplasty of the hip is a relatively new procedure. This paper reports the technical and clinical problems one surgeon encountered in the first 50 consecutive resurfacing arthroplasties of the hip. The mean age of the 14 women and 32 men at the time of surgery was 44.8 years (20 to 65). Four patients underwent bilateral arthroplasty. Technical problems included failure of the acetabular component to seat fully in six hips and failure of the femoral component to seat fully in four. There was varus malalignment of the femoral component in three cases, retention of the alignment pin in one, and retention of a cable fragment in one. Surgical complications included one case of intra-operative femoral neck fracture, one transection of the psoas tendon during capsulotomy, and a femoral nerve palsy, which recovered after six months. Postoperative problems included superficial wound inflammation in five hips and one dislocation. There were radiological signs of impingement of the femoral neck on the acetabular rim in four cases and clinical symptoms of impingement in one. An undisplaced fracture of the femoral neck that occurred eight weeks after surgery was successfully managed conservatively by keeping the limb non-weight-bearing. Despite these problems, only one patient retains any noteworthy symptoms, apparently due to impingement of the femoral neck on the acetabular rim. Modest malalignment or seating failure appears to be of minimal clinical consequence. Patients typically mobilise rapidly and are able to return to a high level of physical activity. It is possible to avoid most technical problems by taking specific precautions

Introduction: Resurfacing arthroplasty of the hip joint has advantages of minimal bone resection, restoration of normal anatomy, and biomechanical circumstances. This study was undertaken to analyze the clinical and radiographic results of the resurfacing arthroplasty in patients with osteonecrosis of the femoral head (ONFH). Materials and Methods: Between September 1998 and September 2001, 40 hips in 39 patients with ONFH had a resurfacing arthroplasty with the Birmingham Hip Resurfacing (BHR) system. The mean age at the time of operation was 38.3 years. The average follow-up period was 36.8 months after operation. The patients were clinically evaluated by hip pain, Harris hip scores, range of motion, and radiographically evaluated for wear, change of cup position, loosening, and osteolysis. Results: The preoperative Harris hip score averaged 70.4 points and the degrees of flexion and internal rotation were 94° and 8°, respectively. The average Harris hip score at the last follow-up was 95.4 points. The degrees of flexion and internal rotation at last follow-up were 120°, and 20°, respectively. No patient complained of limb length discrepancy or pain in the hip or thigh. Rehabilitation programs and return to normal activities were earlier than that of conventional total hip arthroplasty (THA). There was no osteolysis, change of cup position, loosening, or detectable wear on the latest radiographic evaluation. Conclusions: Our experience with resurfacing arthroplasty for ONFH indicates that the overall results are superior than conventional THA with respect to pain relief, range of hip motion, earlier rehabilitation, and early return to preoperative activity. This procedure with BHR could be an alternative between joint preserving procedure and conventional THA in ONFH especially in younger patients

Purpose: A multicenter prospective evaluation of the Conserve Plus resurfacing implant (Wright Medical Technology) was undertaken to assess clinical and radiographic outcomes as well as ion levels. This study focuses on the serum, erythrocyte and urinary levels of cobalt and chromium in those patients undergoing hip resurfacing arthroplasty. Methods: A subset of patients enrolled in a multicenter trial to assess hip resurfacing arthroplasty had serum, erythrocyte and urinary cobalt and chromium levels measured. Levels were assessed preoperatively, then at three months, six months then yearly thereafter. Clinical outcome measurements were performed with WOMAC and Rand questionnaires. Results: Fifty-four out of 124 patients enrolled in the overall study had cobalt and chromium ion assessments performed. During the first year there was an increase in serum cobalt levels from 1.4 ug/l at 3 months to 2.4 ug/l at one year. Serum chromium levels increased from 1.4 ug/l at 3 months to 3.5 ug/l at one year. Erythrocyte cobalt levels increased from 0.8 ug/l at 3 months to 1.4 ug/l at one year. Erythrocyte chromium levels decreased from 1.5 ug/l at 3 months to 1.4 ug/l at one year. Urinary levels for cobalt increased from 12.7 ug/l at 3 months to 13.8 ug/l at one year. Urinary chromium levels rose from 4.0 ug/l at 3 months to 5.1 ug/l at one year. Conclusions: Increasing ion levels were seen during the first year post hip resurfacing arthroplasty. Clinical outcomes demonstrate predictable improvements in pain and function consistent with hip replacement surgery. Resurfacing arthroplasty is a viable option to total hip arthroplasty for younger active patients. The clinical significance of increased cobalt and chromium ions remains unknown. Funding: Commerical funding Funding Parties: Wright Medical Technology Inc

Purpose of study: We report the results of a prospective case series of 10 patients who developed tumour-like masses following resurfacing arthroplasty. Method: Ten subjects were referred to the tumour service at the Nuffield Orthopaedic Centre with symptomatic masses around the hip, all had previously received a resurfacing arthroplasty. We report the clinical, radiographic and histologic features of these cases. Results: MRI and ultrasound scanning was preformed, which demonstrated masses with solid and cystic components. Biopsy was performed and subsequent histological examination revealed a profound plasma-cell lymphocytic response associated with metal wear debris. There were no infections in this series. Three subjects required revision surgery. Conclusion: Over 50,000 resurfacing arthroplasties have been implanted worldwide over the past ten years. Although the early clinical results are encouraging little is known about the long term consequences of large head metal on metal bearing surfaces. Despite this, these devices are being widely marketed and are often implanted in younger patients. Resurfacing arthroplasties are associated with high serum and urine metal ion concentrations, metal particles have also been shown to migrate along the lymphatic system. In addition, there is now evidence that high local metal ion concentrations can induce haempoietic cancers. This study suggests that resurfacing arthoplasty can also induce a local hypersensitivity reaction in response to metal wear debris. It therefore raises new concerns regarding the long-term safety of this procedure

Aim: We present the outcome of Birmingham Hip Resurfacing Arthroplasty performed by a single surgeon after at least five years follow up. Patients and Methods: One hundred hips in 84 patients were studied with a mean follow-up of 6.4 years (5–8.3 years), performed by a single surgeon. Three patients died of unrelated causes and 2 patients were lost to follow-up, hence the study group comprised of 79 patients with 95 hips. Birmingham resurfacing femoral and acetabular components were used in all patients. The clinical outcome was measured using Harris, Charnley, Oxford hip scores and quality of life using SF-36. Radiographs were systematically analysed for implant position, fixation, and loosening. Results: The mean age was 54 years (20–74years) and BMI of 28 (19–35). Primary osteoarthritis was seen in 69 hips. Six patients (6.1%) underwent revision of the femoral component (3 for peri-prosthetic fractures of the neck of femur, 2 for deep infection and 1 for collapse due to AVN). None of the patients had evidence of loosening around the acetabular component and femoral components in 28 patients. Type 1 pedestal sign was seen in 61 hips and Type 2 in 2 hips. The clinical scores were respectively, Harris 85 (25–100), Oxford 21.5 (12–52), mean Charnley score 4.8 for pain, 5.3 for movement and 4.3 for mobility; the mean SF-36 score were 44 (12–58) for the physical and 51.4 (19–71) for the mental component. With an end point of definite or probable aseptic loosening, the probability of survival at 5 years was 100% and 97.3% (95% CI = 2.9) for acetabular and femoral components respectively. Overall survival at 5years with removal or repeat revision of either component for any reason as the end point was 91% (95% CI: 82 to 97%). Conclusion: The results of this study support the continued use of Birmingham Hip Resurfacing Arthroplasty in young active individuals. As loosening can occur as a late phenomenon, a longer follow up is needed to determine longevity, durability of this prosthesis

Introduction. Hip Resurfacing Arthroplasty (HRA) has been performed in the United States for over 10 years and is an alternative to standard Total Hip Arthropastly (THA). It is appealing to younger patients with end stage osteoarthritis who seek to maintain active lifestyles. Benefits of HRA versus THR include a larger femoral ball size, potential to return to impact activities, decreased dislocation rates, and restoration of normal hip biomechanics. Patients ≤50 years old are a particularly challenging patient group to treat with THA because of their young age and high activity level, and as such, are well-suited for HRA. However, there are limited reports in the literature about clinical, radiographic and functional outcomes for this patient cohort. We present results of a clinical investigation at our institution for this patient cohort with minimum 5-year follow up, including long term survivorship and outcome scores. Methods. HRA, using the Birmingham Hip Resurfacing (BHR), was performed for 538 procedures between 2006–2009 by a single surgeon at a United States teaching hospital. After Institutional Review Board approval, medical and radiographic study records were retrospectively reviewed. Harris Hip Scores (HHS) were routinely collected. Patients who had not returned for follow-up examination were contacted by telephone for information pertaining to their status and implant, and a modified HHS was also administered. A Kaplan Meier survival curve was constructed to evaluate time to revision. Statistical analysis was performed (SAS version 9.3; SAS Institute, Cary, NC). Results. Of the 538 patients who underwent HRA from 2006–2009, 238 were aged ≤50 years (44%). Five-year follow up data was obtained from 209 of these patients (88%), using medical record documentation, and telephone survey as needed. The mean follow-up for all patients was 6 years (range 5–8 years). A total of 3% (8/238) were revised. Reasons included: (i) femoral loosening in 4, (ii) Iliopsoas impingement in 1, (iii) metallosis/adverse tissue reaction in 1, (iv) femoral neck fracture following motor vehicle accident in 1, and (v) unknown reasons in 1. Of the 238 patients, 55 (23%) were female, 2 (2/55; 3.6%) of whom have since undergone revision surgery for either metallosis/adverse tissue reaction, or unknown reasons. Of the 53 women who retained their BHR at 5-year follow up, the average HHS was 96.5. Of the 238 patients, 183 (77%) were male patients, 6 (6/183; 3.2%) of whom have since undergone revision surgery for femoral component loosening, iliopsoas impingement, or femoral neck fracture sustained in a motor vehicle accident. At 5-year follow-up, 177 male patients retained their implant and had an average Harris Hip Score of 98.8. The overall implant survival was 96.6% at approximately 5 years. Conclusion. In our cohort of patients aged ≤50 treated with BHR [Fig. 1], our results demonstrated 5-year survivorship of 96.6%, with average HHS of 98.8 in males and 96.5 in females. This study demonstrates HRA is a successful alternative to traditional THA in a challenging cohort of younger, active patients

Introduction. There is no consensus on the ideal management of young, active patients with disabling coxarthrosis. Within this group, patients with femoral head defects secondary to cysts or avascular necrosis pose particular challenges. Resurfacing arthroplasty is contraindicated and the results of traditional total hip arthroplasty are suboptimal in this group. The BMHR was designed to offer a bone conserving option for these patients. We report the outcome of this device in the short term. Methods. This prospective study examines the clinical and radiological outcome of a consecutive series of patients treated with the BMHR arthroplasty. All patients had femoral head defects and disabling hip pain. Patients were reviewed pre operatively and then at 6 weeks, 12 weeks, and 1year post operatively and then yearly. Oxford, Harris and WOMAC hip scores were calculated at each review. Radiological assessment was also performed at each follow up. Results. Forty one patients were included (28 males, 13 females). Average age was 48.0 years (3.8 to 65.1 years). All patients participated in 2 or more sporting activities. Average follow up was 12 months (3–19). Pre and post operative OHS, HHS and WOMAC scores were 34, 46 and 42 and 18, 91 and 6 respectively (p< 0.0001 in all cases). There were no complaints of pain or reduced function at last follow up and there were no revisions or pending revisions up to last follow up. All components were well fixed radiographically. Discussion. The BMHR arthroplasty has shown good early results in treatment of young, active patients with femoral head defects. It seems to offer a resurfacing option in this group with the inherent benefits of improved stability and while allowing preservation of femoral bone stock. There is also the potential for a technically less demanding future revision on the femoral side

Aims: Resurfacing arthroplasty of the hip is increasing in popularity. Recently concerns have been raised about resorbtion of the femoral neck after hip resurfacing, which may increase the risk of femoral neck fracture. We conducted a study to assess the degree of femoral neck resorbtion after using a cemented femoral component at hip resurfacing arthroplasty and to compare this with an uncemented femoral component. Patients and Methods: We included 130 patients who had undergone a hip resurfacing arthroplasty in our study. Our uncemented group included 70 consecutive patients who had received an uncemented Cormet hip resurfacing arthroplasty (Corin, Cirencester, UK). Our cemented group included 60 patients who had received a cemented Birmingham hip resurfacing arthroplasty (Smith and Nephew, Cambridge, UK). All patients were regularly followed up for a minimum of two years. Clinical outcome was assessed using Harris hip scores. Femoral neck resorbtion was assessed by measuring the cup-neck ratio on post-operative radiographs by two independent observers. Results: The mean age of the patients was 50.7 years for the cemented resurfacing group and 51.5 years for the uncemented resurfacing group. No difference was found in Harris hip scores between the two groups at any of the follow-up periods. The overall survival rate at two years was 100% for the cemented group and 98.6% for the uncemented group. There was however, a significant increase in femoral neck resorbtion for the cemented resurfacing group compared to the uncemented resurfacing group (median cup-neck ratio 1.11 vs. 1.04), p< 0.0001. Conclusion: We found a significant increase in femoral neck resorbtion with the use of a cemented femoral component at hip resurfacing arthroplasty compared with an uncemented femoral component. This may increase the risk of femoral neck fracture and could affect the long-term outcome if a cemented femoral component is used

Purpose: Resurfacing arthroplasty (RA) is becoming popular as an alternative to total hip arthroplasty (THA). Direct to consumer advertising reports good to excellent outcomes and patients sometimes seek RA on the assumption that it provides increased survivorship over THA. We report the 5 year survivorship of 25 RA procedures done at one institution. Method: 25 patients were prospectively followed after receiving a Conserve Plus RA through a direct lateral approach between 2002 and 2005. There were 22 males and 3 females with an mean age at surgery of 42 years. The average length of follow-up was 40 months. Failure was defined as revision of the components or a pending revision. Results: At a mean of 2 years follow-up, 3 patients had been revised and 2 more were scheduled for revision surgery for a failure rate of 20%. Reasons for revision included 1 neck fracture and 2 aseptically loose acetabular components. The 2 patients waiting for revision also had aseptically loose acetabular components. Patients receiving or requiring revision were operated on throughout the series and were not necessarily part of the surgical learning curve. Conclusion: RA of the hip done through a direct lateral approach in this series had an unacceptably high failure rate for aseptic loosening of the acetabular component

A ceramic-on-ceramic hip resurfacing implant (cHRA) was developed and introduced in an MHRA-approved clinical investigation to provide a non metallic alternative hip resurfacing product. This study aimed to examine function and physical activity levels of patients with a cHRA implant using subjective and objective measures both before and 12 months following surgery in comparison with age and gender matched healthy controls.

Eighty-two unilateral cHRA patients consented to this study as part of a larger prospective, non-randomised, clinical investigation. In addition to their patient reported outcome measures (PROMs), self- reported measures of physical activity levels and gait analysis were undertaken both pre- operatively (1.5 weeks) and post operatively (52 weeks). This data was then compared to data from a group of 43 age gender and BMI matched group of healthy controls. Kinetics and kinematics were recorded using an instrumented treadmill and 3D Motion Capture. Statistical parametric mapping was used for analysis.

cHRA improved the median Harris Hip Score from 63 to 100, Oxford Hip score from 27 to 48 and the MET from 5.7 to 10.3. cHRA improved top walking speed (5.75km vs 7.27km/hr), achieved a more symmetrical ground reaction force profile, (Symmetry Index value: 10.6% vs 0.9%) and increased hip range of motion (ROM) (31.7° vs 45.9°). Postoperative data was not statistically distinguishable from the healthy controls in any domain.

This gait study sought to document the function of a novel ceramic hip resurfacing, using those features of gait commonly used to describe the shortcomings of hip arthroplasty. These features were captured before and 12 months following surgery. Preoperatively the gait patterns were typical for OA patients, while at 1 year postoperatively, this selected group of patients had gait patterns that were hard to distinguish from healthy controls despite an extended posterior approach. Applications for regulatory approval have been submitted.

Introduction: Preliminary results of the Birmingham Hip Resurfacing Arthroplasty were promising. The first series with minimum 5 year follow up was published in 2005 and came from the designing centre. Survivorship and functional results were good. This is the first series with a minimum 5 year follow up not from the designing centre. Methods: All patients who underwent BHR between the dates of October 1999 and May 2002 were included in the study. Results: We report 114 of 117 (97% follow up) consecutive metal-on-metal hip resurfacings in 105 patients with a minimum of 5 years follow up. Revision of either the femoral or acetabular component during the study period is defined as failure. We had 4 failures giving a survivorship at 5 years of 96.5% (95% confidence interval (CI) 93–100). The mean follow up was 72 months and the mean age at implantation was 54.5 years old (Range 35–75). All patients were followed up clinically and radiographically. The mean Harris hip score at follow up was 96.4. The mean Oxford Hip Score fell from 41.6 preoperatively (Range 16–57) to 15.3 postoperatively (Range 12–49) p< 0.0001. The UCLA Activity Scale rose from 3.93 preoperatively (Range 1–10) to 7.54 postoperatively (Range 4–10) p< 0.001. Radiographic analysis revealed an average stem shaft angle of 130.6 degrees (Range 112–148) with average cup alignment of 36 degrees (Range 22–47). Neck thinning was present in 16 hips (14%) and we define a technique for measuring thinning. Discussion: This study confirms that metal-on-metal resurfacing produces an excellent clinical and functional outcome in the younger patient who requires surgical intervention for hip disease. The results compare favourably with those from the originating centre and confirm that resurfacing is well suited for younger higher demand patients

In 1997 the Birmingham Hip Resurfacing was introduced to address the needs of young active patients. Alternative designs were introduced to try and improve wear performance. The aim of this study was a comparative cohort study of two types of metal-on-metal bearing to determine the mechanism of failure at 15 years.

The study reviewed 91 Brimingham Hip Resurfacings (BHR) (Smith and Nephew) and 715 DUROM hip resurfacing (Zimmer) procedures in prior to 2009. Failure was defined as revision of either component for any reason. Kaplan-Meyer survivorship analysis performed. Routine follow-up with serum metal ion levels and radiographs.

Mean follow-up was 17.9 years (range 15.2 – 25.1). The mean age at operation was 51.6 years (SD 8.6, range 20.7 to 70.2), including 299 women (37.1%). The Birmingham resurfacing demonstrated 92.3% survivorship at 15 years (SE 2.8, 95% CI 3.9 – 7.8) and 90.0% at latest follow-up (SE 3.5, 95% CI 4.9 to 9.4). By comparison, the DUROM survivorship at 15 years was 89.1% at 15 years (SE 1.2, 95% CI 2.0 to 2.5) and 87.4% (SE 1.3, 95% CI 2.5 to 2.3) at latest follow-up. There was no statistically significant difference in survivorship between groups (p= 0.32). Survival in male patients was 92.7% compared to 80.0% in females. The reported failures occurred from Adverse Reaction to Metal Debris (32 patients), periprosthetic femoral neck fracture (6) and aseptic loosening (41), PJI (12) and undiagnosed pain (6). The mean cobalt and chromium levels at last follow-up were 33.4 nmol/L and 36.5 nmol/L respectively.

This study demonstrates two differently designed metal-on-metal hip resurfacing provided a durable alternative to total hip replacement, particularly in younger male patients with osteoarthritis. Differences in design did determine the reason for revision with acetabular fixation being one of the principal failure mechanisms for the DUROM compared to elevated ion levels.

Iliopsoas tendonitis occurs in up to 30% of patients after hip resurfacing arthroplasty (HRA) and is a common reason for revision. The primary purpose of this study was to validate our novel computational model for quantifying iliopsoas impingement in HRA patients using a case-controlled investigation. Secondary purpose was to compare these results with previously measured THA patients.

We conducted a retrospective search in an experienced surgeon's database for HRA patients with iliopsoas tendonitis, confirmed via the active hip flexion test in supine, and control patients without iliopsoas tendonitis, resulting in two cohorts of 12 patients. The CT scans were segmented, landmarked, and used to simulate the iliopsoas impingement in supine and standing pelvic positions. Three discrete impingement values were output for each pelvic position, and the mean and maximum of these values were reported. Cup prominence was measured using a novel, nearest-neighbour algorithm.

The mean cup prominence for the symptomatic cohort was 10.7mm and 5.1mm for the asymptomatic cohort (p << 0.01). The average standing mean impingement for the symptomatic cohort was 0.1mm and 0.0mm for the asymptomatic cohort (p << 0.01). The average standing maximum impingement for the symptomatic cohort was 0.2mm and 0.0mm for the asymptomatic cohort (p << 0.01). Impingement significantly predicted the probability of pain in logistic regression models and the simulation had a sensitivity of 92%, specificity of 91%, and an AUC ROC curve of 0.95.

Using a case-controlled investigation, we demonstrated that our novel simulation could detect iliopsoas impingement and differentiate between the symptomatic and asymptomatic cohorts. Interestingly, the HRA patients demonstrated less impingement than the THA patients, despite greater cup prominence. In conclusion, this tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis.

Abstract