Metal-on-metal hip resurfacing in osteonecrosis of the femoral head

Outcomes of Birmingham Hip Resurfacing Based on Clinical Aspects and Retrieval Analysis of Failed Prosthesis

This research aims to identify the prevalence of failure for Birmingham Hip Prosthesis (BHR) in total hip arthroplasty and to analyze its reasons from biomaterials and biofunctional perspectives. We present our current analysis and tests on a series of different BHR-retrieved prostheses after premature failure. Relevant clinical data, such as X-ray investigations and intraoperative images for clinical case studies, were analyzed to better understand all factors involved in BHR prosthesis failure. A detailed analysis of the failures highlighted uneven cement distribution, overloading in certain areas, and void formation in the material. A closer investigation using microscopical techniques revealed the presence of a crack originating from the gap between the cement mantle and human bone. Additionally, scanning electron microscopy analyses were conducted as part of the investigation to examine bone cement morphology in detail and better understand the interactions at the interfaces between implant, cement, and bone. In conclusion, this research emphasizes the importance of surgical technique planning and the cementation procedure in the success rate of BHR prostheses. It also underscores the need to carefully evaluate patient characteristics and bone quality to minimize the risk of BHR prosthesis failure. The cementation procedure seems to be essential for the long-term functionality of the BHR prosthesis.

Effect of surgical treatment on the quality of life in patients with non-traumatic avascular necrosis of the femoral head

Objective

Avascular necrosis of the hip is a common debilitating disease during the fourth and fifth decades of life. This study attempted to evaluate quality of life in patients with avascular necrosis of the hip joint before and after surgery.

Methods

In this study, 40 patients with avascular necrosis of the hip who underwent total hip arthroplasty, bipolar surgery, or cord compression were examined during 2006–2013. Harris Hip Score was used to assess the hip joint function and quality of life before and after surgery. The mean scores and standard deviation were used to describe data for quantitative variables, while frequency percentage was used to describe qualitative variables. Data were analyzed through SPSS v.19 and paired t-test. p < 0.05 was considered significant.

Results

This study involved 40 subjects with a mean age of 32 ± 7.38 years, ranging from 21 to 45 years old. The mean Harris Hip Score for patients before and after surgery were 20.36 and 96.15, respectively, showing a statistically significant difference (p < 0.001). The average patient activity scores before and after surgery (8.9 and 44.2, respectively), non-deformity (1.6 and 3.9), and movement (3.6 and 4.9) indicated significant differences (p < 0.001). Furthermore, 80% of patients felt no hip joint pain six months after surgery, while 92.5% patients did not use any assistive device to walk.

Conclusions

The results of this study demonstrated that surgery substantially contributed to relieving pain and improving hip function in patients with osteonecrosis of the hip joint in the short term.

Hip arthroplasty for treatment of advanced osteonecrosis: comprehensive review of implant options, outcomes and complications

Surgical treatment for late stage (post-collapse) osteonecrosis of the femoral head is controversial. In these situations, the outcome of joint preservation procedures is poor. There are several arthroplasty options for late-stage disease. The clinical outcomes of hemiarthroplasty and hemiresurfacing are unpredictable because of progressive acetabular cartilage degeneration. Total hip resurfacing may be associated with further vascular insult to the femoral head and early failure of the implant. Total hip replacement with metal-on-conventional polyethylene bearing surfaces has been the gold standard, but implant survivorship is limited in young active patients due to wear and osteolysis. Newer alternative bearing surfaces may have improved wear characteristics, but their durability must be confirmed in longer-term studies.

Long-Term Results of Total Hip Arthroplasty with 28-Millimeter Cobalt-Chromium Femoral Heads on Highly Cross-Linked Polyethylene in Patients 50 Years and Less

Highly cross-linked polyethylene (HXLPE) is the most commonly used bearing surface in total hip arthroplasty (THA) because of its superior wear properties, but long-term results in young patients are limited. We report on the clinical outcome, radiographic wear patterns and survivorship of 72 patients ≤50 years old who had a 28-millimeter cobalt-chromium femoral head on HXLPE acetabular liner. Mean and median true linear wear rates at average ten-year follow-up were 0.0104 and 0.01 mm per year ± 0.07 mm. Mean and median two-dimensional volumetric wear rates were 12.79 mm(3) and 5.834 mm(3) per year ± 26.1mm(3) as determined by Martell analysis. As a result of the minimal wear profile, there was no evidence of radiographic osteolysis and no wear-related revisions.

Short-stem hip arthroplasty in osteonecrosis of the femoral head

INTRODUCTION

Osteonecrosis of the femoral head (ONFH) is a locally destructive and complex disorder. Without treatment, infraction of the femoral head is likely. There is also a lack of consensus in the literature about the most appropriate arthroplasty method in patients with progressive ONFH. During the last decade, the number of short-stem prostheses has increased. Some short-stem designs have a metaphyseal anchorage. It is questionable whether ONFH represents a risk factor for failure after implantation of short stems. The aim of this study was to review existing literature regarding the outcome of short-stem arthroplasty in ONFH and to present the pros and cons of short-stem hip arthroplasty in osteonecrosis of the femoral head.

MATERIALS AND METHODS

This review summarises existing studies on short-stem hip arthroplasty in osteonecrosis of the femoral head.

RESULTS

Few studies have analysed the clinical and radiological outcome of short-stem THA in patients with ONFH. Only a handful of studies present clinical and radiological outcome after implantation of a short-stem arthroplasty in patients with the underlying diagnosis of osteonecrosis of the femoral head.

CONCLUSION

The short- to medium-term results show predominantly good outcomes. However, due to differences in the design of short stems and their fixation, it is hard to draw a general conclusion. Short stems with primary diaphyseal fixation do not reveal a high increased risk of failed osseointegration or loosening. For designs with a primary metaphyseal anchorage, an MRI should be conducted to exclude that the ostenecrosis exceeds the femoral neck.

Survivorship and clinical outcome of Birmingham hip resurfacing: a minimum ten years' follow-up

INTRODUCTION

Resurfacing as a percentage of total hip arthroplasty rose from 5.6 % in 2001 to 8.9 % in 2005 in Australia. During the same period the resurfacing to conventional prosthesis rose from 19.6 % to 29 % in the younger age group (less than 55 years). Long term (more than ten years) functional results of BHR are sparingly documented. Among the literatures available, the patient selection criteria vary from osteoarthritis, avascular necrosis, and dysplastic hip to slipped capital femoral epiphysis. The objective of the current study is to evaluate long term survivorship and functional outcome of Birmingham hip resurfacing surgery in osteoarthritic hip patients performed by a single surgeon.

PATIENTS AND METHODS

In this retrospective clinical study, all patients who underwent hip resurfacing for osteoarthritis of hip between 1999 and 2004 are included. All surgeries were performed by single surgeon (SJM) and in all patients Smith & Nephew system (Midland Medical Technologies, Birmingham, United Kingdom)) was used. Revision surgery is considered the end point of survivorship. Means, standard deviations, and confidence interval were calculated for all continuous measures. Survival analysis was performed with the Kaplan-Meier method and 95 % confidence intervals were calculated.

RESULT

The result is based on 222 patients (244 hips). This included 153 males and 69 females. Our mean follow up was 12.05 years and overall survival was 93.7 %. In terms of gender, survival in males was 95.43 % while in females it was 89.86 %. Failure was seen in 14 patients (16 hips), which included seven female (10.14 %) and seven male (4.57 %) patients. Failure of femoral components due to aseptic loosening and varus collapse was seen in eight patients after a mean 9.6 years. Metal allergy was seen in three patients (five hips), all of them were female of which two had bilateral resurfacing. Other complications included femoral neck stress fractures in two patients and acetabular component loosening in one patient. We observed that the failure rate is higher if the BHR femoral component size is 46 or less (ten out of 16 hips revised).

CONCLUSION

If patient selection is judiciously done and surgical technique is meticulously followed, hip resurfacing offers acceptable survivorship, satisfactory range of motion and enables patients to resume high demand activities including sports. Future improvements in the bearing surfaces, and possibly in the design, might alleviate concerns posed by high serum metal level and provide options that continue to benefit younger patients in future.

Hip resurfacing arthroplasty in treatment of avascular necrosis of the femoral head

Background

Hip resurfacing is a conservative type of total hip arthroplasty but its use is controversial, especially in patients with osteonecrosis. The aim of this study was analysis of the clinical and radiographic outcomes of hip resurfacing in patients with osteonecrosis.

Material/Methods

Between 2007 and 2008, 30 hip resurfacing arthroplasties were performed due to osteoarthritis secondary to avascular necrosis of femoral head staged as Ficat III and IV.

Patients were qualified to resurfacing arthroplasty when the extent of avascular necrosis using Kerboul’s method was <200° and the angle between avascular necrosis and head-neck junction was >20°. All patients were evaluated clinically and radiologically before and 60 months after the operation.

Results

The mean Harris Hip Score (HHS) score increased from 47.8 to 94.25 (p<0.05). Physical activity level (University of California, Los Angeles activity score – UCLA activity score) improved from 3.7 to 7.55 (p<0.05). No implant migration was observed.

Conclusions

Management of osteonecrosis of the hip with resurfacing arthroplasty seems to be effective in strictly-selected patients.

Current status of modern fully porous coated metal-on-metal hip resurfacing arthroplasty

Between March 2007 and July 2010, 1000 consecutive fully porous coated hip resurfacing arthroplasties (HRA) were performed by a single surgeon in 871 patients. The average length of follow-up was 3 ± 1 years. Three cases (0.3%) in three patients showed adverse wear related failures. Another 17 (1.7%) failures were identified at the time of this study. Using any failure of any component as the endpoint, the survivorship rate was 98.8% at two years and 97.4% at five years. Excluding the failed cases, all components were radiographically stable; there was only one partial femoral radiolucency seen. The clinical and radiological outcomes of this fully porous coated hip resurfacing were comparable to, if not better than, those reported by others using hybrid fixation methods at five years post-operatively.

Early failure of the Durom prosthesis in metal-on-metal hip resurfacing in Chinese patients

Hip resurfacing (HR) is being used increasingly as an alterative to total hip arthroplasty in osteonecrosis (ON) and ankylosing spondylitis (AS) of the hip. We performed 141 consecutive HR arthroplasties in 111 patients comprising 3 etiology groups: ON, AS, and osteoarthritis (OA). After retrospective study of retrieved components, we hypothesized that the main reason for revision was femoral loosening in the ON group (4 of 46 hips; 8.7%) and femoral-neck fracture in the AS group (3 of 58 hips; 5.2%). Necrotic areas were seen on femoral heads retrieved from patients with femoral loosening, whereas femoral heads were fixed tightly to components in patients with femoral-neck fractures. Etiology may be an important risk factor for postoperative complications.

Does the extent of osteonecrosis affect the survival of hip resurfacing?

BACKGROUND

The effect of the extent of osteonecrosis on the survival of hip resurfacing for osteonecrosis of the femoral head (ONFH) has not been well documented, but is a potentially important variable in the decision to perform resurfacing.

QUESTIONS/PURPOSES

We examined (1) the relationship between the volume of osteonecrosis in the femoral head before surgery and the extent of the residual necrotic bone after femoral head machining, (2) how the extent of the residual necrotic bone relative to the resurfaced femoral head (after femoral head machining) affected the survival of total hip resurfacing for patients with ONFH, and (3) how the extent of the necrotic bone relative to the entire femoral head (before femoral head machining) affected the survival and clinical outcome scores of patients who underwent total hip resurfacing.

METHODS

Thirty-three patients (39 hips) who underwent hip resurfacing were reviewed after a mean followup of 8 years. The extent of osteonecrosis in the femoral head and residual osteonecrosis in the implant bony bed after femoral head machining were estimated using a three-dimensional MRI-based templating system.

RESULTS

There was a statistically significant difference in the extent of osteonecrosis before and after femoral head machining, although the two were well correlated (r = 0.97). The mean percentage of osteonecrosis in the implant bony bed after femoral head machining was 5% smaller than that relative to the entire femoral head (range, -9% to 15%). There were no significant differences in implant survival between groups with small and large osteonecrosis classified by either the total amount of osteonecrosis before surgery or residual osteonecrosis after femoral head machining.

CONCLUSION

The extent of osteonecrosis in the femoral head significantly decreased after femoral head machining. Neither the residual osteonecrosis volume in the implant bony bed after femoral head machining nor the total amount of osteonecrosis before femoral head machining had significant influence on the survival of hip resurfacing.

Cementless short stem hip arthroplasty METHA® as an encouraging option in adults with osteonecrosis of the femoral head

INTRODUCTION

The implantation of a total hip arthroplasty is the standard treatment for patients with progressive osteonecrosis. However, there is uncertainty about the type of arthroplasty that provides the best outcome and whether short stem arthroplasty represents a reasonable alternative for young patients in order to have more options in case of revision. This uncertainty exists due to the lack of studies analysing contemporary short stem arthroplasty in osteonecrosis.

AIM

The aim of this study was to determine the outcome of the METHA(®) short stem arthroplasty in patients with progressive osteonecrosis.

PATIENTS AND METHODS

This study evaluated the clinical and radiological short- to midterm results after implantation of the cementless short stem arthroplasty METHA(®). 73 hips in 64 patients with progessive osteonecrosis after implantation of the METHA(®) arthroplasty were investigated by measuring the clinical outcome, the Harris Hip Score (HHS) and visual analogue pain scale for the preoperative stage and follow-up. Radiological analyses of X-rays were conducted to assess the bone ingrowth as well as subsidence, osteolysis or fracture.

RESULTS

The pain scale improved from preoperatively 7.8 to postoperatively 1.7, while the HHS increased from 41.4 to 90.6 points 34 months post-surgery. Complications associated with revision of the METHA(®) short stem included two traumatic femoral shaft fracture and one deep infection. The radiological assessment showed good bone ingrowth in all patients despite osteonecrosis.

CONCLUSION

The study confirms encouraging results as well as good bone ingrowth of the cementless short stem arthroplasty METHA(®) even in patients with osteonecrosis.

Risk factor analysis for early femoral failure in metal-on-metal hip resurfacing arthroplasty: the effect of bone density and body mass index

Background

The importance of appropriately selecting patients based on factors such as bone mineral density, body mass index, age, gender, and femoral component size has been demonstrated in many studies as an aid in decreasing the rate of revisions and improving the outcomes for patients after hip resurfacing arthroplasty (HRA); however, there are few published studies quantitatively specifying the potential risk factors that affect early femoral component failures. Therefore, the purpose of this study was to investigate the specific causes of early femoral component failures in hip resurfacing separately and more carefully in order to develop strategies to prevent these failures, rather than excluding groups of patients from this surgical procedure.

Methods

This retrospective study included 373 metal-on-metal HRAs performed by a single surgeon using the vascular sparing posterior minimally invasive surgical approach. The average length of follow-up was 30 ± 6 months. In order to understand the causes of early femoral failure rate, a multivariable logistic regression model was generated in order to analyze the effects of bone mineral density (T-score), gender, diagnosis, body mass index, femoral implant fixation type, age, and femoral component size.

Results

The average post-operative Harris hip score was 92 ± 11 points and the average post-operative UCLA score was 7 ± 2 points. There were three revisions due to femoral neck fracture and two for femoral component loosening. These occurred in two female and three male patients. In the multi-variable regression model, only T-score and body mass index showed significant effects on the failure rate of femoral components. Patients with a lower T-score and a higher body mass index had a significantly increased risk of early femoral component failure.

Conclusion

We recommend that dual energy x-ray absorptiometry scan T-score tests should be routinely performed on all hip resurfacing patients pre-operatively. If a patient has a low T-score (≤ -1.5), consideration should be given to additional precautions or treatments to alleviate his or her risk, especially when the patient has a higher body mass index (≥ 29 kg/m²).

BONE-PRESERVING HIP ARTHROPLASTIES AS AN ALTERNATIVE TO CONVENTIONAL HIP REPLACEMENT FOR YOUNG PATIENTS — A REVIEW ARTICLE

Hip replacement is one of the most successful orthopedics' procedures in terms of restoring quality of life. In the past, indications for hip replacement were restricted to elderly people, but nowadays advances in bioengineering technology have driven development of hip implants with less wear and loosening and therefore with longer longevity. Early wear and loosening as well as stress shielding and bone preservation are considered as major issues especially when dealing with young patients. The main reason for this is the fact that younger patients might require one or more hip revision procedures during the course of their life due to their age and high activity level.

Especially in young patients it could be an advantage to use primary implants that are more bone preserving and allow more physiological load transfer which cause no or minimal stress shielding at the proximal femur. The two options which exist today are hip resurfacing which preserves the femoral head and various short stem prostheses which transfer the forces in the femur more proximally and more physiologically.

This review looks at the options which are available today in bone preserving hip arthroplasties.

Radiographic evaluation of midterm failure rates following metal-on-metal hip resurfacing

This prospective study examined patient characteristics and radiographic findings for 89 subjects undergoing total hip resurfacing. Thirteen (14.6%) of 89 hips have required revision. Female sex, smaller implant size, and diagnosis of osteonecrosis were associated with lower device survival. No significant differences in acetabular cup angle and stem angle were observed between revised and nonrevised hips. Revision rates for the first 25 hips were 24% and 8% for the last 64 hips. Females accounted for 56% of subjects 1 to 25 and 23% of subjects 26 to 89. Despite representing only 33% of included subjects, females accounted for 62% of revision procedures. The lower device survival proportion in subjects 1 to 25 could not be attributed to acetabular or femoral component malpositioning and can likely be explained by a significantly higher proportion of females enrolled early in the study.

Review of total hip resurfacing and total hip arthroplasty in young patients who had Legg-Calvé-Perthes disease

Patients with Legg-Calvé-Perthes disease can often be successfully treated with femoral head-preserving measures, such as bracing, or containment procedures with osteotomies. However, in some cases, after resolution of the disease, the femoral head may proceed to collapse or progress to severe arthritis at a young age. If nonoperative methods have failed, the only treatment options available for these adolescents or young adults may be a total hip resurfacing or a total hip arthroplasty (THA). This article focuses on the results and unique technical considerations of resurfacing and THA for patients who have severe hip osteoarthritis after resolved Legg-Calvé-Perthes disease.

Hip resurfacing in patients who have osteonecrosis and are 25 years or under

BACKGROUND

Young patients with osteonecrosis (ON) treated with THA often have suboptimal function and radiographic failure with eventual revision. Resurfacing may be an option because of potentially increased functionality and decreased radiographic failure, although neither has been confirmed in the literature.

QUESTIONS/PURPOSES

We therefore compared the clinical scores and radiographic failures of resurfacing patients 25 years or younger with osteonecrosis with those for patients with ON treated with THA.

METHODS

We identified 17 patients (20 resurfaced hips) who were 25 years or younger and treated by resurfacing for ON. Mean followup was 62 months (range, 32-103 months). This group was matched by gender, age, BMI, and followup to 16 patients (20 hips) treated with THA with a mean 61 month followup (range, 34-88 months). Additionally, the group was compared to 78 patients (87 hips) with ON over age 25 who underwent resurfacing during the same time with a mean followup of 61 months (range, 27-112 months).

RESULTS

The mean Harris score improved from 48 points preoperatively to 93 points with a 100% 7.5 year survivorship in the young resurfacing group. In the THA cohort, the mean score improved from 44 points preoperatively to 94 points postoperatively, with a 93.3% 7.5 year survivorship; similar to the results for all resurfacing patients. Radiographs did not reveal malalignment or progressive radiolucencies in any cohort.

CONCLUSION

At approximately 5 year followup, young resurfacing patients were similar to other resurfacing patients and standard THA patients regarding clinical ratings and radiographic failures.

The effect of patient selection and surgical technique on the results of Conserve® Plus hip resurfacing--3.5- to 14-year follow-up

The results of metal-on-metal hip Conserve® Plus resurfacings with up to 14 years of follow-up with and without risk factors of small component size and/or large femoral defects were compared as performed with either first- or second-generation surgical techniques. There was a 99.7% survivorship at ten years for ideal hips (large components and small defects) and a 95.3% survivorship for hips with risk factors optimized technique has measurably improved durability in patients with risk factors at the 8-year mark. The lessons learned can help offset the observed learning curve of resurfacing.

Complications after metal-on-metal hip resurfacing arthroplasty

This article determines the incidence and cause of the complications commonly associated with metal-on-metal hip resurfacing implants and the proposed methods to prevent these complications. The literature available in PubMed was reviewed. Complication rates after hip resurfacing are low, and the procedure has shown both safety and efficacy in the hands of surgeons trained in specialized centers. Proper surgical technique can further reduce the incidence of femoral neck fracture, component loosening, and abnormal wear of the prosthesis. A more systematic detection of adverse local tissue reactions is needed to provide accurate assessments of their prevalence.

Total hip arthroplasty in advanced osteonecrosis: the short-term results by metal-on-metal hip resurfacing

BACKGROUND

Characteristically, osteonecrosis affects younger patients who typically refer to the orthopedic surgeon for the first time in the third to fifth decades of life, in the late stages of the disease. Femoral metal-on-metal hip resurfacing is as an alternative to conventional total hip arthroplasty in treating osteoarthritis of the hip. Since there are already many reports regarding the successful outcome of resurfacing in advanced osteoarthritis, the purpose of this study was to analyze the clinical outcomes of this procedure in patients with osteonecrosis of the femoral head and to compare them with a matched group of patients with osteoarthritis.

MATERIAL/METHODS

This retrospective cohort study evaluated a consecutive series of 52 patients with end-stage osteonecrosis (28 patients) and osteoarthritis (24 patients) of the femoral head, managed by metal-on-metal hip resurfacing in a referral orthopedic center from Feb 2002 to May 2007. Pain, function and deformity were evaluated with the use of the Harris hip score after the operation. Patients were clinically followed for a mean of 41 months.

RESULTS

The patients in the osteoarthritis group had a significantly higher mean age than those in the osteonecrosis group (47.88 ± 12.6 vs 30.86 ± 7.5, p=0.003). The clinical outcomes were similar for both groups. There was no significant difference in mean Harris hip score (p=0.347) and hip joint range of motion (p=0.346) between osteonecrosis and osteoarthritis groups after surgery.

CONCLUSIONS

On the basis of these initial findings, we recommend MOM resurfacing as a viable treatment option for patients with advanced stages of osteonecrosis.

Influence of cementing the pin on resistance to fracture in hip resurfacing

BACKGROUND

Since the introduction of modern hip resurfacing systems, there has been a controversy regarding the fixation of the centering pin in the femoral component. It has been suggested that cementing the pin may increase strength of the femoral neck. This in-vitro analysis investigated the influence of a cemented, femoral pin on resistance to fracture in the resurfaced hip.

METHODS

Five pairs of cadaveric, fresh-frozen femora underwent hip resurfacing (ASR™) using a high viscosity cementing technique. In one side of each pair only the inner surface of the implant was cemented, in the other side, cement was additionally hand-pressurized down the pinhole prior to implantation of the femoral component. Specimen were then mounted on a material testing machine and cyclic loading with increasing load steps was applied until fracture of the femoral neck.

FINDINGS

Fracture load was increased (P = 0.013) in the cemented pin group (Median = 4200 N) when compared with the cementless pin group (Median = 2800 N). The number of cycles to failure in the group with the cemented pin (Median = 8072) was likewise higher (P = 0.01) when compared to the group, in which the pin was not cemented (Median = 5906).

INTERPRETATION

Cementing the pin may provide additional fixation in hips with low bone mineral density or osteonecrotic lesions, as resistance to fracture could be improved in the presented in-vitro scenario. Although this was shown for a specific hip resurfacing system, this effect might be extrapolated to other, similar implant designs.

The Birmingham hip resurfacing prosthesis: an independent single surgeon's experience at 7-year follow-up

An independent single surgeon's 7-year experience with Birmingham hip resurfacing is presented. The study also involved investigation of the significance of pedestal sign in patients requiring revision. A consecutive 117 hips in 101 patients (59 male and 42 female patients) operated on by the senior author (VGJ) were assessed at a mean follow-up of 7 years (range, 5-9.4 years). Mean age at surgery was 54 years (range, 20-74 years). Seventy-three hips had a preoperative diagnosis of primary osteoarthritis, and secondary osteoarthritis was seen in 44 hips. Failure was defined as revision for any reason. Revision of the femoral component alone was undertaken in 8 hips (6.8%): 5 within first year for periprosthetic fracture neck of femur and in 3 hips after 5 years of follow-up. In 2 patients who were known to have osteonecrosis of the femoral head preoperatively, the femoral component progressively collapsed into varus after 5 years of follow-up. Pedestal sign was the earliest radiologic sign noted in these 2 patients and progressed rapidly within 1 year on serial radiographs well before the onset of clinical symptoms. Kaplan-Meier survival with revision as end point at 7 years was 91.5% (95% confidence interval, 97.6%-85.4%).

Resurfacing arthroplasty of the hip for avascular necrosis of the femoral head

We performed 96 Birmingham resurfacing arthroplasties of the hip in 71 consecutive patients with avascular necrosis of the femoral head. A modified neck-capsule-preserving approach was used which is described in detail. The University of California, Los Angeles outcome score, the radiological parameters and survival rates were assessed. The mean follow-up was for 5.4 years (4.0 to 8.1). All the patients remained active with a mean University of California, Los Angeles activity score of 6.86 (6 to 9). Three hips failed, giving a cumulative survival rate of 95.4%. With failure of the femoral component as the endpoint, the cumulative survival rate was 98.0%. We also describe the combined abduction-valgus angle of the bearing couple, which is the sum of the inclination angle of the acetabular component and the stem-shaft angle, as an index of the optimum positioning of the components in the coronal plane.

Using a modified surgical technique, it is possible to preserve the femoral head in avascular necrosis by performing hip resurfacing in patients with good results.

Hip resurfacing for rheumatoid arthritis: independent assessment of 11-year results from an international register

Total hip replacement has shown good outcomes for patients with rheumatoid arthritis. Can hip resurfacing give similar results for patients with rheumatoid arthritis? Using an international hip resurfacing register, 47 patients with rheumatoid arthritis were identified and age and gender matched to a group of 131 randomly selected patients with osteoarthritis of the hip joint. Patients completed a questionnaire to record function and implant revision. Hierarchical regression, Cox regression and Kaplan-Meier method were used for analysis. There was a significant increase in post operative hip score in both groups (p < 0.001) with rheumatoid group scoring higher as compared to the osteoarthritis group (p = 0.23). The post operative score was not significantly influenced by pre-operative score and age (p = 0.15 and 0.84, respectively) but the pre-operative score was a predictor of implant failure (p = 0.02). Patient mobility was affected by age with younger patients scoring high on mobility as compared to older patients (p = 0.01). The Kaplan-Meier analysis showed a survival rate of 96.3% in the rheumatoid group and 97.8% in the osteoarthritis group. This difference was not significant (Log rank test, p = 0.45). Our results from an independent and international register show that hip resurfacing provides good post-operative hip function and excellent implant survival for patients with rheumatoid arthritis of the hip joint. This procedure can be considered as a viable option for management of rheumatoid arthritis of the hip joint.

Hip resurfacing arthroplasty: a review of the evidence for surgical technique, outcome, and complications

Hip resurfacing arthroplasty has reemerged as a valid reconstruction option for the osteoarthritic hip. Patient selection is critical for excellent surgical outcomes, especially when compared with total hip arthroplasty. However, concerns regarding surgical technique and postsurgical complications persist. The authors review the evidence for surgical technique, outcomes, and complications related to modern metal-on-metal hip resurfacing arthroplasty.

Outcome of primary resurfacing hip replacement: evaluation of risk factors for early revision

BACKGROUND AND PURPOSE

The outcome of modern resurfacing remains to be determined. The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) started collection of data on hip resurfacing at a time when modern resurfacing was started in Australia. The rate of resurfacing has been higher in Australia than in many other countries. As a result, the AOANJRR has one of the largest series of resurfacing procedures. This study was undertaken to determine the results of this series and the risk factors associated with revision.

PATIENTS AND METHODS

Data from the AOANJRR were used to analyze the survivorship of 12,093 primary resurfacing hip replacements reported to the Joint Replacement Registry between September 1999 and December 2008. This was compared to the results of primary conventional total hip replacement reported during the same period. The Kaplan-Meier method and proportional hazards models were used to determine risk factors such as age, sex, femoral component size, primary diagnosis, and implant design.

RESULTS

Female patients had a higher revision rate than males; however, after adjusting for head size, the revision rates were similar. Prostheses with head sizes of less than 50 mm had a higher revision rate than those with head sizes of 50 mm or more. At 8 years, the cumulative per cent revision of hip resurfacing was 5.3 (4.6-6.2), as compared to 4.0 (3.8-4.2) for total hip replacement. However, in osteoarthritis patients aged less than 55 years with head sizes of 50 mm or more, the 7-year cumulative per cent revision for hip resurfacing was 3.0 (2.2-4.2). Also, hips with dysplasia and some implant designs had an increased risk of revision.

INTERPRETATION

Risk factors for revision of resurfacing were older patients, smaller femoral head size, patients with developmental dysplasia, and certain implant designs. These results highlight the importance of patient and prosthesis selection in optimizing the outcome of hip resurfacing.

Hip resurfacing results for osteonecrosis are as good as for other etiologies at 2 to 12 years

A bone-conserving prosthetic solution, such as hip resurfacing arthroplasty, is desirable for patients with osteonecrosis (ON) of the femoral head because of their young age. However, many surgeons are reluctant to perform hip resurfacing for ON because of large femoral head defects. To ascertain whether this reluctance is warranted, we determined the mid- to long-term effects of ON on the survivorship, radiographic implant fixation, and disease-specific and quality-of-life scores of hip resurfacing. We compared the results of metal-on-metal resurfacing performed for ON of the hip (including large lesions) with those of resurfacing performed for other causes. The ON group had 70 patients (85 hips) and the control group 768 patients (915 hips) including all other etiologies operated on during the same period. The ON group was younger and had a greater incidence of femoral defects, a smaller component size, and a lower body mass index, three variables previously shown to reduce survivorship in hip resurfacing. We observed no difference in survivorship between the ON group and the control group even after adjusting for head size, body mass index, and defect size. Pain relief, walking, and function scores were comparable postoperatively. The activity level was lower in the ON group. Our data suggest ON is not a contraindication for resurfacing even with large femoral head defects.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Articular Surface Replacement of the hip: a prospective single-surgeon series

We present the early clinical and radiological results of Articular Surface Replacement (ASR) resurfacings in 214 hips (192 patients) with a mean follow-up of 43 months (30 to 57). The mean age of the patients was 56 years (28 to 74) and 85 hips (40%) were in 78 women.

The mean Harris hip score improved from 52 (11 to 81) to 95 (27 to 100) at two years and the mean University of California, Los Angeles activity score from 3.9 (1 to 10) to 7.4 (2 to 10) in the same period. Narrowing of the neck (to a maximum of 9%) was noted in 124 of 209 hips (60%). There were 12 revisions (5.6%) involving four (1.9%) early fractures of the femoral neck and two (0.9%) episodes of collapse of the femoral head secondary to avascular necrosis. Six patients (2.8%) had failure related to metal wear debris. The overall survival for our series was 93% (95% confidence interval 80 to 98) and 89% (95% confidence interval 82 to 96) for hips with acetabular components smaller than 56 mm in diameter.

The ASR implant has a lower diametrical clearance and a subhemispherical acetabular component when compared with other more frequently implanted metal-on-metal hip resurfacings. These changes may contribute to the higher failure rate than in other series, compared with other designs. Given our poor results with the small components we are no longer implanting the smaller size.

Hip resurfacing after failed free vascularized fibular graft

Metal-on-metal resurfacing of the hip is a bone sparing arthroplasty that may be an option when a head-sparing nonarthroplasty option fails. We present the first published report of 5 cases of failed free vascularized fibular graft treated with modern hip resurfacing arthroplasty. This selected group of patients had avascular necrosis with less than 20% head involvement and cysts less than 1 cm in diameter. Follow-up ranging from 2 to 5 years (mean, 38 months) showed improvement in hip function without evidence of prosthesis loosening. There were no femoral neck fractures or revisions. A vascularized fibular bone graft does not prevent good early results with hip resurfacing but may add technical complexity owing to its position within the femoral head and neck.

Cementless femoral components in young patients: review and meta-analysis of total hip arthroplasty and hip resurfacing

The study purpose was to analyze current results of modern cementless femoral components in young patients having total hip arthroplasty (THA) or hip resurfacing. Twenty-two studies (n = 5907; hips = 6408) evaluating modern cementless THA in young patients and 15 studies evaluating hip resurfacing (n = 3002; hips = 3269) were included. Meta-analysis techniques were used to pool failure rates. The pooled failure rate for THA using femoral revision for mechanical failure as an end point was 1.3% (95% confidence interval [CI], 1.0%-1.7%) at a mean 8.4 years of follow-up. At a mean of 3.9 years of follow-up, the pooled mechanical failure rate of the femoral component for hip resurfacing was 2.6% (95% CI, 2.0-3.4). In conclusion, the enthusiasm for hip resurfacing should be tempered by these data. Longer follow-up and direct comparison trials are required to confirm these findings.

Current status of hemi-resurfacing arthroplasty for osteonecrosis of the hip: a 27-year experience

The purpose of the study discussed in this article is to review the authors' long-term experience with this procedure, compare their clinical results to those of other centers, particularly regarding the difficulty of predicting pain relief, and determine the role of hemi-resurfacing in the future.

Initial American experience with hip resurfacing following FDA approval

In May 2006, the US Food and Drug Administration approved the first metal-on-metal total hip resurfacing. Surgeons wanting to implant this device were required to undergo formal industry-sponsored training before performing their first case and a technical specialist attended their initial 10 cases. Safety surveys were completed on the first 537 cases performed and included patient age, gender, diagnosis, and occurrence of any unexpected events perioperatively or postoperatively. Intraoperative data were available for all 537 cases (100%), hospital discharge and six-week data were available for 524 cases (97.6%), three-month data were available for 523 cases (97.4%), six-month data were available for 509 cases (94.3%) and one-year data were available for 449 cases (83.6%); the mean followup was 10.4 months. We documented adverse events in 40 (32 major, 8 minor) of the 537 cases including nine nerve injuries and eight dislocations. There were 14 component revisions (3.1%) [corrected] within the first year, including 10 for femoral neck fracture, two for dislocations, and two for acetabular component loosening. Complications were frequently seen among patients older than 55 years of age and in women, emphasizing the importance of appropriate patient selection for the procedure.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Metal-on-metal hip resurfacing arthroplasty: a review of periprosthetic biological reactions

Metal-on-metal hip resurfacing arthroplasty has undergone a recent resurgence as an alternative treatment option for young and active patients with significant osteoarthritis. The claimed advantages of metal-on-metal hip resurfacing arthroplasty include lower wear rate, preservation of bone stock for subsequent revision procedures, restoration of anatomic hip mechanics, and enhanced stability due to the larger diameter of articulation. A disadvantage, however, is that the metal-on-metal resurfacing releases large amounts of very small wear particles and metal ions. The long-term biological consequences of the exposure to these Co-Cr particles and ions remain largely unknown. The purpose of this review is to provide an overview of the current literature on the adverse periprosthetic biological reactions associated with metal-on-metal hip resurfacing arthroplasty.

The influence of surgical approach on outcome in Birmingham hip resurfacing

Various approaches have been described for metal-on-metal hip resurfacing. We compared the posterolateral and direct lateral approaches for complications, pain, function, and implant survival in the short and medium term for two surgeons in a consecutive series of 790 patients (909 hips; July 1997 to July 2004) followed until July 2007. The direct lateral approach group included 135 resurfacing procedures and the posterolateral group included 774 procedures. There was no difference between the two groups for age or gender. The minimum followup for the anterolateral group was 2 years (mean, 5.1 years; range, 2.0-9.4 years) and for the posterolateral group 2 years (mean, 5.5 years; range, 2.0-9.6 years). There were no differences between the two approaches for complications, additional surgery, implant survival, or Oxford hip scores. The 8-year survival rate was 97.9% (95% confidence interval, 89.9-100) for the direct lateral approach and 97.2% (95% confidence interval, 93.9-99.3) for the posterolateral approach. This study indicates both approaches offer excellent pain reduction and return to function after Birmingham hip resurfacing with no difference in survival or in the incidence of complications. An 8-year survival rate of 97% can be achieved using either the posterolateral approach or the direct lateral approach.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Guidelines for authors for a complete description of levels of evidence.

One- or two-stage bilateral metal-on-metal hip resurfacing arthroplasty

Patients considered suitable for total hip resurfacing arthroplasty often have bilateral disease. The peri-operative complications, transfusion requirements, hospital stay, outcome and costs in patients undergoing one-stage bilateral total hip resurfacing were compared with a group of patients undergoing a two-stage procedure. A total of 92 patients were included in the study, of which 37 (40%) had a one-stage and 55 (60%) had a two-stage resurfacing. There were no significant differences in age, gender, or American Society of Anaesthesiologists grade between the groups (p = 0.31, p = 0.23, p = 0.13, respectively). There were three systemic complications in the one-stage group (8.1%) and one in the two-stage group (1.8% of patients; 0.9% of procedures). There was no significant difference in the complication rate (p = 0.72) or the transfusion requirements (p = 0.32) between the two groups. The one-stage group had a reduced total hospital stay of five days (95% confidence interval 4.0 to 6.9; p < 0.001), reduced length of time to completion of all surgery of five months (95% confidence interval 2.6 to 8.3; p < 0.001), and the reduced cost was 35% less than that of a two-stage procedure. However, the total anaesthetic time was significantly longer for the one-stage group (p < 0.001; 95% confidence interval 31 to 52). This study demonstrates that consideration should be given to one-stage surgery for patients with bilateral symptomatic disease suitable for metal-on-metal hip resurfacing. A one-stage procedure appears to have benefits for both the patient and the hospital without additional complications.