HIP REPLACEMENT AND RESURFACING: CURRENT CONSIDERATIONS REGARDING METAL-ON-METAL ARTHROPLASTY

Transcription

1 HIP REPLACEMENT AND RESURFACING: CURRENT CONSIDERATIONS REGARDING METAL-ON-METAL ARTHROPLASTY Michelle L. McIsaac, Robert C. Lee, Tom Noseworthy Centre for Health and Policy Studies, University of Calgary May 4, /4/2007 page 1

2 This pre-assessment document is based on a limited synthesis of existing reviews, evaluations and health technology assessments. This document is meant to be an overview of the topic and does not represent an exhaustive or systematic review. FOREWORD Acknowledgements: Production of this report has been made possible by a financial contribution from Health and Wellness and under the auspices of the Alberta Health Technologies Decision Process initiative: the Alberta model for health technology assessment and policy analysis. The views expressed herein do not necessarily represent the official policy of Alberta Health and Wellness. We thank Anita Blackstaffe (University of Calgary) for her contributions to the analysis of the data provided by Alberta Health and Wellness. 5/4/2007 page 2

3 LIST OF ABBREVIATIONS THR CoC DJD MoM M-MHR OA RA RCT Total hip replacement Ceramic-on-ceramic Degenerative joint disease Metal-on-metal Metal-on-metal hip resurfacing Osteoarthritis Rheumatoid arthritis Randomized controlled trial 5/4/2007 page 3

4 ABSTRACT This Review summarizes the findings of seven recent health technology reviews on metal-on-metal hip resurfacing (M-MHR). Specifically, this Review assesses findings pertaining to: Appropriate clinical indications for M-MHR Safety Efficacy/effectiveness Patient outcomes Cost/cost-effectiveness Overall, the seven reviews found the evidence on the subject to be lacking in both quantity and quality; only one randomized controlled trial was reviewed. M-MHR is generally deemed suitable for young (<65 years), active, and otherwise healthy patients. Nonetheless, due to the lack of comparative evidence, the appropriate clinical indications for M-MHR are currently not known. M-MHR is generally regarded as having similar risks to patients as total hip replacements (THRs), although any procedure using metalon-metal (MoM) may cause metal ion release. However, there is insufficient evidence regarding health outcomes (i.e. carcinogenicity and cardiotoxicity) related to metal ion release in the body. Most reviews conclude that further investigation on effectiveness (relative to other approaches) and long-term effectiveness need to be completed before conclusive evidence of M-MHR effectiveness can be drawn. Nonetheless, observational studies suggest improved patient outcomes (reduced pain, quicker recovery, etc.) associated with M-MHR; therefore it is thought to be a promising alternative to THR. M- MHR has higher upfront costs than currently used standards of care. Downstream costs of this treatment are uncertain and contingent on long-term revision rates. Based on this limited review of the cited works, M-MHR would not be a preferred form of arthroplasty in the majority of patients. By the same token, this approach appears to have sufficient merit for a selective group of patients and therefore should not be completely dismissed. In summary, long-term controlled and observational studies need to be performed in order to appropriately address the merit and appropriateness of M-MHR. 5/4/2007 page 4

5 1. INTRODUCTION Degenerative joint disease (DJD) causes pain and reduces function. Implantation of a prosthetic joint is a common surgical intervention intended to alleviate symptoms of DJD when other interventions (physiotherapy, drug-based treatments, etc.) are not successful. Total hip replacement (THR) has been the primary and preferred surgical approach for these patients. Since the inception of THR approximately 30 years ago 1, an important limitation has become apparent; the need for revision surgery. Revisions are required when the prosthesis deteriorates due to wear and tear. Revisions are most notably a concern for younger, more active patients who are likely to outlive a THR prosthesis. Metal-on-metal hip resurfacing (M-MHR) has been presented as an alternative to THR for younger, more active patients due to purportedly lower revision rates and superior patient outcomes. At present, many orthopedic surgeons in Canada and internationally are offering this alternative to patients. The goal of this summary is to review current considerations regarding M-MHR using relevant literature reviews (health technology assessments and systematic reviews). 2. BACKGROUND Degenerative joint disease (DJD) is the degeneration of cartilage and bone in a joint. This results in chronic pain and stiffness 2. The main underlying causes of DJD are osteoarthritis (OA), and to a lesser extent rheumatoid arthritis (RA) and trauma. International data suggest that the prevalence of OA and RA are approximately 1-2% and 0.5%, respectively and that OA and RA account for 75% and 6% of DJD cases Epidemiology In Alberta, over 300,000 individuals are likely affected by OA and RA 2. The exact prevalence of DJD is unknown. In 2006, there were approximately 3,100 patients and 3,200 procedures relating to hip disease in Alberta (see Table A1 for a description of the health service codes included), this has increased almost 60% since 1997 (Figure A2). There is variation regarding the utilization of these services across health regions in the Province. Capital Health Region and the Calgary Health Region perform substantially more hip procedures than other health regions in the Province. In 2006, Capital Health performed 40% and the Calgary Health Region performed 33% of all hip procedures in Alberta (Figure A3). In 2006, more females in Alberta underwent hip procedures than males (Figure A4), and older patients were more likely to be receiving these services than younger individuals. Individuals aged 65 and older represented 66% of patients receiving these services (Figure A5); nonetheless, there were over 1,000 patients under the age of 65 who are receiving hip procedures. In 2006, THR represented 74% of hip procedures in Alberta, hemiarthroplasty (partial arthroplasty; i.e. replacement of only the femoral head with a 5/4/2007 page 5

6 prosthesis) was the second most common procedure representing 24% of hip services (Figure A6). 2.2 Treatment Watchful waiting Watchful waiting with non-surgical management is considered a treatment option for patients with DJD. It involves patient monitoring, anti-inflammatory drugs, medication for pain, and supportive activities such as physiotherapy. Watchful waiting is more common in younger patients, as THR in such patients is often postponed due to higher revision rates associated with longer life expectancy Total hip replacement (THR) A THR removes the entire femoral head and neck; these are replaced with a ball and stem that fits inside the femur. There are various THR prostheses available, including a polyethylene liner with a metal ball, metal-on-metal (MoM) THR, and ceramic-onceramic (CoC) THR. Outcomes of THR are generally considered to be good in terms of reducing pain, improving functional status and health-related quality of life, and having high survival rates. Nonetheless, THR revisions are common in younger patients due to the longer-life expectancy and higher activity level of these patients. Swedish data reports revision rates of 26.5% and 29.2% (at 13 years) for males and females younger than 50 years of age, compared to revision rates of 4.3%-12% and for patients older than 60 years of age Metal on metal hip resurfacing (M-MHR) M-MHR involves removing and replacing the surface of the femoral head with a metal hollow cap that fits into a metal acetabular (hip socket) cup 6. The metal-on-metal bearings currently use high carbon-cobalt-chromium alloy. Other types of hip resurfacing include metal-on-polyethylene, and CoC bearings. Table A7 contains a list of various types of M-MHR devices, and Table A8 reports the six devices approved for use in Canada (as of 2005) 7. A purported benefit of M-MHR compared to THR is a more natural loading of the joint; presumably increasing tolerance for strenuous exercise, and reducing the chance of dislocation. Additionally, because more bone is preserved in M-MHR, there appear to be more options if a revision is required 2. 5/4/2007 page 6

7 2.3 Clinical indications There is no consensus on the appropriate clinical indications for M-MHR 6. The target group to date has been younger, more active patients. This younger, more active group has higher rates of revision surgery for THR than older patients, due to their longer lifeexpectancy and potential of a more active lifestyle. The M-MHR technique removes less bone from the femur than THR, so revision surgery is purportedly less complex. Studies to date on M-MHR generally select younger (<65 years of age, occasionally <55 years of age) active patients with DJD (often limited to OA or RA) who also meet the criteria for a THR 2. However, limiting the patient group to this category is not substantiated by available evidence, potentially causing bias. This may also be impeding conclusions about appropriate clinical indications; as such selectivity does not facilitate large sample sizes or valid comparisons among patient groups (e.g. comparing various patient groups who receive M-MHR with those who receive THR). Osteopenic disorders, Gaucher s disease, deformity of the head of the femur or the acetabulum, and destructive arthritis have been considered contraindications for M-MHR 2. Overall, clinical indications and contraindications have not been thoroughly studied. Definitive conclusions cannot be drawn regarding the appropriate clinical indications, groups that are expected to yield the most significant clinical benefit, and the proportion of patients that could benefit from M-MHR. 3. EVIDENCE OF SAFETY AND EFFICACY 3.1 Methods of literature review Seven high-quality reviews were examined for this summary (see table A9 in the appendix). Most of these studies included a systematic review of the literature, with the most recent systematic review current as of October Safety Overall, M-MHR is expected to result in similar risks to the patient as THR, including blood loss, infection, deep venous thrombosis, nerve injury, hip dislocation, and very rarely pulmonary embolism 2. A notable safety concern relates to metal wear debris. There are several reports of elevated cobalt and chromium concentrations in serum and/or urine of patients who have received metal hip implants (although comparators in these studies were not cited) 5. The potential serious toxicological effects of elevated metal ions in the body relate to carcinogenicity and cobalt cardiotoxicity. However, there is inadequate evidence of a link between increased levels of cobalt and chromium associated with hip prostheses and adverse health outcomes 5. Additional high-quality, long-term studies are needed to provide a more conclusive understanding of the safety of MoM THR and M-MHR. 5/4/2007 page 7

8 3.3 Efficacy/effectiveness The main efficacy measures reported in the literature have been survival rates and revision rates post-m-mhr. Although procedure-related deaths were not reported, high survival rates were reported; 94-98% for short follow-up periods ( years) 5. Revision rates of the M-MHR prostheses currently used in Canada are expected to range from % for a short follow-up period ( years) 5. The seven reviews captured several observational studies and one relevant randomized controlled trial (RCT). Most observational data suggests a clinical benefit associated with M-MHR, however RCTs are important in order to demonstrate the relative effectiveness and any additional clinical benefit that M-MHR might have over current standards of care. Vendittoli et al. (2006) 8 evaluated the outcomes of M-MHR (Durom system) versus MoM THR (Zimmer system) in a RCT with over 200 patients. Although this study represents the highest level of evidence reviewed, the comparator of the MoM THR is not standard in Alberta. The study found that M-MHR had longer surgical times (average of 16 minutes longer) and shorter hospital stays (approximately 1 day shorter) than MoM THR. Follow-up was too short to capture any significantly different revision or survival rates; although the M- MHR system had slightly higher rates of revision (1.9% compare to 1% for MoM THR). No long-term randomized studies have been completed, making conclusions regarding the long-term relative effectiveness of M-MHR difficult. 3.4 Patient Outcomes The main patient outcomes reported in the literature have been pain scores and functional status. Specifically, Harris hip scores (measures pain, walking function, range of motion etc.) and SF-12 (measure physical and mental health) are the most commonly reported health outcomes measures 5. Studies show improvement in these scores and statistically significant improvement was demonstrated in four studies (1 Harris hip, 2 SF-12, and 1 UCLA hip score (measures pain and function)). Further, there is an expected improvement in the range of motion (flexion, rotation, etc.) following M-MHR 5. Observational studies also suggest that there may be quicker recovery associated with M- MHR, therefore patients can return to normal daily activities (including work) sooner 2. A RCT comparing M-MHR to MoM THR 8 found that at a follow-up of one-year patients had fairly similar outcomes; with the M-MHR group doing slightly better and returning to daily activities more quickly 8. Overall, M-MHR appeared to yield better patient outcomes than current standards of care in younger patients. 3.5 Summary of review findings In general, the reviews evaluated for this Report did not find the available evidence on M-MHR to be of high quality. Most data collected addressing M-MHR was observational and came from purposely selected younger, healthier, more active patients. Further, no long-term data on effectiveness or safety was available. Due to the lack of 5/4/2007 page 8

9 long-term comparative evidence, conclusions can not be drawn on the value of M-MHR, as compared to THR or other standards of care. The conclusion of most national and international reviews is that further controlled studies with long-term follow up periods should be completed before definitive recommendations can be made 5. Nonetheless, NICE recommends M-MHR as one option for people with advanced hip disease who would otherwise receive and are likely to outlive a conventional primary total hip replacement, and that data be collected via a national registry on the clinical and cost-effectiveness of the technology COST M-MHR is generally expected to have a higher up-front cost than THR 7. In Ontario, the estimated prosthesis cost for M-MHR ranges from $4,300 to $6,000 a, and THR protheses cost approximately $ Two RCTs of M-MHR versus THR (one remains unpublished) indicate that M-MHR has a longer surgical time than THR 7. In Alberta, non-randomized data from the Alberta Hip Improvement Project show that there is no statistically significant difference in surgical time between M-MHR and THR 9. Both randomized and non-randomized evidence demonstrate shorter in-patient length of stay post-surgery for M-MHR compared to THR. The Alberta Hip Improvement Project calculated the up-front costs of M-MHR, ceramic-on-ceramic (CoC) THR, and other THR. This demonstrated equivalent surgical times, shorter length of say for M-MHR, and higher device cost of M-MHR. They calculated the up-front costs of M-MHR, CoC THR, and other THR to be $11,661, $10,929, and $11,226, respectively. An Ontario economic analysis (using Ontario costing data) estimated the total up-front cost for hip resurfacing to be approximately $15, Although up-front costs are likely the major cost driver, other costs such as the cost of clinical training and costs incurred outside of the hospital are important to consider when making cost comparisons. Further, downstream costs should be considered, but due to the lack of long-term follow up data any potential downstream costs or savings are speculative. 4.1 Budget Impact Alberta Health and Wellness paid over $3 million dollars for hip services in 2006, which has doubled in the last decade (Figure A10). About 64% of this was for services rendered to patients 65 years and older. Although there is some indication that M-MHR is currently being performed to some extent in Alberta, there was no information available to the team on the extent of this practice, how it is being billed, or the proportional costs to Alberta Health and Wellness and the Health Regions performing M-MHR. a Costs are in 2005/2006 Canadian dollars. Inflation was calculated using the Bank of Canada inflations calculator ( and currency converter ( 5/4/2007 page 9

10 An analysis in Ontario assessing a M-MHR policy for individuals needing a THR who are under the age of 55 showed that the net budget impact over a 5-year period is expected to range from $500,000 to $4.7 million 5. Nonetheless, without better data on effectiveness and the target population, it is difficult to develop a reliable estimate of budgetary impact Cost-Utility There is wide variation in cost-utility assessments of M-MHR. The Alberta Hip Improvement project estimated the cost-utility of M-MHR of $4,827 per quality-adjusted life year (although the comparator was unclear, thus suggesting that this is not referring to the incremental cost-utility) 9. A cost-utility analysis from the UK compared M-MHR to THR and watchful waiting followed by THR in both the younger, more active population and the older, more active population. The analysis found that THR proved to be a better procedure (yielded better health outcomes and was less costly) than M-MHR for both younger and older active patients. However, M-MHR was likely to yield better health outcomes and be slightly more expensive than watchful waiting followed by THR for younger, more active patients (approximately $20 to $2000 per quality-adjusted life year, with longer time horizons becoming more cost-effective and potentially cost saving) 4. Uncertainty in outcomes, especially long-term outcomes, means that estimates of costeffectiveness are based on assumptions and not on reliable evidence. Cost-utility analyses to date have shown that the estimated revision rate accounts for a large degree of variation in the study results 3, therefore better long-term data of effectiveness are required in order to reliably assess the long-term cost-utility of M-MHR. 5. CONCLUSION THR is a commonly used surgical intervention to treat degenerative hip disease. The employment of M-MHR could potentially reduce the rates of revision and improve patient outcomes for younger more active patients. Nonetheless at this point in time, there is no compelling evidence that M-MHR will greatly reduce revisions and improve patient outcomes in the long-term; therefore, the actual clinical benefit of these prostheses remains unknown. The body of literature on M-MHR is limited in both quality and scope. Long-term safety (especially with regards to metal ion release) and efficacy data are not available beyond 4 years. The selective inclusion of patients and small sample size of these studies do not allow for comparisons among patients subgroups, therefore restricting any inference about the groups of patients who are the most likely to benefit from M-MHR, and what the appropriate clinical indications for M-MHR should be. No reductions in short-term mortality, other adverse events, or costs have been unequivocally demonstrated. The primary potential benefits of M-MHR lie in the expected short-term improvement in patient outcomes and the expectation that M-MHR could cost less in the long-term. Based on the current evidence many concerns remain unanswered and the outcomes of 5/4/2007 page 10

11 widespread adoption of M-MHR are uncertain. It is clear that M-MHR should not be considered a preferred treatment for all patients; however M-MHR could be beneficial (and indeed cost less) for certain patient groups. Appropriate patient groups and/or clinical indications for M-MHR remains unclear; suggesting that un-biased, comparative studies (likely RCTs) should be undertaken, with due regard to appropriate clinical indications/candidates, incremental effectiveness, and long-term follow-up. Further, an economic analysis is necessary to fully assess the opportunity cost of M-MHR. 5/4/2007 page 11

12 APPENDIX Table A1: Description of the Health Services Codes Included for Hip Disease Procedures in Alberta Health Service Description Code 92.8 B Arthroscopy (Arthroscopy, hip-diagnostic) 92.8 C Arthroscopy (Arthroscopy, hip, therapeutic intervention, including debridement/drilling, etc.) Arthrodesis of hip 93.59A Other total hip replacement (Total hip arthroplasty) 93.6 A Other arthroplasty of hip (Resection arthroplasty of hip) 93.6 B Other repair of hip (Surgical hip dislocation with trochanteric flip, osteochondroplasty +/- labral repair) 93.69A Other repair of hip (Congenital dislocation of hip with acetabuloplasty or iliac osteotomy, or shelf) 93.69B Other repair of hip (Hemiarthroplasty hip with uncemented prosthesis) 93.69C Other repair of hip (Hemiarthroplasty hip with cemented prosthesis) 93.99PC Total hip arthroplasty, physician first assistant 93.99PD Total hip arthroplasty, nurse first assistant Source: Alberta Health and Wellness, Figure A2: Trend of Number of Hip Disease Procedures in Alberta: Number of Procedure Services Year Source: Alberta Health and Wellness, /4/2007 page 12

13 Figure A3: Total Hip Disease Procedures in Alberta by Health Region: 2006 Number of Procedure Services 1,400 1,200 1, Chinook Palliser Calgary David Thompson East Central Health Region Capital Aspen Peace Country Northern Lights Source: Alberta Health and Wellness, Figure A4: Total Hip Disease Procedures in Alberta by Gender: 2006 Female, 59.3% Male, 40.7% Source: Alberta Health and Wellness, /4/2007 page 13

14 Figure A5: Total Hip Disease Procedures in Alberta by Age Group: to 25, 0.6% 26 to 50, 7.2% 65 & Older, 66.1% 51 to 64, 26.1% Source: Alberta Health and Wellness, Figure A6: Total Hip Disease Procedures in Alberta by Procedure Type: 2006 Total hip arthoplasty, 74.4% Hemiarthoplasty, 23.7% Other, 1.1% Source: Alberta Health and Wellness, Arthoscopy, 0.8% 5/4/2007 page 14

15 Table A7: Types of Metal-on-Metal Hip Resurfacing Device Name Manufacturer Conserve Plus Wright Medical Technology Birmingham Hip Resurfacing (BHR) Smith & Nephew (formerly Midland) Cormet Corin Medical, Ltd. Durom (Bonesave in the UK) Zimmer Articular Surface Replacement (ASR) Depuy (a division of Johnson and Johnson) ReCap Femoral Resurfacing System Biomet ADEPT Finsbury Orthopedics, Ltd N/A ICON N/A Nemoto Shokai (Japan) and Tornier (France) Source: 11 Table A8: Devices approved for use in Canada by Health Canada (as of 2005) Device Name Approval Date Birmingham Hip Resurfacing 2002 Conserve Plus 2004 ReCap Femoral Resurfacing System 2004 Durom Hip Resurfacing 2003 (special access approval) Cormet (special access approval) Articular Surface Replacement 2004 (special access approval) Source :CCOHTA, /4/2007 page 15

16 Table A9: Main Findings of Reviews Review source Safety Efficacy/Effectiveness Costs (date) Type of review Alberta Bone and Joint Health Institute, (2006) 9 Technote/ primary research - consequence of metal ion release unclear - 3 month follow-up no significant difference in effectiveness of M-MHR vs. THR - revision rates of M- MHR vs. THR uncertain - long-term cost-effectiveness unknown -2004/05 CoC THR most cost-effective for patients <56 years in year 1 - M-MHR total implant cost Medical Advisory Secretariat, Ontario Ministry of Health & Long-term Care, (2006) 5 HTA Wyness, L. et al. (2004) 12 Systematic Review Alberta Heritage Foundation for Medical Research (2002) 2 Technote Vale, L. et al. (2002) 4 Systematic Review/ HTA - insufficient evidence regarding risk of cancer and cobalt cardiotoxicity - femoral neck fracture not common (0.4%-2.2% in shortrun) - improvements in health outcomes from baseline - high survival - case-series evidence shows M-MHR to be effective in younger patients (in short-run) - revision rates 0.3%-3.6% at years - N/A - sparse effectiveness data - relative effectiveness uncertain - only short-term data available - no firm conclusions can be made - risk of complication comparable to THR - some concern of metal toxicity and increased risk of cancer - no controlled comparative studies - inadequate follow-up - N/A - no comparative evidence - revision rates of 0-14% at 3-years - 91% pain-free at 4 years $11,661-5 year net budget impact $500,000 - $4.7 million - M-MHR total implant cost $15,000 - cost-effectiveness uncertain - UK device cost $4,500- $5,000 and procedure cost $12,000 - THR more effective and less costly than M-MHR - M-MHR more effective and less costly than watchful waiting at 20 years for patients <65 years National Institute for Clinical Excellence, (2002) 3 Technology Appraisal Guidance National Horizon Scanning Centre, (2000) 6 Horizon scanning review - limited data on dislocation rates but expected to be minimal (0.05%) - few complications reported by literature - no randomized evidence - limited evidence on time to device failure - revision (THR and M- MHR) ranges from 0%- 14.3% - N/A - lack of controlled trials and inadequate follow-up - high survival - good health outcomes - manufacturer costeffectiveness analysis at 5 years for <65 years found the incremental cost per quality adjusted life year $35,000 - cost-effectiveness uncertain 5/4/2007 page 16

17 Figure A10: Trend of charges to Alberta Health and Wellness for Hip Disease Procedures: Procedure Amount Paid Year Source: Alberta Health and Wellness, /4/2007 page 17

18 REFERENCES (1) Agency for Healthcare Research and Quality. Horizon Scan on Hip Replacement Surgery (2) Alberta Heritage Foundation for Medical Research. Metal-on-metal hip resurfacing for young, active adults with degenerative hip disease. Edmonton: Alberta Heritage Foundation for Medical Research (AHFMR) 2002;16. (3) National Institute for Clinical Excellence. Guidance on the use of metal on metal hip resurfacing arthroplasty. Systematic review (4) Vale L, Wyness L, McCormack K, McKenzie L, Brazzelli M, Stearns SC. A systematic review of the effectiveness and cost-effectiveness of metal-on-metal hip resurfacing arthroplasty for treatment of hip disease. Systematic review (5) Ontario Ministry of Health and Long-Term Care. Metal-on-metal total hip resurfacing arthroplasty: health technology policy assessment. Systematic review (6) National Horizon Scanning Centre. Metal on metal resurfacing hip arthroplasty (hip resurfacing) - horizon scanning review. Birmingham: National Horizon Scanning Centre (NHSC) 2000;6. (7) Canadian Coordinating Office for Health Technology Assessment. Minimally Invasive Hip Resurfacing (8) Vendittoli PA, et.al. A prospective randomized clinical trial comparing metal-onmetal total hip arthroplasty and metal-on-metal total hip resurfacing in patients less than 65 years old. Hip International 2006;16:S73-S81. (9) Alberta Bone and Joint Institute. Metal-On-Metal Hip Resurfacing for Young Active Adults with Degenerative Hip Disease (10) Alberta Health and Wellness. Hip Codes Data (11) Hip Resurfacing Surgery. ActiveJoints 2007;Available at: URL: (12) Wyness L, Vale L, McCormack K, Grant A, Brazzelli M. The effectiveness of metal on metal hip resurfacing: a systematic review of the available evidence published before BMC Health Serv Res 2004 December 27;4(1):39. 5/4/2007 page 18