Abstract
Introduction
Hip resurfacing arthroplasty (HRA) has seen a recent revival with third generation Metal-on-Metal prostheses and is now widely in use. However, safety and effectiveness of hip resurfacing are still questioned. We systematically reviewed peer-reviewed literature on hip resurfacing arthroplasty to evaluate implant survival and functional outcomes of hybrid Metal-on-Metal hip resurfacing Arthroplasty.
Method
Electronic databases and reference lists were searched from 1988 to September 2009. Identified abstracts were checked for inclusion or exclusion by two independent reviewers. Data were extracted and summarized by one reviewer and verified by a second reviewer. Main study endpoint was implant survival, which we compared with the National Institute of Clinical Excellence (NICE) benchmark. We also evaluated radiological and functional outcomes, failure modes and other adverse events.
Results
We identified 433 articles, of which 24 met the inclusion criteria. Data were extracted from these 24 articles, totalling 8745 resurfaced hips, providing details on five out of 11 resurfacing devices on the market. Maximum follow up was 9 years, mean follow up ranged from 0.6 to 8 years. Implant survival ranged from 88.7% to 100%. Of the 8745 hips, 276 were revised (3.2%), with fracture of the femoral neck as most frequent failure mode. With implant survival plotted against time, 10 studies showed satisfactory implant survival percentages compared to the 3 year NICE entry-benchmark. Nine of these 10 studies used the BHR implant, the other study used the Cormet 2000 implant.
Discussion
None of the HRA implants used to date meet the full 10 year NICE benchmark (≥ 90% survival at 10 years follow up). If follow up is too short for the full benchmark, implants are still recommendable if they meet the NICE three year ‘entry benchmark’ (> 3 year revision rate experience, consistent with the 10-year benchmark). Compared to the 3 year NICE entry-benchmark, 10 studies showed satisfactory implant survival percentages. Nine used the BHR implant, the other study used the Cormet 2000 implant. The quality of evidence is low according to the GRADE classification. Future research has to address the most important failure mode for HRA trying to explain the large variation in the frequency of femoral neck fractures.
