Ten-Year Results of the BIRMINGHAM HIP Resurfacing Implant System
There have been 3 historic cycles of interest in surface replacement of the hip in the last 40 years. The second cycle occurred in the 1980s into the 1990s, when very high failure rates were reported. Biomaterial and design advancements fueled the most recent cycle of interest, which began 12 to 15 years ago. However, the enthusiasm that occurred at the advent of this most recent cycle ebbed as it became increasingly apparent that patient selection is critical and that the fairly difficult hip resurfacing procedure requires experience to reproducibly place the implants correctly.
In the latest issue of JBJS, Su et al. report the 10-year results of the post-market-approval study of the BIRMINGHAM HIP Resurfacing (BHR) implant system, a metal-on-metal system approved by the U.S. Food and Drug Administration in 2006. The study included a cohort of 280 hips (253 patients) undergoing primary BHR procedures across 5 sites. The mean patient age at the time of surgery was 51 years; 74% of the BHRs were implanted in male patients, and 95% of the hips had a diagnosis of osteoarthritis.
Among the findings:
- 10-year survivorship free from all-cause component revision was 92.9%. Among male patients <65 years of age at the time of the procedure, the rate was 96%.
- Twenty hips underwent revision (at a mean of 5 years).
- Whole-blood cobalt and chromium levels were higher at 1 year after surgery compared with preop levels; they remained stable through 5 years, and then decreased somewhat at 10 years.
- Improvements in the EQ-5D visual analogue scale score and Harris hip score were noted at 1 year and were maintained through 10 years.
These outcomes are encouraging, but as Su et al. point out, the cohort is not representative of typical total hip arthroplasty populations, who tend to be older and include a greater percentage of female patients. Moreover, the surgeons who performed the procedures were all experienced. Patient selection remains key, with younger male patients being the best candidates. Data such as these can help sharpen our focus as we refine arthroplasty concepts for further improvement in patient outcomes.
For additional perspective on this study, see the commentary by Timothy S. Brown, MD.
Marc Swiontkowski, MD