Causes of early failure in a multicenter clinical trial of hip resurfacing

The purpose of this study was to evaluate the clinical outcomes and possible causes of early failure in a multicenter trial of metal-on-metal hip resurfacing. Two hundred patients were prospectively enrolled and followed for an average of 31.2 months (range, 12-54 months). Of 200 patients, 14 (7.0%) required revision surgery at a mean time of 19.5 months (range, 3-47 months). Patients with failures were significantly younger and heavier than the nonfailures, and all were male. Patients who were revised did not differ from those who were not revised in terms of radiographic outcomes, but they did report lower functional outcome scores at all preoperative and postoperative testing intervals. Most failures (10/14) were related to early acetabular loosening. The learning curve was likely a factor in these cup failures. This report highlights the importance of patient selection and surgical technique in hip resurfacing arthroplasty. It is anticipated that further surgical experience will lead to a reduction in this high early failure rate.