Preliminary results of partial surface replacement of the femoral head in osteonecrosis

We report our initial results using a partial surface replacement for osteonecrosis of the femoral head. We believe the prosthesis has the most minimalist design that has been reported either in Europe or North America. The surgical technique, implant design, and instrumentation cause minor soft tissue disruption and require little bony resection. We report the results of our first 25 prostheses performed over the past 5 years in 19 patients. The mean age was 42.5 years, (range, 24-59 years), with a preoperative Ficat classification of 15 hips, stage III; 9 hips, stage IV; and I hip, stage II. For the surviving prostheses, mean follow-up was 43 months, (range, 20-60 months). Of these 19 surviving implants, 15 continue to function well with excellent or good hip scores according to the Merle d'Aubigne system. We have had 6 failures: 1 owing to technical error, 4 owing to local tissue factors, and 1 owing to a progression of the osteonecrosis. The parameters for the use of this prosthesis are defined with our increasing experience, and the prosthesis is compared with other prosthetic implants available. In comparison with alternative techniques, the operative surgery is straightforward requiring little preoperative planning; immediate weight bearing is allowed postoperatively. Should failure occur, little bone stock loss is incurred, and revision to a total hip replacement is as simple as primary hip arthroplasty.