PAPER 016: METAL-ON-METAL TOTAL HIP REPLACEMENT: FOUR TO TEN-YEAR RESULTS

Abstract

Purpose: Metal-on-metal articulations in total hip arthroplasty (THA) have been recently re-introduced for the treatment of osteoarthritis. There have been excellent short-term clinical outcomes reported. The long-term clinical results of these implants are still unknown. In this study, we examined the four to ten -year results of metal-on-metal total hip arthroplasty at our institution.

Method: All patients receiving a metal-on-metal prosthesis were prospectively registered in a computerized database. The period July 1997 – May 2003 was selected for analysis. This group contained 251 cases (207 patients) and had an average follow-up of 6.8 years. Of the 251 implants the femoral head components were either Metasul^™ (203) or Ultamet^™ (48) and the acetubular component Fitek^™ (12), Interop^™ (191) or Pinnacle^™ (48). All patients were assessed with the Harris hip and UCLA activity scores at routinely scheduled follow-up visits. The mean age of patients at surgery was 52 years (18 to 70 years old). The average follow-up was of 6.8 years (4.2–10 years). No patients were lost to follow-up.

Results: The mean UCLA and Harris hip score pre-operatively were 3.6 (1–8) and 42 (15–81), respectively. Values of the UCLA and the Harris hip scores on the most recent follow-up visit were 7.0 (60% of patients had a score equal to or greater than 7) and 85 (70% of patients had a score equal to or greater than 85), respectively. Thirteen hips (5.1%) were revised in total: 1 (0.4%) for early deep infection, 1 (0.4%) for revision of undersized stem and 11 (4.3%) for acetabular revisions due to manufacturing defects. Radiological results showed no osteolysis and 9 non-progressive radiolucency.

Conclusion: At four to ten year follow-up, metal-on-metal total hip replacement provides consistently good clinical and radiographic results with a low revision rate. They provide longstanding pain alleviation and improved function and activity levels in patients suffering from osteoarthritis.