Minimum 4 Year Follow-up Results of Metalon Metal Hip Resurfacing Arthroplasty

Abstract

Purpose : To report the minimum 4 year follow up results of metal on metal hip resurfacing arthroplasty. Materials and Methods : 39 hips from 36 patients, who received hip resurfacing from November 1998 to September 2001 and were followed up for at least 4 years, were enrolled in this study. The average age was 45 years (28-69 years) and the average follow up period was 51.9 months (48-82 months). A clinical evaluation was performed with the Harris Hip Score and gait analysis postoperatively. A radiologic evaluation was performed regularly after surgery using anteroposterior and lateral simple radiographs. The post-operative cobalt-chrome serum concentration was measured and compared using 21 cases of ceramic-on-ceramic total hip arthroplasty as a control group. Results : The Harris Hip Score improved from 61 points (31-74) preoperatively to 96 points (85-99) postoperatively. There were no cases of acetabular loosening, and the average angle of femoral insert to the shaft was 136˚ with 22 hips (61.1%) being within 130-140˚. The 4 year follow-up survival rate was 97.4%. The serum cobalt and chrome levels were higher than the control group (p＜0.05). Conclusion : Hip resurfacing showed excellent survival rate after a short-term follow-up, but still requires a long-term evaluation with more cases and further metal ion release studies.