To report the minimum 4 year follow up results of metal on metal hip resurfacing arthroplasty.

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.

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).

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.