Metal-on-metal hip resurfacing with an uncemented femoral component. A seven-year follow-up study.

BACKGROUND Metal-on-metal hip resurfacing with hybrid fixation has been introduced as an alternative to standard total hip arthroplasty, especially for young and active patients. There are few studies in the literature on the midterm results of cementless femoral side resurfacing. The purpose of this study was to present our seven-year clinical results of a series of twenty cementless metal-on-metal hip resurfacing procedures. METHODS Between 1999 and 2000, eighteen patients (twenty hips) underwent primary metal-on-metal hip resurfacing with uncemented femoral and acetabular components. One patient was lost to follow-up. This left eleven men and six women, who had a mean age of forty-five years at the time of surgery. Clinical and radiographic examinations were performed prospectively, and the results were analyzed. RESULTS The mean duration of follow-up was 7.4 years. There were four revisions, none of which was due to aseptic failure of the femoral component. Two were due to loosening of the acetabular component, one was due to a late hematogenous infection, and one was due to persistent pain despite normal radiographic findings. The mean preoperative Harris hip score was 54 points, and it increased to 94 points at the time of the last follow-up. Radiographic examination of the hips for which the procedure was successful revealed no femoral or acetabular radiolucencies, no migration of any implant, and no osteolysis. The radiographs of one patient (two hips) showed substantial narrowing of the femoral necks (a mean of 12%), which stabilized at three years postoperatively. This patient had a Harris hip score of 100 points for both hips at six years. CONCLUSIONS This study suggests that cementless femoral fixation may be a viable alternative to fixation with cement in metal-on-metal hip resurfacing. Further study of this concept in larger numbers of patients is warranted.