The long-term results of Charnley low-friction arthroplasty in young patients who have congenital dislocation, degenerative osteoarthrosis, or rheumatoid arthritis.J Bone Joint Surg Am 1997; 79(11):1599-617JB
We present the long-term results of 226 Charnley low-friction arthroplasties that were performed with use of cement in 161 patients between 1966 and 1978. Forty-four patients (sixty hips) had congenital dislocation of the hip, fifty-four patients (sixty-six hips) had degenerative osteoarthrosis, and sixty-three patients (100 hips) had rheumatoid arthritis. There were 114 female patients and forty-seven male patients. The average age of the patients at the time of the operation was 31.7 years (range, seventeen to thirty-nine years). Sixty-five patients (40 per cent) had a bilateral hip replacement. Thirty-eight patients (24 per cent; fifty-five hips), twenty-seven of whom had juvenile-onset chronic rheumatoid arthritis, died during the follow-up period. The average duration of follow-up for the entire series until the time of death, revision of both components, or the latest evaluation was 236 months (19.7 years; range, twenty-four to 361 months). Survivorship analysis was performed with the Kaplan-Meier method. At twenty-five years, the survival of the femoral component (with 95 per cent confidence intervals) was 89 per cent (80 to 98 per cent) in the patients who had congenital dislocation of the hip, 85 per cent (77 to 93 per cent) in the patients who had rheumatoid arthritis, and 74 per cent (61 to 87 per cent) in the patients who had degenerative osteoarthrosis. The rate of survival of the acetabular component was lower: at twenty-five years, it was 58 per cent (42 to 74 per cent) in the patients who had congenital dislocation, 79 per cent (70 to 88 per cent) in the patients who had rheumatoid arthritis, and 59 per cent (41 to 77 per cent) in the patients who had degenerative osteoarthrosis. The forty-four patients (sixty hips) who had congenital dislocation had the highest rates of aseptic loosening (twenty-two hips; 37 per cent), migration (seventeen hips; 28 per cent), and revision (twenty-two hips; 37 per cent) of the acetabular component. The fifty-four patients (sixty-six hips) who had degenerative osteoarthrosis had the highest rates of aseptic loosening (seventeen hips; 26 per cent) and revision (eighteen hips; 27 per cent) of the femoral component as well as the highest rate of femoral endosteal lysis (thirteen hips; 20 per cent). The sixty-three patients (100 hips) who had rheumatoid arthritis had the lowest prevalences of loosening and revision of the acetabular component but the highest rates of trochanteric non-union (fifteen hips; 15 per cent) and mortality (twenty-seven patients; 43 per cent). The average rate of wear of the acetabular component for the entire series was 0.11 millimeter per year; the average rate for the revised components (0.19 millimeter per year) was higher than that for the surviving components (0.09 millimeter per year). This was a consistent finding in each of the three diagnostic groups, and an increased annual rate of wear was found to be significantly associated with increased rates of migration and revision of the acetabular component (p < 0.01 for both). The femoral component proved to be durable: the twenty-five-year rate of survival for the entire series was 81 per cent (95 per cent confidence interval, 76 to 87 per cent). The major factors that limited the longevity of the cemented total hip implants in the present study were wear, loosening, and revision of the acetabular component, for which the twenty-five-year probability of survival was 68 per cent (95 per cent confidence interval, 61 to 75 per cent).