Charnley arthroplasty in osteoarthritis secondary to congenital dislocation or subluxation of the hip.

A follow-up study was made on 129 consecutive Charnley arthroplasties in osteoarthritis secondary to congenital dislocation of the hip. The acetabular component was placed as far distal as possible using a standard technique. Bone grafting was not performed. The survival of the prostheses was assessed by the survivorship method. The cumulative survival rate of the prostheses was 93% after five years, 89% after ten years, and 80% after 15 years. In 77% of the cases the acetabular component had been placed in the true acetabulum or levels the rate of mechanical loosening of the acetabular levels the rate of mechanical loosening of the acetabular component (revisions and acetabular components showing a radiolucent line of increasing width) was 13% compared with 42% in the group where the acetabular component was placed proximal to the roof of the true acetabulum (p less than 0.005).