Socket wear in Charnley low friction arthroplasty of the hip.

Five hundred forty-seven Charnley hip arthroplasties were measured for wear radiographically after an average period of 8.3 years. The operations were performed in 1967 and 1968 and the average rate of wear was 0.07 mm per year. This is only half that recorded for the operations in 1963, 1964, and 1965. Clinical radiographic methods of measuring socket wear are valid provided that the socket is inserted with the wear marker not more than 10 degrees from the coronal plane. This can be estimated provided that radiopaque cement is used.