Risk factors affecting radiological failure of the socket in primary Charnley low friction arthroplasty. A 10- to 20-year followup study.

To identify the factors affecting Hodgkinson Type 3 or 4 radiological demarcation (presence of complete demarcation or migration, respectively) of the Charnley socket, 328 sockets with 10- to 20-year followup were studied. Fifty-five sockets (16.8%) developed Type 3 or 4 demarcation. In the osteoarthrosis group (237 sockets), removal of eburnated bone at the acetabular roof, the presence of large acetabular angles before and after surgery, and high placement of the socket were related to development of Type 3 or 4 demarcation. In the rheumatoid group (32 sockets), young patient age predisposed the socket to Type 3 or 4 demarcation. Rapid polyethylene wear, correlated with young age, male gender, and thin cement mantle in Zones I and II, was another important factor related to Type 3 or 4 demarcation in both groups and in the entire series. These risk factors should be taken into account when assessing the indications for arthroplasty, when performing arthroplasty, and when educating the patient.