Factors influencing survival of the socket after primary low-friction arthroplasty of the hip.

Two hundred and sixty-seven consecutive primary low-friction arthroplasties, followed for 5 to 18 years after surgery, were studied to assess the factors influencing survival of the socket, using the Kaplan-Meier method. The end point of survival was defined radiologically in two ways: incipient failure (migration of 3 mm or more or rotation of 4 degrees or more) and definite failure (progressive change of position). Twenty-four sockets (9.0%) developed incipient failure, and 14 of them progressed to definite failure. Preservation of the subchondral bone plate or eburnated bone in the acetabular roof, multiple 6-mm anchor holes, and two steps of evolution in socket design (the advent of a pressure-injection socket and than an ogee-flanged socket) benefited socket survival. Polyethylene wear was considered to be the most important factor limiting longevity of the socket.