Activity and socket wear in the Charnley low-friction arthroplasty.

A clinical study was undertaken to assess the influence of patient-related factors on wear of the socket in Charnley low-friction arthroplasty. One hundred nine arthroplasties in 79 patients were reviewed at an average of 10.3 years. A new method of activity assessment was designed and used to estimate the distance walked by each patient. This method was validated by a pedometer that recorded the time taken by each patient to walk 20 m. Activity level was related to the amount of movement at the level of the prosthetic articulation by calculating the sliding distance of a point at the center of the surface of the head of the femoral component. Wear was found to correlate with patient activity, but not with the physical characteristics of the patient or the time since operation.