Effect of activity levels on polyethylene wear in Charnley low-friction arthroplasty

Polyethylene wear debri has been implicated as a major cause of aseptic loosening following total hip replacement. The purpose of this study is to classify patient activity levels following total hip replacement and determine if it has an effect on radiographic wear of the socket. 97 patients (115 hips) with osteoarthritis who underwent Charnley low-friction arthroplasty with a minimum of 10 year follow-up were selected. Nine patients had died. Eighty-eight questionnaires were sent of which 59 replied. However, only 40 patients (45 hips) with a complete set of x-rays were finally studied. Activity levels were classified according to post-operative occupation and activities into 'active' and 'less active' groups. Radiographic wear was measured by studying the post-operative and the 10-year review radiograph. There was a significant difference in acetabular wear between the active and the less active group (p = 0.024). No correlation was found between weight and acetabular wear (p = 0.475) or between age and acetabular wear (p = 0.278). It was concluded, therefore, that surgeons who advise their patients to avoid heavy or high intensity activities for prolonged periods, after Charnley low-friction arthroplasty, are justified in this approach.