We reviewed the clinical and radiological outcomes of total hip arthroplasty and bipolar hemiarthroplasty for avascular necrosis of the femoral head.

From January 1986 to December 1989, 24 cases were treated with total hip arthroplasty and 27 cases with bipolar hemiarthroplasty for avascular necrosis of the femoral head. Clinical outcomes were assessed using Harris Hip Score. Serial radiographs of the hip were used to assess stability of the femoral component, change of the acetabular cup angle, osteolysis of acetabulum or femur, wear of polyliner and erosion of the acetabular cartilage.

The average Harris Hip Score was 93.1 in bipolar hemiarthroplasty group and 86.8 in total hip arthroplasty group at last follow up. Femoral osteolysis was observed in 17 patients of 24 total hip arthroplasties and in 14 patients of 27 bipolar hemiarthroplasties. Acetabular osteolysis was observed in 8 cases of 24 total hip arthroplasties. Revision was undertaken 8 cases (33.3%) in the total hip arthroplasty group and 6 cases (22.2%) in the bipolar hemiarthroplasty group. The main causes of revision were wear of polyliner and severe osteolysis in the total hip arthroplasty group and erosion of the acetabular cartilage in the bipolar arthroplasty group.

The main cause of failure after total hip arthroplasty for avascular necrosis of the femoral head was using a 32 mm femoral head and a polyliner less than 8mm thickness.