Acetabular protrusion and the Monk Duopleet prosthesis in subcapital femoral neck fractures.

A total of 166 patients with acute, displaced subcapital fractures of the femoral neck were treated over a 5-year period with the Monk Duopleet bi-articular prosthesis. The average age at operation was 77.8 years. 81 patients were available for review at an average of 37.1 months after surgery. Radiographic evidence of acetabular protrusion was found in 3 patients (3.7 per cent). This incidence of protrusion is considerably lower than that normally reported for one-piece prostheses such as the Austin Moore or Thompson. The causes of acetabular protrusion are discussed.