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Commonly, total hip prostheses have had a higher neck-shaft angle than the host bone and thus a tendency to reduce the femoral offset. Restoration of the femoral offset may be important as it has been shown to enhance hip stability and to improve the range and strength of abduction. The purpose of this study was to determine which of two designs was best able to restore femoral offset in comparison to the contralateral normal hip. Two hundred and two primary total hip patients were included in a radiographic study. Measurements were taken from a postoperative anteroposterior radiograph of the pelvis. The Synergy femoral component with a more varus neck-shaft angle of 131 degrees and a standard or high offset option tended to restore the femoral offset more reliably than did the Mallory-Head femoral component with a neck shaft angle of 135 degrees.

We reviewed the results of 172 plasma-sprayed, titanium primary total hip arthroplasties inserted without cement and followed 5 to 7 years. Hips were replaced for a wide range of diagnoses and patient ages. No femoral components had been revised nor were considered unstable. Clinical results have been excellent; 88% of hips had either no or a slight amount of pain and only 5% of patients had thigh pain when specifically asked. Radiographically, this femoral component achieved stability after an initial subsidence in 9% of cases. Extensive femoral bone resorption was rare, and distal cortical hypertrophy was commonly seen. Pelvic osteolysis occurred in 16 (9%) cases and was considered major in 10 of these. It was the cause of failure of 3 acetabular components. Femoral endosteal lysis was not observed. We concluded that mechanical stability of the Mallory-Head titanium total hip prostheses is excellent. However, significant pelvic osteolysis has occurred commonly with this implant design, and will continue to pose major reconstructive problems in the future.