Abstract
Introduction: The results of noncemented press-fit bipolar hip endoprostheses were reviewed in patients with osteonecrosis of the femoral head.
Materials and Methods: Twenty-nine hips in 24 patients with osteonecrosis of the femoral head were studied. The average follow-up period was 12 years and 5 months (range from 9 years 2 months to 17 years 11 months). All hips were classified as stage 3 or 4 (osteonecrosis) before surgery using the classification method of the Japanese Investigation Committee. Acetabular reaming was performed in 5 hips with stage 4 osteonecrosis.
Results: Four prostheses have been revised to a total hip arthroplasty at the time of follow-up examination. The average clinical hip score of Japanese Orthopaedic Association was 88.9 (98–82) with 23 hips rated excellent and good, and 6 hips rated fair. Radiologically, stem subsidence more than 5 mm occurred in 5 hips and stem loosening occurred in 6 hips (21%). Five hips with stage 4 osteonecrosis (3 hips received acetabular reaming, 2 hips in elderly patients with osteoporosis) developed outer head migration more than 4 mm in both superior and axial direction. Osteolytic lesions, seen on 11 hips in the femur and 3 hips in the acetabulum, appeared at an average of 4.2 years postoperatively.
Conclusion: These results suggest that cementless pressfit bipolar endoprosthesis for osteonecrosis demonstrated a high incidence of acetabular protrusio and osteolysis. Cementless THA with a porous coating stem should be recommended for treatment of osteonecrosis of the femoral head.
The abstracts were prepared by Michael A. Mont, M.D. and Lynne C. Jones, Ph.D. Correspondence should be addressed to L. Jones at Good Samaritan Prof. Bldg., Suite 201, 5601 Loch Raven Blvd., Baltimore, MD 21239
