Abstract
Bipolar hip arthroplasty was performed on 117 hips with acetabular dysplasia, 100 of them with acetabuloplasty using autograft. The average age of the patients at the time of operation was 59.5 years (range : 19 to 86 ) . The postoperative outcome was followed for an average period of 3.4 years (range: 1 to 6), and the clinical results were assessed by the hip rating score of the Japanese Orthopaedic Association. Postoperative migration of the outer head was measured from serial roentgenograms. Improvement of pain and ROM score reached a plateau within a year whereas improvement of gait score reached a plateau within 2 years. The ADL score gradually improved up to 5 years. The migration of the outer head within the first year was 4.4mm on an average, but the amount of the migration was reduced in the second or third year. While no additional migration was noticed in about 70% of hips after 3 years, in some cases it took 5 to achieve complete stabilization of the acetabulum. In the cases in which the femoral head was pulled down more than 5mm from the original position with the bone graft, the amount of the migration was greater than in the cases in which it was less than 5mm. These results demonstrate that is better to replace the head without grafting the bone at the load-bearing area for the construction of the acetabulum even in dysplastic cases.
