Abstract
Thirty-three bipolar revisions with bone-allografting were performed for cavitary acetabular deficiency at revision. We used 80°C heat-treated or freeze-dried bones as allograft. The average follow-up period after surgery was 3 years 9 months (range, 1-10 years 3 months) . The operative time averaged 157 minutes (range, 55-290 minutes) and mean intraoperative blood loss was 648ml (range, 40-1700ml) . Outer head size averaged 42mm before revision and 47mm after it. The mean CE angle after surgery was 22° (range, 2-35°) and the mean medial thickness of the acetabulum after surgery was 15mm (range, 5-25mm) . There were 6 hips with perioperative complications, and 2 hips with postoperative complication without dislocation. Medial migration averaged 3.2mm (range, 0-14mm) and superior migration averaged 3.7mm (range, 0-15mm) at 1 year after surgery. Eventual migration figures were 4.7mm (range, 1-17mm) and 6.6mm (range, 1-18mm) at the last follow-up period. Radiographic evidence showed satisfactory bone incorporation of allograf ts. However, one hip required a second revision at four years after surgery, due to rapid progressive allograft resorption. The clinical score was assessed by the hip rating score of the Japanese Orthopaedic Association, and the mean score increased from 49 preoperatively to 83 points postoperatively at the last follow-up period. These results reveal that a bipolar endoprosthesis with allografts is a useful and safe procedure for cavitary acetabular deficiency at revision.
