Abstract
Bipolar hip arthroplasty was performed without bone graft on 15 hips of 13 RA patients with acetabular cartilage which conserved the surface without destruction. The mean age was 58 years (range 44-76), and the mean disease duration was 17.4 years (range 3-59) . Postoperative observation was done for a mean of 3.1 years (range 5 months-5 years) . We analyzed the clinical features using the hip rating score of the Japanese Orthopaedic Association and the Lansbury Index. Furthermore, we assessed roentogenographic features by measuring the KC length, which indicates medial migration, the TC length, which indicates upward migration of the outer head, and the CE angle.
Improvement of hip score was obtained postoperatively. The Lansbury Index did not change dramatically during the five years after the operation. The KC length decreased in 36% of the patients, and the TC length increased in 58%, with 27% showing an increase of more than 5° in the CE angle. These results may indicate that bipolar hip arthroplasty for RA patients who had had intact acetabular cartilage induced medial and upward migration of the outer head in some cases. But since other cases did not show any medial and upward migration for five years, we must study the etiology of such migration and determine more precisely the indication of bipolar hip arthroplasty without bone graft for RA patients.
