Bipolar hip arthroplasty in ankylosing spondylitis.

Nineteen severely affected hips in 12 young patients with ankylosing spondylitis were treated with bipolar hip arthroplasty followed by a comprehensive postoperative rehabilitation programme. Additional operative procedures of adductor tenotomy, knee flexion release, supracondylar femoral osteotomy for genu valgum and tendo Achillis lengthening for equinus contracture were required in 13 limbs. After a mean follow-up of 45.8 months, results were good in all cases with respect to relief from pain, and there was significant improvement in posture and function. All the patients resumed employment. The average gain in sum total range of hip movements was 194 deg, and the mean preoperative Harris hip score of 27.8 improved to 82.6 after bipolar arthroplasty. Ectopic ossification did not develop in any case. Bipolar hip arthroplasty appears to be ideally suited for young patients with ankylosing spondylitis.