ABSTRACT
Sixteen spontaneously ankylosed hips were converted to total hip arthroplasties in 12 patients. The average length of follow up was three years. The predominant indications for conversion were progressively disabling pain in the low back, contralateral hip pain, loss of function due to immobility or malposition of the hip, processive pain and instability of the ipsilateral knee. Many problems were faced in this kind of hip arthroplasty including difficult exposure, tissue contracture, atrophy of hip abductors and distortion of anatomy, especially in patients who developed this ankylosis after infection. Long rehabilitation period should be expected in such cases. The postoperative range of motion was markedly improved. The average arc of flexion for all hips was 85 degrees. The average arc of abduction-adduction was 47 degrees [32 of abduction to 15 degrees of adduction] and the rotational arc averaged 42 degrees [18 degrees of internal rotation to 24 degrees of external rotation]. Three hips in this study were rated as failures