Total hip arthroplasty for bilaterally ankylosed hips.

The purpose of this study was to evaluate the results of bilateral total hip arthroplasties (THAs) with special regard to angle of cup position in patients with bilaterally ankylosed hips. Twenty-four ankylosed hips were converted to THAs in 12 patients. Their mean age was 36 years and they were followed up for more than 3 years (average, 11 years). The mean Harris hip score increased from 55.4 to 82.3 points. Osteolysis and loosening were found in 3 and 2 hips, respectively. Eleven cups of 24 hips (46%) were outside the safe ranges of Lewinnek. Overall outcome after bilateral conversion of bilaterally ankylosed hips to THA was favorable, but the fused position of the contralateral limb had the tendency to define the direction of the malposition of the acetabular cup.