Objective    To evaluate the intermediate-term efficacy of total hip arthroplasty (THA) in the management of ankylosing spondylitis (AS).     Methods    THA was performed in 26 hips of 17 AS patients

and the patients were followed up for average 3.8 (ranging 2 to 7 ) years. The clinical outcomes were evaluated by the Harris hip scoring system

radiographic analysis by Gruen’s zonal method for the stem and the zonal classification of Delee and Charnley for the cup implants.     Results    The average Harris hip score improved from preoperative 27 (ranging 4 to 47) to 81.3 (ranging 57 to 90) at the final postoperative evaluation. The overall clinical outcomes were rated as good or excellent in 88.5%. There were no signs of loosening

dislocation or fracture of the prosthesis. According to the system of Brooker

the incidence of heterotopic ossification was 15.3% (4 hips).     Conclusion    Our intermediate-term follow-up indicates THA is an effective method for AS patients to reconstruct the function of hip joint.