Primary total hip arthroplasty in patients with ankylosing spondylitis

The results of total hip arthroplasty in a group of patients with ankylosin g spondylitis are described. Ninety-five arthroplasties were performed in 5 6 men and 2 women whose average age at operation was 38.9 years (standard d eviation [SD], 11.6; range, 19.2-78.8). They were followed for an average o f 135.4 months (SD, 81.6; range, 24.4-331.2), We encountered 4 deep infecti ons necessitating the removal of prostheses. Two of 3 dislocations were ant erior dislocations. Nineteen arthroplasties were revised at an average of 1 62.0 months (SD, 49.6; range, 55.1-250.5) after the primary surgery; 9 of t hem had only the acetabular component revised because of aseptic loosening. Hyperextension of the hips is a common phenomenon that can lead to surgica l error and predispose the prosthesis to anterior dislocation.