Clinical and radiographic features of spondylitic hip disease.

The clinical and radiographic features of hip disease in 76 patients with definite ankylosing spondylitis have been studied. Symptomatic hip involvement occurred late in the course of the disease, with a mean delay after the onset of 12 years in males and 7 years in females. Patients with disease onset before the age of 20 developed hip symptoms at an earlier stage. Associated diseases included uveitis (13%), colitis (4%). Bilateral concentric loss of hip joint space with a relatively undeformed femoral head was the commonest radiological change (61%). Localised loss of joint space at the upper pole (16%) was associated with femoral head destruction and a greater degree of osteophytosis, suggesting coincidental or secondary osteoarthrosis. Bony ankylosis of the hips (10%) was present only in women, and the absence of osteophytes, cysts, and bone lesions of the iliac crests and ischial rami suggests that it is a distinct radiographic manifestation of female ankylosing spondylitis.