Apophyseal arthritis limits lumbar motion in patients with ankylosing spondylitis.

Ankylosing spondylitis patients who develop progressive spinal flexion may assume this posture to alleviate the pain of apophyseal arthritis. To examine this relationship, we scored injury to L4-L5 and L5-S1 apophyseal joints, as assessed by computed tomography, in 10 men with early ankylosing spondylitis. Both by the modified Schober test and by radiography of the lateral spine, impaired spinal motion correlated highly with evidence of apophyseal injury.