Overview

Ankylosing spondylitis is a HLA-B27 associated spondyloarthropathy. It typically presents in males (sex ratio 3:1) aged 20-30 years old.

Features

• typically a young man who presents with lower back pain and stiffness of insidious onset
• stiffness is usually worse in the morning and improves with exercise
• the patient may experience pain at night which improves on getting up

Clinical examination

• reduced lateral flexion
• reduced forward flexion - Schober's test - a line is drawn 10 cm above and 5 cm below the back dimples (dimples of Venus). The distance between the two lines should increase by more than 5 cm when the patient bends as far forward as possible
• reduced chest expansion

Other features - the 'A's

• Apical fibrosis
• Anterior uveitis
• Aortic regurgitation
• Achilles tendonitis
• AV node block
• Amyloidosis
• and cauda equina syndrome
• peripheral arthritis (25%, more common if female)