128 Ankylosing spondylitis
Salient features
History
• Back stiffness and back pain: worse in the morning, improves on exercise and worsens on rest
• Symptoms in the peripheral joints (in ~40%), particularly shoulders and knees
• Onset of symptoms is typically insidious and in the 3rd–4th decade
• Extra-articular manifestations: red eye (uveitis), diarrhoea (GI involvement), history of aortic regurgitation, pulmonary apical fibrosis (worse in smokers).
Examination
• ‘Question mark’ posture (as a result of loss of lumbar lordosis, fixed kyphoscoliosis of the thoracic spine with compensatory extension of the cervical spine)
• Ask the patient to look to either side: the whole body turns when the patient does this.
• Examine the cervical, thoracic and lumbar spines (remember that cervical spine involvement occurs later in the disease and results in pain and a grating sensation on movement of the neck).
• Measure the occiput-to-wall distance (inability to make contact when heel and back are against the wall indicates upper thoracic and cervical limitation).
• Perform Schober’s test. This involves marking points 10 cm above and 5 cm below a line joining the ‘dimple of Venus’ on the sacral promontory. An increase in the separation of <5 cm during full forward flexion indicates limited spinal mobility.
• Examine for distal arthritis (occurs in up to 30% of patients and may precede the onset of the back symptoms). Small joints of the hand and feet are rarely affected.
• Measure chest expansion with a tape (<5 cm suggests costovertebral involvement).
• Tell the examiner that you would like to examine the following:
