Ankylosing spondylitis

Ankylosing spondylitis is a chronic inflammatory disease that primarily affects the axial skeleton, with sacroilitis being the main feature. It is one of the spondyloarthropathies.

It affects more males than females (5:1) 
There is a strong association with HLA B27 (around 95% of patients)

Classic presentation: 
  • Low back pain 
    • Worse in morning 
    • Worse after rest
    • Improves with activity 

  • Restricted flexion and extension of lumbar spine 
    • Schober’s test: 2 marks on patient’s back 10cm apart, with lower mark at level of posterior superior iliac spine normal flexion results in an increase of 5cm or more
  • Loss of lumbar lordosis
  • Increased thoracic kyphosis 
  • Decreased chest expansion 

  • Spinal XR
    • Squaring of vertebral bodies
    • Ossification of spinal ligaments
    • Fusion of vertebral column - ‘bamboo spine’ 
  • MRI 

Extra-articular associations: 
  • Psoriasis
  • Uveitis 
  • Inflammatory bowel disease 
  • Increased risk of cardiovascular disease 
  • Increased risk of osteoporosis 
  • Aortic regurgitation 
  • Pulmonary fibrosis 
  • Cardiac conduction problems 

  • Regular exercise
  • NSAIDs 
  • Anti-TNF therapy
  • No evidence for DMARDs in axial disease, but sulfasalazine may be considered for peripheral arthritis 


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