Case of the Week – Ankylosing Spondylitis

A 45 year old man with a history of low back pain is referred to you for further management and pain control.  His X-ray is provided.

What do you think he has and what therapy would you suggest?

This X-ray is suggestive of ankylosing spondylitis (AS). AS isa sero-negative arthritis, which means that you would not expect to see Rheumatoid Factor positivity.  AS is part of a larger family of conditions called “Spondylarthropathies” which also includes: reactive arthritis, psoriatic arthritis, IBD associated, juevenile spondylarthritis, and undifferentiated.

Common presenting manifestations include joint stiffness and low back pain (for those with Axial involvement), which is improved with activity and worse first thing in the morning.

Radiographically, AS is characterised by inflammation and new bone formation (also known as ankylosis).  This can present as:

Lumbar X-Ray
Case courtesy of Dr J Yeung From the case
  • Sacroiliac joint involvement:
    • Joint space widening is an initial sign, however narrowing occurs later.
    • Subchrondral erosions, sclerosis and proliferation
    • Late stage: joint fusion
  • Small erosions at the corners of vertebral bodies (“Shiny Corner sign”)
  • Vertebral Squaring
  • Syndesmophytes form in spinal ligaments causing “bamboo spine”
  • Ossification of other spinal ligaments, joints and discs
  • Fragility fractures

Management of Ankylosing Spondylitis:

The goal of treating ankylosing spondylitis is to manage symptoms, improve quality of life and prevent complications of spinal disease.

Smoking cessation is very important as it can lead to poor functional outcomes in patients with AS.

Non steroidal anti-inflammatory agents are first line therapy and may be sufficient for many patients. If patients have ongoing symptoms of their disease, they should be using NSAIDs continuously. When symptoms clear, there is conflicting evidence about whether NSAIDs should be continued between flares.

Second line therapy for AS that does not respond to NSAIDs are TNF Alpha antagonists. Other immunosuppressive medications like steroids and methotrexate are not typically used.



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