Ankylosing = fusion, stiffness

Spondylitis = inflammation of spine

AS belongs to the group of Spondyloarthropathies, which are seronegative (Rheumatoid Factor -ve). There is chronic inflammation of mainly the spine and sacroiliac joints. This eventually leads to fusion and reduced movement if not adequately treated.


Other spondyloarthropathies:

  - Reactive arthritis

  - Psoriatic arthritis

  - Enteropathic spondyloarthropathy eg. IBD

Prevalence and Aetiology

UK Prevalence is estimated at 0.25-1%, with AS being more common in men. At 16 years, men:women is 6:1; at 30yrs, this ratio is 2:1.

The aetiology is currently unknown, but there is a definite genetic predisposition with >95% of AS patients being HLA-B27 +ve.




Mainly clinical diagnosis


  • FBC - normocytic anaemia
  • ESR, CRP (useful monitoring)
  • HLA B-27


X-Ray + MRI

  • Sacroileitis
  • Erosions
  • Sclerosis
  • Syndesmophytes (bony proliferations due to enthesitis between ligaments and vertebrae. T11-L1 initially)
  • Romanus lesions ('shiny'corner appearance), anterior erosions.

Diagnosis and Monitoring


  - Physio + Exercise

  - Analgesia

  - NSAIDs eg. Ibuprofen (gives rapid improvement in 48hrs)

  - TNFalpha blockers eg. Etanercept, Adalimumab, Infliximab

  - Bisphosphonates (to prevent osteoporosis)

  - Surgery eg. Hip replacement


  - Oxford Handbook of Clinical Medicine 8th edition.

  - British Society for Rheumatology Guidelines for Prescribing TNFalpha blockers in Adults with Ankylosing Spondylitis, July 2004; Dr. Andrew Keat.

  - NICE guidelines TA143: Ankylosing Spondylitis - Adalimumab, Etanercept and Infliximab: guidance, May 2008


  - Physical Medicine and Rehabiliation Board Review, 2004; editor Cuccurullo S.

  - Sieper J, Rudwaleit M, Baraliakos X, Brandt J, Braun J, Burgos-Vargos R, Dougados M, Hermann K-G, Landewe R, Maksymowych W, van der Heijde D. The Assessment of SpondyloArthritis international Society (ASAS) handbook: a guide to assess spondyloarthritis. Ann Rheum Disease 2009, Vol 68 supplement.


  - Tam LS, Gu J, Yu D. Pathogenesis of Ankylosing Spondylitis. Nat Rev Rheumatol 2010, Vol 6 p399-405.

  - Maksymowych WP. Disease Modification in Ankylosing Spondylitis. Nat Rev Rheumatol 2010 Vol 6 p75-81.


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