Noninfective arthritis
Ankylosing spondyloarthritis (AS)

Author: Vijay Shankar, M.D. (see Authors page)

Revised: 28 August 2017, last major update April 2013

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Ankylosing spondyloarthritis [title]

Cite this page: Shankar, V. Ankylosing spondyloarthritis (AS). website. Accessed August 19th, 2018.
Definition / general
  • Chronic inflammatory disease of axial joints, especially sacroiliac
  • Affects teenage boys, 90% are HLA-B27 positive
  • M:F: 2-3:1
  • Typically involves sacroiliac joints and slowly ascends
  • Chronic synovitis destroys articular cartilage and causes bony ankylosis
  • Inflammation of tendinoligamentous insertion sites cause osteophytes
  • CD3+ T cells and CD68+ macrophages are main inflammatory cells
Clinical features
  • Symptoms: low back pain that gets progressively worse
  • Reactive bone formation may be seen in ring apophysis with erosions of margins
  • Calcification of posterior longitudional ligament is seen
  • In later stages spine appears fused with fixed kyphosis (Bamboo spine)
  • Complications: uveitis, aortitis, amyloidosis
Case reports
Clinical images

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Anterior flexion