Ankylosing spondylitis
Radiographic axial spondyloarthritis causing inflammatory back pain, sacroiliitis and progressive structural new bone formation in susceptible people.
Definition
Ankylosing spondylitis is radiographic axial spondyloarthritis with inflammatory involvement of the sacroiliac joints and spine, usually accompanied by characteristic inflammatory back pain and possible extra-articular disease.
First principles
Ankylosing spondylitis is radiographic axial spondyloarthritis
Axial spondyloarthritis is the wider disease spectrum. Ankylosing spondylitis describes radiographic disease in which sacroiliitis meets the modified New York criteria; non-radiographic axial disease can have the same inflammatory symptoms without those X-ray changes. A normal X-ray does not end the assessment when clinical suspicion remains high.
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