What are the New York diagnostic criteria for ankylosing spondylitis (AS)?

Updated: Feb 02, 2021
  • Author: Lawrence H Brent, MD; Chief Editor: Herbert S Diamond, MD  more...
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The New York criteria for the diagnosis of AS, which are based on clinical and radiographic findings, include the following:

  • Limitation of motion of the lumbar spine in all 3 planes

  • History of pain or presence of pain at the thoracolumbar junction or in the lumbar spine

  • Limitation of chest expansion to 1 inch or less, as measured at the fourth intercostal space

Radiographic sacroiliac (SI) changes are graded as follows:

  • Grade 0 – Normal

  • Grade 1 – Suspicious

  • Grade 2 – Minimal sacroiliitis

  • Grade 3 – Moderate sacroiliitis

  • Grade 4 – Ankylosis

The disease progression is a gradual process, and the grading is somewhat subjective.

A definite diagnosis of AS is met if there is (1) grade 3-4 bilateral sacroiliitis with at least 1 clinical criterion or (2) grade 3-4 unilateral sacroiliitis or grade 2 bilateral sacroiliitis with clinical criterion 1 or with both clinical criteria 2 and 3. A probable diagnosis of AS is made if grade 3-4 bilateral sacroiliitis exists without any signs or symptoms that satisfy the clinical criteria.

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