Table 1.

Modified New York criteria for ankylosing spondylitis

A. Diagnosis

1. Clinical criteria

a. Low back pain and stiffness for more than 3 months which improves with exercise, but is not relieved by rest

b. Limitation of motion of the lumbar spine in both the sagittal and frontal planes

c. Limitation of chest expansion relative to normal values corrected for age and sex

2. Radiologic criterion   Sacroiliitis grade ≥2 bilaterally or sacroiliitis grade 3–4 unilaterally

B. Grading

1. Definite ankylosing spondylitis if the radiologic criterion is associated with at least one clinical criterion

2. Probable ankylosing spondylitis if

a. Three clinical criteria are present

b. The radiologic criterion is present without any signs or symptoms satisfying the clinical criteria