Table 1.

Modified New York criteria for Ankylosing Spondylitis ⁵

A) Clinical criteria Low back pain with stiffness for more than 3 months which improves with exercise but is not relieved with rest. Limitation of chest expansion relative to normal values corrected for age and sex. Limitation of motion of the lumbar spine in both the sagittal and frontal planes.

B) Radiological criteria Sacroiliitis grade ≥ 2 bilaterally Or Sacroiliitis grade 3–4 unilaterally

Definite AS: Radiological criterion with at least one clinical criterion.