Ankylosing spondylitis 1984 New York, USA revised criteria: meeting radiological criteria and more than l clinical criteria, can be diagnosed as ankylosing spondylitis. 1, clinical criteria: ① low back pain and stiffness for more than 3 months, with improvement in activity and no improvement at rest; ② limited activity in the frontal and sagittal planes of the lumbar spine; ③ lower thoracic mobility than normal people of corresponding age and sex. 2, radiological criteria (1966 AS New York standard) ① Grade 0: normal; ② Grade I: suspicious changes; ③ Grade II: mild abnormality, limited erosion and sclerosis visible, but no joint space changes; ④ Grade III: obvious abnormality, moderate or progressive sacroiliac arthritis with one or more of the following changes (erosion, sclerosis, joint space widening or narrowing, or partial ankylosis); ⑤ Grade IV. Severe abnormalities, complete joint ankylosis. Radiological criteria: bilateral sacroiliac arthritis ≥ grade 2 or unilateral sacroiliac arthritis grade 3 to 4.