Seronegative spondyloarthropathy or spondyloarthropathy (SpA) is a group of interrelated multisystemic inflammatory diseases characterized by a familial tendency to cluster and a negative serum RF with mesial and/or peripheral joint involvement, and is associated with HLA-B27 There are varying degrees of correlation. Within the context of SpA, currently recognized diseases include the prototype of SpA, ankylosing spondylitis (AS), as well as reactive arthritis (ReA), Rett syndrome (RS), psoriatic arthritis (PsA), inflammatory bowel disease (IBDA), juvenile spondyloarthropathy (JSpA), leukoarthrosis (BD), and Whipple disease (intestinal lipid disorder), SAPHO syndrome (synovitis, acne, pustulosis, osteochondrosis and osteitis syndrome) and a group of unclassified spondyloarthropathies (uSpA). Table 3-8 SpA classification criteria for (ESSG, 1991) inflammatory spondylodynia or asymmetric synovitis predominantly of the lower extremities, plus at least 1 of the following: 1. positive family history (AS, psoriasis, ReA, inflammatory bowel disease); 2. previous or current psoriasis as diagnosed by a physician; 3. previous or current inflammatory bowel disease as diagnosed by a physician and confirmed by radiology or colonoscopy; 4. within A history of urethritis or cervicitis (non-gonococcal) or acute diarrhea within 1 month prior to arthritis; 5. Alternating pain in the right and left buttocks; 6. Previous or current tendon attachment point inflammation (e.g., pain at the heel or metatarsal key attachment, i.e., heel pain); 7. Bilateral grade 2 to 4 or unilateral grade 3 to 4 sacroiliac arthritis. The sensitivity of this criterion is said to be 87.0%, and the specificity is 86.7%. SpA diagnostic criteria (Amor, 1991) 1. clinical symptoms or past history ① nocturnal back or back pain, or morning stiffness (1 point); ② asymmetric oligoarthritis (2 points); ③ hip pain (1 point); if alternating right and left hip pain (2 points); ④ salami-like fingers (toes) (2 points); ⑤ heel pain or other definite tendon attachment point pain (2 points); ⑥ iritis (2 points); ⑦ occurrence of History of non-gonococcal urethritis or cervicitis within 1 month prior to arthritis (1 point); ⑧ History of acute diarrhea within 1 month prior to arthritis (1 point); ⑨ Psoriasis, glomerulitis or inflammatory bowel disease (ulcerative colitis or segmental ileitis) (2 points). 2, radiological manifestations Sacroiliac arthritis (bilateral grade 2-4 or unilateral grade 3-4) (2 points). 3. Genetic background HLA-B27 positive or family history of AS, ReA, iritis, inflammatory bowel disease (2 points). 4.Response to treatment The symptoms improve significantly within 48 hours after taking NSAIDs, but relapse soon after stopping (2 points). The above 12 points ≥ 6 can be diagnosed as SpA. uSpA is defined as a patient with clinical and/or radiological changes suggestive of SpA and not meeting any of the definite SpA diagnostic criteria. uSpA should be considered in patients with asymmetric arthritis of the lower extremities and/or with inflammatory spondylolisthesis without diarrhea, psoriasis, inflammation of the attachment points and without alternating hip pain and a positive family history. uSpA patients diagnosed with uSpA should be followed for a long time, as some patients may eventually be diagnosed with some kind of SpA (e.g., AS, etc.) as their disease progresses. For a definitive diagnosis, a thorough medical history should be taken, including a positive family history of low back and leg pain from early childhood.