Psoriatic arthritis (PSA) is an inflammatory arthropathy associated with psoriasis, mainly accumulating in the distal interphalangeal and spinal joints. The peak age of onset is 40 years, and the prevalence is similar in men and women; joint involvement in PSA is usually asymmetric, with joint destruction and deformity, and rheumatoid factor is usually negative. Clinical manifestations: 1. symmetrical polyarticular type; 2. asymmetrical oligoarticular type; 3. distal interphalangeal (toe) arthritis type; 4. destructive arthritis type 5. spondyloarthropathy type: manifestation of spondylitis and sacroiliac joints mainly, but often accompanied by peripheral arthritis, especially HLA-B27-positive people often belong to this type, mainly based on X-ray typical performance to aid the diagnosis. The sacroiliac joint is often different from AS, often with unilateral involvement and paraspinal ossification of the right spine. For people with psoriasis, if they have low back pain from time to time, they can go to the pain department or rheumatology department of the hospital for consultation. If they are found to have sacroiliac joint lesions at the same time, it often indicates psoriatic arthritis.