The prevalence of ankylosing spondylitis (AS) is a chronic inflammatory disease that mainly affects the sacroiliac joints, spinal prominences, paraspinal soft tissues and peripheral joints, and is accompanied by extra-articular manifestations in the town, and in severe cases, spinal deformity and ankylosis. The prevalence of AS varies from country to country, with 0.05%-0.2% in Japan and 0.3% in China in a preliminary survey. The ratio of men to women is about 2-3:1, and the onset of the disease is slow and mild in women. The age of onset is usually 13-31 years old, with a peak at 20-30 years old. The etiology of AS is not known. Genetic and environmental factors have been found to play a role in the development of the disease from epidemiological investigations. It has been shown that the development of AS is closely related to human leukocyte antigen (HLA)-B27. and there is a clear tendency for family aggregation. One of the pathological signs and early manifestations of AS is sacroiliac arthritis. The typical manifestation of advanced spinal involvement is a “bamboo-like change”. Synovitis of peripheral joints is histologically indistinguishable from rheumatoid arthritis (RA). Tendinopathy is a characteristic feature of the disease. Clinical manifestations The disease has an insidious onset. Patients gradually develop pain and/or morning stiffness in the low back or sacroiliac region and wake up in the middle of the night with pain. Difficulty in turning over, getting up in the morning or after sitting for a long time, morning stiffness of the lumbar region is obvious when the evidence is given, but it is relieved after activity. Some patients have dull pain in the buttocks or severe pain in the sacroiliac region. Occasional radiation to the periphery. Coughing, sneezing, and sudden twisting of the lumbar pain can be aggravated. In the early stage of the disease, the hip pain is mostly intermittent or alternating on one side, and after a few months, the pain is mostly bilateral and persistent. In most patients, as the disease progresses from the lumbar spine to the thoracic and cervical spine, pain, restricted movement or spinal deformity occurs in the corresponding areas. Hip and peripheral joint lesions occur in 24-75% of AS patients at the beginning or during the course of the disease, with the knee, ankle and shoulder joints predominating, and occasional involvement of the elbow and small joints of the hand and foot. Arthritis of the large joints of the lower extremities is one of the features of peripheral arthritis in this disease. Arthritis or arthralgia in the hip and knee, as well as in other joints, occurs early in the course of the disease and causes little or no joint destruction or disability. The hip joint is involved in 38%-66% of cases, with localized pain, limited motion, flexion contracture, and joint ankylosis, most of which are bilateral, and 94% of hip symptoms begin within the first 5 years after onset. Uveitis occurs unilaterally or bilaterally in a quarter of patients and can be recurrent or even lead to visual impairment. The systemic manifestations of the disease are mild, with a few severe cases having fever, fatigue, emaciation, anemia, or other organ involvement. Plantar fasciitis, Achilles tendinitis, and other sites of tendon telangiectasia are common in this disease. Neurologic symptoms arise from compressive spinal neuritis or sciatica, vertebral fractures or incomplete dislocations, and cauda equina syndrome, the latter of which can cause impotence, nocturnal urinary incontinence, bladder and rectal dullness, and loss of ankle reflexes. Very few patients develop fibrosis of the upper lobe of the lung, sometimes accompanied by cavity formation and mistaken for tuberculosis, or the condition may be exacerbated by concurrent mycobacterial infections. Aortic atresia and conduction disturbances are seen in 3.5-10% of patients, and AS can be complicated by IgA nephropathy and amyloidosis.