Although the spine is the main site of ankylosing spondylitis, the incidence of joint lesions in the extremities is not uncommon. The incidence of joint involvement of the extremities as the first symptom varies, and is generally considered to be 43%. Ankylosing spondylitis in children is more common when the first symptom is arthrosis of the extremities. 24%-75% of patients develop arthrosis of the extremities during the course of the disease, with some as high as 91%. About 25% have permanent peripheral joint damage. It generally occurs more often in the large joints and in the lower extremities than in the upper extremities. Although the spine is the main site of ankylosing spondylitis, the incidence of extremity joint lesions is not uncommon. The incidence of joint involvement of the extremities as the first symptom varies from report to report and is generally considered to be 43%. Ankylosing spondylitis in children is more common when the first symptom is arthrosis of the extremities. 24%-75% of patients develop arthrosis of the extremities during the course of the disease, with some as high as 91%. About 25% have permanent peripheral joint damage. It usually occurs in the large joints, more in the lower extremities than in the upper extremities. Statistically, the rate of joint involvement in the extremities is 40% for the hip and shoulder, 15% for the knee. The ankle is 10%, the foot and wrist are 5% each, and the hand is rarely involved. The incidence of ankylosing spondylitis arthropathy is reported to be 38% abroad, often bilateral, easily occurring in the early stages of the disease and causing lifelong disability in 1/3 of patients. In 80 cases of ankylosing spondylitis reported in China, the hip was involved in 66% of the joints of the extremities, 74% of which occurred on both sides, and hip pain was a sensitive sign of early involvement (100%); limitation of movement (64%), flexion contracture (38%), muscle atrophy (25%), and the occurrence of joint ankylosis (37%) were the main causes of disability in patients with ankylosing spondylitis. Hip symptoms appear within 5 years of onset in 94% of cases, suggesting that if the hip joint is not involved within the first 5 years of ankylosing spondylitis onset, it is unlikely to be involved later. When the shoulder joint is involved, joint movement is more restricted than pain, and activities such as combing and lifting the head are limited. When the knee joint is involved, the joint is compensated for bending, which makes walking, sitting and standing more difficult in daily life. Since the disease is a lesion of the tendon attachment point, there are also inflammatory changes in the periarticular tissues, which are characteristic pathological changes of ankylosing spondylitis and have received more and more attention in recent years. Due to inflammation of the attachment points of the thoracic rib joints and the stalk-thoracic joints, patients may experience chest pain that is aggravated by coughing or sneezing. Tendon attachment point lesions are also seen in the cribriothoracic junction, vertebral eminence, iliac crest, greater trochanter, sciatic tuberosity, tibial tuberosity, and heel, with early manifestations of local soft tissue swelling and pain and late bony grossness.