The extra-articular manifestations of ankylosing crestitis include systemic symptoms and symptoms of other organ damage, especially eye damage is common. 1. Systemic symptoms: some patients have fever, wasting, weakness, and decreased appetite. 2. Ocular symptoms: conjunctivitis, iritis, uveitis can occur in 25% of patients and can be seen at any time of the disease. Very few patients with severe disease and without proper treatment may develop blindness. 3. Cardiac manifestations: seen in patients with advanced disease, pericarditis, myocarditis, atrioventricular or bundle branch block, and other diseases affecting the heart may occur. 4. Pulmonary manifestations: apical pulmonary fibrosis occurs in a few patients, with coughing, hemoptysis and shortness of breath, and more severe symptoms when complicated by infection or pleurisy. In addition, thoracic stiffness can lead to the inability to fully expand the lungs during inspiration, compensatory whistling by the diaphragm, and difficulty in inspiration. 5. Neurological manifestations: more severe patients in the late stage have symptoms of crestal medullary compression due to crestal ankylosis and osteoporosis, causing vertebral fractures and disc herniation. Fractures occurring in the cervical spine have serious consequences and may cause quadriplegia. Cauda equina syndrome occurs for unknown reasons and manifests as pain in the buttocks or lower legs, loss of sensation in the sacral nerve distribution area, and urinary and defecation dysfunction. 6. Renal damage: relatively rare, a few patients present with hematuria, which may improve with systemic treatment of ankylosing crestitis.