If you have pain in the lower back or buttocks, accompanied by symptoms such as limited mobility, you need to be alert to the possibility of ankylosing spondylitis (ankylosing spondylitis), and you should consult a doctor for an examination in order to diagnose the disease. Ankylosing spondylitis is a chronic inflammatory disease that affects the spine, sacroiliac joints, etc. It mainly manifests as pain and stiffness in the lower back or buttocks, and is accompanied by stiffness in the lower back, which is more pronounced in the morning or when one is sedentary, and is relieved by activity. If the above symptoms occur, you need to consider whether you have ankylosing spondylitis. Patients should seek medical treatment for relevant examinations, commonly X-ray, if it is found that bilateral sacroiliac joint surfaces are blurred, with irregular edges, or even manifestations such as narrowing, disappearance or fusion of joint space, suggesting ankylosing spondylitis. If ankylosing spondylitis is diagnosed, it is recommended that the patient actively cooperate with the doctor to carry out relevant treatment to avoid delaying the condition.