Physical examination: Sacroiliac joint and paravertebral muscle pressure is a positive sign in the early stage of the disease. As the disease progresses, the lumbar lordosis flattens, the movement of the spine is limited in all directions, the thoracic extension is reduced, and the cervical vertebrae protrude. The following methods can be used to check the progression of sacroiliac joint pain or spinal lesions: ① Occipital wall test: In normal people, when the heels are pressed against the wall in a standing position, the back of the occiput should be close to the wall without gaps. In the case of cervical stiffness and/or thoracic segmental deformity, the gap increases to more than a few centimeters, resulting in the occipital area not being able to be attached to the wall. ② Thoracic expansion: The normal value of the difference between the range of thoracic expansion during deep inspiration and deep expiration is not less than 2.5 cm when measured at the level of the 4th rib space, while the thoracic expansion is reduced in those with extensive rib and vertebral involvement. Schöber’s test: mark the midpoint of the posterior superior iliac spine at a vertical distance of 10 cm above and 5 cm below the midpoint of the posterior superior iliac spine, and then ask the patient to bend over (keeping both knees in an upright position) to measure the maximum forward flexion of the spine. ④Pelvic compression: the patient lies on his side, and pressure on the pelvis from the other side can cause pain in the sacroiliac joint. ⑤Patrick test ⑤Patrick’s test (lower extremity 4-way test): The patient lies on his back with one knee flexed and the heel placed on the opposite knee that is straight. The examiner presses the flexed knee with one hand (when the hip is in flexion, abduction and external rotation) and presses the opposite pelvis with the other hand, and the pain in the opposite sacroiliac joint is considered positive. The 4-character test cannot be completed in people with knee or hip lesions.