How does ankylosing spondylitis happen

The disease development process of patients with ankylosing spondylitis is as follows: the primary lesion is mainly located at the attachment of tendons and joint capsules, mainly presenting chronic and pannus destructive inflammation, and ossification is a secondary repair lesion. Generally, the disease starts from the sacroiliac joint, and gradually extends upward along the spine until the whole spine is involved and fusion rigidity occurs. The process of this disease can stop at any stage or location, which is a self limited disease. At the same time, it can also spread downward and involve bilateral hip joints, but rarely involve knee joints and upper limb joints. Sometimes the lesion starts at the cervical vertebra and gradually extends downward.