AS causes stiffness, usually starting in the lower back. Over time it may spread into the upper spine, causing joints and bones to become fused. This makes the spine rigid.
About a third of all persons with AS may have symptoms that affect other parts of the body besides the joints and ligaments, including ones affecting the heart and blood vessels.
Causes and Risk Factors
This condition tends to be inherited. It most commonly occurs in men between the ages of 16 and 30, but can also occur in women.