Ankylosing spondylitis (AS) is a type of inflammatory arthritis that occurs when the joints and ligaments along the spine become inflamed. It mainly affects the spine or back. AS patients typically experience pain and stiffness that begins in the lower back area. The pain may spread to the upper back, chest and neck area. Eventually, the joints and bones may grow together and cause the spine to become rigid and inflexible. Other joints, such as the hips, shoulders and knees as well as organs, may also be affected.
Researchers don’t know the cause of AS, but heredity plays a clear role. It occurs most frequently in Caucasians, Asian and Hispanic populations and is more common in men. The disease can develop in children as well.