Ankylosing spondylitis

Overview 

Ankylosing spondylitis (AS)  is a kind of arthritis that causes chronic (long-term) inflammation of the spine. Ankylosing spondylitis causes inflammation of the sacroiliac joints, which are positioned between the base of the spine and the pelvis. Sacroiliitis, or inflammation of the sacroiliac joints, is one of the initial symptoms of AS. Inflammation frequently extends to the joints between the vertebrae, the bones that form the spinal column. Spondylitis is the medical term for this condition.

Some persons with AS report significant, ongoing back and hip discomfort and stiffness. Others get lesser symptoms that come and go. Over time, new bone forms may fuse vertebral portions together, making the spine stiff. This is known as ankylosis.