Spondylitis

Ankylosing spondylitis is a type of arthritis that causes chronic inflammation of the spine. Ankylosing spondylitis (AS) causes inflammation of the sacroiliac joints located between the base of the spine and the pelvis. This inflammation, called sacroiliitis, is one of the first signs of AS. Inflammation often spreads to the joints between the vertebrae, the bones that make up the spine. This condition is called spondyloarthritis.