Ankylosing spondylitis is a type of arthritis that affects the spine. "Ankylosing" means stiff or rigid, "spondyl" means spine, and "itis" refers to inflammation. The disease causes inflammation of the spine and large joints, resulting in stiffness and pain.
Ankylosing spondylitis may result in erosion at the joint between the spine and the hip bone (the sacroiliac joint), and the formation of bony bridges between vertebrae in the spine, fusing those bones. In addition, bones in the chest may fuse.
Who is affected by ankylosing spondylitis?
AS is more common among young people, ages 16 to 30. The disease affects more than 500,000 Americans.