Ankylosing spondylitis is an inflammatory disease that can cause some of the vertebrae in your spine to fuse together. This fusing makes the spine less flexible and can result in a hunched-forward posture. A severe case of ankylosing spondylitis can make it impossible for you to lift your head high enough to see forward.

Ankylosing spondylitis affects men more often than women. Signs and symptoms of ankylosing spondylitis typically begin in early adulthood. Inflammation also can occur in other parts of your body — such as your eyes and bowels.

There is no cure for ankylosing spondylitis, but treatments can decrease your pain and lessen your symptoms.

In ankylosing spondylitis, the spinal joints, ligaments and the sacroiliac joints (the joints at the base of the spine) become inflamed. This inflammation causes pain and stiffness in the neck and back. Sacroiliitis (inflammation of the sacroiliac joints) leads to pain in the lower back and buttocks.
It is not known what causes the condition, but there is thought to be a link with a particular gene known as HLA-B27