Ankylosing Spondylitis Ankylosing spondylitis is a chronic disorder that causes inflammation of the joints and bones of the spine. The disorder can also cause inflammation of the tendons that attach the spine to the pelvis, as well as of the cartilage that connects the ribs to the spine. Over time, the inflammation can lead to new bone formation and the eventual fusion of the spine. This can cause the spine to become rigid and inflexible, and can also lead to a hunched-over posture.