Ankylosing spondylitis (ankylosing spondylitis) is a chronic inflammatory rheumatic disease. It primarily affects the spine and sacroiliac joints. The disease often begins with inflammation with blunt pain in the lumbar vertebrae and buttocks. The persistent and recurring inflammation can lead to destruction and ultimately to ossification and stiffening of the surrounding joints.

The exact cause is still unclear. Modern medicine assumes that it is a disorder of the body's own defence system, which leads to the corresponding inflammation. For this reason, ankylosing spondylitis is classed as an autoimmune disease. A genetic predisposition also appears to play a role.

Ankylosing spondylitis is considered incurable. The aim of therapy is to maintain mobility and delay stiffening. It also aims to alleviate pain and thus improve quality of life.