Ankylosing spondylitis, also called Bechterew’s disease, is a chronic immune disorder that causes inflammation in the spine, sacroiliac joints, and sometimes in larger joints such as the hips, shoulders, or knees. It is the most common form of spinal arthritis and occurs due to inflammation where ligaments, tendons, and joint capsules attach to the bone, particularly in the back, pelvis, and chest.

The disease is caused by a combination of hereditary factors and environmental influences. About 90% of patients have the HLA-B27 tissue type, which is only found in a small portion of the population. Having this tissue type significantly increases the risk, but infections may also act as a triggering factor.

Bechterew’s disease develops gradually, typically between the ages of 20 and 30, and is more common in men. About 0.1–0.5% of the population is affected.

The most typical symptom is stiffness and pain in the lower back, thoracic, or cervical spine, often worse in the morning or after rest. The pain usually improves with movement but not with rest, and nighttime pain may force one to get up and move around. The pain can spread up the spine, causing reduced flexibility and difficulty breathing. Many also experience inflammation in the hips, shoulders, knees, or Achilles tendon.

About one-quarter of patients develop inflammation of the iris (uveitis), causing red eye, pain, and light sensitivity. In rare cases, the disease can lead to heart rhythm disturbances, inflammation of the heart valves, or reduced lung flexibility. General symptoms may include weight loss, fatigue, fever, or reduced appetite.

The disease can range from mild discomfort to severe bone fusion, which can make the spine rigid. However, most people retain their ability to work despite the chronic nature of the condition.