Category B - full version without watermark 720x576 (check terms and conditions at www.teledesign.de) The embed version with watermark is free of charge. - Description: First symptoms of ankylosing spondylitis appear at the sacro-iliac-joint. The tendon insert as well as the capsules of the facet joints are affected. The ligaments calcify which can lead to new bone formation between adjacent vertebrae. This causes the spine to fuse in a fixed position, sometimes creating a forward-stooped posture if treatment is not in time.