ABSTRACT
Pathophysiology Musculoskeletal disease Characteristic symptoms of AS are spinal stiffness and loss of spinal mobility, which are explained by spinal infl ammation, structural damage or both. Spinal infl ammation can arise as spondylitis, spondylodiscitis or spondylarthritis. Structural changes are mainly caused by osteoproliferation rather than by osteode struction. Syndesmophytes and ankylosis are the most characteristic features of this disease, which are visible on conventional X-rays after some months to many years. Low bone density, osteoporosis and an increased rate of fractures may add to the hyperkyphosis predominantly s een in male patients. Decreased movement of the lumbar spine results w ith a proportion progressing to ankylosis and complete rigidity with a classical X-ray picture of ‘bamboo spine’.
