ankylosing spondylitis

Ankylosing spondylitis (AS, from Greek ankylos, crooked; spondylos, vertebra; -itis, inflammation), previously known as Bekhterev's disease and Marie-Strümpell disease, is a chronic inflammatory autoimmune disease of the axial skeleton, with variable involvement of peripheral joints and nonarticular structures. AS is one of the seronegative spondyloarthropathies and has a strong genetic predisposition. It mainly affects joints in the spine and the sacroiliac joint in the pelvis. In severe cases, complete fusion and rigidity of the spine can occur.