Ankylosing spondylitis is a chronic progressive inflammatory disorder that, unlike other rheumatological diseases, affects men or more often than women. It involves primarily the joints between articular processes, costovertebral joints , and sacroiliac joints , and occasionally, the iris or heart valves. Bilateral sclerosis of sacroiliac joints is a diagnostic sign. Affected persons have a high incidence of a specific human leukocyte antigen (HLA-B27), which may predispose them to the disease. Changes occurring in the joints are similar to those seen in RA. Ankylosis may occur, giving rise to a stiff back (poker spine). NSAIDs (Non steroidal Anti-inflammatory Drugs) and physical therapy are the primary forms of treatment.