Ankylosing spondylitis

Abstract

Ankylosing spondylitis (AS) is the prototypical form of the spondyloarthritides, a group of disorders that involves inflammation of the sacroiliac joints, spine, joints, and entheses, as well as extraspinal lesions of the eye, bowel, and heart. Human leukocyte antigen (HLA) B27 is a strong genetic risk factor for AS. However, this gene is neither necessary nor sufficient to cause the disease. Other recently recognized genes are also involved in the pathophysiology of this condition. The principal musculoskeletal lesions of AS are sacro-iliitis, spondylitis, synovitis, and enthesitis. Enthesitis consists of inflammation at the site of tendinous insertions into bone. Sacroiliitis causes inflammatory back pain often localized to the buttocks that can be uni-or bilateral and typically alternates between the left and right side. Spondylitis begins characteristically in the lumbosacral region and proceeds cephalad. The most common extraspinal joints involved are the hips, knees, ankles, and metatarsophalangeal joints. The pattern of arthritis is typically an asymmetric oligoarthri-tis that involves the large joints of the lower extremities. Acute anterior uveitis usually occurs in one eye at a time, although either eye can be involved in any given episode. Patients usually present with a red, painful, photophobic eye. © 2010 Springer-Verlag London.