Ankylosing spondylitis: clinical aspects

Abstract

Abstract Ankylosing spondylitis (AS) is a chronic systemic inflammatory rheumatic disorder of the axial skeleton, that is to say the sacroiliac (SI) joints and the spine; the presence of sacroiliitis is its hallmark. Hip and shoulder joints, and less commonly peripheral joints or certain extraarticular structures, may also be involved. Its aetiology is as yet not fully understood, but there is a strong genetic predisposition in association with the histocompatibility antigen HLA-B27. The disease sometimes occurs in association with reactive arthritis (including Reiter’s syndrome), psoriasis, ulcerative colitis, or Crohn’s disease. In such cases it is called secondary AS. Most cases, however, show no evidence of these associated diseases and are classified as primary or uncomplicated AS (Khan 1993, 1997a).