Clinical features of ankylosing spondylitis

Abstract

  Ankylosing spondylitis, a prototype of spondyloarthritis（SpA）, mainly affects axial joints, including sacroiliac joints and spine. AS frequently develops in young males having HLA-B27 with inflammatory back pain. Inflammation in AS starts from entheses. It induces consequent bone erosions, and then new bone formation occurs and syndesmophytes slowly develops, resulting in bridging between vertebral bodies in the long disease duration. For early intervention of the disease, ASAS proposed criteria for axial spondyloarthritis. In these criteria, non-radiographic axial SpA（nr-axSpA）can be classified, however, it has been reported that nr-axSpA does not always become radiographic. It is important to understand the clinical features of AS and consider differential diagnosis for the appropriate diagnosis of AS, and careful follow-up is also needed even after the diagnosis. In the treatment of AS, physical therapy is highly recommended. In active AS despite a TNF inhibitor, it is recommended to switch to another TNF inhibitor in the secondary failure and to an IL-17 inhibitor secukinumab in the primary failure.