Ankylosing Spondylitis and Axial Spondyloarthritis.

Chronic back pain is common worldwide and is cared for by a variety of providers, but specific, satisfactory treatment is often lacking. Ankylosing spondylitis, an inflammatory disorder that in its extreme form can lead to the bony fusion of vertebral joints, is an uncommon but well-established cause of chronic back pain. During the past decade, ankylosing spondylitis has come to be considered as a subset of the broader and more prevalent diagnostic entity referred to as axial spondyloarthritis. The estimated prevalence of axial spondyloarthritis in the United States is 0.9 to 1.4% of the adult population, similar to that of rheumatoid arthritis.Axial spondyloarthritis is generally diagnosed and treated by rheumatologists, and there is specific treatment for it. However, prolonged delay in reaching the diagnosis is common and is usually the result of the failure of recognition by nonrheumatologists.This review is intended to enhance awareness and understanding of axial spondyloarthritis and ankylosing spondylitis — and the relationship between the two — in order to facilitate prompt and accurate diagnosis and proper treatment. Recent advances in our understanding and treatment of these conditions are discussed.