Axial spondyloarthritis is a relatively new term, now becoming widely accepted in clinical practice, referring to inflammatory disease predominantly of the spine where the main symptom is back pain. The most common subset of AxSpA is ankylosing spondylitis. This is a rapidly evolving field with new diagnostic criteria and treatments, which are likely to evolve further. This book covers the significant recent advances in the epidemiology, genetics, pathogenesis, classification, and treatment of this disabling disease, from a truly global perspective.