Ankylosing Spondylitis (AS) is an autoimmune disease characterized by inflammation of the spine and sacroiliac joints, historically described in young males with progressive structural damage of the spine, and later used as model to identify a group of inflammatory diseases known as Spondyloarthritis (SpA) [1]. AS is currently considered the advanced stage of Axial Spondyloarthritis (axSpA), when chronic joint inflammation has progressed to erosions and ankylosis, features that are detectable be means of conventional radiology (x-rays) and therefore defined as radiographic axial spondyloarthritis (r-axSpA)1 [2].
