Spondyloarthritis (SpA) is a group of inflammatory diseases characterized by the involvement of the axial skeleton (axSpA) and/or the peripheral joints (p-SpA). It affects young adults of both sexes and manifests with chronic back pain (CBP), mainly affecting the sacroiliac joints (SIJ), while it may also implicate the entire spine and the entheses. The prototype of axSpA is ankylosing spondylitis (AS) with the presence of structural damage in SIJ, visible on conventional radiography (CR), so-called radiographic axSpA (r-axSpA).
