Axial spondyloarthritis

Axial spondyloarthritis (axSpA) is a chronic inflammatory condition that predominantly involves the axial skeleton. The term describes a disease spectrum including patients with radiographic axSpA (also called ankylosing spondylitis), which have established (chronic) sacroiliitis on radiographs, and a further subgroup of ‘non-radiographic axSpA’, which typically shows evidence of active sacroiliitis on magnetic resonance imaging (MRI) in the absence of definite radiographic changes. The association between axSpA and HLA-B27 has been known for some time, and newer genetic links have been found with IL23R and ERAP1. Animal studies also support a link between the gut microbiome, gut inflammation and axSpA, and biomechanical stress may play a role. Chronic back pain, often with inflammatory features, is the cardinal manifestation, with enthesitis being the key pathological lesion. Many patients develop peripheral features such as enthesitis, arthritis or dactylitis, and some develop extra-articular manifestations (also called extra-musculoskeletal manifestations), namely uveitis, psoriasis or inflammatory bowel disease. Diagnosis of early-stage disease can be challenging, and MRI plays a key role in detecting inflammatory changes. Non-steroidal anti-inflammatory drugs and physical therapy are cornerstones of management, with tumour necrosis factor and interleukin (IL)-17 inhibitors vastly improving clinical outcomes. Newer treatments include new IL-17 inhibitors and JAK inhibitors