Ankylosing Spondylitis (AS), or sometimes referred to as axial spondyloarthritis (AxSpA), is an autoimmune condition causing inflammation in the spine and sacroiliac joints. The immune system, which normally protects the body from infections, begins to turn against the body's own healthy tissues, leading to symptoms of pain and stiffness (predominantly early morning stiffness) of the affected areas. Other joints, including knees, hips, ankles and shoulders can sometimes be affected.

It more commonly occurs in males and may be linked to a genetic predisposition which can be checked with a blood test for HLA-B27, although the presence of this marker is not necessarily diagnostic as it can be found in almost 10% of the general United Kingdom population.

The presence of this condition can be found in other rheumatic conditions such as psoriatic arthritis, reactive arthritis or enteropathic arthritis (the latter linked to the presence of inflammatory bowel disease, including Crohn’s disease or ulcerative colitis). Other organs - such as the lungs, heart and eyes - can sometimes also be affected in ankylosing spondylitis.

Physical examination, blood tests and an MRI scan of whole spine, pelvis and sacroiliac joints are undertaken to make the diagnosis. Treatment typically involves reducing and controlling inflammation with non-steroidal anti-inflammatories, occasional short courses of steroids, and disease modifying anti-rheumatic drugs (DMARDs).