Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory arthritis that primarily affects the axial skeleton — the spine and sacroiliac joints — causing progressive pain, stiffness and, in advanced cases, fusion of the vertebrae. It belongs to the broader family of spondyloarthropathies and is now understood within the wider category of axial spondyloarthropathy (axSpA), which also includes non-radiographic axial SpA where structural changes on X-ray are not yet evident.

AS typically presents in early adulthood — usually before the age of 45 — and is more common in men, though women are frequently underdiagnosed due to milder or atypical presentations. There is a strong genetic association with the HLA-B27 antigen, which is present in over 90% of patients with AS in White European populations. The condition can also affect peripheral joints, entheses, eyes (uveitis), the bowel and skin, reflecting its systemic nature.

Diagnosis is often delayed by several years from symptom onset, as inflammatory back pain can be mistaken for mechanical causes. Specialist assessment with appropriate imaging and serological testing is essential to reach the correct diagnosis and begin disease-modifying treatment promptly.

Exercise is central to the management of AS and is one of the most effective interventions for maintaining spinal mobility and reducing pain. Regular physiotherapy with a programme tailored to axial disease is strongly recommended. NSAIDs — taken regularly rather than as needed — provide effective anti-inflammatory relief and may even slow radiographic progression when used continuously in patients with high disease activity.

For patients with persistently active disease despite NSAIDs, biologic therapies have revolutionised treatment outcomes. TNF inhibitors (adalimumab, etanercept, certolizumab, golimumab, infliximab) have a well-established evidence base and are highly effective in reducing pain, stiffness, and inflammation. IL-17 inhibitors (secukinumab, ixekizumab, bimekizumab) provide an alternative with particular benefit for patients with co-existing psoriasis or inflammatory bowel disease considerations. JAK inhibitors (tofacitinib, upadacitinib, filgotinib) offer effective oral options.

Conventional DMARDs such as methotrexate have limited efficacy for axial disease but may be used for peripheral joint involvement. Local corticosteroid injections into sacroiliac joints can provide relief during flares. Surgical intervention is occasionally required for severe hip disease or spinal correction.