Ankylosing spondylitis (pronounced ank-kih-low-sing spon-dill-eye-tiss), or AS, is a form of inflammatory arthritis that primarily affects the spine, although other joints can become involved. It onsets early in life, typically before age 40 (although patients may not be diagnosed until later in life). It causes inflammation of the spinal joints (vertebrae) that can lead to severe, chronic pain and discomfort. In the most advanced cases (but not in all cases), this inflammation can lead to new bone formation on the spine, causing the spine to fuse in a fixed, immobile position, sometimes creating a forward-stooped posture. This forward curvature of the spine is called kyphosis. Although (like most autoimmune and autoinflammatory diseases) the “cause” is not known, AS is associated with the gene for human leukocyte antigen B27 (HLA-B27).
There are both musculoskeletal and extra-articular (outside the joints) features of AS. The major musculoskeletal features are inflammation and arthritis of the sacroiliac joints and spine, hip, shoulder, and other peripheral joint involvement, costochondral (in between the ribs) inflammation, and enthesitis (inflammation at points of attachment of tendons and ligaments to the bone). Unlike “mechanical” low back pain, AS causes an “inflammatory” back pain which has several distinguishing features: early age of onset, insidious onset, improvement with exercise, worsening or no improvement with rest, and pain at night followed by morning stiffness that gradually improves with movement.
Extra-articular manifestations of AS include anterior uveitis or iritis (inflammation of the eyes), psoriasis, cardiovascular disease, and inflammatory bowel disease.
How Do We Treat AS?
There are both pharmacological (medicines) and non-pharmacological component important in the management of AS. Exercise & education are key components even for patients who are responding well to medications. A home exercise program may include range of motion stretching and postural training. Initial assessment and creation of a home program by a qualified physical therapist is often helpful. Everyone can benefit from whatever level of exercise they can manage – swimming and hydrotherapy are gentle on joints, and weight-bearing exercise will help maintain bone density. Many
The first-line pharmacologic option is traditionally NSAIDs (non-steroidal anti-inflammatory drugs such as ibuprofen, meloxicam, celecoxib). Steroids such as prednisolone may be used for short-term therapy. Recent research has shown little clinical benefit for methotrexate in AS. In more recent years, biologic medicines have been developed and approved for treating AS, including TNF-alpha antagonists (infliximab, etanercept, adalimumab, golimumab, certolizumab). Anti-TNFs have been shown to benefit patients with both early and late-stage disease, but may be more successful in inducing remission when used earlier in the disease process. Recently, an anti-IL-17A drug – secukinumab – was approved for AS, and other IL-17 inhibitors are under development.