Spondyloarthritis (SpA) represents a spectrum of HLA-B27–related rheumatic diseases that have a predilection for axial (spinal and sacroiliac joint) inflammation. The predominant symptom is low back pain, but a small subset of patients lacks axial symptoms and has primary peripheral disease characterized by pain and swelling in the arms and legs. Males are affected 2–3 times more often than females. Among these diseases are ankylosing spondylitis (AS), reactive arthritis, psoriatic arthritis, and the enteropathic arthropathies linked to inflammatory bowel disease (ulcerative colitis and Crohn disease). Syndromes that do not clearly fall into one of these categories and show no x-ray evidence of sacroiliitis are sometimes referred to as nonradiographic axial spondyloarthritis. What distinguishes SpA, in general, from other forms of arthritis is its tendency to cause inflammation in the ligaments and tendons that insert onto bone (enthesitis); the heel or Achilles tendon are common targets. Other features include asymmetric oligoarthritis and inflammation of fingers or toes (dactylitis), giving the appearance of “sausage digits.” Axial radiographs or magnetic resonance imaging (MRI) of the sacroiliac joints can be helpful, although abnormalities are not always present in the early course of the disease.
Spondyloarthritis may occur in childhood, although it is rare before the second decade of life. The juvenile-onset spondyloarthropathies are generally classified as a type of juvenile idiopathic arthritis known as enthesitis-related arthritis. Because the radiographic findings are similar, SpA is sometimes misdiagnosed as the result of trauma. As in adults, most young patients are HLA-B27–positive, and more males than females seem to be affected. These patients may develop acute uveitis characteristic of HLA-B27–positive uveitis.
Ophthalmologists should be familiar with these diseases, as acute recurrent HLA-B27–associated anterior uveitis may be the presenting feature of SpA (see “Ophthalmic considerations”). With appropriate referral of suspected patients, early disease can be recognized and treated to limit future morbidity. See BCSC Section 9, Uveitis and Ocular Inflammation, for further discussion of the ophthalmic manifestations.
Ankylosing spondylitis (AS) is the most common type of axial SpA. The cause is unknown, but the strong association with HLA-B27 (positive in 90% of patients with AS) suggests a genetic predisposition. The disease occurs most commonly in young men. Low back pain with limitation in spinal mobility is typical; complete spinal fusion may develop in later stages. Peripheral arthritis may also be present, most frequently affecting the ankles, hips, and knees. Extra-articular features of AS include a higher risk of cardiovascular disease, venous thromboembolism, stroke, and restrictive pulmonary disease.
NSAIDs are often the first-line treatment and are very effective, with 70%–80% of patients reporting significant improvement in symptoms. TNF-α inhibitors appear to be effective as a second-line treatment; most clinicians consider their use after failure of 2 separate NSAID trials. Nonbiologic DMARDs (eg, sulfasalazine or methotrexate) tend to work better for peripheral arthritis than for primary axial disease. Local glucocorticoid injection is helpful in some patients.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.