Occurring in 5–20% of IBD patients, peripheral arthritis classically involves large joints and is asymmetric.5 Peripheral arthritis is also classically rheumatoid factor–negative (and, hence, seronegative), nondeforming, and nonerosive, although erosive lesions mimicking rheumatoid arthritis have been described.
Type 1 peripheral arthritis is pauciarticular—involving fewer than 5 joints—and is strongly associated with IBD activity and other EIMs. The knee is the most commonly affected site. Occurring in approximately 3.6% of UC patients and 6% of CD patients, fares are self-limiting, with attacks lasting 5–10 weeks.6 Flares usually parallel the severity of bowel symptoms.
Type 2 peripheral arthritis is polyarticular, independent of disease activity, and associated with fares that can last months or years. The metacarpophalangeal joint is the most commonly involved site. Less commonly involved sites include the knees, ankles, shoulders, proximal interphalangeal joint, and metatarsophalangeal joint. Type 2 peripheral arthritis is not usually associated with other EIMs, with the exception of uveitis. The severity of this arthritis appears to be independent of active bowel disease.
Spondylitis can occur in 1–26% of patients with IBD. Males are more frequently affected than females. Typical presentations include back or buttock pain, which worsens in the morning or after rest and is relieved with exercise. Spinal pain is often felt moving from the lumbar spine to the cervical spine. Buttock pain often alternates with chest wall pain. A physical examination may reveal limited spinal flexion and reduced chest expansion. AS occurs in 3–12% of patients with IBD. Nearly all IBD patients who are positive for human leukocyte antigen B27 will develop AS. Axial involvement is independent of gut pathology.