Clinical features of the peripheral Spondyloarthritis associated with IBD
• Type 1: Acute, pauciarticular, parallels IBD activity. Occurs in ∼5% of IBD patients, sometimes prior to (30% of cases) or early in the course of the bowel disease and is strongly associated (80%) with flares of IBD and other extraarticular manifestations (erythema nodosum, uveitis). Synovial fluid analysis reveals an inflammatory fluid (normally 5000–12,000 but can be up to 50,000 white blood cells/mm3, predominantly neutrophils) and negative crystal examination and cultures. Most arthritic episodes are self-limited with 90% resolving within 3 to 6 months. This type of arthritis does not result in radiographic changes or deformities. Associated with human leukocyte antigen (HLA)-B27, B35, and DRβ1∗0103.
• Type 2: Chronic, polyarticular, independent of IBD activity. It is less common, occurring in 3% to 4% of IBD patients. The arthritis tends to be symmetric (80%), polyarticular (metacarpophalangeal > knees and ankles > other joints), runs a course independent of the activity of IBD, and does not correlate with extraarticular manifestations, except uveitis. Active arthritis is chronic (90%), and episodes of exacerbations and remissions may continue for years. Due to its chronicity, this type of arthritis can cause erosions and deformities. Associated with HLA-B44.