Reactive arthritis

Definition

Reactive arthritis is an acute spondyloarthritis usually triggered by a preceding genitourinary or gastrointestinal infection. It is a postinfectious arthritis: microbial antigens can sometimes be detected in the synovium by PCR, but the organizms cannot be cultured from joint fluid. The spectrum ranges from transient monoarthritis to a severe multisystem disorder.

Occurrence & epidemiology

The sexually transmitted form occurs primarily in men aged 20 to 40. The postenteric (dysenteric) form occurs in both sexes. HLA-B27 is found in up to about 80 % of patients compared with about 7 % of healthy controls.

Aetiopathogenesis

• Genitourinary form: most often after infection with Chlamydia trachomatis.
• Postenteric form: after infections with Shigella, Salmonella, Yersinia, Campylobacter, or Clostridioides difficile.
• Also described after BCG instillation for bladder cancer.
• In about 40 %, no pathogen can be identified.
• Genetic predisposition through HLA-B27.

Clinical features

• Urethritis 7–14 days after sexual contact (less often after diarrhea), followed over the next weeks by low-grade fever, conjunctivitis, and arthritis; incomplete forms are common.
• Arthritis: asymmetric and oligoarticular, mainly toes and large joints of the legs; large, often surprisingly minimally painful knee effusions; dactylitis.
• Enthesitis (plantar fasciitis, Achilles tendinitis, digital periostitis) is common and characteristic.
• Back pain in severe disease; chronic axial involvement more often in HLA-B27-positive patients, with asymmetric, bulky syndesmophytes.
• Skin and mucosa: painless superficial ulcers on the oral mucosa, tongue, and glans penis (balanitis circinata); keratoderma blennorrhagicum on palms and soles; nail dystrophy; erythema nodosum especially after Yersinia infection.
• Eyes: conjunctivitis most common, also keratitis and anterior uveitis.
• Rarely aortitis, aortic insufficiency, conduction abnormalities, pleuritis.
• Constitutional symptoms: fever, fatigue, weight loss.

Diagnosis

• The diagnosis is clinical: typical peripheral arthritis plus symptoms of a genitourinary or gastrointestinal infection or another extra-articular feature. Because features appear at different times, diagnosis may take months.
• Suspicious is acute asymmetric arthritis of the large leg joints or toes, especially with enthesitis, dactylitis, or preceding diarrhea or dysuria.
• Complement levels in serum and synovial fluid are elevated but not diagnostic.
• In severe reactive arthritis, HIV infection is considered.

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Further reading (open access)

1. MSD Manual Professional: Reactive Arthritis
2. MSD Manual Professional: Uveitis Caused by Systemic Rheumatic Disease

Cross-references