Overview
Definition
An autoimmune, sterile inflammatory arthritis that develops 1-4 weeks after a gastrointestinal or genitourinary infection.
Epidemiology
Typically affects young adults (aged 20-40). Strongly associated with the HLA-B27 genotype.
Etiology & Risk Factors
- Autoimmune response triggered by an infection: GU (Chlamydia trachomatis) or GI (Salmonella, Shigella, Campylobacter, Yersinia)
Clinical Symptoms
- Asymmetric oligoarthritis (typically lower extremities: knees, ankles)
- Enthesitis (Achilles tendonitis, plantar fasciitis)
- Dactylitis ('sausage digits')
- Conjunctivitis / Urethritis / Circinate balanitis
- Classic triad: 'Can't see, can't pee, can't climb a tree' (conjunctivitis, urethritis, arthritis)
Clinical Approach
Diagnosis
- Clinical presentation
- Elevated ESR/CRP
- HLA-B27 positive (in ~30-50% of cases)
- Synovial fluid analysis showing inflammatory fluid but sterile cultures
Management
- NSAIDs (first-line)
- Intra-articular or oral corticosteroids for refractory joints
- Antibiotics only to treat active, ongoing Chlamydia infection (does not alter arthritis course)
- DMARDs (Sulfasalazine) for chronic disease
Complications
- Chronic persistent arthritis
- Recurrent uveitis
- Aortic regurgitation (rare)