What are the clinical features of reactive arthritis?

Clinical Features of Reactive Arthritis

Reactive arthritis is characterized by asymmetric oligoarthritis predominantly affecting large joints, typically following a genitourinary or gastrointestinal infection, and may be accompanied by extra-articular manifestations including conjunctivitis, urethritis, and skin lesions. 1, 2

Key Joint Manifestations

• Asymmetric oligoarthritis primarily affecting large joints (knees, ankles, elbows, wrists) is the predominant presentation 1, 3
• Arthritis typically develops within 2-4 weeks after a preceding infection, though in approximately 25% of cases the triggering infection may be asymptomatic 4
• Joint symptoms include pain, swelling, and stiffness after inactivity 1
• Migratory pattern may be observed, with pain and swelling moving from one joint to another 3
• Self-limited course in most cases, typically lasting approximately 4 weeks even without therapy 3
• Rapid improvement with NSAIDs is characteristic 3
• Dactylitis (sausage-like swelling of fingers or toes) may be present 5, 2
• Enthesitis (inflammation at tendon/ligament insertion sites) is common 1, 2
• Axial involvement with sacroiliitis occurs less frequently 5, 2
• Absence of long-term joint deformity in most cases 3

Extra-Articular Manifestations

• Conjunctivitis/uveitis - anterior uveitis may develop and requires ophthalmologic evaluation 1, 2
• Urethritis - inflammation of the urethra with dysuria and discharge 1, 2
• Skin manifestations - pustular lesions on plantar surfaces (keratoderma blennorrhagicum) 2
• Mucosal lesions - painless ulcers on oral mucosa or glans penis (circinate balanitis) 2

Clinical Phenotypes

• Post-enteric reactive arthritis - follows gastrointestinal infections with enterobacteria such as Salmonella, Shigella, Campylobacter, or Yersinia 5
• Post-venereal reactive arthritis - follows genitourinary infections, most commonly Chlamydia trachomatis 5
• Post-streptococcal reactive arthritis - follows group A streptococcal pharyngitis, with cumulative and persistent arthritis involving large joints, small joints, or axial skeleton 6

Laboratory and Diagnostic Features

• HLA-B27 positivity is found in approximately 50% of cases and serves as a prognostic indicator 5, 2
• Elevated inflammatory markers (ESR, CRP) are common 1
• Evidence of triggering infection through cultures (stool, urogenital) or serology 4
• No validated diagnostic criteria exist; diagnosis is primarily clinical 4, 2
• Synovial fluid analysis shows inflammatory characteristics but is sterile on culture 5

Disease Course and Prognosis

• Self-limiting in majority of cases 2
• Approximately 25-50% of patients may experience recurrent episodes of acute arthritis 4
• About 25% progress to chronic spondyloarthritis of varying activity 4
• HLA-B27 positivity is associated with more severe and prolonged disease course 2
• Estimated prevalence is 40/100,000 with an incidence of 5/100,000 5

Differential Diagnosis

• Other spondyloarthropathies (ankylosing spondylitis, psoriatic arthritis) 1, 3
• Crystal arthropathies (gout, pseudogout) 6, 3
• Septic arthritis (requires urgent exclusion) 3
• Rheumatoid arthritis 3
• Immune checkpoint inhibitor-induced arthritis 1
• Acute rheumatic fever (differs by having migratory polyarthritis with predominant carditis) 1

Clinical Pitfalls and Caveats

• Diagnosis is primarily clinical and requires exclusion of other causes of arthritis 2
• The triggering infection may be asymptomatic in about 25% of cases 4
• Post-streptococcal reactive arthritis may occasionally progress to valvular heart disease, requiring careful cardiac monitoring 6
• No standardized serological tests exist for confirming the diagnosis 4
• Antibiotic treatment of established reactive arthritis generally does not shorten disease duration, though treatment of acute Chlamydia infection is important 4, 5
• Without proper management, reactive arthritis can progress to chronic destructive arthritis 7

Understanding these clinical features is essential for prompt recognition and appropriate management of reactive arthritis, which can significantly improve patient outcomes and reduce complications.