Reactive Arthritis

Infection induced systemic illness characterised primarily by an inflammatory synovitis from which viable microorganisms cannot be cultured

Aetiology

  • Most common preceding infections are urogenital (e.g. chlamydia, neisseria) and enterogenic (e.g. salmonella, campylobacter)
  • HLA B27 positive
  • Young adults (20-40)
  • Equal sex distribution

Pathophysiology

  • Occurs in response to an infection in another part of the body
  • Large joints e.g. the knee become inflamed around 1‐3 weeks following the infection
  • The infection triggers an autoimmune arthropathy

Clinical presentation

Symptoms

  • Present 1-4 weeks after infection
  • General symptoms - fever, fatigue, malaise
  • Asymmetrical monoarthritis or oligoarthritis
  • Enthesitis

Signs

  • Mucocutaneous lesions
    • Keratodema blenorrhagica
    • Circinate balanitis
    • Painless oral ulcers
    • Hyperkeratotic nails
  • Ocular lesions (uni or bilateral) - conjuntivitis, iritis
  • Vissceral manifestations - mild renal disease, carditis
  • Reiter's syndrome: triad of urethritis, conjuctivitis/uveitis/iritis and arthritis

Investigations

  • Bloods - ↑ inflammatory markers, FBC, U+Es, LFTs, HLA B27 (rarely necessary)
  • Cultures - blood, urine, stool
  • Joint fluid analysis - rule out infection (aspirate should be negative)
  • X-ray of affected joints
  • Ophthamology opinion

Management

  • Treatment is aimed at the underlying infectious cause and symptomatic relief, including IA or IM steroid injections
 
  • Most cases self-limiting - 90% resolve spontaneously within 6 months
  • Remaining 10% - chronic progressive erosive disease, requiring DMARDs