Reactive Arthritis

Intro & Causes - The Trigger Tale

• Reactive Arthritis (ReA): A seronegative spondyloarthropathy, an immune-mediated aseptic synovitis triggered by infection elsewhere.
• Key Triggers:
  • Urogenital: Chlamydia trachomatis
  • Gastrointestinal: Salmonella, Shigella, Yersinia, Campylobacter spp.
  • 📌 Mnemonic (GI/GU): ShY ChiCS (Shigella, Yersinia, Chlamydia, Campylobacter, Salmonella)
• Genetic Link: Strong HLA-B27 association (↑ susceptibility, often more severe disease).

⭐ Reactive arthritis is classically an aseptic synovitis occurring after an extra-articular infection. oka

Symptoms - Can't See, Can't Pee, Can't Climb a Tree

📌 Classic Triad: "Can't see, can't pee, can't climb a tree"

• Arthritis: Asymmetric oligoarthritis (≤ 4 joints), predominantly lower limbs. (Can't Climb a Tree)
  • Dactylitis ("sausage digits").
  • Enthesitis (e.g., Achilles tendonitis, plantar fasciitis).
  • Sacroiliitis & inflammatory low back pain.
• Urethritis/Cervicitis: Dysuria, discharge. (Can't Pee)
• Conjunctivitis/Uveitis: Eye pain, redness. (Can't See)

Extra-articular Manifestations:

• Skin: Keratoderma blenorrhagicum (palms/soles), circinate balanitis.
• Nails: Onycholysis, subungual hyperkeratosis.
• GI: Diarrhea (often preceding).
• Cardiac (rare): Aortitis, conduction abnormalities.

⭐ Dactylitis ('sausage digit') is a characteristic feature of reactive arthritis and other spondyloarthropathies.

Diagnosis - Detective Work

Primarily a clinical diagnosis; no single pathognomonic test.

• Laboratory Findings:

  • ↑ESR, ↑CRP (indicate inflammation).
  • HLA-B27: Positive in 30-50% of patients.
  • Synovial fluid: Inflammatory, culture-negative.

• Imaging (X-rays):

  • Features: Erosions, joint space narrowing, periostitis ('fluffy').
  • Key sites: Sacroiliitis (often asymmetric), enthesophytes (e.g., heel).

• Exclude Triggering Infections:

  • Stool and urine cultures.
  • Chlamydia PCR (if clinically suspected).

⭐ Synovial fluid analysis in reactive arthritis typically shows inflammatory changes (WBC 5,000-50,000/mm³) but is culture-negative.

Rule-Outs - Not That Arthritis!

Treatment - Taming the Reaction

Goals: Relieve symptoms, eradicate active infection (if present), prevent chronic complications.

• NSAIDs: First-line for acute arthritis and enthesitis, providing symptomatic relief.
• Corticosteroids: Intra-articular or systemic for refractory symptoms unresponsive to NSAIDs.
• DMARDs: Sulfasalazine, Methotrexate for chronic or severe disease to prevent progression.
• Antibiotics: Only if active infection (e.g., Chlamydia) is proven; controversial for post-dysenteric ReA.

  ⭐ Antibiotics are generally not recommended for post-enteric reactive arthritis unless an active infection is proven.

• Physiotherapy: Essential for maintaining joint function and muscle strength throughout.

Outlook & Issues - The Long Haul

• Prognosis: Variable; often self-limiting (weeks/months). Chronic/recurrent in 15-30% of cases.
• Complications:
  • Chronic arthritis, sacroiliitis, ankylosing spondylitis.
  • Recurrent uveitis.
  • Cardiac: conduction defects, aortic regurgitation.

⭐ A significant minority (15-30%) of patients with reactive arthritis may develop chronic or recurrent disease.

High‑Yield Points - ⚡ Biggest Takeaways

• Reactive Arthritis: an aseptic inflammatory arthritis triggered by GI (Salmonella, Shigella, Yersinia) or GU (Chlamydia) infections.
• Classic triad: "Can't see, can't pee, can't climb a tree" (conjunctivitis/uveitis, non-gonococcal urethritis, arthritis).
• Strong association with HLA-B27 positivity.
• Typically an asymmetrical oligoarthritis, predominantly affecting lower limb large joints.
• Extra-articular features: enthesitis, dactylitis, keratoderma blenorrhagicum, circinate balanitis.
• Synovial fluid: inflammatory, sterile (culture-negative).