Lecture Notes: Reactive Arthritis

Introduction

• Presented by Tom from Zero Defiance
• Topic: Reactive Arthritis
• Additional Resources: zerodefinals.com/reactivearthritis

Definition

• Reactive Arthritis:
  • Synovitis occurs in joints following a recent infection.
  • Synovitis: inflammation of the synovium, a cushioning inside the joints.
  • Previously known as Reiter Syndrome.

Clinical Features

• Acute Monoarthritis:
  • Often affects a single joint, usually in the lower limb (commonly the knee).
  • Presents as a warm, swollen, and painful joint.
  • Differential Diagnosis: Septic Arthritis (infection in the joint but not in reactive arthritis).

Common Infective Triggers

• Gastroenteritis
• Sexually Transmitted Infections (STIs)
  • Chlamydia: most common STI causing reactive arthritis.
  • Neisseria gonorrhoeae: can cause gonococcal septic arthritis.

Pathophysiology

• Response to a recent infection (gastroenteritis or STI) triggers immune response affecting joints.
• Associated with HLA B27 gene.
• Part of the seronegative spondyloarthropathies group, including:
  • Psoriatic Arthritis
  • Ankylosing Spondylitis

Associated Features

• Bilateral Conjunctivitis (non-infective)
• Anterior Uveitis
• Circinate Balanitis (dermatitis of the penis head)
• Mnemonic: "Can't see, pee, or climb a tree" - helps remember eye problems, balanitis, and arthritis.

Management

• Acute Presentation:
  • Treat as presumed septic arthritis initially due to potential severity.
  • Administer antibiotics until septic arthritis is excluded.
  • Joint aspiration:
    • Sample joint fluid for gram staining, culture, sensitivities, and crystals (gout/pseudogout).
• Post-Exclusion of Septic Arthritis:
  • Non-Steroidal Anti-Inflammatories (NSAIDs)
  • Steroid Injections into affected joint
  • Systemic Steroids (e.g., oral prednisone) for multiple joint involvement.

Prognosis

• Most cases resolve within six months.
• Recurrent cases may require disease-modifying antirheumatic drugs (DMARDs) or anti-TNF medications.

Additional Resources

• Zero to finals website offers more details, podcasts, quizzes, and books to aid study and exam preparation.
• Books contain mnemonics and tips for efficient learning and exam success.