Table of Contents
Overview – Reactive Arthritis
Reactive arthritis is a post-infectious autoimmune condition characterised by asymmetric arthritis, usually affecting the lower limbs, occurring within weeks of a gastrointestinal or genitourinary infection. It is most common in young, HLA-B27-positive males, and often presents alongside ocular and genitourinary symptoms — especially in the classic Reiter’s Syndrome triad of arthritis, conjunctivitis, and urethritis. This article outlines the key clinical features, diagnosis, and management strategies for final-year medical students.
Definition
Reactive arthritis is an aseptic inflammatory arthritis that occurs within one month of an infection, typically of the GI or genitourinary tract. It is part of the seronegative spondyloarthropathy family.
Aetiology
Infectious Triggers
- Gastrointestinal Infections (→ Enteropathic Arthritis)
- Shigella
- Salmonella
- Campylobacter
- Genitourinary Infections (→ Reiter’s Syndrome)
- Chlamydia trachomatis
Host Susceptibility
- HLA-B27 positive
- Typically affects males aged 20–40
- Male:Female ratio ≈ 10:1
Pathophysiology
- Triggering infection induces an autoimmune response targeting joint tissues
- Bacterial antigens are thought to persist in synovial tissues, leading to chronic inflammation
- Sterile synovitis with no live organisms in joint aspirate
Clinical Features
Onset & Duration
- Symptoms begin within 1 month of infection
- Often self-limiting (duration: weeks to years)
Articular Manifestations
- Asymmetric, peripheral arthritis
- Predominantly lower limb involvement (knees, ankles)
Extra-Articular Features
- Conjunctivitis or iritis
- Urethritis or cervicitis
- Skin changes (e.g. keratoderma blennorrhagicum in Reiter’s)
- Mucosal ulcers (less common)
Reiter’s Syndrome Triad
- Arthritis
- Conjunctivitis
- Urethritis/Cervicitis
Investigations
- Clinical diagnosis
- Sterile joint aspirate (excludes septic arthritis)
- Normal inflammatory markers and lab tests
- No specific serological marker
Management
- Antibiotics: Only if active infection is present
- NSAIDs: For symptomatic relief
- Intra-articular corticosteroid injections: For persistent joint inflammation
- Exercise and physiotherapy: To maintain joint mobility and prevent stiffness
Complications
- Chronic or relapsing arthritis
- Recurrent uveitis
- Enthesitis or sacroiliitis (progression to spondyloarthropathy in some cases)
Differential Diagnosis
- Septic arthritis
- Rheumatoid arthritis
- Gout or pseudogout
- Ankylosing spondylitis
- Psoriatic arthritis
Summary – Reactive Arthritis
Reactive arthritis is an autoimmune arthritis triggered by recent GI or GU infections, most commonly in young HLA-B27-positive males. It often presents with an asymmetric peripheral arthritis, and in Reiter’s Syndrome, may be accompanied by conjunctivitis and urethritis. Diagnosis is clinical, and management focuses on symptomatic relief and physiotherapy. For a broader context, see our Musculoskeletal Overview page.