What are the various clinical presentations of reactive arthritis?

Clinical Presentations of Reactive Arthritis

Reactive arthritis presents in three distinct clinical patterns: (1) oligoarthritis of large joints (knees, ankles, wrists) often with extra-articular features like conjunctivitis and urethritis; (2) symmetrical polyarthritis resembling rheumatoid arthritis affecting small joints; or (3) seronegative oligo/polyarthritis with enthesitis and dactylitis. 1, 2, 3, 2

Primary Articular Patterns

Large Joint Oligoarthritis (Most Common)

• Asymmetric involvement of 1-4 large joints, predominantly lower extremities
• Knees, ankles, and wrists most frequently affected 1, 4
• Often accompanied by classic triad features:
  • Conjunctivitis or uveitis
  • Urethritis or urethral discharge
  • Back or cervical pain suggesting sacroiliitis 1, 3
• May present with dactylitis (sausage digits) 5, 6
• Enthesitis is considered a hallmark finding 6

Polyarticular Pattern

• Symmetrical involvement of multiple joints (>4 joints)
• Can mimic rheumatoid arthritis clinically
• May affect small joints of hands (MCP, PIP joints) or wrists 2
• Autoantibodies (RF, anti-CCP) occasionally present but most patients seronegative 1

Seronegative Oligo/Polyarthritis

• Typically starts in medium to large joints
• Characterized by synovitis with tendon and entheseal involvement
• May or may not develop joint erosions 2

Extra-Articular Manifestations

Mucocutaneous Features

• Circinate balanitis (penile lesions)
• Oral erosions on palate, gums, tongue, or cheeks 7
• Keratoderma blennorrhagicum (skin lesions)

Ocular Involvement

• Conjunctivitis (most common)
• Anterior uveitis/iridocyclitis
• May occur with or without conjunctivitis 1, 2, 7

Genitourinary Symptoms

• Urethritis with or without discharge
• Dysuria
• More prominent in sexually-acquired reactive arthritis 7, 8

Temporal Characteristics

Onset timing: Arthritis typically develops 2-4 weeks (mean 22.3 days) after the triggering infection 9

Duration: Most cases are self-limiting, lasting approximately 4 weeks untreated, though 20% become chronic 10

Key Diagnostic Clues

Laboratory Findings

• Markedly elevated inflammatory markers (ESR, CRP) help differentiate from non-inflammatory conditions 1, 3
• HLA-B27 positive in approximately 50% of cases 11, 10
• Synovial fluid is sterile (culture-negative) but may contain pathogen DNA or antigens 11

Preceding Infections

Look for history of:

• Genitourinary: Chlamydia trachomatis, Ureaplasma, Neisseria gonorrhoeae 11, 6
• Gastrointestinal: Salmonella, Shigella, Yersinia, Campylobacter 11, 10, 6
• Respiratory: Less common, Chlamydia pneumoniae 11

Important Clinical Pitfalls

Monoarticular presentation: While oligoarthritis is typical, monoarticular involvement occurs in 13-14% of cases 4. Don't dismiss reactive arthritis based on single joint involvement.

Incomplete triad: The majority of patients do not present with the complete classic triad of arthritis, urethritis, and conjunctivitis 8. Absence of extra-articular features does not exclude the diagnosis.

Delayed onset: Arthritis can manifest weeks after the infection has resolved, and the initial infection may have been asymptomatic 11, 10.

Axial involvement: While peripheral arthritis dominates, sacroiliitis and spondylitis can occur, particularly in HLA-B27 positive patients 5, 6.

Differential Considerations

The inflammatory markers being markedly elevated is crucial for distinguishing reactive arthritis from:

• Osteoarthritis (normal inflammatory markers)
• Crystal arthropathies (gout, pseudogout)
• Septic arthritis (requires joint aspiration to exclude)
• Other spondyloarthropathies 1, 3