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Reactive Arthritis

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Overview

Reactive arthritis is a seronegative arthropathy associated with inflammatory back pain, oligoarthritis, and extra-articular symptoms that usually occur 1-6 weeks after a gastrointestinal or urogenital infection. The organism cannot be recovered from the joint and is not present in it.

It was formerly known as Reiter’s syndrome but has since been renamed as Reiter, the doctor who first described it, was a Nazi war criminal.

Reactive arthritis is sometimes subdivided into two subgroups:

  • Post-enteric – the most commonly associated pathogens are:
    • Campylobacter
    • Salmonella
    • Shigella
  • Post-venereal – typically following Chlamydia trachomatis infection

Epidemiology

  •  Commonly affects young men
  • Sexually-acquired reactive arthritis is more commonly seen in men
    • There’s a 10:1 ratio of men: women with this form
  • Most cases of sexually-acquired reactive arthritis are due to Chlamydia trachomatis

Risk Factors

  • Male sex
  • HLA-B27
  • Preceding chlamydial or gastrointestinal infection

Presentation

Reactive arthritis develops around 2-4 weeks post-infection. Its features can be remembered using “can’t see (eye involvement), pee (urethritis), or climb a tree (arthritis)”:

  • Arthritis – usually an asymmetrical oligoarthritis affecting larger joints of the lower extremity
  • Urethritis
  • Eye involvement – conjunctivitis, anterior uveitis, episcleritis 
  • Skin involvement – circinate balanitis, keratoderma blennorrhagia
  • Lower back pain
  • Enthesitis (inflammation where a tendon inserts into the bone)
  • Dactylitis (swelling of an entire digit)

Differential Diagnoses

Psoriatic arthritis (PsA)

  • There is no history of infectious disease
  • There is no urethritis or conjunctivitis in PsA

Rheumatoid arthritis (RA)

  • There is no history of infectious disease
  • RA does not involve the lumbar spine or sacroiliac joints
  • RA tends to cause a symmetrical polyarthropathy affecting small joints in the hands and feet
  • There is no urethritis or conjunctivitis in PsA

Ankylosing spondylitis (AS)

  • There is no history of infectious disease
  • There is no urethritis or conjunctivitis in AS

Rheumatic fever

  • Symptoms are usually seen after an infection with group A Streptococcus (such as sore throat)
  • The migratory arthritis seen in rheumatic fever does not involve the axial spine or sacroiliac joints

Disseminated gonococcal disease

  • There are usually features of gonorrhoea, such as urethral discharge
  • Nucleic acid amplification testing (NAAT) may identify the presence of Neisseria gonorrhoeae

Gout

  • There is no history of infectious disease
  • There may be gouty tophi present
  • Gout tends to affect distal interphalangeal joints

Septic arthritis

  • Usually affects a single joint in most cases
  • The affected joint is erythematous, swollen, and warm
  • Patients may have a fever

Lyme disease

  • Erythema migrans may be present at the site of the tick bite
  • The arthritis seen in Lyme disease is migratory and tends to affect 1 joint at a time, usually large joints such as the knee
  • There may be additional features of Lyme disease such as fever, fatigue, and headaches

Investigations

  • ESR and CRP:
    • These are both increased
  • Anti-nuclear antibody (ANA):
    • Negative
  • Rheumatoid factor (RF):
    • Negative
  • Urogenital NAAT testing for Chlamydia trachomatis/Neisseria gonorrhoeae:
    • Negative
  • Stool cultures:
    • Negative
  • Plain x-rays:
    • Sacroiliitis may be present
  • Arthrocentesis and synovial fluid analysis:
    • Negative

Management

In the case of acute reactive arthritis:

  • 1st line: NSAIDs e.g. naproxen/ibuprofen/diclofenac/indomethacin
  • 2nd line: corticosteroids:
    • Intra-articular if mono-/oligoarticular reactive arthritis
    • Systemic steroids if many joints are affected or ocular manifestations present

If persistent or chronic reactive arthritis:

Complications

Prognosis

  • Usually self-limiting within 3-5 months
    • If it lasts longer than 6 months, this suggests chronicity
  • Hip involvement, unresponsiveness to NSAIDs, or an ESR >30 suggests a worse prognosis
  • Higher incidence if HLA-B27 positive
  • Recurrence of the disease may be triggered

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