Reactive Arthritis

Introduction

  • Reactive arthritis, formerly known as Reiter’s syndrome, is a term used to refer to the appearance of rheumatologic disease following an infection
  • It is called "reactive" because the musculoskeletal complaints are triggered by an autoimmune reaction to the initial infection

Pathogenesis

  • Some GI infections can produce arthritic symptoms
    • Yersinia
    • Camplobacter
    • Salmonella
    • Chlamydia
    • Shigella
  • The incidence of arthritis after an acute attack of dysentery is reported to be between 2 – 33%
  • The HLA-B27 phenotype in particular, seems to predispose to reactive arthritis following Yersinia infection
  • HLA-B27 genotype has been reported in up to 90% of reactive arthritis due to Yersinia infection
  • E. coli has also been noted to produce an arthritic picture, but no connection between HLA-B27 and the subsequent development of reactive arthritis has been found

Natural History

  • Reactive arthritis is an uncommon disease
    • Prevalence estimated at 30-40 per 100,000 adults
    • Annual incidence 5-28 per 100,000
  • It is more prevalent in Scandinavian populations; in fact, most studies on reactive arthritis are conducted in Scandinavian populations
  • Most cases are sporadic, but there have been outbreaks reported with specific strains of each pathogen
  • The peak age is the 3rd and 4th decades
  • The condition is more common in white, male patients

Clinical Presentation

  • Typically, the arthritis will develop between 2 – 3 weeks following the GI infection
  • Sacroiliitis is present in 25% of patients, but more asymmetric than in Ankylosing Spondylitis
  • Usually affects large joints
    • The knee, ankle, wrist, and sacroiliac joints are commonly involved
    • The typical arthritis pattern is lower extremity dominant
    • Asymmetrical
    • Mono/oligo-articular pattern
  • Associated findings
    • Enthesitis (insertional tendinopathy)
      • Enthesitis can present as sausage like digits and swelling of the heels
      • The insertions of the Achilles tendon and the plantar fascia on the calcaneus are commonly involved
    • Ocular involvement
      • Conjuctivitis
      • Anterior uveitis
    • Urethritis
      • May be sterile
      • Can present with dysuria and increased frequency of urination
      • Skin or genital rash may be seen

Differential Diagnosis

  • Chlamydia or Gonnococal infection may cause urethritis
  • Analyzing synovial fluid for culture and crystal involvement is important to rule out septic arthritis and gout

Imaging and other Diagnostic Studies

X-Ray

  • Initially normal, then shows erosive arthropathy
  • Vertebral changes similar to Ankylosing Spondylitis
  • Sacroiliitis
  • Periosteal changes in
    • Ischial tuberosity
    • Greater trochanter
    • Site of insertion of Achilles tendon

Laboratory tests

  • Only 50% of patients with reactive arthritis will be HLA-B27 positive
  • The genotyping test is usually reserved in highly suspect circumstances  

Treatment

  • Treat the underlying infection
  • Provide palliation for the reactive symptoms

Outcome

  • The prognosis depends on
    • The strain of pathogen
    • Genetic and environmental factors
  • Overall prognosis is good, with the arthritis remitting in < 6 months
  • Only 4 – 10% of patients in one Finland study had reactive arthritis that lasted >1 year. Their reactive arthritis was induced by strains of either Yersinia, Salmonella, Shigella or Chlamydia
  • Importantly, the presence of HLA-B27 does not seem to correlate with either the severity or the duration of the disease
  • It was noted that patients who develop reactive arthritis following a GI infection are more likely to develop other auto-immune associated conditions like psoriasis, ankylosing spondylitis, and inflammatory bowel disease later in life

Related Topics

  • The triad of "Can’t see; can’t pee; can’t bend my knee" suggests reactive arthritis
  • German physician Hans Reiter first described reactive arthritis and gives his name to the eponym
  • Reactive arthritis is a so-called "seronegative spondylarthropathy" in that it appears similar to rheumatoid arthritis; i.e. it’s a "spondylarthropathy", but the rheumatoid factor test is negative; hence "seronegative"

References