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
- 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
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