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Pauciarticular JRA

(see: juvenile RA menu)

Discussion

  • definition: < 4 involved joints.
  • most frequently encoutered subgroup, accouting for 30-40% of JRA;
  • peak age is 2-4 years
  • more common in girls (4x)
  • differential dx

Clinical Presentation>

  • begins w/ incidious onset which can be painless
  • swelling, warmth, and restriction of motion are common sx;
  • knee, ankle, and elbow (& wrist) may be involved (initial involvement of hip or neck is uncommon);
  • systemic signs are absent;
  • chronic iridocyclitis:

Labs

  • ESR and WBC are frequently normal;
  • RF is rarely positive (if RF is positive then consider polyarticular arthritis);
  • 1/2 of patients have a positive ANA
    • however positive titers are not exceedingly high ( < 1:320)
    • if test is negative, note that it may become positive w/ time;

Prognosis

  • good prognosis: 70% will be in remission 15 yrs after onset.
  • < 15% have severe joint destruction or disability;
  • subluxation of the knee may occur;
  • disease may last several years;
  • leg length inequality may occur (either larger or smaller)
    • usually occurs w/ knee involvment.
    • if JRA occurs before age 9, tend to get overgrowth (< 3cm)
    • affected hip jont: in young patient there is premature growth arrest of the acetabulum and the femoral head)
    • if JRA occurs after age 9, may get premature closure which may cause subtanial shortening ( > 6 cm)

References