(see: juvenile RA menu)
- 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
- 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:
- is a common symptom (20-35 %) at the time of diagnosis
- w/ iridocyclitis, ANA will usually be positive;
- may precede or follow the arthritis;
- note that incidious blindness may occur 2nd to adhesions.
- posterior synechiae: deform the pupil;
- cataract formation;
- ref: Prevalence and outcome of uveitis in a regional cohort of patients with juvenile rheumatoid arthritis.
- 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;
- 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)