Juvenile Rheumatoid Arthritis (JRA)

Michael P. D'Alessandro, M.D.
Peer Review Status: Internally Peer Reviewed

Etiology/Pathophysiology:
Is a connective tissue disease with a predilection for joint involvement. Pathologically is the same as adult rheumatoid arthritis but they differ in clinical presentation, joint involvement and radiographic findings. Distribution is: knee (90% ), ankle (70% ), wrist (70% ), elbow (40% ), hip (35% ), and shoulder.

Pathology:
Not applicable

Imaging Findings:
In legs symmetric bilateral periarticular osteopenia involving the epiphyses and metaphyses is seen with overgrowth of the distal femoral and proximal tibial epiphyses, expansion of the intercondylar notch, and epiphyseal erosion with decreased joint space. In the hands periarticular osteopenia is seen around the metatarsal phalangeal and interphalangeal joints with swelling around the wrists and joints of fingers, accelerated skeletal maturation, erosive changes in the carpal bones, distal radius, and ulna with joint space narrowing. The spine is also involved in up to 70% of patients and you see soft tissue swelling, destruction and obliteration of articular surfaces and joint spaces, generalized rarefaction of bone, and focal subchondral necrosis. Affects the true joints between the articular facets the most, and does not affect synarthroses like the intervertebral discs. Diffuse ankylosis of posterior articular joints without disc space abnormalities is diagnostic of JRA.

DDX:

• Psoriatic arthritis
• Farber's disease
• Ulcerative colitis or Chrons
• Systemic Lupus Erythematosus
• Familial Mediterranean fever

References:
See References Chapter.

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