Pediatric Radiology Case of the Month
September 2008



CLINICAL HISTORY:2-year-old boy previously healthy boy with limp, swollen knee and refusing to bear weight .
 
 
QUESTION 1: Describe the findings on these knee x-rays.
 
QUESTION 2: What is the next best test?
      
 
QUESTION 3:Describe the findings on these ultrasound images.
 
QUESTION 4:What is the next best test?
 
 
QUESTION 5:Describe the findings on these MRI images ?
 
QUESTION 6:What is your differential diagnoses?
 
QUESTION 7: Answer(T/F)
      a. Marrow edema is a classic feature of transient synovitis?
      b. What are some clinical features of septic arthritis?
      c. What joint is most commonly affected by Lyme arthritis?
      d. MRI readily distinguishes between oligoarticular JRA, septic arthritis, and Lyme arthritis?
      e. The presence of fever (oral temperature> 38.5 c). Non-weight bearing, ESR >40 mm per hour, and a WBC> 12,000 favor diagnosis of septic arthritis.
      f. MRI also in used to evaluate complication of septic arthritis, including epiphyseal ischemia, growth arrest, secondary osteomyelitis, and premature degenerative changes.
      g. The diagnosis of septic arthritis is made when there is a positive culture from joint aspiration or a white blood cell count in the joint fluid>50,000 cell/mm3 with a positive blood culture.