Sonography of the knee in normal and abused infants.

Sonography of an infant's knee is relatively easy and can show the non-ossified cartilage and adjacent soft tissues with great clarity. The normal anatomic features are characteristic and easy to learn and recognize. In abused infants, sonograms can confirm subtle or questionable radiographic abnormalities. In infants with metabolic bone disease, detection of occult fractures of the epiphyses is clinically important. Metaphyseal abnormalities due to neonatal ricktes should not be mistaken as signs of child abuse.