Sonography of the elbow in infants and children.

High-resolution real-time sonography of the musculoskeletal system of infants and young children is being used with increasing frequency, in part because of the inability of plain film radiography to visualize unossified cartilage. Real-time sonography now plays an important role in the evaluation of infantile hip dysplasia, as well as in the identification and aspiration of joint effusion. The purpose of this essay is to illustrate clinical situations in which sonography of the elbow is helpful.