Musculoskeletal ultrasonography of the lower extremities in infants and children.

Ultrasonography is a powerful diagnostic imaging tool for evaluating lower extremity anatomy and pathology in children. Indications for pediatric musculoskeletal lower extremity sonography include developmental dysplasia of the hip, hip joint sonography for the child with a painful hip, evaluation and characterization of superficial soft-tissue masses, evaluation for deep venous thrombosis, and foreign body localization, characterization and removal. This review highlights these established indications, but primarily focuses on additional US applications for evaluation of the lower extremities, including diagnosis and characterization of arthritis and monitoring of therapy, evaluation of tendon tears and muscle strain injuries, characterization of soft-tissue masses and evaluation of certain congenital abnormalities of the lower extremities. Techniques for optimal utilization of musculoskeletal US in children are also discussed.