Imaging pediatric sports injuries: lower extremity.

Injuries to pediatric athletes, which are becoming increasingly common, take the form of acute injuries and chronic overuse injuries. Acute injuries of the lower extremity include avulsions of the pelvic apophyses, muscle-tendon injuries, transient dislocation of the patella, ankle sprains, and acute tears of the anterior cruciate ligament and menisci. Magnetic resonance (MR) imaging of the latter 2 injuries should approach the accuracy of MR imaging of the adult knee. Chronic overuse injuries of the lower extremity in this age group include stress fractures, which are most common in the tibia; ankle impingement syndromes; osteochondritis dissecans of the knee and osteochondral lesions of the talus; and traction apophysitis, most commonly presenting as Osgood-Schlatter disease and Sinding-Larsen-Johannson disease, affecting the patellar tendon. Imaging findings of all these lesions are characteristic, and allow radiologists to assist their clinical colleagues in diagnosing and treating pediatric athletic injuries.