US for diagnosis of musculoskeletal conditions in the young athlete: emphasis on dynamic assessment.

Ultrasonography (US) is increasingly recognized as an important tool for diagnosis and therapeutic management of a variety of musculoskeletal conditions. Advantages of US use in the young athlete include the ability to diagnose dynamic conditions that are occult with other modalities, provide additional diagnostic information, and aid in treatment. Uses of US in young patients include evaluation of acquired musculoskeletal conditions that manifest with symptoms and assessment of congenital variants that may manifest with pain or limitations in activity. Acquired conditions in the young athlete include tendon disorders, such as proximal tendinosis, and ligament disorders, such as anterior talofibular ligament or ulnar collateral ligament tears. While static images are frequently able to depict these disorders without difficulty, a dynamic examination that provides stress to the joint of interest may be able to uncover a ligament tear or insufficiency and concurrently provide the clinician with information regarding joint stability. Numerous congenital variants that occur throughout the musculoskeletal system can be associated with awkward sensations such as snapping, popping, and clunking and occasionally with pain. Pathologic processes associated with congenital variants in the upper extremities include slipping rib syndrome, atraumatic anterior subluxation of the sternoclavicular joint, and snapping triceps syndrome. Conditions that affect the lower extremities include internal and external snapping hip syndrome, snapping knee syndrome, and medial plica syndrome. The dynamic capability of US is ideal for diagnosis of many conditions that affect the musculoskeletal system of the young athlete, many of which would be difficult or impossible to identify with use of other imaging modalities.