The immature athlete.

The skeletally immature athlete poses unique problems in diagnosis and treatment of injuries to the extensor mechanism of the knee. An accurate and detailed history and physical examination of the knee are essential for making a specific diagnosis and formulating an appropriate treatment plan. This article presents an overview of acute and chronic injuries of the extensor mechanism of the knee that are unique to skeletally immature athletes. The subjects of femoral trochlear dysplasia and medial subluxation of the patella are briefly discussed. The etiopathology, clinical evaluation, and management (non-operative and operative) of sleeve fractures of the patella and avulsion fractures of the tibial tubercle in children and adolescents are discussed. The pathoanatomy, clinical features, and management of synovial plica syndrome, Hoffa's syndrome, Osgood-Schlatter disease, and Sinding-Larsen-Johansson disease are presented.