Osgood-Schlatter Disease - Osgood-Schlatter (OS) disease is one of the most common causes of knee pain in the adolescent. Consisting of pain and edema of the tibial tubercle (and hence this is an extra-articular disease), OS disease is generally a benign, self-limited knee condition associated with traction apophysitis in adolescent boys and girls.Paget first described the clinical syndrome in ...