An epiphyseal fracture commonly results from avulsion of the epiphysis by traction through the attached ligaments. A fracture of the proximal tibial epiphysis is, therefore, a rare injury because of the absence of collateral ligament attachments. Most proximal tibial epiphyseal injuries occur as avulsion fractures of the tibial tubercle; Salter-Harris Types I or II injuries involving pressure epiphyses are rare. In the current case of a thirteen-year-old boy, the proximal tibial epiphyseal injuries in both knees occurred during quadriceps contraction in the absence of violent trauma, and there was a six-month interval between the two injuries.