A rare case is reported of bilateral physeal lesions of the proximal tibia classified as Salter-Harris type II, which occurred simultaneously after a "flexion type" injury in a 14-year-old boy. Treatment was conservative on the nondisplaced side and surgical, by closed reduction and internal fixation, on the displaced side. There was no previous diagnosis of Osgood-Schlatter disease. After reviewing all the cases described previously, which occurred either consecutively or simultaneously, we conclude that less resistance of the growth plate, typical of late adolescence, likely represents the cause of this type of lesion.