Two cases of avulsion fracture of the tibial tubercle are reported. They were fifteen-and sixteen-old boy injured their left knees when they jumped in volley-ball practice. Roentgenographic examinations revealed displacement of the tubercle with extension of the fracture into the knee joints. Fractures were treated by open reduction and internel fixation and the knees were immobilized in extension for four weeks. Two months after operations, they had full range of motion of the knees and no complaints.
