A 16-year-old male basketball player had sustained an injury upon landing after a forceful jump. Plain radiography demonstrated bilateral tibial tubercle avulsion fracture involving partially proximal physis. Open reduction and internal fixation were performed at once. Continuous passive motion was started immediately after operation, and the patient was ambulated with hinged knee extension braces. After 27 months follow-up his knees completely regained normal range of motion except a 3degrees extension loss in the left knee. He resumed all daily functional activities (Lysholm functional score of 99), but he slightly lost his level of activity (Tegner activity level from 7 to 6). No angular deformity at all on the frontal plane was determined upon radiological examination. Tibial slope angles were symmetrical and within the normal range. There were visible small bone fragments inside the left patellar tendon.