Tibial tubercle avulsion fractures are uncommon injuries that are seen mostly in adolescent male patients during athletic activities. The mechanism of injury usually involves a strong eccentric contraction of the quadriceps femoris muscle when the proximal tibial physis is closing, leading to failure of the physis at the patellar tendon insertion. The treatment of patients with tibial tubercle avulsion fractures depends on the fracture pattern; it can be conservative with immobilization in a long leg cast in extension for 6 weeks with minimal displacement (< 2 mm) and/or acceptable displacement after closed reduction/cast application. Or it can be surgical. This article presents a 14-year-old boy with an Ogden type IIIB tibial tubercle avulsion fracture that was misdiagnosed on radiographs at presentation as type IB. Open reduction and cannulated screw osteosynthesis was done. The outcome was excellent after a 12-week rehabilitation protocol.