Tibial tuberosity avulsion fractures are uncommon and usually associated with sports activities that require jumping. Avulsion occurs with violent active extension of the knee or passive flexion against contracted quadriceps muscles.
Although an acute injury, tibial tuberosity avulsion is most frequently seen in young adolescents with ongoing Osgood-Schlatter disease.
The Watson-Jones classification is used to grade tibial tuberosity avulsion fractures:
- type 1: avulsion of the apophysis without injury to the tibial epiphysis
- type 2: epiphysis is lifted cephalad and incompletely fractured
- type 3: displacement of the proximal base of the epiphysis with the fracture line extending into the joint