Imaging Case of the Week 432 Answer

The ankle x- rays show a Tillaux fracture which is a Salter-Harris III fracture of the distal tibial epiphysis.

On the AP view, there is a vertical lucency (fracture line) in the mid distal tibial epiphysis. The lateral ankle x-ray shows forward protrusion of anterior aspect of the distal tibial epiphysis and an ankle tear drop sign indicating ankle joint effusion.

This patient underwent operative fixation of fracture.

Tillaux fracture is a fracture of the anterolateral distal tibial epiphysis with avulsion of the fragment due to pull from the anterior tibiofibular ligament. Mechanism of injury is external rotation of the ankle. Commonly seen in adolescents, during the closure of the growth plate which starts medically and extends laterally. This means anterolateral part of the distal tibial growth plate is the last one to fuse and represents weakest point.

Reference: https://www.eurorad.org/case/2699