The PTFL is the strongest and deepest of the three lateral ankle ligaments, running nearly horizontally between the posterior lateral malleolus and the lateral talar posterior process. It is rarely torn in isolation, becoming involved only in severe ankle injuries including complete ankle dislocations. Its horizontal orientation means it becomes taut in ankle dorsiflexion, providing the primary restraint against posterior talar displacement in this position.
| Origin | Medial surface of the posterior lateral malleolus (malleolar fossa) |
|---|---|
| Insertion | Posterolateral talar surface (lateral tubercle of posterior process) |
| Actions | Strongest of the three lateral ankle ligaments — resists posterior talofibular displacement and external rotation |
|---|
PTFL injuries indicate severe ankle ligament disruption and are associated with transchondral talar dome fractures from the posterior talus impacting the posterior tibial plafond in extreme plantarflexion or with the peroneal tendons being stripped from their groove in severe inversion-external rotation injuries. Isolated PTFL injuries require MRI for diagnosis as they cannot be tested with simple stress views.
ATFL, CFL, and PTFL combined disruption with ankle dislocation requiring surgical stabilisation and assessment for associated osteochondral and peroneal tendon injuries.
