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Posterior Talofibular Ligament (Full)

ligamentum talofibulare posterius

The PTFL is the strongest of the three lateral ankle ligaments, running nearly horizontally from the posterior fibula to the posterior talus. It is only torn in severe lateral ankle injuries — frank ankle dislocations — as it requires extreme plantarflexion and inversion beyond what ATFL and CFL failure alone allows. Its integrity provides the posterior constraint that prevents posterior dislocation of the talus from the mortise.

Region: Foot & Ankle

Anatomical Data

Origin, Insertion & Supply

Origin	Posterior lateral malleolus (digital fossa)
Insertion	Posterior talar process (lateral tubercle)

Biomechanics

Function & Actions

Actions	Strongest lateral ankle ligament; resists posterior talar displacement and extreme plantarflexion; only torn in complete ankle dislocations

Clinical Relevance

Clinical Notes

PTFL tears are rare in isolation and indicate a high-energy lateral ankle injury with probable concurrent deltoid and syndesmotic involvement. MRI confirms PTFL disruption as part of the assessment of severe ankle injuries. Its intact status is confirmed by the absence of posterior ankle instability on examination.

Pathology

Common Injuries & Conditions

Ankle Dislocation

PTFL disruption as part of complete lateral ankle ligament failure in ankle dislocation requiring urgent reduction and ligamentous assessment.