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Posterior Malleolus

malleolus posterior

The posterior malleolus is the posterior lip of the distal tibia at the ankle, forming the posterior boundary of the tibial plafond (ankle mortise). It provides the posterior attachment of the posterior tibiofibular ligament and contributes to rotational stability of the ankle joint. The flexor tendons (FHL, FDL, tibialis posterior), neurovascular bundle, and peroneal tendons pass behind and around it.

Region: Lower Leg

Clinical Relevance

Clinical Notes

The posterior malleolus is the third element of trimalleolar ankle fractures (medial malleolus, lateral malleolus, posterior malleolus). Posterior malleolus fragments exceeding 25% of the tibial articular surface require fixation to restore posterior tibiotalar contact area and prevent instability. Fixation is performed with anteroposterior lag screws or a posterior buttress plate. Large posterior malleolus fragments also indicate posterior tibiofibular ligament avulsion, contributing to syndesmotic instability. The Bartonicsek classification guides fixation decisions based on fragment size and morphology.

Pathology

Common Injuries & Conditions

Posterior Malleolus Fracture in Trimalleolar Ankle Fracture

Trimalleolar ankle fracture with posterior malleolus fragment exceeding 25% of the tibial plafond requires fixation to restore posterior articular stability and prevent malreduction of the syndesmosis; fixation is achieved by anteroposterior screws from front or by a posterolateral plate approach providing direct buttress of the posterior fragment.