Posterior tibiotalar ligament

The deep posterior tibiotalar ligament (dPTTL) is a component of the deep layer of the deltoid (medial collateral) ligament complex of the ankle. It is one of the most consistently present and structurally prominent bands of the deltoid ligament.

The dPTTL originates from the inferior surface of the medial malleolus from the intercollicular groove,and courses posteriorly to insert on the medial surface of the talus, attaching to the depression below the articular facet for the medial malleolus.

It is the largest and thickest band of the deltoid ligament complex, with the greatest ligament surface area of attachment to both the tibia and talus.

It is one of the most constant components of the deltoid, identified in 96.7100% of cadaveric specimens across multiple studies.

The dPTTL can be further subdivided into a superficial band and a deep band, both arising from the medial malleolus but distinguishable on coronal MRI as two thick, lowsignalintensity structures.

On MRI (particularly fluidsensitive sequences), the dPTTL commonly appears hyperintense and striated even in asymptomatic individuals (~70% hyperintense, ~80% striated), which can simulate a tear a wellrecognized pseudotear appearance.

Injury to the dPTTL can result in posteromedial ankle impingement, with scar formation and hypertrophic response visible on MRI and ultrasound.

The dPTTL functions as a key restraint against lateral talar shift and external rotation of the talus within the ankle mortise. Biomechanical testing shows it most commonly fails near its talar insertion.