Posterior tibiotalar ligament: an anatomic study correlated with MRI.

This study was performed to clarify the morphologic characteristics of two layers of the posterior tibiotalar ligament (PTT) and two bands of the deep PTT (dPTT), and to correlate the dissection findings with MR images. Sixty-four ankles from 42 cadavers were examined. The origin and insertion sites of the superficial PTT (sPTT) and the two bands of the dPTT were identified, and their length, width, and thickness were measured. MRI was performed on four ankles before serial sectioning or dissection. The serial sections were taken at a thickness of 2 mm. The sPTT was observed in 50 out of 60 dissected specimens (83.3%), taken from 64 ankles of 42 cadavers. The dPTT was observed in all specimens. The sPTT, superficial band of the dPTT (sdPTT), and deep band of the dPTT (ddPTT) arose from the inferior surface of the medial malleolus. The sPTT attached to the posterior process of the talus, and the sdPTT and ddPTT attached to the depression below the articular facet for the medial malleolus. The sPTT and two bands of the dPTT could be distinguished on coronal MR images, where the sPTT appeared as a thin string superficial to the two bands of the dPTT, which were separated as two thick, low-density strings. In the coronal plane of frozen sections, the outermost sPTT appeared as a thin, white bundle attached to the sdPTT. The PTT is composed of superficial and deep layers, and the dPTT is composed of superficial and deep bands.