The accessory anteroinferior tibiofibular ligament as a cause of talar impingement - A cadaveric study

Background: A distal fascicle of the anteroinferior tibiofibular ligament has been reported as a possible cause of anterolateral ankle impingement. Hypothesis: This fascicle represents an independent accessory ligament in the anterior aspect of the inferior tibiofibular syndesmosis. Study Design: Descriptive anatomical study. Methods: The inferior tibiofibular syndesmosis was exposed in 24 fresh-frozen cadaveric ankles. Morphological characteristics of the inferior tibiofibular ligaments and interactions between the anterior ligaments and the talus were investigated in different degrees of ankle motion. Results: A separate accessory anterior ligament was identified in 22 specimens. Its orientation was parallel and distal to the anterior tibiofibular ligament, from which it was separated by a fibrofatty septum. Its length ranged from 17 to 22 mm, its thickness from 1 to 2 mm, and its width from 3 to 5 mm. Impingement of this ligament against the talar dome was documented in all specimens in neutral ankle position, with bending of the ligamentous bands in dorsiflexion. Distraction maneuvers reproducing traction during arthroscopic approaches relieved contact. Conclusions: An accessory anteroinferior tibiofibular ligament with distinct anatomical features was recognized. Clinical Relevance: Based on its increased incidence in the cadaver ankles, the accessory ligament reflects a normal anatomical finding. Nevertheless, it could lead to anterolateral impingement in cases with coexistent ankle instability.