Anatomic Basis of Ankle Instability

Abstract

The surgeon must have a thorough understanding of ankle ligamentous anatomy in order to grasp new concepts including ankle microinstability and rotational instability. The anterior talofibular ligament (ATFL) has 2 fascicles, a superior fascicle which is intra-articular and an inferior fascicle which is extra-articular. Located within the ankle joint but extrasonovial, the superior fascicle of the ATFL lacks the capacity to heal after a moderate ankle sprain. Because this fascicle controls talar internal rotation, any deficiency may lead to ankle microinstability, which in turn may lead to chronic overloading of the deltoid ligament’s most anterior fascicles and chronic rotational instability. The ATFL inferior fascicle, the calcaneofibular ligament and their connecting fibers form the lateral fibulotalocalcaneal ligament complex. An injury of the lateral fibulotalocalcaneal ligament complex will lead to classic chronic ankle instability. These new findings on the ankle ligaments have major implications for ankle instability. Level of Evidence: Diagnostic Level V — expert opinion. See Instructions for Authors for a complete description of levels of evidence.