Deltoid ligament. Functional analysis of the medial collateral ligamentous apparatus of the ankle joint.

On 34 osteoligamentous ankle preparations the function of the various components of the deltoid ligament has been elucidated by tracing mobility patterns after successive transection of the components in varying sequence. The anterior and posterior talofibular ligaments were included in the study to investigate the interaction between these structures and the deltoid ligament. The tibiocalcaneal and the intermediate tibiotalar ligaments control abduction of the talus. The anterior tibiotalar and talofibular ligaments control plantar flexion, while dorsiflexion is inhibited by the posterior tibiotalar and talofibular ligaments, and partly by the anterior talofibular ligament as well. In combination, the anterior and intermediate tibiotalar ligaments control external rotation, while the intermediate and posterior tibiotalar ligaments control both external and, together with the anterior talofibular ligament, internal rotation of the talus. Isolated, neither the anterior nor the posterior tibiotalar ligament appears to play any major role in ankle stability.