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The ankle joint is a hinged synovial joint that is formed by the articulation of the talus, tibia, and fibula bones. The articular facet of the lateral malleolus (bony prominence on the lower fibula) forms the lateral border of the ankle joint while the articular facet of the medial malleolus (bony prominence on the lower tibia) forms the medial border of the joint. The superior portion of the ankle joint forms from the inferior articular surface of the tibia and the superior margin of the talus. Together, these three borders form the ankle mortise. The talus articulates inferiorly with the calcaneus and anteriorly with the navicular. The upper surface, called the trochlear surface, is somewhat cylindrical and allows for dorsiflexion and plantarflexion of the ankle. The talus is wider anteriorly and more narrow posteriorly. It forms a wedge that fits between the medial and lateral malleoli making dorsiflexion the most stable position for the ankle. The ankle is stabilized by strong collateral ligaments medially and laterally. The main stabilizing ligament medially is the deltoid ligament, and laterally the ankle has stabilization from three separate ligaments, the anterior and posterior talofibular ligaments, and the calcaneofibular ligament. The anterior and posterior talofibular ligaments connect the talus to the fibula, and the calcaneofibular ligament connects the fibula to the calcaneus inferiorly. The anterior talofibular ligament (ATFL) is the weakest of the three lateral ligaments and thus the most frequently injured. The deltoid ligament actually consists of four ligaments that form a triangle connecting the tibia to the navicular, the calcaneus, and the talus. The anterior and posterior tibiotalar ligaments connect the tibia to the talus. The last two ligaments of the triangle are the tibionavicular ligament which attaches to the navicular anteriorly and the tibiocalcaneal ligament which attaches to the calcaneus inferiorly.[1]