Foot & Ankle

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The foot consist of 26 bones and 28 joints which are controlled by 42 muscles that are arranged in 9 compartments and are held together by multiple ligaments. There are 19 tendons that cross the ankle joint and insert on different parts of the foot.

The term ‘ankle’ refers to the ‘talocrural’, or the true ankle joint, which is a hinge joint between the talus and the distal end of tibia and fibula. The talus fits right in between the latter two bones and sits on top of the calcaneus. The body of talus is slightly wider anteriorly than posteriorly.

The subtalar joint is made by an articulation between the talus and the calcaneus. The mid-tarsal joints are formed between the talus and the navicular and between the calcaneus and the cuboid. In full extension (dorsiflexion), the talus becomes firmly wedged between the two malleoli. In flexion (planterflexion), there is slight laxity in the joint and allowing some side to side movements, which occur at the subtalar joint and mid-tarsal joint.

The bones of the foot are arranged in the form of two longitudinal arches. The medial arch comprises calcaneus, talus, navicular, the three cuneiforms and the three medial metatarsals; the apex of this arch is made by the talus. The lateral arch comprises calcaneus, cuboid and the lateral two metatarsals.

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The principle dorsiflexors of the ankle include tibialis anterior assisted by extensor digitorum longus, extensor hallucis longus and peronius tertius. The main planterflexors include gastrocnemius and solius assisted by tibialis posterior, flexor hallucis longus and flexor digitorum longus.

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Main Ligaments

The anterior tibiofibular ligament connects the tibia to the fibula. The lateral ligaments attach the fibula to the calcaneus. There are three main lateral ligaments; the anterior and the posterior talofibular ligaments (ATFL & PTFL) and the calcaneofibular ligament (CFL). The anterior talofibular ligament is a flat band that extends from the anterior malleolus forward to the talus and is relatively weak. The posterior talofibular ligament is thicker and stronger than the former ligament and runs horizontally from the back of the malleolus to the posterior surface of the talus. The calcaneofibular ligament, the longest of the three, is a round cord that goes from the tip of the lateral malleolus down to the lateral surface of the calcaneus.

On the medial side, the deltoid ligaments (superficial & deep) connect the tibia to the talus and calcaneus and are stronger than the lateral ligaments. Other important ligaments include spring ligament (from sustantaculum tali to the navicular), short planter ligament (between the calcaneus and the cuboid) and long planter ligament (between the calcaneus and the 2nd-4th metatarsals). All these ligaments are further supported by planter aponeurosis, a thickened fibrous band, which contributes significantly toward the stress of weight bearing.