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Talocrural Joint

The ankle or talocrural joint is a hinge joint formed by articular facets on the distal tibia, the medial malleolus, and the lateral malleolus, which articulate with the talus. The talus is the second largest tarsal bone and main weightbearing bone of the articulation linking the lower leg to the foot. The relatively square shape of the talus allows the ankle only two movements about the transverse axis: plantarflexion and dorsiflexion. The talus is wider on the anterior aspect than posteriorly, the most stable position of the ankle is dorsiflexion as the talus fits tighter between the malleoli. In contrast, as the ankle moves into plantarflexion, the wider portion of the tibia is brought into contact with the narrower posterior aspect of the talus, creating a less-stable position than dorsiflexion.1

The lateral malleolus of the fibula extends further distally so that the bony stability of the lateral aspect of the ankle is more stable than the medial. Motion at the talocrural joint ranges from 20 degrees of dorsiflexion to 50 degrees of plantarflexion, depending on the patient. An individual requires 20 degrees of plantarflexion and 10 degrees of dorsiflexion for walking. Authors have discerned a runner requires up to 25 degrees of plantarflexion and 20 to 22 degrees of dorsiflexion for normal gait.2,3

Talocrural Joint Ligaments

The ligamentous support of the ankle consists of the articular capsule, three lateral ligaments, two ligaments that connect the tibia and fibula, and the medial or deltoid ligament (Figure 26-1). The three lateral ligaments include the anterior talofibular, posterior talofibular, and calcaneofibular ligaments. The anterior and posterior tibiofibular ligaments bridge the tibia and fibula and form the distal portion of the interosseous membrane. The thick deltoid ligament provides primary resistance to foot eversion. A thin articular capsule encases the ankle joint.

Figure 26-1

Ligaments of the talocrural joint

A. Lateral aspect. B. Medial aspect.

Talocrural Joint Muscles

The muscles passing posterior to the lateral malleolus will produce ankle plantarflexion along ...

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