Ankle Anatomy

The ankle joint consists of the upper bones, the Tibia and fibula and the Talus at the bottom. There are many ligaments supporting the joint, which are frequently injured.

Bones and Joints of the ankle

The ankle is made up of 4 distinct bones, the tibia, fibula, talus and calcaneus. The interaction between these bones allows for movement of the joint in certain planes. In turn, the ankle is made up of 3 separate joints:

  • Talocrural Joint: This is a hinge joint formed by the distal ends of the fibula and tibula that enclose the upper surface of the talus. It allows for both dorsiflexion (decreasing the angle between the foot and the shin) and plantarflexion (increasing the angle).
  • Inferior tibiofibular Joint: This is strong joint between the lower surfaces of the tibia and fibula. This is supported by the inferior tibiofibular ligament.
  • Subtalar Joint: This joint comprises of the articulating surfaces of the talus and the calcaneus. It provides shock absorption and the movements of inversion and eversion (inward and outward ankle movements respectively) occur here.

Ligaments of the ankle joint

The ligaments of the ankle joint are comprised mainly of the collateral ligaments, both medial (inner) and lateral (outer). These are extremely important in the stability of the ankle itself:

A. Lateral Collateral Ligament:

The lateral collateral ligament prevents excessive inversion. It is considerably weaker than the larger medial ligament and thus sprains to the lateral ligament are much more common. It is made up of 3 individual bands:

  • Anterior talofibular ligament (AFTL): passes from the fibula to the front of the talus bone.
  • Calcaneofibular ligament (CFL)- connects the calcaneus and the fibula
  • Posterior talofibular Ligament (PTFL)- passes from the back of the fibula to the rear surface of the calcaneus.

B. Medial Collateral Ligament:

The medial ligament also known as the deltoid ligament is considerably thicker than the lateral ligament and spreads out in a fan shape to cover the distal (bottom) end of the tibia and the inner surfaces of the talus, navicular, and calcaneus.