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What Is the Anatomy of the Ankle Joint?

The ankle joint has a complex anatomy. Commonly referred to as a single joint, the ankle is actually made up of two distinct joints: the true ankle (talocrural) joint and the subtalar joint, both of which are composed of various articulating surfaces and ligaments. Along with the muscles and tendons in the lower leg and foot, these joints must work together to provide stability and support to the body and facilitate a wide range of movements, including walking, running and jumping.

The anatomy of the true ankle joint

Three bones come together to form the talocrural joint: the tibia and fibula in the lower leg, and the talus in the foot. Held together by strong ligaments, the tibia and fibula form a bracket-shaped socket (mortise). The wedge-shaped end of the talus fits snugly into the mortise. A hinge-like structure, the true ankle joint allows the foot to bend upward and downward.

The anatomy of the subtalar ankle joint

Two tarsal bones at the end of the foot – the talus and calcaneus – are connected by a strong ligament to form the subtalar joint. Enclosed within a joint capsule, which is lined with a synovial membrane and strengthened by a fibrous external layer, the subtalar joint is supported by three other ligaments: the posterior talocalcaneal ligament, the medial talocalcaneal ligament and the lateral talocalcaneal ligament. The subtalar joint allows the foot to bend from side to side.

The ends of the bones in each ankle joint are covered with hyaline cartilage, which is made of collagen and other proteins. This protective covering absorbs shock, reduces friction and allows the bones to glide smoothly against each other during movement.

Why is the ankle prone to injury?

Due to the complexity of its anatomy and the significant pressure it sustains on a daily basis, the ankle is susceptible to injuries, such as strains, sprains and fractures. While these injuries are common in sports, they can also result from a fall, trauma or walking on an uneven surface during daily activities.

At Advanced Orthopaedics & Sports Medicine of Houston, TX, our experienced orthopedic specialists provide a full range of treatment options — both conservative and surgical — for ankle injuries. To learn more, contact us to schedule an appointment at one of our offices in the Houston, Texas, area.