Ligaments of the ankle joint

The ankle joint impresses with its high mobility combined with immense stability and resilience. This only works because of the complex ligamentous apparatus, which supports the bony and muscle-tendon apparatus of the ankle joint with numerous ligaments. These ligaments are necessary because of the enormous pressure exerted on the ankle joint by body weight.

They connect the tibia and fibula with each other, as well as the tarsal bones and the foot bones with each other. Strictly speaking, the ankle joint consists of two joints: an upper and a lower ankle joint. Some of the ligaments are restricted to only one of the joints, whereas the other part acts across all joints.

The upper ankle joint is secured by the outer ligaments, the deltoid ligament and the syndesmosis. The lower ankle joint has numerous, generally less common, small ligaments (ligamentum talocalcaneum interosseum and ligamentum talocalcaneum laterale). More familiar, however, is the acetabular ligament partially covered with cartilage (Ligamentum talocalcaneonaviculare plantar).

Tasks of the belts

The ligaments of the ankle joint ensure the movement of the foot in all directions, with varying degrees of stability. They are mainly responsible for limiting mobility, which prevents too frequent “twisting”. They also hold against the tendency of the malleolus fork (formed by the tibia and fibula) to move apart due to body weight. There are also ligaments that do not primarily provide stability, but supplement the joint apparatus by enlarging the joint surface or encapsulating it.

The outer belts

There are three external ligaments at the ankle joint: Ligamentum talofibulare posterius, Ligamentum talofibulare anterius and Ligamentum calcaneofibulare. All in all they form the Ligamentum collaterale laterale. Of all the ligaments of the ankle joint, they are the most susceptible to injuries in the human body.

All three outer ligaments originate from the outer ankle, which belongs to the fibula. The Ligamentum talofibulare posterius and the Ligamentum talofibulare anterius both start at the ankle bone, one at the posterior part, the other at the front. The calcaneofibular ligament ends at the calcaneus.

In comparison to the deltoid on the inside, the outer ligaments do not run as a plate, but in individual strands and are therefore not as stable. Nevertheless, they are an important part of the entire ligamentous apparatus at the ankle. The outer ligaments are intended to prevent the typical inward twisting movement of the foot (supination).

Due to their course and low strength, they only fulfil this task to a limited extent, especially when the foot is standing on tiptoe (plantar flexion) and bony stability is not ensured. In addition, the outer ligaments are intended to prevent a varus position (joint malposition in which the joint axis has a kink to the outside). Nevertheless, they guarantee a safe flexion and extension of the foot.

If a kink (supination) occurs, it can lead to either overstretching of one or all of the outer ligaments or even to a tear, depending on the strength of the movement and the nature of the ligament. In any case, the ankle joint is no longer sufficiently secured when in motion. Therefore, after injury, the ankle joint should be protected and fixed in the pronation position so that the ligaments can grow together again. Later, the load can be slowly increased again.