The ankle joint, also known as the ankle, is an important joint that connects the foot and calf. The ankle joint is actually a pleasant “contemporary”: it usually works well for a lifetime, is hardly noticeable, and only worries its owner once you hurt it. Then a peculiarity becomes clear: “For example, the ankle joint as such does not actually exist – there are two on each side….
What is the ankle joint?
Schematic diagram showing the anatomy and structure of the ankle joint. Click to enlarge. The ankle joint connects the lower leg and foot and is also colloquially referred to as the ankle, taking into account the adjacent bone structures. The ankle joint is subdivided into an upper and a lower ankle joint, which only in cooperation enable the comprehensive mobility of the foot and thus the upright gait. The ankle is formed by several bones. It consists of an upper and a lower ankle joint and enables the mobility of the foot. At the same time, it is the joint that is exposed to the greatest load in everyday life- already during walking, the ankle must bear about seven times the body weight.
Anatomy and structure
First of all, the anatomy of the ankle joint consists of a few bones: From the lower leg, the tibia (shin bone) and, on the outside, the fibula (calf bone) form a kind of ankle fork or pincer, with the talus (trochlea tali), a broad articular surface that curves upward, enclosed in its center from below. It belongs to the talus, which in turn is the first and uppermost tarsal bone. This joint is thus the upper ankle joint. Between the talus and the calcaneus lies another joint surface, the lower ankle joint, which can be further divided into an anterior and a posterior partial joint via three joint surfaces. The calcaneus is the bone that forms the “heel” that can be felt from the outside. Strong lateral ligaments between the ankle bone and the tibia (inner ankle) or the ankle bone and the fibula (outer ankle) secure the hinge movement of the upper ankle joint. In addition, some ligamentous pulls also skip the lower ankle joint by pulling even further down toward the calcaneus or forward toward the navicular bone. The lower ankle joint also has some very tight ligaments to secure it. However, it is far less susceptible to injury than the upper one, since the main leverage in accidents is usually concentrated on the ankle fork. Muscles don’t contribute too much to securing the ankle, but of course are important for mobility. A large sweep of tendons from the posterior lower leg muscles pulls past the back of the medial malleolus over a pulley toward the bottom of the foot to insert on various bony and soft tissue structures. The powerful Achilles tendon attaches to the heel bone and is thus primarily responsible for flexing the foot. The anterior lower leg muscles extend long in front of the lateral malleolus to the lateral edge of the foot. The major blood vessels and nerve pathways also run with the tendons.
Functions and tasks
The function of the ankle joint is primarily to enable an upright gait, a springy stride, to find one’s way on uneven surfaces, and to make rapid twisting and turning maneuvers during locomotion. The upper ankle joint is primarily a hinge joint, the axis of which passes transversely through the ankle bifurcation and the talus. Flexion of the foot by pulling the Achilles tendon is possible to a greater extent than extension of the foot in the direction of the dorsum of the foot (about 50 or 30 degrees from the neutral position in standing). Furthermore, the bone contact between the ankle fork and the anklebone pulley becomes somewhat looser during flexion, so that small lateral movements of the foot against the lower leg then become possible. This is significant in mountaineering, for example: uphill you have a secure footing, downhill you do not. Sprains therefore mostly occur on the descent (although fatigue and poorer visibility certainly play their part here). The lower ankle joint is somewhat more complicated in its mobility: In terms of structure, it is almost a ball and socket joint, but bones and ligaments reduce the axes to one main movement, which is oblique and allows the foot to rotate inward by 60 degrees and outward by 30 degrees.
Diseases and ailments
The ankle is relatively rarely affected by injuries and diseases. Much more common than arthritis, arthritides and gout attacks are injuries caused by external force. Torn ligaments are the most common. This can affect the inner ligament or the partial ligaments of the outer ankle. The most frequently injured ligament in the human body is the talofibular anterior ligament, the foremost of the external ligaments. Most often, ligament tears happen as a result of twisting injuries, for example, when playing soccer with an opponent or simply on uneven turf. Surgeries are usually not necessary for torn ligaments. The torn parts heal on their own with weeks of immobilization, but remain susceptible to recurrent tears for life. Bone fractures are less common, but equally possible, both as a serious sports injury (skiing, soccer, etc.) and in traffic accidents. In these cases, surgery is usually required to restore bone continuity by inserting metal fragments so that the fractures can heal cleanly.
