Definition
A sprain (distortion) of the foot refers to an overstretching of the ligaments of the foot or the joint capsule of the ankle joints. The ligaments of the foot represent connections between the bones of the foot and those of the lower leg. Just like the joint capsule, they stabilize and secure the ankle joint by providing the physiological range of motion of the joint through their limited extensibility.
Although this gives the bony joint a certain degree of protection, it is precisely because of this limited extensibility of the ligament structures that trauma can lead to their overstretching (sprain) or, in the worst case, even to their tearing (torn ligament, rupture). The term “sprain” is misleading because the underlying injury mechanism is not a compression of the foot but a stretching of the ligaments. The sprain of the foot is a very common injury among sports injuries.
The cause of a sprained foot is usually a movement that goes beyond the physiological and intended extent, as is the case when the foot is bent over. As a result, the ligaments that stabilize the joint are overstretched, which is then referred to as a sprain of the foot. A typical injury pattern for a sprained foot is the so-called supination trauma.
The supination trauma (twisting of the foot) was named after the underlying movement, supination. Here, the ankle joint bends so that the inner edge of the foot is lifted and the outer edge of the foot is lowered, causing the outer ankle to deviate outwards. This causes the outer ligaments of the foot to be overstretched and most frequently affects the talofibular anterior ligament, i.e. the anterior ligament connecting the ankle bone (talus) with the fibula of the lower leg.
The ligament connecting the heel bone (calcaneus) with the fibula can also be overstretched and is therefore called the calcaneofibular ligament. Only rarely is the posterior ligament connecting the ankle and fibula (Ligamentum talofibulare posterius) affected by a sprain. As one of the most common sports injuries, a sprained foot often occurs in sports where jumps are required and one can therefore easily bend over when hitting the ground, such as basketball.
Other sports that can quickly lead to a sprained foot are running, such as jogging, but also hiking, especially on uneven ground where it is easy to twist and turn. Often, however, even minor traumas during everyday movements can lead to a sprained foot, such as bending over at a curb. However, it is not only excessive and unphysiological movements of the foot that lead to sprains, but also external forces acting on the ankle or foot, which can occur in an accident, for example.
It is also easier to get a sprained foot if you have a history of sprains. In this case, the ligamentous apparatus of the foot can be worn out due to repeated overloading and stretching to such an extent that it can no longer regenerate completely and thus can no longer reliably perform its stabilizing function on the joint. As a result, even slight stretching of the ankle joint can lead to renewed spraining of the foot more easily due to the lack of ligament tension (ligament insufficiency). A sprain is also favored by existing foot malpositions, such as a hollow foot.
