OSG, Articulatio talocruralis
The upper ankle makes the movement between the lower leg and the foot possible as one of two spiked joints.
Here it combines an optimal combination
It forms a functional unit with the lower ankle joint.
The ankle is actually two joints. The upper and lower ankle.
It represents the articulated connection between lower leg consisting of
The ankle joints must fulfill two essential characteristics. They need to be stable and resilient, as they carry the entire body weight, but at the same time allow high mobility to ensure walking and running - even on uneven terrain.
Figure upper ankle
I - Upper ankle
(Joint line green) -
The upper ankle consists of the articular surface of the lower leg ( Crus ), ie the
The tibia and fibula form the so-called malleolar fork (malleolus = ankle) with their swollen joint ends, which encloses the ankle bone ( trochlea tali ) the uppermost part of the ankle bone. The abducted bone end of the tibia, which corresponds to the inner part of the malleolar fork, forms the inner ankle, the lower bone end of the fibula, ie the outer part of the malleolar fork, forms the outer malleolus. The trochlea tali enclosed by the malleol fork is 4-5 mm wider at the front than at the back. This feature is functionally important (see below).
The OSG (upper ankle joint) is also secured by ligaments in addition to the bone guide. The ligaments, which, as so-called syndesmosis ( Syndesmosis tibiofibularis ) clamp the malleolar fork and thus stabilize it already count to the ligaments of the OSG (upper ankle).
These include the
Because the OSG (upper ankle joint) is a pure hinge joint, there are collateral ligaments that prevent lateral movement of the foot in the upper ankle (OSG). They move from the malleoli (ankles) to the nearest tarsal bones.
Specifically, these are the outer ankle
In their entirety, they are simply referred to as the outer band of the foot. These ligaments prevent a variation or inversion / supination of the foot (ie an inward rotation, as you do it, if you want to look at his sole).
The collateral ligament of the medial malleolus is the broad-ligament deltoid ligament, which consists of four parts:
This band prevents the valgization or even eversion / pronation of the foot (ie the rotation to the outside).
The upper ankle is a pure hinge joint, so there is only one axis of motion with two possible movements:
Starting from the neutral zero position of the joint (ie the foot lying flat on the floor), a dorsal extension of up to 30 degrees is possible, plantarflexion up to a maximum of 50 degrees. In dorsiflexion, the anterior part of the lower articular surface, the trochlea tali, is firmly wedged in the malleolar fork, as its width in the anterior part fits perfectly into the malleolar fork.
However, as it is 4-5 mm narrower in the back, this also means that in case of plantarflexion the malleolar fork is too wide for the trochlea tali . This explains why the highest stability of the foot is ensured in a squatting position (for example downhill skiing), while the foot is the most unstable and therefore the most vulnerable to injury, for example, when going downhill or simply toes or stairs.
As a result, ligament injuries to the upper ankle are often caused by bending over in situations where the foot is just plantarflexed.
The most common injury to the ankle is the so-called supination or inversion trauma of the upper ankle joint.
Here, the foot kinks inwards, which leads to an overstretching and possibly a rupture (tear) of the outer bands. Such an injury may be accompanied by the fracture of the lateral malleolus ( malleolus lateralis ), ie the lowest part of the fibula.