Definition
The anterior cruciate ligament (ligamentum cruciatum anterius) connects the thigh bone (femur) and tibia. As part of the ligamentous apparatus of the knee, it serves to stabilize the knee joint (Articulatio genus). Like the ligament structures of all joints, the anterior cruciate ligament consists mainly of collagen fibers, i.e. connective tissue.
Although the anterior cruciate ligament belongs to the holding apparatus of the knee joint, it is actually located outside the joint surface of the knee. It is separated from the joint cavity by a mucous membrane bag. The anterior cruciate ligament extends from the lateral knot of the thigh bone (condyle lateralis) from the back/top/outside to the front surface of the elevation in the middle of the tibial plateau, i.e. forwards/backwards/inside.
This means that it runs in exactly the opposite direction to the posterior cruciate ligament, which results in increased stability. Since the joint surface (the condyles) of the femur is significantly larger than the joint surface (tibial plateau) of the tibia, the knee joint requires a strong ligament stabilization. The cruciate ligaments serve as a passive guide during the movements of the knee joint and limit the extension in the knee joint.
The front cruciate ligament is the second strongest ligament in the knee joint after the rear cruciate ligament. It prevents the tibia from sliding forward. The anterior cruciate ligament also makes rotation in the knee joint more difficult.
At least parts of the cruciate ligaments are tightened in all positions of the knee joint. This makes clear their important function in stabilizing the knee joint. A torn cruciate ligament (a rupture of the cruciate ligament) of the anterior cruciate ligament is often caused by rotation of the knee and is a typical sports injury in soccer and skiing.
This injury is accompanied by pain and knee joint effusion, and instability of the knee joint, especially in the anterior direction, is the result. In the case of a rupture, this instability is impressively demonstrated by the so-called “drawer phenomenon”: with an angled leg and fixed thigh, the lower leg can be pulled forward like a drawer.
