Knee joint Joint type

The knee joint is a compound joint. It consists of the patellar joint (femoropatellar joint) and the popliteal joint (femorotibial joint). The popliteal joint is the actual knee joint, which enables flexion of the knee.

It is again a combination of a hinge joint and a wheel joint and is therefore also called a hinge joint. Correspondingly executable movements are stretching and flexion, and in the flexed state, outer and inner rotation of the knee. The knee-cap joint is also called a sled joint, since the kneecap merely slides in a bony groove at the lower end of the thigh bone.

It is held by ligaments and slides over the cartilaginous joint surface during knee flexion and extension. Since the knee joint is subject to great stress, it requires additional stabilizers. Therefore, it is equipped with the anterior and posterior cruciate ligaments, as well as the outer and inner meniscus. The menisci buffer shocks and provide a more stable connection between the upper and lower leg.

Knee joint ligaments

In order for the knee joint to be able to withstand daily stress, it is stabilized by numerous ligaments. Depending on their position, these are divided into anterior, posterior, lateral and central groups. In the case of sports injuries, the ligaments are often affected.

Anterior ligaments: The anterior ligaments include the patellar ligament (ligamentum patellae) and the retinaculum patellae. The patellar ligament connects the patella with the front surface of the tibia. It is therefore very important for the transmission of force from the upper leg to the lower leg during the stretching movement in the leg.

The Retinaculum patellae lies to the side of the patella and secures it in position. It is also part of the joint capsule of the knee joint with its various parts. Posterior ligaments: At the back of the popliteal fossa there are two further ligaments that stabilize the knee joint: the oblique popliteal ligament (Ligamentum popliteum obliquum) and the arch-shaped popliteal ligament (Ligamentum popliteum arcuatum).

They are also part of the joint capsule. Lateral ligaments: The lateral ligaments of the knee joint are also called collateral ligaments. The inner collateral ligament (Ligamentum collaterale tibiale) runs along the inside of the knee, while the outer collateral ligament (Ligamentum collaterale fibulare) runs along the outside of the knee.

They stabilize the knee especially in the extension position, since they are relaxed when the knee is bent. This prevents the knee from slipping sideways when the knee is straightened. The ligaments counteract a bow-leg or knock-knee malposition.

It is important that the inner ligament is firmly attached to the joint capsule and the inner meniscus, while the outer ligament has no firm connection to the joint capsule or the outer meniscus. Therefore, an injury to the inner ligament is often accompanied by an injury to the inner meniscus.If the anterior cruciate ligament is injured at the same time, one also speaks of an “unhappy triad”. Central ligaments: The two cruciate ligaments (ligamentum cruciatum anterius and posterius) form the central ligament securing the knee joint.

They cross over between the thigh and lower leg bones. Their position stabilizes the knee in the frontal plane, preventing the bones from sliding back and forth against each other. They also inhibit the internal rotation (inward rotation) of the leg.