Corpus: Posterior cruciate ligament

The posterior cruciate ligament, or PCL for short, is a ligament, which is part of the ligamentous apparatus of the knee joint.

The posterior cruciate ligament is the strongest ligament of the knee joint, connecting the femur to the tibia. It extends from the anterior parts of the intercondylar fossa on the medial femoral condyle, diagonally backwards to the posterior intercondylar area of the tibia, just behind the intercondylar eminence. It is located intracapsularly, but extrasynovially.

The PCL runs from anterior, superior, and medial (front-top-inside) to posterior, inferior, and lateral (back-bottom-outside), opposite in direction to the anterior cruciate ligament.

2.1. Functional categorization

The posterior cruciate ligament consists of numerous different fiber bundles that tighten in different joint positions. A functional distinction is made between two main structures:

• Anterolateral bundle (AL bundle): This bundle is about six times stronger than the PM bundle. It originates femorally in the anterior region and runs to the lateral part of the insertion site on the tibia.
• Posteromedial bundle (PM bundle): The PM bundle is the weaker bundle, originating femorally in the posterior region near the cartilage-bone boundary and running to the medial part of the insertion site on the tibia.

The posterior cruciate ligament stabilizes the knee joint along with the other ligaments. The anterolateral fibers are tensed in the flexion position, and the posteromedial fibers in the extension position. Its course prevents the tibia from sliding posteriorly in relation to the femur. Together with the other ligaments, it also restricts rotation in the knee joint.

Additionally, the posterior cruciate ligament has numerous mechanoreceptors, particularly in the anchoring area on the femur and tibia, which play an important role in the kinematics of the knee joint.

Like the anterior cruciate ligament, the posterior cruciate ligament can also be affected by sports injuries, leading to a cruciate ligament rupture due to overloading. A posterior cruciate ligament rupture can be diagnosed using the drawer test: if the tibia can be pushed backwards in relation to the femur ("posterior drawer"), a PCL rupture is suspected.