What is the purpose of the PCL?

• A. Limits posterior translation of the tibia on the femur
• B. Limits anterior translation of the tibia on the femur
• C. Provides rotational stability
• D. Stabilizes against valgus forces

Answer: (A)

The main function of the PCL is to prevent the tibia from translating posteriorly relative to the femur. When the knee is flexed, the tibia tends to move backward, and the PCL provides the primary restraint against that posterior shear, helping to keep the shin aligned under the thigh during activities like squatting or deceleration. While the PCL does contribute to overall knee stability, its dominant role is limiting posterior tibial movement rather than controlling anterior translation (that’s the ACL’s job) or resisting rotational or valgus forces (those are more the realm of the ACL for rotational stability and the MCL/LCL for valgus stability).