Which statement is true regarding the roles of the ACL and PCL?

Which statement is true regarding the roles of the ACL and PCL?

• A. The PCL limits anterior translation of the tibia
• B. The MCL prevents posterior translation of the tibia
• C. The ACL limits anterior translation of the tibia and provides rotational stability
• D. The ACL limits posterior translation of the tibia

Answer: (C)

The key idea is what each ligament does to tibial movement relative to the femur. The ACL prevents the tibia from moving forward (anterior translation) under the femur and also helps control rotational twisting of the knee, especially during pivoting actions. That combination—limiting anterior tibial translation and providing rotational stability—makes this statement true. In contrast, the PCL's job is to prevent backward (posterior) movement of the tibia, not forward, and the MCL mainly resists valgus stress on the knee rather than posterior tibial translation. So the other statements don’t fit the actual roles of these ligaments.

The key idea is what each ligament does to tibial movement relative to the femur. The ACL prevents the tibia from moving forward (anterior translation) under the femur and also helps control rotational twisting of the knee, especially during pivoting actions. That combination—limiting anterior tibial translation and providing rotational stability—makes this statement true.

In contrast, the PCL's job is to prevent backward (posterior) movement of the tibia, not forward, and the MCL mainly resists valgus stress on the knee rather than posterior tibial translation. So the other statements don’t fit the actual roles of these ligaments.