Which ligament is primarily responsible for preventing anterior translation of the tibia on the femur?

• A. PCL
• B. MCL
• C. ACL
• D. LCL

Answer: (C)

The key idea is anterior-posterior stability of the knee, governed by the cruciate ligaments. The anterior cruciate ligament is the primary restraint to anterior translation of the tibia relative to the femur, meaning it prevents the shinbone from sliding forward under the thighbone during movements that load the knee, especially with pivoting and knee bending. It also helps control rotation. The posterior cruciate ligament does the opposite, resisting posterior translation of the tibia. The collateral ligaments mainly limit side-to-side (valgus/varus) stresses rather than anterior-posterior tibial slide. So the ligament most responsible for preventing the tibia from moving forward is the anterior cruciate ligament.