Which structure prevents varus laxity of the knee?

Which structure prevents varus laxity of the knee?

• A. ACL
• B. PCL
• C. MCL
• D. LCL

Answer: (D)

Varus stability of the knee is provided mainly by the lateral collateral ligament on the outside of the joint. This ligament resists varus stress and external rotation of the tibia, helping keep the knee from opening on the lateral side when a varus force is applied. If the LCL is compromised, the knee shows increased varus laxity because that restraint is lost. The medial collateral ligament handles valgus stress (the medial opening), while the ACL and PCL control anterior-posterior translation and overall rotational stability but are not the primary restraints to varus motion.

Varus stability of the knee is provided mainly by the lateral collateral ligament on the outside of the joint. This ligament resists varus stress and external rotation of the tibia, helping keep the knee from opening on the lateral side when a varus force is applied. If the LCL is compromised, the knee shows increased varus laxity because that restraint is lost. The medial collateral ligament handles valgus stress (the medial opening), while the ACL and PCL control anterior-posterior translation and overall rotational stability but are not the primary restraints to varus motion.