Which exam finding would indicate ACL insufficiency?

Which exam finding would indicate ACL insufficiency?

• A. Anterior translation of the tibia indicating ACL insufficiency on the anterior drawer test
• B. Posterior translation of the tibia indicating ACL
• C. Medial collateral ligament laxity
• D. Lateral cruciate ligament laxity

Answer: (A)

ACL injury removes the knee’s restraint against forward movement of the tibia. When the ACL is deficient, the tibia can translate anteriorly relative to the femur more than normal. The anterior drawer test specifically checks this forward glide, so a finding of increased anterior translation indicates ACL insufficiency. Posterior translation would point to a PCL problem, not ACL. Medial collateral ligament laxity relates to valgus instability at the knee, and lateral collateral ligament laxity relates to varus instability. These do not reflect the anterior-posterior tibial movement that ACL testing assesses.

ACL injury removes the knee’s restraint against forward movement of the tibia. When the ACL is deficient, the tibia can translate anteriorly relative to the femur more than normal. The anterior drawer test specifically checks this forward glide, so a finding of increased anterior translation indicates ACL insufficiency.

Posterior translation would point to a PCL problem, not ACL. Medial collateral ligament laxity relates to valgus instability at the knee, and lateral collateral ligament laxity relates to varus instability. These do not reflect the anterior-posterior tibial movement that ACL testing assesses.