Which ligament is primarily assessed when evaluating anterior knee instability?

• A. PCL (Posterior Cruciate Ligament)
• B. MCL (Medial Collateral Ligament)
• C. LCL (Lateral Collateral Ligament)
• D. ACL (Anterior Cruciate Ligament)

Answer: (D)

The Anterior Cruciate Ligament (ACL) is primarily assessed when evaluating anterior knee instability because it plays a crucial role in providing stability to the knee joint during activities that involve sudden stops, changes in direction, and pivoting motions. The ACL connects the femur (thigh bone) to the tibia (shin bone) and helps to prevent excessive forward movement of the tibia relative to the femur, which is the key factor in maintaining knee stability.

When anterior knee instability is suspected, specific clinical tests, such as the Lachman test or the Anterior Drawer test, are performed to assess the integrity of the ACL. These tests evaluate the amount of anterior translation of the tibia as compared to the femur. If the ACL is injured or torn, there will be increased anterior movement of the tibia, indicating instability.

While the other ligaments contribute to overall knee stability, they are not primarily involved with the anterior motion of the tibia. The Posterior Cruciate Ligament (PCL) primarily prevents posterior translation of the tibia, the Medial Collateral Ligament (MCL) stabilizes the knee against valgus forces, and the Lateral Collateral Ligament (LCL) stabilizes against varus