The portion of the anterior cruciate ligament most often injured when the knee is in extension is the _________.

• A. Anterior bundle
• B. Posterior bundle
• C. Posteriolateral bundle
• D. Anteriomedial bundle

Answer: (C)

When considering injuries to the anterior cruciate ligament (ACL), it is important to understand the specific bundles of the ligament and their susceptibility to stress during different positions of the knee. The ACL consists of two main bundles: the anteromedial bundle and the posterolateral bundle.

The posterolateral bundle is particularly vulnerable during knee extension. This area of the ligament bears the most load when the knee is fully extended, which is a common position during activities that involve cutting or pivoting movements. When the knee is extended, the mechanics of the knee place significant strain on this bundle, making it more prone to injury.

Injuries to the ACL can occur due to excessive rotational forces or direct trauma, but the posterolateral bundle specifically is affected more in extended positions, hence making it the region of the ACL most likely to be injured when the knee is in this position. Understanding the biomechanics involved helps in diagnosing the type of ACL injuries and managing rehabilitation strategies effectively.