How does the anterior drawer test diagnose Anterior Cruciate Ligament (ACL) injury, as laxity typically indicates Posterior Cruciate Ligament (PCL) injury?

From the Guidelines

The anterior drawer test is a specific assessment for ACL integrity, evaluating anterior tibial translation relative to the femur, and laxity in this test indicates ACL injury, not PCL injury. To perform the anterior drawer test, the patient lies supine with the knee flexed to 90 degrees, foot flat on the table. The examiner sits on the patient's foot to stabilize it, places both hands behind the proximal tibia with thumbs on the tibial plateau, and pulls the tibia forward. Excessive forward movement compared to the uninjured knee indicates ACL laxity. While this might seem counterintuitive, the ACL prevents anterior tibial translation, so when it's torn, the tibia can move abnormally forward. In contrast, PCL injuries are evaluated with the posterior drawer test, where the tibia is pushed backward from the same position. In PCL injuries, the tibia may already sit posteriorly (posterior sag) and demonstrate increased posterior translation when pushed.

The anterior drawer test has moderate sensitivity but better specificity for ACL tears, so it's often used alongside other tests like the Lachman test and pivot shift test for more accurate diagnosis 1. It's worth noting that the provided evidence does not directly address the specifics of the anterior drawer test for ACL injury, but the principles of assessing ligament integrity and the distinction between ACL and PCL injuries are crucial for accurate diagnosis and treatment planning. The most recent and highest quality study on ACL rehabilitation 1 emphasizes the importance of comprehensive assessment and goal-based rehabilitation, which includes accurate diagnosis of ACL injuries using tests like the anterior drawer.

Key points to consider in the assessment and diagnosis of ACL injuries include:

• The anterior drawer test is specific for assessing ACL integrity.
• Laxity in the anterior drawer test indicates ACL injury.
• PCL injuries are assessed with the posterior drawer test.
• A combination of tests (anterior drawer, Lachman, pivot shift) is used for accurate diagnosis of ACL tears.
• Rehabilitation after ACL reconstruction should be goal-based and consider the patient's overall functional status and risk of reinjury 1.

From the Research

Anterior Drawer Test for ACL Injury

• The anterior drawer test is a manual laxity examination used to evaluate ACL injuries 2.
• The test is performed with the knee flexed at 90 degrees, and the examiner applies an anterior force to the tibia to assess the amount of anterior translation 3.
• The test is used to detect laxity in the ACL, which is a common symptom of ACL injuries.

Comparison with PCL Injury

• Laxity in the anterior drawer test is not exclusive to ACL injuries and can also be present in PCL injuries 4.
• However, the anterior drawer test is more specific to ACL injuries, and the amount of anterior translation is typically greater in ACL injuries than in PCL injuries 3.
• The Lachman test is considered a more sensitive and specific test for ACL injuries than the anterior drawer test 4, 3.

Diagnostic Accuracy

• The diagnostic accuracy of the anterior drawer test for ACL injuries has been evaluated in several studies, with sensitivity values ranging from 0.18 to 0.92 and specificity values ranging from 0.78 to 0.98 4.
• The pooled sensitivity and specificity values for the anterior drawer test were 0.2 and 0.88, respectively, in a systematic review of 17 studies 4.
• The anterior drawer test is not as accurate as the Lachman test or the pivot shift test for diagnosing ACL injuries, but it can still be a useful tool in the physical examination of patients with suspected ACL injuries 5, 6.