Anterior Drawer Test for the Knee: Protocol for Assessing the ACL

The anterior drawer test for the knee, along with the Lachman test, is one of the best-known maneuvers for assessing the integrity of the anterior cruciate ligament (ACL). It's a classic move in any knee exam, although nowadays it's considered somewhat less sensitive than the Lachman test in many clinical situations.

What does this test measure?

The anterior drawer test assesses the anterior translation of the tibia relative to the femur with the knee flexed at 90°, a position in which structures other than the ACL (posterior capsule, collateral ligaments, hamstrings) have a greater influence on stability. So while it's still useful, it needs to be interpreted carefully.

What you'll need

• A treatment table
• No additional equipment

Step-by-step protocol

1. The patient lies supine, with the hip flexed about 45° and the knee flexed at 90°, with the foot resting on the table
2. Gently sit on the patient's foot to stabilize it (the classic technique), or have someone hold it in place
3. Place both hands around the proximal tibia, with your thumbs on the anterior joint line and your fingers in the popliteal fossa, making sure the hamstrings are relaxed
4. Apply a gentle but firm anterior translation force, as if trying to "pull" the tibia forward
5. Assess the amount of displacement and the end-feel, always comparing with the contralateral knee

Common mistakes

• Not making sure the hamstrings are relaxed (their contraction masks the displacement)
• Performing the test with the knee at an incorrect flexion angle
• Not comparing with the healthy side, which makes it hard to interpret what's "normal" for that person

How to interpret the result

Result	Interpretation
Displacement similar to the healthy side, firm end-feel	Negative — ACL likely intact
Greater displacement than the healthy side, soft end-feel	Positive — suggests ACL rupture (there may also be associated damage to the posteromedial/posterolateral capsule)
Marked displacement in multiple directions	Suspect combined injury (ACL + peripheral structures)

The anterior drawer test has lower sensitivity than the Lachman test in the acute phase (due to hamstring spasm limiting flexion to 90°), so a negative result doesn't rule out an ACL rupture. If there's clinical suspicion, MRI confirmation is recommended.

How it relates to other tests

This test is part of the assessment of anterior instability, alongside:

• Lachman test — more sensitive, especially useful in the acute phase
• Pivot shift test — adds the rotational dimension of instability

Documenting laxity over time

In knee rehabilitation processes (with or without ACL surgery), comparing laxity and stability test results at different points in time helps you understand the overall progression of the case. In Movalytics you can log the anterior drawer test result alongside other knee tests and keep an organized history by assessment date.

FAQ

Why is the Lachman test considered more reliable than the anterior drawer? Because it's performed with less knee flexion (20-30°), which reduces the influence of the hamstrings and the posterior capsule, giving a "purer" measure of ACL function. So is the anterior drawer test useful at all? Yes, it's still useful as part of a complete exam, especially for assessing the overall instability pattern alongside other tests, although it's rarely used as a standalone test. Can the anterior drawer be increased without an ACL rupture? In people with generalized ligamentous laxity (constitutional hypermobility), there may be greater baseline displacement, which is why comparing with the contralateral side is essential.