How do you perform an anterior drawer test for Anterior Cruciate Ligament (ACL) injury?

How to Perform the Anterior Drawer Test for ACL Injury

The anterior drawer test should be performed with the patient supine, knee flexed to 90 degrees, hip flexed to 45 degrees, and foot stabilized while the examiner applies an anteriorly directed force to the proximal tibia—though this test is less sensitive than the Lachman test and should ideally be delayed 4-5 days post-injury for optimal accuracy. 1

Patient Positioning

• Position the patient supine on the examination table 2
• Flex the knee to 90 degrees 2, 3
• Flex the hip to approximately 45 degrees 2
• Stabilize the patient's foot by sitting on it or securing it between your thighs to prevent movement 4

Examiner Hand Placement and Technique

• Place both hands around the proximal tibia with thumbs on the tibial plateau and fingers wrapped posteriorly around the calf 2
• Ensure the hamstring muscles are relaxed before applying force, as muscle guarding can produce false-negative results 2, 5
• Apply an anteriorly directed force to the proximal tibia, attempting to translate it forward relative to the femur 2, 3
• Compare the amount of anterior translation to the contralateral uninjured knee 6

Interpretation of Results

• Positive test: Excessive anterior translation of the tibia (>5mm difference compared to contralateral side) suggests ACL rupture 6
• The test demonstrates anterior subluxation of the tibia on the femur when the ACL is torn 2
• Grade the laxity: slight (Grade I), definite subluxation (Grade II), or marked subluxation with momentary locking (Grade III) 3

Critical Timing Considerations

The sensitivity (84%) and specificity (96%) of the anterior drawer test are optimized if clinical assessment is delayed 4-5 days post-injury, as acute pain and swelling limit examination accuracy in the first 48 hours 1

Important Limitations and Caveats

• The anterior drawer test is less sensitive than the Lachman test for detecting ACL tears because it does not produce maximal tension in the ACL fibers 2
• At 90 degrees of knee flexion, baseline tension in the ACL is lower than at 15 degrees (Lachman position), making the anterior drawer less reliable 2
• The test may be falsely negative in acute settings due to pain, muscle spasm, and hemarthrosis 1, 5
• Examiner proficiency matters: Studies show the anterior drawer test was correct only 59% of the time in patients with large thigh girth (>43 cm) 5

Alternative Testing Approaches

• Consider the "drop leg Lachman test" as an alternative: performed with the patient supine, leg abducted off the table side and flexed 25 degrees, which produces 1.8-2.4 mm greater average excursion than standard tests 4
• The Lachman test (at 15 degrees flexion) is superior to the anterior drawer test and should be the primary manual test for ACL evaluation 2, 5
• Pivot shift tests (particularly drawer-type versions) may be more sensitive when performed without causing significant pain 3

Adjunctive Diagnostic Measures

• KT-1000 arthrometer measurements correlate well with manual anterior drawer testing (r=0.46) and can provide objective quantification 6
• Ultrasound evaluation using a prone position technique shows sensitivity of 0.96 and specificity of 0.98 for ACL tears when a minimum 5mm intra-individual difference is present 6
• Physical examination findings including swelling, hematoma, pain on palpation, and positive anterior drawer test together have 96% correlation with lateral ligament rupture 1