Special Tests Quick Reference
All 33 ortho special tests across 6 body regions on one printable sheet.
To better understand the mechanics of this test and why it is effective, you may want to review basic knee anatomy.
What is the Anterior Drawer Test of the Knee?
The Anterior Drawer Test is an orthopedic examination used to assess the integrity of the anterior cruciate ligament (ACL) of the knee. It is one of the most widely taught ACL tests and remains a standard part of knee examination, though the Lachman Test has largely replaced it as the preferred assessment for acute injuries.
Involved Structures
The primary structure assessed is the anterior cruciate ligament (ACL), which runs from the posterolateral femoral condyle to the anterior intercondylar area of the tibia. Its primary function is to resist anterior translation of the tibia on the femur.
Secondary restraints — including the medial and lateral capsule, the menisci, and the posterior cruciate ligament — also contribute to anterior stability. In chronic ACL deficiency, these structures may partially compensate, which can affect test results.
How to Perform the Anterior Drawer Test
Starting Position
- Patient lies supine on the examination table
- Hip flexed to approximately 45°
- Knee flexed to 90°
- Foot flat on the table in a neutral position
- The examiner sits on the patient’s foot to stabilize the lower leg
Test Movement
- Place both hands around the proximal tibia with thumbs resting on the tibial plateau and fingers wrapping around the posterior calf
- Before applying force, palpate the hamstring tendons to confirm they are relaxed — tight hamstrings are a leading cause of false negatives
- Apply a firm, steady anterior force to the proximal tibia, drawing it forward on the femur
- Assess the amount of anterior translation and the quality of the end feel
Positive Anterior Drawer Test
A positive test is indicated by excessive anterior translation of the tibia relative to the femur, combined with a soft or absent end feel.
In a normal knee, the intact ACL provides a firm, abrupt stop to anterior tibial movement. When the ACL is disrupted, this firm end feel is lost. Secondary restraints may still limit some translation, but the end feel will be soft or mushy rather than firm.
Grading Anterior Translation
| Grade | Anterior Translation | Interpretation |
|---|---|---|
| 1+ | Up to 5 mm | Mild laxity — may indicate partial ACL tear or capsular laxity |
| 2+ | 5–10 mm | Moderate laxity — suggests significant ACL disruption |
| 3+ | Greater than 10 mm | Severe laxity — consistent with complete ACL rupture |
Always compare findings to the contralateral knee to establish a baseline, as individual laxity varies considerably between people.
Accuracy of the Anterior Drawer Test
The Anterior Drawer Test has limited sensitivity in acute ACL injuries. Pain and muscle guarding typically prevent full hamstring relaxation, which masks anterior translation. Sensitivity improves considerably in chronic ACL deficiency, where pain and guarding are less of a factor.
| Condition | Sensitivity | Specificity |
|---|---|---|
| Acute ACL injury | ~38–62% | ~95% |
| Chronic ACL deficiency | ~80–95% | ~95% |
High specificity means a positive test is a meaningful finding — when the Anterior Drawer is positive, ACL disruption is very likely. The limitation is sensitivity: the test misses a significant proportion of acute ACL tears.
Anterior Drawer Test vs. Lachman Test
The Lachman Test is the preferred clinical test for acute ACL injuries and is generally more sensitive than the Anterior Drawer. Two factors explain this:
- Knee position: At 90° flexion, the ACL is not at its maximum tension. The Lachman is performed at 20–30° flexion, where the ACL is under greater stress and disruption is easier to detect.
- Hamstring influence: At 90° flexion, the hamstrings act as strong posterior tibial stabilizers. Even with the foot stabilized, residual hamstring tension can mask anterior translation and reduce sensitivity.
The Anterior Drawer Test retains clinical value in chronic ACL deficiency, where laxity is established and guarding is minimal. It is also useful for bilateral comparison in follow-up assessments.
Common Causes of a Positive Test
- Complete ACL rupture: Most common cause of a clearly positive test with a soft end feel
- Partial ACL tear: May produce mild 1+ laxity with a firm but slightly reduced end feel
- Posterolateral corner injury: Can contribute to apparent anterior laxity — external tibial rotation during the test may suggest combined injury
- Chronic ACL deficiency: Long-standing laxity with secondary restraint stretching
- Posterior sag (false positive): If the PCL is injured, the tibia sags posteriorly at 90° — drawing it forward to neutral can appear as anterior laxity when it is not
Clinical Pearls
- Check for posterior sag first. Before applying anterior force, view the tibial plateau from the side. If the tibia is sagging posteriorly (PCL injury), the anterior drawer will appear falsely positive.
- Confirm hamstring relaxation. Palpate the medial and lateral hamstring tendons before testing. If they are tense, have the patient take a breath and consciously relax. Guarding is the leading cause of false negatives in acute injuries.
- Test in multiple foot positions. Some examiners perform the test with the foot neutral, internally rotated 30°, and externally rotated 15°. External rotation tightens the posterolateral structures and can help isolate ACL laxity; internal rotation slackens them.
- Always test bilaterally. Individual baseline laxity varies. A 2+ result is only meaningful in comparison to the contralateral side.
- A negative test does not rule out ACL tear. In acute injury, proceed to the Lachman Test and consider MRI referral if clinical suspicion remains high.
Video Demonstration
Related Tests
- Lachman Test — preferred ACL test in acute injuries; performed at 20–30° knee flexion
- Pivot Shift Test — most specific test for ACL functional instability
- Bounce Home Test — assesses full knee extension and meniscal integrity
- McMurray Test — meniscal assessment, commonly performed alongside ACL testing
Frequently Asked Questions
Is the Anterior Drawer Test accurate for diagnosing ACL tears?
It is moderately accurate but not the most sensitive test available, particularly in acute injuries. High specificity (~95%) means a positive result is meaningful, but sensitivity in acute injuries is limited by hamstring guarding. The Lachman Test is preferred for acute ACL assessment. The Anterior Drawer is more reliable in chronic ACL deficiency.
What is the difference between the Anterior Drawer Test and the Lachman Test?
Both tests assess anterior tibial translation, but they differ in knee position. The Anterior Drawer is performed at 90° flexion; the Lachman at 20–30° flexion. The Lachman is more sensitive because the ACL is under greater tension at lower flexion angles and hamstring interference is reduced.
What does a positive Anterior Drawer Test mean?
Excessive anterior tibial translation with a soft end feel suggests ACL disruption. A positive result should always be correlated with clinical history, other orthopedic tests, and imaging (MRI) before a diagnosis is confirmed.
Can the Anterior Drawer Test be negative with an ACL tear?
Yes. False negatives are common in acute injuries due to hamstring guarding, pain, and swelling. A negative result does not rule out ACL disruption. If clinical suspicion is high, perform the Lachman Test and consider MRI referral.
What is a posterior sag and why does it matter for this test?
A posterior sag occurs when the PCL is injured and the tibia drops posteriorly under gravity at 90° knee flexion. If not recognized before testing, pulling the tibia from its sagged position back to neutral will appear as excessive anterior translation — a false positive. Always inspect for posterior sag before performing the Anterior Drawer Test.
>> Return to the list of Common Tests in Orthopaedic Examination of the Knee
Here are some other articles you may be interested in:
- Introduction to Osteoarthritis of the Knee
- Lachman’s Test – for ACL integrity
- Bounce Home Test – for meniscus injury