Anterior Drawer Test: Assessing ACL Injuries in the Knee

What Is the Anterior Drawer Test?

Anterior drawer test is a physical examination manoeuvre used to assess the integrity of the anterior cruciate ligament (ACL) in the knee joint. It involves applying an anterior force to the tibia (shinbone) to test for excessive forward movement relative to the femur (thighbone), which would indicate ACL laxity or tear. The anterior drawer test is one of the most commonly used clinical tests for ACL injury diagnosis, along with the Lachman test and pivot shift test. An accurate diagnosis is crucial for determining the appropriate treatment plan.

Why is the Anterior Drawer Test Performed?

The primary purpose of the anterior drawer test is to diagnose ACL tears or laxity. The ACL is a key stabilising ligament in the knee that prevents the tibia from sliding too far forward. Injuries to the ACL are common, especially in athletes involved in sports with sudden stops, jumps or changes in direction. An ACL tear can cause knee instability, pain, swelling and reduced range of motion. The anterior drawer test helps identify ACL damage so that proper treatment can be initiated.

When Is the Anterior Drawer Test Recommended?

Your doctor may recommend an anterior drawer test if you have symptoms suggestive of an ACL injury, such as:

• Knee pain, especially when twisting or pivoting
• Swelling around the knee within 24 hours of an injury
• Feeling of instability or "giving way" of the knee
• Popping sound at the time of injury
• Reduced range of knee motion

The test is often done as part of the initial evaluation after a knee injury or during a routine physical exam in athletes.

Step-by-Step: How the Anterior Drawer Test Is Done

The anterior drawer test procedure involves the following steps:

• You will lie on your back on the exam table with your injured knee bent at about a 90-degree angle.
• The examiner will sit on your foot to stabilize it and grasp your tibia just below the knee with both hands.
• The examiner will then pull your tibia forward, attempting to "draw" it out in front of the femur.
• The amount of forward movement of the tibia is compared to the uninjured knee.

A positive test is indicated by more than 6 mm of forward tibial translation compared to the other knee. The examiner will also note any difference in the feel of the endpoint (hard vs soft) between the two knees.

What Should I Expect During the Anterior Drawer Test?

The anterior drawer test is generally not painful, although you may feel some discomfort or apprehension, especially if you have an acute injury. Let your doctor know if you experience any sharp pain during the test.

What Should I Expect After the Anterior Drawer Test?

Anterior drawer test results are immediate - your doctor will discuss the findings with you right after performing the test. If the test is positive and an ACL tear is suspected, your doctor will likely recommend additional tests to confirm the diagnosis and determine the extent of the injury. These may include magnetic resonance imaging (MRI), knee X-rays, and knee arthroscopy (keyhole surgery). Treatment options will depend on the severity of your ACL injury and your individual needs and goals.

Also Read: Anterior Cruciate Ligament (ACL) Injury or Tear: Treatment & Recovery Tips

What Does a Positive Anterior Drawer Test Indicate?

A positive anterior drawer test suggests an ACL tear or significant laxity. The ACL's main function is to prevent forward translation of the tibia on the femur. When this ligament is torn or stretched out, the tibia can move too far forward during the test, indicating ACL insufficiency.

However, it's important to note that the anterior drawer test alone is not definitive for diagnosing an ACL tear. Imaging tests like an MRI are often needed to confirm the diagnosis and rule out other injuries.

Difference Between Anterior Drawer Test and Lachman Test

The anterior drawer test and Lachman test are both used to assess ACL integrity, but they differ in patient positioning and sensitivity.

In the Lachman test, the knee is bent at about 20-30 degrees, compared to 90 degrees in the anterior drawer test. The Lachman test is generally considered more sensitive for detecting ACL tears, especially in the acute phase after injury.

However, the anterior drawer test can still provide valuable information and is often used in conjunction with the Lachman test for a comprehensive knee exam.

Conditions That May Affect Test Accuracy

Certain factors can make the anterior drawer test more challenging to perform or interpret accurately:

• Acute knee swelling and pain, which can cause muscle guarding
• Partial ACL tears, which may not produce a distinct endpoint
• Concurrent injuries to other knee structures like the meniscus or collateral ligaments
• Examiner experience and technique

In some cases, the anterior drawer test may need to be repeated at a later time or with the patient under anesthesia for optimal accuracy. Complementary tests are often used to paint a complete diagnostic picture.

Are there any risks to an anterior drawer test?

The anterior drawer test is a very safe and low-risk procedure. In rare cases, if not performed gently in an acutely injured knee, it could potentially cause some additional discomfort or stress to damaged structures. However, a skilled examiner can usually perform the test without any significant problems.

Managing Abnormal Anterior Drawer Test Results

If your anterior drawer test result is positive, the next step is usually to get an MRI to visualize the ACL and check for related injuries. Depending on the extent of your ACL tear and your goals, treatment may involve:

• Physical therapy to strengthen muscles and improve stability
• Wearing a hinged knee brace during activities
• Activity modification to avoid high-risk movements
• Surgery to reconstruct the torn ACL, especially in athletes

Your doctor will work with you to develop an individualised treatment plan to help you safely regain function and return to your desired activities.

Imaging and Other Diagnostic Tools Used Alongside

While the anterior drawer test is a useful screening tool, ACL tear diagnosis typically involves multiple assessment methods for optimal accuracy. These may include:

• MRI, considered the gold standard for visualising ACL tears and other soft tissue injuries
• Knee x-rays, to rule out fractures and assess joint alignment
• Pivot shift test, another clinical test to assess rotational stability of the knee
• Knee arthroscopy, a minimally invasive surgical procedure that allows direct visualization of knee structures

Using a combination of clinical tests and imaging helps ensure an accurate and complete diagnosis.

Benefits of the Anterior Drawer Test

The purpose of anterior drawer test is to serve as an initial screening tool for ACL injuries:

• Quick and easy to perform in a clinic setting
• Non-invasive and relatively painless
• Provides immediate results to guide further diagnostic workup
• Can be repeated over time to assess healing and progress
• Helps identify patients who may benefit from early referral to an orthopedic specialist

When used as part of a comprehensive knee assessment, the anterior drawer test results can help facilitate timely diagnosis and appropriate management of ACL tears, optimizing long-term outcomes for patients.

Conclusion

The anterior drawer test is a valuable clinical tool for evaluating ACL integrity and guiding the diagnosis of ACL tears. If you are dealing with a known or suspected ACL injury or an anterior drawer test shoulder, consider reaching out to Metropolis Healthcare, a leading chain of diagnostic clinics across India. Metropolis offers a full range of imaging services, including MRI and other advanced testing to help diagnose knee injuries.

FAQs

What does a positive anterior drawer test mean?

A positive result suggests that the ACL (anterior cruciate ligament) is torn or overly stretched, allowing the tibia to move forward too much in relation to the femur. However, imaging like an MRI is usually needed to confirm the diagnosis.

How accurate is the anterior drawer test for ACL injuries?

Its accuracy varies based on factors like timing, swelling, and technique. Sensitivity ranges from 60–90%, and specificity is about 90–95%, meaning it's more reliable at ruling out ACL injuries than confirming them.

Is the test painful?

The test is typically not painful, but some discomfort may occur, especially in acute injuries. Let your doctor know if you feel sharp pain during the exam.

Can the anterior drawer test be done at home?

No. It should only be done by trained professionals like doctors or physical therapists to ensure accurate results and avoid worsening the injury.

What is the difference between anterior and posterior drawer tests?

The anterior drawer test assesses the ACL, while the posterior drawer test evaluates the PCL (posterior cruciate ligament), which prevents the tibia from shifting backward.

What are the next steps after a positive test?

Your doctor may order imaging like an MRI to confirm the injury. Treatment could include bracing, physical therapy, or ACL surgery based on your condition and activity goals.

Can this test detect partial ACL tears?

It may suggest a partial tear, though it's harder to detect than a complete tear. Imaging is usually required for an accurate diagnosis and treatment planning.