The anterior drawer test is a hands-on physical exam used to check whether the anterior cruciate ligament (ACL) in your knee is torn. A clinician pulls your lower leg forward while your knee is bent, and if it slides further than normal, that suggests the ACL is damaged. The test can also be performed on the ankle to evaluate a different ligament. It takes less than a minute and requires no equipment.
What the Test Checks For
The ACL is one of four ligaments in the knee. It connects your thighbone to your shinbone and prevents the lower leg from sliding too far forward or rotating excessively. When the ACL is torn, that restraint is lost, and the shinbone can shift forward in a way it normally wouldn’t. The anterior drawer test is designed to reveal exactly that movement.
The word “anterior” simply means forward. The test draws the lower leg forward relative to the thigh. If the ACL is intact, it acts like a check-rein and limits that motion. If it’s torn, the lower leg keeps going.
How It’s Performed
You lie on your back on an exam table. Your hip is bent to about 45 degrees, your knee is bent to 90 degrees, and your foot rests flat on the table. The examiner sits or stabilizes your foot to keep it from moving, then wraps both hands around the top of your shinbone, just below the knee joint line. From there, they pull your lower leg forward with a steady, controlled force.
The examiner is feeling for two things: how far the shinbone travels and what the movement feels like when it reaches its limit. A healthy ACL creates a firm stop at the end of that forward glide. A torn ACL allows more travel, and the stop feels soft or mushy rather than solid. The test is almost always performed on both legs so the examiner can compare your injured side to your healthy one.
What a Positive Result Means
A positive anterior drawer test means the shinbone moved further forward than expected, suggesting ACL damage. Clinicians grade this excess movement on a scale:
- Grade 1: 3 to 5 millimeters of extra forward movement compared to the other knee. This suggests a partial tear or mild laxity.
- Grade 2: 5 to 10 millimeters. This points to a more significant, possibly complete tear.
- Grade 3: More than 10 millimeters, indicating a complete ACL rupture.
Along with the distance, the quality of the endpoint matters. A firm stop at the end of the movement, even with some extra travel, is more reassuring than a soft, undefined endpoint. When both the distance is large and the endpoint is mushy, a complete tear is likely.
How Accurate Is It?
The anterior drawer test performs well, particularly for injuries that aren’t brand new. A study in JAAOS Global Research and Reviews found the test had 92% sensitivity and 91% specificity when used for chronic ACL injuries. That means it correctly identifies the vast majority of tears and rarely flags a healthy knee as torn.
Accuracy drops in the first hours and days after an injury, though. A freshly injured knee is often swollen and painful, which causes the hamstring muscles on the back of the thigh to tighten up protectively. That involuntary muscle guarding can hold the shinbone in place and mask the extra movement a torn ACL would otherwise allow, producing a false negative. Swelling inside the joint itself can also physically block the forward glide. Under general anesthesia, when muscles are fully relaxed, the test’s sensitivity climbs to about 96%, which confirms that muscle guarding is a major source of missed diagnoses in the clinic.
There’s also a measurable difference between men and women in office-based testing. One study found sensitivity of 95% in men but only about 73% in women. That gap disappeared under anesthesia, where both groups reached the mid-90s, suggesting the difference is related to muscle guarding and body composition rather than any fundamental limitation of the test itself.
Anterior Drawer vs. the Lachman Test
The Lachman test is the other common hands-on exam for the ACL, and the two are frequently compared. The Lachman is performed with your knee bent only about 20 to 30 degrees instead of 90, and the examiner pulls the shinbone forward from that straighter position. Because the hamstrings are more relaxed at that angle, the Lachman is traditionally considered better for evaluating acute injuries when muscle guarding is a problem.
In practice, the two tests perform similarly overall. Research comparing them head-to-head found sensitivities of about 94% for the anterior drawer and 94% for the Lachman. For chronic injuries, both tests are highly accurate. For acute injuries examined without anesthesia, the Lachman has a modest edge because it’s less affected by muscle tightness and swelling. Both tests are subjective and depend on the skill and experience of the examiner, which is why clinicians typically use them together rather than relying on either one alone.
An MRI is usually the next step if either test is positive, as imaging can confirm the tear, reveal its exact location, and check for damage to other structures like the meniscus or other ligaments.
The Ankle Version of the Test
The anterior drawer test isn’t only for knees. A similar maneuver is used at the ankle to evaluate the anterior talofibular ligament, or ATFL, which is the ligament most commonly sprained during an ankle roll. The ATFL is the main structure preventing the ankle bone from sliding forward out of the joint socket.
For the ankle version, you lie on your back with your leg relaxed and your foot held in a neutral or slightly pointed-down position. The examiner stabilizes your lower leg with one hand and pulls the foot forward with the other. If the ATFL is torn, the ankle bone shifts forward more than it should, just as the shinbone does in a knee with a torn ACL. The logic is identical: pull the bone forward, and if the ligament meant to stop it is damaged, excess movement appears.
What to Expect After the Test
The test itself is brief and causes minimal discomfort in most cases, though it can be uncomfortable if your knee or ankle is already swollen and sore from a recent injury. A positive result doesn’t automatically mean surgery. The treatment path depends on the severity of the tear, your activity level, your age, and how unstable the joint feels during daily life. Partial tears and lower-grade laxity are sometimes managed with physical therapy and bracing, while complete tears in active people often lead to surgical reconstruction.
If your test is negative but your symptoms are suspicious, that doesn’t rule out a tear either, especially if the exam happened soon after the injury. A follow-up exam once swelling and muscle guarding have settled, or an MRI, can provide a clearer answer.