The anterior drawer test checks for a torn anterior cruciate ligament (ACL) in the knee. It can also be used on the ankle to check for a torn anterior talofibular ligament (ATFL), the most commonly injured ankle ligament. In both cases, the examiner pulls part of the joint forward and measures how far it slides compared to normal.
How the Knee Test Works
The ACL is one of four ligaments that connect your thighbone to your shinbone. Its job is to prevent the shinbone from sliding too far forward and to limit excessive rotation. When the ACL tears, that restraint disappears, and the shinbone can shift forward under the thighbone more than it should.
During the test, you lie on your back with your knee bent. Your provider wraps both hands around the top of your shinbone and gently pulls it forward. If the shinbone slides forward noticeably more than on your healthy side, the test is positive, meaning the ACL is likely torn or significantly damaged.
Providers grade the amount of forward movement on a three-point scale. A Grade 1 result corresponds to roughly 7 mm of forward translation, Grade 2 to about 7.5 mm, and Grade 3 to around 9 mm or more. The uninjured knee is always tested for comparison, since everyone’s natural joint looseness differs.
How the Ankle Test Works
The same concept applies to the ankle. The ATFL runs along the outside of the ankle and prevents the talus (the bone sitting on top of the foot) from sliding forward out of the ankle joint. It’s the ligament most often torn during an ankle sprain.
For this version, your knee is bent to about 90 degrees and your foot is pointed slightly downward (10 to 20 degrees of plantarflexion). In that position, the ATFL is under maximum tension. The examiner stabilizes the lower leg with one hand and pulls the heel forward with the other. If the talus shifts forward about 3 mm or more compared to the uninjured ankle, the ligament is likely torn. Damage to both the ATFL and a second ligament on the outside of the ankle results in even greater forward movement across all ankle positions.
One large clinical study found that combining a positive ankle drawer test with tenderness over the ATFL, visible bruising, and swelling on the outer ankle correctly identified a ligament tear 95% of the time. Equally useful: a negative drawer test combined with no discoloration always indicated the ligament was intact.
How Accurate Is the Knee Test?
For the knee, studies report the anterior drawer test has a sensitivity around 77 to 94% and a specificity around 86%. In practical terms, sensitivity means how well the test catches real ACL tears, and specificity means how well it avoids flagging a healthy knee as torn. Those numbers vary based on timing: the test tends to be less reliable in the first few weeks after injury, when pain and swelling are at their worst, and more reliable once swelling has settled (typically after three weeks or so).
Accuracy also improves significantly when the test is performed under anesthesia, especially in women. Without anesthesia, pain causes the hamstring muscles on the back of the thigh to tighten up reflexively, preventing the shinbone from sliding forward even when the ACL is torn. This “guarding” is the single most common reason for a false negative result.
Other Factors That Affect Results
Beyond hamstring guarding, several practical issues can make the test less reliable. A soft or cushioned exam table can absorb some of the forward pull, masking the movement. Providers with smaller hands may have difficulty generating enough grip on a patient with a large calf or thigh. And a torn meniscus can sometimes wedge into the joint space and physically block the shinbone from sliding forward, hiding the ACL tear underneath.
Because of these limitations, the anterior drawer test is rarely used alone. It’s typically one part of a broader physical exam that includes other maneuvers like the Lachman test and the pivot shift test. A study of 653 patients found the anterior drawer and Lachman tests had nearly identical sensitivity (94.4% vs. 93.5%) for non-acute ACL injuries, meaning neither consistently outperforms the other. When the clinical exam strongly suggests a torn ACL, imaging with MRI is usually ordered to confirm the diagnosis and check for additional damage to the meniscus or other ligaments before planning treatment.
What a Positive Result Means for You
A positive anterior drawer test doesn’t automatically mean surgery. It means the ligament in question, whether in the knee or ankle, has significant laxity and is likely torn or stretched beyond function. What happens next depends on the severity of the tear, your activity level, and whether other structures in the joint are also damaged.
For a partial ACL tear or a lower-demand lifestyle, rehabilitation focused on strengthening the muscles around the knee can sometimes compensate for the lost ligament. For complete tears in active people, especially those who play sports involving cutting or pivoting, surgical reconstruction is the more common path. For ankle ATFL tears, most people recover well with bracing and physical therapy, though chronic instability from repeated sprains can eventually require surgical repair.