Your doctor or therapist uses the anterior drawer test to check your anterior cruciate ligament, or ACL, for an injury. This is one of the common assessments used in knee injuries.
What Is the Anterior Cruciate Ligament?
The anterior cruciate ligament is part of the connective tissue inside your knee joint on the front of your knee. The cruciate ligaments cross in an X pattern over the front and back. They help control back-and-forth knee movement. Your ACL helps keep your knee joint stable.
This ligament can tear during activity or sports. When it does, it’s called a sprain. Other damage often happens alongside this sprain. Other parts of the knee that can be affected include the meniscus, cartilage, and other ligaments.
These tears are usually graded by severity.
Grade 1 sprain. This type of sprain includes mild ligament damage. The ligament has been stretched, but it can still keep the joint stable.
Grade 2 sprain. This sprain causes a partial tear. The ligament has been stretched, and the joint is now loose.
Grade 3 sprain. This type of sprain causes a complete tear. The ligament has been torn into two pieces and the joint is unstable. Most anterior cruciate ligament injuries are complete tears.
Tears or sprains can happen during any activity that requires you to:
- Suddenly stop
- Change direction quickly
- Land a jump the wrong way
- Slow down during running
- Take a hit in the knee
Most of the time, these types of knee injuries happen during direction changes and landings. The twisting and force of landing causes the ligament to tear.
Anterior cruciate ligament injuries seem to happen more to women. This could be because women’s joints are looser and have less muscle mass. It could also be because estrogen relaxes muscles and ligaments, but more research needs to be done to know for sure.
If you’ve injured your ACL, you might have different symptoms, including:
- A popping sound when you land or twist the wrong way
- Your knee buckles out from under you
- Swelling within 24 hours
- Tenderness during walking
- Trouble moving your knee or leg
What Is the Anterior Drawer Test?
The anterior drawer test is a knee assessment that your doctor, physical therapist, or sports therapist uses to check for an ACL injury. It might be used along with a Lachman test, a pivot shift test, and an MRI.
The test is simple:
- You lay on your back with your knee at a 90-degree angle and your foot in neutral position.
- The therapist sits on your foot.
- They wrap their hands around the back of your knee, place their thumbs on the front of your kneecap, and pull the knee forward.
- Your foot is rotated to a different direction, and they pull forward again.
This test is done on your uninjured knee first to compare and check for differences. If the tibia, or shinbone, has more movement, or if the ligament is loose compared with the other knee, the anterior drawer test is considered to be positive.
Your physical therapist might suggest that you see your doctor for imaging like a magnetic resonance imaging (MRI).
Limitations of the Anterior Drawer Test
Knee injuries are usually physically examined. These physical tests are often enough to find out if there’s an injury. Some studies show that the anterior drawer test is 94% accurate and is better at diagnosing a tear than imaging tests. These extra tests are still usually recommended, though.
Some factors that might cause an inaccurate test include:
- Swelling in the knee that makes it hard to bend at 90 degrees
- A torn meniscus that affects movement during the test
- A hamstring spasm that affects movement during the test
- Your therapist isn’t in the right position, or their hands aren’t in the right position
- You’re not relaxed and comfortable
After a Positive Anterior Drawer Test
If you have a positive anterior drawer test along with other positive tests and scans, your doctor or therapist might suggest that you:
- Take nonsteroidal anti-inflammatory drugs
- Ice your knee
- Do physical therapy
- Brace your knee
- Have surgery
Not everyone needs surgery to heal an ACL injury. If your sprain is mild, if it doesn’t impact your quality of life, if you don’t do high-intensity sports, or if you’re older, you might do well with physical therapy alone.
If the injury is severe, you might have trouble moving and walking. Major damage can cause instability and more damage to your knee. If you want to continue to play high-intensity sports or have a very active lifestyle or job, you will probably want surgery.
Even after you have surgery, you might easily re-sprain your ACL, though. It might still be unstable, and you might still have pain and swelling.
If you think you have a knee injury, talk to your doctor or physical therapist. They might recommend starting with an anterior drawer test, and they will help you decide if surgery is right for you.