How to Know If You Tore Your ACL

A torn anterior cruciate ligament (ACL) is a common sports injury. You can have a torn ACL when engaging in football, soccer, skiing, and other sporting activities that involve pivoting, cutting, and extension of the legs. As it involves the ligaments in the knee, you are likely to experience excruciating pain after sustaining the injury. However, you have to learn the signs of torn ACL because you will feel pain after other types of accidents.

How to Know If You Tore Your ACL

You will certainly experience severe pain when you have an ACL tear, but there will be some other signs as well. Here is what you are likely to feel when you have this type of an injury.

1. Your Knee Gives Out

The anterior cruciate ligament is essential for the stability of your knee joint, and your knee joint will feel unstable when you have an ACL tear. You are likely to experience instability with pivoting or cutting movements quite common in several sports. In some cases, it is also possible to notice knee instability while walking.

2. You Have Weak Leg Muscles

You will notice a degree of weakness in your thigh muscles after having a torn ACL. Sometimes, it becomes extremely difficult to lift your leg. It usually happens due to severe pain and swelling. To learn how to know if you tore your ACL, simply get to your feet, if you can, and try to lift your leg up. If you feel severe pain, call your doctor immediately.

3. You Feel Pain While Bending Knee

It is obvious to lose a range of motion after getting an ACL tear. It means you will find it difficult to bend your knee. If you fail to bend your knee to a 90-degree angle because of stiffness, pain, or swelling, chances are you have torn your ACL.

4. You Hear a Popping Noise

It is quite common with most injuries people sustain during sporting activities, but most people say they hear a clear popping noise when they get an ACL tear. That popping or snapping noise suggests that there is something wrong with your ACL. Do not forget to tell your doctor about the noise your knee made when you injured your leg.

5. Your Knee Feels Warmer

Touching your knee to confirm how warm it feels is another way of how to know if you tore your ACL. If there is swelling and your knee feels warm to the touch, chances are you have torn your ACL.

6. You Experience Swelling

As with other types of injuries, you will have swelling after getting a torn ACL. Swelling is actually your body's way to repair the injury, so any swelling around your knee following an injury usually means that you have suffered at least a partial ACL tear. Sometimes, you do not notice any swelling right after getting injured, but do not ignore it even if starts showing up after some time.

7. You Fail to Move Your Knee

Even after suffering a partially torn ACL, you will find it extremely painful to move your knee back and forth. There may also be pain when moving it from side to side. If your tear is rather severe, you will not be able to stand up and walk.

Get It Tested

Your doctor will order certain tests to check the ligaments of your knee. Checking the results of the following tests is another way of how to know if you tore your ACL.

  • Lachman Test: Usually performed to check how the tibia moves in the forward direction, the Lachman test can also help a surgeon determine if you have an ACL tear or not. They will stabilize the femur and bend your knee slightly. At the same time, they will shift the tibia in the other hand to feel for an ACL tear.
  • Drawer Test: To perform this test, your doctor will hold your knee with a 90-degree bend in it. They will then shift the tibia forward and back to confirm if the ACL is intact or not.
  • Pivot Shift Maneuver: As it is difficult to perform this maneuver in the office, your doctor is likely to perform it in the operating room with you under anesthesia. This helps detect abnormal motion of your knee joint when it is confirmed that you have torn your ACL.

How to Treat It

Learning how to know if you tore your ACL is important but you should also know what you can do to manage things better. For starters, you should use the R.I.C.E principle to control pain and swelling. Here is what it means:

  • Rest: You should take some rest and give your knee some time to heal.
  • Ice: You should apply ice to your knee after sustaining an injury. Apply it for 20 minutes at a time and repeat every two hours.
  • Compression: You should wrap an elastic bandage around your knee to control pain and swelling.
  • Elevation: You should lie down, take some rest, and keep your knee elevated. Simply keep a few pillows under your injured leg to raise your knee.


You will have to undergo rehabilitative therapy to restore strength and flexibility to your knee. Your physical therapist will explain how to perform some exercises to strengthen the ligament and muscles around the affected area. It is also common to wear a brace and walk with crutches to give your affected knee some time to heal. You are likely to notice good results in a short time if you are relatively inactive and engage in moderate recreational activities.


You may have to undergo surgery if you are an athlete and want to return to sport with full potential. You may also need surgery if you have more than one ligament injured or you have injured the cartilage in your knee. If your knee buckles during everyday activities, your doctor may also recommend surgery. Your doctor will remove your damaged ligament and use a segment of tendon (graft) in place of it. Your surgeon can use a piece of tendon from a tendon from a deceased donor or take it from another part of your knee. It usually takes up to 8-12 months to return to sport after your surgery.

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