How to Confirm a Partial ACL Tear

Three Methods:Recognizing Symptoms and Risk FactorsHaving a Physical Examination DoneTreating a Partial ACL Tear

It can be hard to determine whether or not your ACL is partially torn, particularly because a partial tear keeps your ACL from presenting normal signs of being torn, like you knee ‘buckling’. Luckily, there are still ways you can self-diagnose a partially torn ACL before going to the doctor’s office. To do this, you’ll need to know what symptoms to look for, understand how the ACL works, and then make a trip to the doctor’s office for a professional diagnosis. Scroll down to Step 1 for more information.

Method 1
Recognizing Symptoms and Risk Factors

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    Take note if you hear a ‘popping’ noise when the injury happens. Most people state that they hear a popping noise when the ACL is injured. If you heard a ‘popping’ or ‘snapping’ noise when you experienced your injury, it is likely that your ACL has been at least partially torn. You should go to the doctor to get this diagnosis confirmed.
    • Though you will most likely be in pain, try to remember the exact sound your knee made. Describing the noise your knee made can actually help your doctor to diagnose your injury.
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    Monitor any pain you feel. Injuring your knee, regardless of whether it is a partial tear or just a minor sprain, can really hurt. In particular, you will most likely feel a radiating or gnawing pain when trying to do any physical activity.
    • When you suffer a partial tear of you ACL, the pain receptors in your knee get activated. This can lead to a moderate to severe pain.
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    Keep track of any swelling that occurs. Swelling is your body’s way of repairing internal structures whenever it has suffered an injury. If you notice that your knee has become swollen after your accident, you have most likely suffered at least a partial tear.[1]
    • You should also take note if your knee becomes swollen after any time you do a physical activity. While you may not have noticed the swelling right after your accident, swelling after physical activity is a definite sign that you knee has been injured and could be partially torn.
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    Check to see if your knee is warmer than normal and has a red color. Along with the swelling, your knee will become warm to the touch and reddish in color. Your body will increase the temperature at the spot where the injury occurred to prevent infection since bacteria can’t generally thrive in a warm environment.[2]
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    See if you can move your knee. If you have suffered a partially torn ACL, you will most likely have trouble moving your knee from side to side and back and forth. This is because the ligament has been injured, so you will probably have a hard time walking.[3]
    • Even if you can walk, your knee will most likely feel weak.
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    Know the common causes of ACL injuries. An ACL injury almost always occurs when motion is involved. You may have suddenly changed direction in a basketball game, or you may have landed awkwardly while going off a jump on the ski slopes. If you think you may have partially torn your ACL, it is important to know the instances in which ACLs are generally injured. These instances include[4]:
    • Suddenly changing direction.
    • Suddenly stopping while you were in motion.
    • Having a heavy force or pressure put on your knee, such as when colliding with someone in football.
    • Jumping and landing incorrectly or awkwardly.
    • Suddenly slowing down when running.
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    Be aware of the risk factors that can lead to ACL injuries. While anyone can get an ACL injury, some factors or activities can predispose you to getting injured.[5] You are much more likely to get an ACL injury when:
    • You engage in athletic sports that involve the active use of your legs. Sports that involve physical contact can also increase your chances of ACL injury.
    • You experience muscular fatigue. Muscular fatigue can also make a person prone to ACL injury. Since the muscle works together with the bones, ligaments and tendons, exerting your muscles and making them tired can lead to a higher risk of injury. For example, a tired soccer player is more susceptible to ACL injury than an energetic player who has just started playing.
    • You have a medical condition that causes you to have weak muscles or bones. For example, having weak and brittle bones, having ineffective development of your cartilage, or being obese can all increase your chances of an ACL tear.

Method 2
Having a Physical Examination Done

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    Go to a doctor if you notice any of the symptoms listed in this article. While you may be able to use this article as a guide to help you figure out if you are injured, you still must go to the doctor to get a professional diagnosis. It would be bad to think that you are ok, only to put pressure on your knee and injure it further.
    • Schedule an appointment for as soon as possible after the injury. If you can, you may also go to the hospital to deal with the injury right away.
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    Be aware that there are three grades of ACL injury. When your ACL gets injured, it is referred to as a sprain rather than a broken bone because it is a ligament (though it can feel as painful as breaking a bone). The term 'sprain' refers to more than just the stretching of the ligament, it is actually the classification the is used to refer to ligament injuries. There are three levels of ACL injury.
    • A grade 1 ACL sprain involves mild injury to the ligament. It has been slightly stretched but not torn. It can still sustain the knee joint and will help the leg remain stable.
    • A grade 2 ACL sprain is when the ligament is stretched beyond its capacity to the point it becomes loose. This is when the technical term “partial tear of the ACL” is used.
    • A grade 3 ACL sprain makes the knee joint unstable and the ligament is completely torn apart.
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    Have a doctor perform the Lachman test. You must have a doctor do this test—do not try it yourself. This is the preferred test for figuring out if you have a partial ACL tear because it can show that you have a partial tear even when the rest of the ligaments and tendons in your knee are uninjured. A doctor will[6]:
    • Have you lie down on a table. Your doctor will first look at your uninjured knee to see how far your shin moves forward when your knee is bent. Your ACL keeps your shin from moving very far forward. Your doctor will then look at your injured knee and see how far your shin moves forward when the knee is bent. If it moves forward further than normal but your doctor can still feel resistance, it means that you have a partial tear. If there is no resistance, your ACL has been fully torn.
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    Be prepared for the Pivot Shift test. This test is meant to determine how much pressure can be put on your injured knee before it becomes unstable. Your doctor will move your injured leg a little ways away from your body (this is called hip abduction).[7] She will then:
    • Straighten your leg while simultaneously press inward against the outer part of your knee and twist your leg outward. Doing this will show how well your ACL is functioning because it is a movement that only involves the ACL.
    • Your leg will be slowly bent while continuous pressure is put on it. When your knee is bent at a 20 to 40° angle, your doctor will look at your shin bone. If the bone slides forward a bit it means that your ACL has been partially torn.
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    Have an x-ray taken of your knee. While the ACL cannot be seen through an x-ray, your doctor can look for other evidence that you ACL has been partially torn. An x-ray of both knees is necessary to detect signs of injury such as fracture, improper alignment of the bony structures, and narrowing of the spaces between joints.[8]
    • All three of these injuries are associated with a partial ACL tear.
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    Know that an MRI might need to be done. Unlike an x-ray, an MRI will help your doctor to examine your soft tissue structures in your knee, including your ACL. Your doctor will also look at your meniscus and other knee ligaments to make sure that they are not injured.
    • Your doctor might also request an oblique coronal image if he or she is still not sure about the extent of your injury. This image will give the doctor a better view of your knee in addition to the MRI.

Method 3
Treating a Partial ACL Tear

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    Protect your knee with a brace or cast. If you do have a partial ACL tear, your doctor will most likely give you a brace or cast to wear while your ACL recovers. Luckily, most partial ACL tears do not require surgery. You will, however, have to protect your knee from further injury. The best way to do this is to wear a brace or cast that will keep your knee stabilized while it heals.
    • Your doctor might give you crutches to use along with your brace. Crutches are used to keep you from putting pressure or too much weight on your knee while it heals.
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    Rest your knee as much as possible. While your knee is healing, it will need to rest as much as possible. Try to keep weight off of it at all times. You should sit with your knee elevated so that it can begin to repair itself. When you sit down, prop your knee up so that it is raised above your hip.
    • If you are lying down, prop your knee and leg up so that it is above your heart and chest.
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    Ice your knee. To control the swelling and pain caused by your partially torn ACL, you will need to ice your knee every day. Write a bag of ice or an ice pack in a towel to keep the ice from directly touching your skin, as this could cause a burn. Keep the ice on your knee for 15 to 20 minutes for the best results.[9]
    • Any amount of time shorter than 15 minutes will not do much to control swelling or pain. Keeping the ice on your knee for longer than 20 minutes may result in the ice burning your skin.
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    Consider surgery as a last resort. If your ACL is fully torn, or if your tear falls between a partial and full tear, you may need surgery for the knee to be fully repaired. If this is the case, you will have to have a graft done to replace the torn ligament. The most common graft used is the tendon of the kneecap or hamstring. However, acquiring tendons from donor knee is also an option.
    • Talk to your doctor about the best option for your specific case.
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    Go to physical therapy to strengthen your knee. Talk to your doctor about going to physical therapy. After you have let your knee heal, you will have to begin rehabilitating your knee so that the injury does not occur again. Go to a physical therapist who can help you with increasing your range of motion, strength training, and stability exercises.[10]


  • To decrease your chances of suffering a partial ACL tear, practice strength training to make your knees as strong as possible.


  • If you think that you have have sustained a partial or full ACL tear, go to the doctor right away.

Sources and Citations

  1. Tjoumakaris FP, Donegan DJ, and Sekiya JK. Partial Tears of the Anterior Cruciate Ligament: Diagnosis and Treatment. Am J Orthop. 2011; 40(2):92-97.
  2. Duthon VB, Barea C, Abrassart S, Fasel JH, Fritschy D, Menetrey J. Anatomy of the anterior cruciate ligament. Knee Surg Sports Traumatol Arthrosc. 2006; 14(3):204-213.
  3. Steckel H, Starman JS, Baums MH, Klinger HM, Schultz W, Fu FH.Anatomy of the anterior cruciate ligament double bundle structure: a macroscopic evaluation. Scand J Med Sci Sports. 2007;17(4):387-392.
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