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. 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. 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: 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. 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). 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. 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. All three of these injuries are associated with a partial ACL tear. 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.
What is a summary of what this article is about?
Go to a doctor if you notice any of the symptoms listed in this article. Be aware that there are three grades of ACL injury. Have a doctor perform the Lachman test. Be prepared for the Pivot Shift test. Have an x-ray taken of your knee. Know that an MRI might need to be done.