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Anterior Cruciate Ligament (ACL) Injuries

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Topic Overview


Symptoms of an acute ACL injury include:

  • Feeling or hearing a pop in the knee at the time of injury.
  • Pain on the outside and back of the knee.
  • The knee swelling within the first few hours of the injury. This may be a sign of bleeding inside the knee joint. Swelling that occurs suddenly is usually a sign of a serious knee injury.
  • Limited knee movement because of pain or swelling or both.
  • The knee feeling unstable, buckling, or giving out.

After an acute injury, you will probably have to stop whatever you are doing because of the pain, but you may be able to walk.

The main symptom of chronic ACL deficiency is the knee buckling or giving out, sometimes with pain and swelling. This can happen when an ACL injury is not treated.

Your doctor can tell whether you have an ACL injury by asking questions about your past health and examining your knee. The doctor may ask: How did you injure your knee? Have you had any other knee injuries? Your doctor will check for stability, movement, and tenderness in both the injured and uninjured knee.

You may need X-rays, which can show damage to the knee bones. Or you may need other imaging tests, such as an MRI. An MRI can show damage to ligaments, tendons, muscles, and knee cartilage. Arthroscopy may also be done. During arthroscopy, your doctor inserts surgical tools through one or more small cuts (incisions) in the knee to look at the inside of the knee.

Start first aid right away. These first-aid tips will reduce swelling and pain. Use the RICE method. The letters stand for Rest the knee, put Ice on it, use an elastic bandage to give gentle Compression to the knee, and Elevate the leg by propping it up above the level of your heart. And at first it's also important to move your leg as little as possible. Take over-the-counter pain medicine.


WebMD Medical Reference from Healthwise

Last Updated: November 14, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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