Skip to Content

Acl Injury


What is an anterior cruciate ligament (ACL) injury?

An ACL injury is a partial or complete tear of the ACL. The ACL is a ligament in your knee that connects the tibia (shin bone) to the femur (thigh bone). Ligaments are strong tissues that connect bones. The ACL stops the tibia from sliding too far forward and keeps the knee stable.

What causes an ACL injury?

Trauma such as from a car accident or a fall may cause a tear in the ACL. An ACL injury may happen when the outer or inner side of the knee gets hit hard. This often happens in contact sports, such as football, basketball, and hockey. You may also injure your ACL by twisting your knee while you are standing, overextending your knee, or suddenly stopping or changing direction while you are running.

What are the signs and symptoms of an ACL injury?

  • A pop, snap, or tear when your ACL is injured
  • Sudden swelling or pain in your knee
  • The knee gives way
  • A change in the way you walk, such as with stiff legs
  • Trouble putting weight on your leg or straightening the knee

How is an ACL injury diagnosed?

Healthcare providers may test the function of your ACL by moving your knee, leg, or foot in different directions. You may be asked to lean or hop using your leg with the injured knee. Tell your healthcare provider if you feel pain while you do these or other activities. Both of your knees may be checked for any abnormal movement. You may need the following tests:

  • An x-ray or MRI may be used to look for an ACL tear. You may be given contrast liquid to help the pictures show up better. Tell a healthcare provider if you have ever had an allergic reaction to contrast liquid. Do not enter the MRI room with anything metal. Metal can cause serious injury. Tell the healthcare provider if you have any metal in or on your body.
  • Arthroscopy is a procedure used to look inside your knee for an ACL injury. A small incision is made in your knee and a scope is inserted. The scope is a long, bendable tube with a camera and light on the end.

How is an ACL injury treated?

  • Support devices such as a knee brace may be used to limit your movement and protect your knee. You may need to use crutches to help decrease your pain as you move around.
  • Prescription pain medicine may be given. Do not wait until the pain is severe before you take your medicine.
  • NSAIDs , such as ibuprofen, help decrease swelling, pain, and fever. This medicine is available with or without a doctor's order. NSAIDs can cause stomach bleeding or kidney problems in certain people. If you take blood thinner medicine, always ask your healthcare provider if NSAIDs are safe for you. Always read the medicine label and follow directions.
  • Physical therapy is used to teach you exercises to help improve movement and strength, and to decrease pain. The exercises can also help increase the range of motion in your knee.
  • Surgery may be needed if you have an ACL tear or damage to other knee ligaments.

How can I manage my ACL injury?

  • Rest your joint so that it can heal. Return to normal activities as directed.
  • Ice helps decrease swelling and pain. Ice may also help prevent tissue damage. Use an ice pack, or put crushed ice in a plastic bag. Cover the ice pack with a towel and place it on your injured ligament for 15 to 20 minutes every hour. Use the ice for as long as directed.
  • Compression provides support and helps decrease swelling and movement so your joint can heal. Ask your healthcare provider if you should wrap an elastic bandage around your injured ligament.
  • Elevate your injured area raised above the level of your heart as often as you can. This will help decrease or limit swelling. Elevate the injured area by resting it on pillows.

When should I seek immediate care?

  • Your toes are cold or numb.
  • Your knee becomes more weak or unstable.
  • Your pain has increased or returned, even after you take your pain medicine.
  • Your swelling has increased or returned.
  • Your symptoms are not getting better.

When should I contact my healthcare provider?

  • You have a fever.
  • You have questions or concerns about your condition or care.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

© 2017 Truven Health Analytics Inc. Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes. All illustrations and images included in CareNotes® are the copyrighted property of A.D.A.M., Inc. or Truven Health Analytics.

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.