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Anterior Cruciate Ligament (ACL) Injury: Care Instructions

Parts of the knee


The anterior cruciate ligament (ACL) is one of the four ligaments that join the thigh bone (femur) to the shin bone (tibia). The ACL helps keep the knee stable. You can tear it when you plant your foot and then push off, change direction, or twist. This can happen during sports like soccer or basketball. Your ACL can also tear when you get hit around your knee. This is more common in a sport like football.

Treatment usually starts with staying off the leg and elevating it, icing the knee, and using a compression bandage.

Your doctor may discuss letting your knee heal with time and physiotherapy (PT). You may choose surgery to repair your ACL, especially if you're very active, if other parts of your knee are injured, or if your knee is unstable. Whether you have surgery or not, PT to help you strengthen the muscles around your knee is important.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

How can you care for yourself at home?

  • Follow your doctor's directions for wearing a brace or an immobilizer, which limits movement of your knee. Wrapping your knee with an elastic bandage may help reduce or prevent swelling.
  • Use crutches as directed in the first few days after your injury if your doctor recommends them.
  • Rest your knee when possible. But try to flex your calf muscles often to help blood circulate in your legs.
  • Put ice or a cold pack on your knee for 10 to 20 minutes at a time. Try to do this every 1 to 2 hours during the next 3 days (when you are awake) or until the swelling goes down. Put a thin cloth between the ice and your skin.
  • Prop up your leg on a pillow when you ice it or anytime you sit or lie down during the next 3 days. Try to keep it above the level of your heart. This will help reduce swelling.
  • Take pain medicines exactly as directed.
    • If the doctor gave you a prescription medicine for pain, take it as prescribed.
    • If you are not taking a prescription pain medicine, take an over-the-counter medicine to reduce pain and swelling. These include ibuprofen (Advil, Motrin) and naproxen (Aleve). Read and follow all instructions on the label.
  • Follow your doctor's or physiotherapist's directions for strength exercises. Exercises to make your thigh muscles stronger and increase knee motion can help you get ready for a physical rehabilitation (rehab) program or surgery with a rehab program. Here are a few exercises you can do if your doctor says it is okay.
    • Quad sets: Lie down on the floor or the bed with your injured leg straight. Fully extend your leg—there should be no or little bend in your knee. Tighten the thigh (quadriceps) of your injured leg for 10 seconds. Do not lift your heel up. Relax your quadriceps for 10 seconds. Repeat 8 to 12 times several times during the day.
    • Straight-leg raises: Lie down on the floor or the bed with your injured leg flat and your uninjured leg bent so that the bottom of your foot is on the floor or bed. Tighten the quadriceps of your injured leg. Keeping your knee as straight as possible, lift your injured leg off the bed until it is about 45 centimetres above the bed or floor. Lower your leg back down and relax for 5 seconds. Do 3 sets of 8 to 12 repetitions.
    • Heel slides: Lie down on the floor or the bed with your leg flat. Slowly begin to slide your heel toward your rear end (buttocks), keeping your heel on the floor. Your knee will begin to bend. Slide your heel and bend your knee until it becomes a little sore and you can feel a small amount of pressure inside your knee. Hold this position for 15 to 30 seconds. Slide your heel back down until your leg is straight on the floor. Relax for 10 seconds. Repeat 2 to 4 times several times during the day.
    • Side-lying leg lifts: Lie on your side with your legs straight and the injured leg on top. Keeping your leg straight, raise your injured leg up and backward about 15 centimetres. Lower the leg to the starting position. Do 3 sets of 20 repetitions, or if you tire quickly, 3 sets of 8 to 12 repetitions.

When should you call for help?

Call 911 anytime you think you may need emergency care. For example, call if:

  • You have chest pain, are short of breath, or you cough up blood.

Call your doctor or nurse advice line now or seek immediate medical care if:

  • You have new or worse pain.
  • Your foot is cool or pale or changes colour.
  • You have tingling, weakness, or numbness in your toes.
  • Your cast or splint feels too tight.
  • You have signs of a blood clot in your leg (called a deep vein thrombosis), such as:
    • Pain in your calf, back of the knee, thigh, or groin.
    • Redness or swelling in your leg.

Watch closely for changes in your health, and be sure to contact your doctor or nurse advice line if:

  • You have a problem with your splint or cast.
  • You do not get better as expected.

Where can you learn more?

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Care instructions adapted under license by your healthcare professional. If you have questions about a medical condition or this instruction, always ask your healthcare professional. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.