General info

Data about the condition

An ACL (Anterior Cruciate Ligament) injury is a tear or sprain of the anterior cruciate (KROO-she-ate) ligament (ACL) — one of the major ligaments in your knee. ACL injuries most commonly occur during sports that involve sudden stops or changes in direction, jumping and landing — such as soccer, basketball, football and downhill skiing.

Many people hear or feel a “pop” in the knee when an ACL injury occurs. Your knee may swell, feel unstable and become too painful to bear weight.

Depending on the severity of your ACL injury, treatment may include rest and rehabilitation exercises to help you regain strength and stability or surgery to replace the torn ligament followed by rehabilitation. A proper training program may help reduce the risk of an ACL injury.


  • A loud “pop” or a “popping” sensation in the knee
  • Severe pain and inability to continue activity
  • Rapid swelling
  • Loss of range of motion
  • A feeling of instability or “giving way” with weight bearing


Ligaments are strong bands of tissue that connect one bone to another. The ACL, one of two ligaments that cross in the middle of the knee, connects your thighbone (femur) to your shinbone (tibia) and helps stabilize your knee joint.

ACL injuries often happen during sports and fitness activities that can put stress on the knee:

  • Suddenly slowing down and changing direction (cutting)
  • Pivoting with your foot firmly planted
  • Landing awkwardly from a jump
  • Stopping suddenly
  • Receiving a direct blow to the knee or collision, such as a football tackle

When the ligament is damaged, there is usually a partial or complete tear of the tissue. A mild injury may stretch the ligament but leave it intact.


Prompt first-aid care can reduce pain and swelling immediately after an injury to your knee. Follow the R.I.C.E. model of self-care at home:

  • Rest. General rest is necessary for healing and limits weight bearing on your knee.
  • Ice. When you’re awake, try to ice your knee at least every two hours for 20 minutes at a time.
  • Compression. Wrap an elastic bandage or compression wrap around your knee.
  • Elevation. Lie down with your knee propped up on pillows.

The objectives of the Recovery Program

  • Pain relief
  • Restoring the range of motion
  • resumption of walking
  • Increased muscle strength and endurance

The content of the Recovery Program

Heel slides – involve the extension of the knee without bearing any weight:

  1. Start by sitting on the floor with your legs outstretched.
  2. Slowly bend the injured knee while sliding your heel across the floor toward you. Slowly slide the foot back into the starting position.
  3. Repeat 10 times.

Isometric Quad Contractions – isometric contractions of the quads are also done seated:

  1. Sit on the floor with your injured leg extended and your other leg bent.
  2. Slowly contract the quadriceps of the injured knee without moving the leg.
  3. Hold for 10 seconds.
  4. Relax.
  5. Repeat 10 times.

Prone knee flexion involves lying on your stomach:

  1. Lie on your stomach with your legs straight.
  2. Now bend your injured knee and bring your heel toward your buttocks.
  3. Hold 5 seconds.
  4. Relax.
  5. Repeat 10 times.

Passive knee extensions – require two chairs of equal height. Place the chairs facing each other at a distance slightly shorter than the length of your leg:

  1. Sit in one chair and place your heel on the seat of the other.
  2. Relax your leg and allow your knee to straighten.
  3. Rest in this position 1 to 2 minutes several times a day to gradually stretch out the hamstrings.

Heel raises are done while standing:

  1. Start by placing one hand on the back of a chair for balance.
  2. Now slowly lift the heel of your injured leg up, standing on your tiptoes.
  3. Stay there for 5 to 10 seconds.
  4. Slowly lower your heels.
  5. Repeat 10 times.

Half squats – are done standing while holding a sturdy table with both hands:

  1. Placing your feet a shoulder’s width apart, slowly bend your knees and lower your hips into a half squat.
  2. Hold for 10 seconds and then slowly return to a standing position.
  3. Repeat 10 times.

Knee extensions require either a TheraBand or a length of an exercise band:

  1. To begin, loop one end of Theraband around the leg of the table and the other around the ankle of your injured leg. (Alternately, tie both ends of the exercise band around the table leg and insert the ankle of your injured leg into the looped end.)
  2. Facing the table, slowly bend your knee about 45 degrees against the resistance of the tubing.
  3. Hold for a few seconds and slowly return to a standing position.
  4. Repeat 10 times.

Standing on One Leg is a great way to build and evaluate your strength and balance:

  1. Stand up on both feet.
  2. Lift the uninjured leg and standing unassisted on the injured leg for 10 seconds.

This exercise may not be so easy at first, but, with time and patience, you should able to do so while a few weeks.

Methodical Indications

  • Long-term warm-up before physical exertion
  • Avoiding knee hyperextension
  • Avoiding sudden movements

Did you know?

A loud “pop” or a “popping’ sensation may be heard or felt in the knee. It is the 1st symptom that may indicate an ACL injury.
The anterior cruciate ligament (ACL) is the most commonly injured knee ligament.
The most common sports in which ACL injuries occur include football, basketball, rugby and more.

You can also read about Knee osteoarthritis.

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