Definition

An anterior cruciate ligament (ACL) injury is a tear in the ACL ligament. The ACL is located in the middle of the knee joint. It connects the lower leg bone to the thigh bone. It stabilizes the knee and prevents the lower leg bone from sliding too far forward at the knee.

Anterior Cruciate Ligament Injury

ACL injury

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Causes

ACL injury occurs when your knee gets twisted or during a hard landing from a jump. It can also happen with:

    
  • Sudden stops or changes in direction
  • Sidestepping or pivoting
  • Direct contact
  • Risk Factors

    ACL injuries are more common in women. Other factors that increase your chance of ACL injury include:

        
  • Weak knee structure
  • Muscle strength imbalance between the quadriceps and hamstrings
  • Playing sports that require sudden changes of direction and deceleration
  • Use of incorrect technique for cutting, planting, pivoting, or jumping
  • Symptoms

    Symptoms may include:

        
  • A popping sound at the time of the injury
  • Pain and swelling in the knee
  • Loss of full range of motion
  • Weakness or instability in the knee
  • Difficulty walking
  • Diagnosis

    You will be asked about your symptoms and how you injured your knee. A physical exam will be done.

    Your knee will need to be viewed. This can be done with:

        
  • X-ray
  • MRI scan
  • Arthroscopy
  • Ligament sprains are graded according to their severity:

        
  • Grade 1—Mild ligament damage.
  • Grade 2—Partial tearing of the ligament.
  • Grade 3—Complete tearing of the ligament.
  • Treatment

    Talk with your doctor about the best treatment plan for you. Recovery time ranges depending on the grade of your injury. Treatment steps may include:

    Acute Care

    Rest

    Your ligament will need time to heal. Avoid activities that place extra stress on the knee:

        
  • Do not do activities that cause pain. This includes running, jumping, and weight lifting using the legs.
  • Do not play sports until your doctor has said it is safe to do so.
  • Your doctor may advise a knee brace to stabilize the knee, and crutches to keep extra weight off your leg.

    Cold

    Apply an ice or a cold pack to the area for 15-20 minutes, four times a day, for several days after the injury. Do not apply the ice directly to your skin. Wrap the ice or cold pack in a towel.

    Pain Relief Medications

    To manage pain, your doctor may recommend:

        
  • Over-the-counter medication, such as ibuprofen or acetaminophen
  • Topical pain medication—creams or patches that are applied to the skin
  • Prescription pain relievers
  • Compression

    Compression can help prevent more swelling. Your doctor may advise an elastic compression bandage around your knee. Be careful not to wrap the bandage too tight.

    Elevation

    Elevation can also help keep swelling down. Keep your knee higher than your heart as much as possible for the first 24 hours. A couple of days of elevation might be recommended for severe sprains.

    Recovery Steps

    Physical Therapy

    You may be referred to a physical therapist. Your therapist will provide you with exercises to help promote recovery.

    Heat

    Use heat only when you are returning to physical activity. Heat may then be used before stretching or getting ready to play sports to help loosen the ligament.

    Stretching

    When the acute pain is gone, start gentle stretching as advised. Stay within pain limits. Hold each stretch for about 10 seconds and repeat six times. Stretch several times a day.

    Strengthening

    Begin strengthening exercises for your ligaments as advised.

    Surgery

    Surgery may be needed to fully restore function of the knee. The decision to have surgery should be made after discussion with your doctor about your athletic needs, age, and related factors.

    Prevention

    To reduce your chance of injuring the ACL, take these steps:

        
  • Plyometrics , a form of jumping exercises, can be used to train and strengthen the leg muscles for jumping and landing.
  • When jumping and landing or turning and pivoting, your hips and knees should be bent, not straight.
  • Strengthen both the quadriceps and the hamstrings.
  • Maintain proper technique when exercising or playing sports.