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Medial Collateral Ligament (MCL) Injuries

About Knee Injuries

Knee injuries are common among active kids and teens, especially athletes. A torn medial collateral ligament (MCL) — a ligament that helps give the knee its stability — is one of the more serious injuries.

Kids who tear their MCL tend to play contact sports, like football and soccer. More severe injuries happen when the outside of the knee is struck, causing it to unnaturally bend inward (toward the other knee). MCL tears can also happen when the lower leg twists or bends out too far. This creates tension on the MCL, a rope-like band, and it stretches or breaks in half.

Children with a partially or completely torn MCL might have swelling and pain in the first 24 hours of injury. Fortunately, this injury can heal on its own from 1 to 6 weeks of resting the joint.

Most kids and teens will still need to undergo rehabilitation ("rehab") therapy to help regain strength in the joint.

What an MCL Does

The MCL is one of the four main ligaments in the knee joint. It's located on the side of the knee that's closer to the other knee. One end of the ligament is attached to the femur, while the other end is attached to the tibia.

With the lateral collateral ligament (LCL), which is in the same location on the outside of the knee, the MCL helps prevent the knee joint from bending too far from side-to-side.


Signs and Symptoms

A child with a partially or completely torn MCL may or may not have symptoms, depending on the severity of the injury.

Pain and swelling can be intense initially, and some kids and teens with more severe injuries will have instability when walking, feeling "wobbly" or unable to bear weight on the affected leg.

Many kids and teens, especially those who are familiar with the injury or have torn a ligament before, report hearing a "pop" sound — the sound of the shinbone popping out of and back into the knee joint.

A child who has injured a knee — whether on the field or at home — should stop all activity, to prevent further injury, and seek immediate medical care. In the meantime, keep the area iced — place the ice in a plastic bag, wrap the bag in a cloth, and hold it to the knee for 20 minutes at a time. Also, keep the knee elevated as much as possible to reduce swelling. As long as walking isn’t painful, it’s OK to walk with an MCL tear. But if standing or walking causes any pain, don't let your child put weight on the knee.


At the doctor's office or emergency room, doctors will perform physical exams and imaging tests to determine if there's a knee injury and, if so, how severe it is.

To help diagnose an MCL injury, doctors do a Valgus test. The child lies down flat, and the affected leg is moved out to the side, and the knee is flexed about 30 degrees. The doctor places one hand on the back of the knee joint and the other on the top side of the ankle. The doctor then rotates the shin bone and pushes the foot outward, to see how far the MCL will extend. Too much flexibility can signal an injury.

To properly diagnose MCL injuries, doctors usually perform these tests in combination or in addition to other physical exams.

While X-rays might be taken to determine the extent of the injury, they only look at bone and can only confirm the presence of bone fractures in the knee. An MRI, which looks at soft tissue (like ligaments and muscles), can confirm a partial or complete MCL tear, so some doctors will order one to confirm a diagnosis.

Types of Injuries

Doctors categorize MCL injuries according to the following criteria:

  • Grade I tear. This is a slight tear (or stretch) of the MCL. Both ends of the ligament are still attached to the bone, but part of the ligament may sag and be less tight. Recovery usually takes 1 to 2 weeks; therapy may not be needed.
  • Grade II tear. This is a slightly more severe tear of the MCL, with part of the ligament sagging. Pain and swelling is usually more severe than with a grade I tear. Kids usually need 3 to 4 weeks of rest and sometimes therapy.
  • Grade III tear. With this type of injury, the MCL breaks in half. Kids and teens often can't bend the knee or put weight on it without pain. They might be unstable while walking, and the knee may sometimes "give out." Doctors may recommend a temporary knee brace for this injury as well as rehab therapy for 6 weeks or longer.


Treatment of MCL injuries requires initial rest of the joint, along with icing, elevation, and compression bandages to help ease discomfort. It’s OK for your child to put weight on the knee as long as it's not painful. Depending on the severity of the injury, doctors may recommend crutches, limiting physical activity, and a temporary knee brace. Putting too much pressure on the knee can cause reinjury. Over-the-counter or prescription painkillers and anti-inflammatory medicine can help kids and teens deal with the pain and feel more comfortable.

Doctors usually recommend rehabilitation therapy to help heal the knee and to:

  • restore range of motion
  • regain strength in the knee, thigh, and shin muscles (and prevent atrophy, the breakdown of muscle tissue)
  • reduce pain and swelling
  • improve balance

Most kids undergo rehab at a center three times a week, with daily exercises they practice at home. Accelerated rehab programs involve more frequent therapy, but that won't necessarily speed recovery.

While most sports are off limits — especially the activity that caused the injury — kids and teens can do low-impact activities that may be fun and even therapeutic, like swimming, bike riding, or protected running. Talk to your doctor about what activities might benefit your child.

Helping Your Child Cope

Being told that you can't do the things you love — like running or playing football, field hockey, or softball — can be a devastating blow to any child. Kids and teens recovering from an MCL injury, especially a severe one, may feel angry, frustrated, and even depressed, especially if they're no longer participating in team sports with their friends.

But in the meantime, there are ways to still feel like part of the team. Keeping score, being a coach's assistant, or bringing water to the games may help. If your son or daughter doesn't want to do these things, suggest starting a hobby, like playing the guitar, painting, drawing, or another activity that won't put too much strain on the knee. Low-impact activities, like swimming, are another option.

In time, kids and teens can again do the things they love. But if your child continues to feel angry or depressed during recovery, encourage him or her to talk to a school psychologist or counselor, who can help your child cope and look ahead to better days.

Date reviewed: October 2015