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Medial Collateral Ligament (MCL) Injuries

About Knee Injuries

Knee injuries often occur among active 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.

Teens who have a torn 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.

Someone 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 after 1 to 6 weeks of resting the joint.

Most people with an MCL injury 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 close 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

Someone 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 people with more severe injuries will have some instability when walking, feeling "wobbly" or unable to put weight on the affected leg.

Many people, 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.

Someone 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 and 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 it hurts to put weight on your knee, don't 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 person lies down flat, and the doctor moves the affected leg out to the side while flexing the knee 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 osft 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. People usually need 3 to 4 weeks of rest and sometimes therapy.
  • Grade III tear. With this type of injury, the MCL breaks in half. Many people are unable to bend the knee or put weight on it without pain. They may be unstable while walking, and the knee may sometimes "give out." Doctors may recommend a temporary knee brace for people with this injury as well as rehab therapy for 6 weeks or longer.


Treating MCL injuries requires initial resting of the joint with ice, elevation, and elastic compression bandages to help ease discomfort, pain, and swelling. It's OK 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 you deal with the pain and feel more comfortable.

Doctors usually recommend rehab 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 people do rehab at a center three times a week, with daily exercises they practice at home. Some people do accelerated rehab programs with more frequent therapy sessions, but recovery may not be any faster.

While most sports are off limits — especially the activity that caused the injury — you might try some low-impact activities, like swimming, bike riding, or protected running. Talk to your doctor about what you can do. Some of these activities might even work as rehab therapy.

Coping With an MCL Injury

Being told that you can't do the things you love — like running or playing football, field hockey, or softball — can be frustrating. If you're recovering from an MCL injury, especially a severe one, you might feel angry, even depressed, especially if you can't play a sport with friends.

As you heal, there are ways to still feel like part of the team. Keeping score, being a coach's assistant, or bringing water to your teammates may help. Or use this as a chance to try something completely different: Start a new activity that doesn't strain the knee like playing the guitar, painting, or drawing.

In time, you can again do the things you love. But if you still feel frustrated or depressed about missing out on your sport, consider talking to a school psychologist or counselor.

Date reviewed: October 2015

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Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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