Knee injuries are common among active kids, especially athletes, and a torn medial collateral ligament (MCL) — a ligament that helps give the knee its stability — is a common type of knee injury.
Kids who play contact sports, like football and soccer, are most likely to have a torn MCL. The injury happens when the outside of the knee is struck, causing it to unnaturally bend inward (toward the other knee). 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 within the first 24 hours of injury. Fortunately, this injury can heal on its own with anywhere from 1 to 6 weeks of resting the joint.
Most kids 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 that connect it to the shinbone (tibia) and thighbone (femur). It is located on the side of the knee that is closer to the other knee. One end of the ligament is attached to the femur, while the other end is attached to the tibia.
Together with the lateral collateral ligament (LCL), which is in the same location on the outside of the knee, the MCL helps prevent the overextension of the knee joint 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 very intense initially, and some kids (with more severe injuries) will have some instability when walking, feeling "wobbly" or unable to bear weight on the affected leg.
Many kids, especially those who are familiar with the injury or have torn a ligament before, report hearing a "pop" sound — the sound of the ligament tearing.
A child who has injured a knee — whether out 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. Do not let the child bear weight on the knee.
At the doctor's office or emergency room, doctors will perform physical exams and imaging tests to determine if there is a knee injury and, if so, how severe it is.
These tests can help diagnose an MCL injury:
- Lachman test. During this exam, a child will lie down flat on his or her back with the affected knee lifted and flexed at a 20- to 30-degree angle. The doctor then places one hand on the back of the shin and the other on the top of the thigh, applying pressure to move the shin forward. If it moves too far forward, it can signal a torn MCL.
- Varus load test. As in the Lachman test, a child lies down flat, and the affected led is moved out to the side, and the knee is flexed at 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. Pressure is applied, rotating the shin bone, 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 image bone and, therefore, can only confirm the presence of bone fractures in the knee. An MRI, which images 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 a portion of the ligament may sag and be less taut. 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 a portion 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. Many kids are unable to bend the knee or bear weight on it without pain. They may be unstable while walking, and the knee may sometimes "give out." Kids with this injury need to wear a knee brace and undergo therapy for 6 weeks or longer.
In addition to tearing the MCL partially or completely, some kids have "collateral" injuries. This means that other ligaments, bones, or tissue in the knee joint are also affected. And sometimes during a tear, the MCL detaches from the tibia or femur. Any of these complex cases would require longer recovery times, more therapy, and sometimes even surgery to repair the ligaments
Treatment of MCL injuries requires long-term rest of the joint. Depending on the severity of the injury, a child will need to walk with the assistance of crutches, limit physical activity, and wear a knee brace. Putting too much pressure on the knee can cause reinjury.
Rehabilitation ("rehab") therapy is needed 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 require more frequent therapy and can speed up recovery.
In the early stages of recovery, keep the knee iced and elevated to help to reduce pain and swelling. Over-the-counter or prescription painkillers and anti-inflammatory medicine can help kids deal with the pain and feel more comfortable.
While most sports are off limits — especially the activity that caused the injury in the first place — kids can do some 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 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 child doesn't want to do these, suggest starting a hobby, like playing the guitar, painting, drawing, or another sedentary activity that won't put too much strain on the knee. Low-impact activities, like swimming, are another option.
In time, your child can again do the things he or she loves. But if, during recovery, your child continues to feel angry or depressed, consider talking to a school psychologist or counselor, who may be able to help your child cope and look ahead to better days.
Reviewed by: Kenneth Rogers, PhD, ATC | Date reviewed: June 2009