Medial collateral ligament (MCL) injury is a stretch, partial tear, or complete tear of the ligament on the inside of the knee.

The medial collateral ligament (MCL) extends from the upper-inside surface of the shin bone to the bottom-inside surface of the thigh bone. The ligament stabilizes the joint on the inside of the knee.

The MCL is usually injured by pressure placed on the knee joint from the outside.

It is often injured at the same time as an anterior cruciate ligament (ACL) injury.

• Knee instability
• Knee pain and tenderness along the inside of the joint
• Knee swelling

The health care provider will examine your knee. An MCL test will be done to detect looseness of the ligament. This test involves bending the knee to 25 degrees and putting pressure on the outside surface of the knee.

Other tests may include:

• Knee MRI
• Knee joint x-rays

Treatment includes applying ice to the area, raising the knee above heart level, and nonsteroidal anti-inflammatory drugs (NSAIDS). You should limit physical activity until the pain and swelling go away.

After an initial period of keeping the knee still (usually with a knee brace), knee strengthening and stretching exercises should be done. Physical therapy may be helpful to help regain knee and leg strength.

Surgery is not usually used for isolated tears of the MCL.

Call your health care provider if symptoms of MCL injury occur.

Call your health care provider if you are being treated for MCL injury and you notice increased instability in your knee, if pain or swelling return after they initially subsided, or if your injury does not resolve with time.

Also call if you reinjure your knee.

Use proper techniques when playing sports or exercising. Many cases are not preventable.