Knee injury - medial collateral ligament (MCL)

Alternative names
Medial collateral ligament (MCL) injury of the knee; MCL injury

MCL injury is a stretch, partial tear, or complete tear of the medial collateral ligament (MCL) of the knee. (The term “medial” means the ligament is on the inside of the knee.)

During physical eaxmination with a medial collateral ligament test, the doctor can 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:

  • a knee MRI  
  • a knee joint X-ray  
  • a knee joint X-ray with stress applied


The medial collateral ligament (MCL) is a ligament extending from the upper-inside surface of the tibia (the shin bone) to the bottom-inside surface of the femur (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, resulting in stress on the inside of the knee joint (valgus stress).

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


  • knee pain and tenderness along the inside of the joint  
  • knee swelling may be present  
  • knee instability (giving way) may occur

First Aid

Initial treatment of an MCL injury includes ice to the area, elevation of the joint (above the level of the heart), non-steroidal anti-inflammatory drugs (NSAIDS), and limited physical activity until the pain and swelling subside.

After an initial period of immobilization (usually with a knee brace), gradual mobilization of the knee with strengthening and stretching should be performed. Physical therapy may be helpful to help regain knee and leg strength.

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

Call immediately for emergency medical assistance if
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.

Johns Hopkins patient information

Last revised: December 8, 2012
by Armen E. Martirosyan, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.