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Rady Children's Specialists

Knee Medial Collateral Ligament (MCL) Tear

The medial collateral ligament (MCL) is one of the four major ligaments in the knee.  Ligaments attach bones to bones, and the MCL is found on the inner side of the knee. It is designed to stabilize the knee by preventing the shin bone from moving to the side (creating a knocked-knee look) relative to the thighbone.

MCL injuries can occur by direct contact or by non-contact (when an athlete is running or jumping and then suddenly slows and changes direction or twists). This injury can occur at any age.


Symptoms of a MCL tear include:

  • Initial sharp pain that resolves over a month on the inner side of the knee.
  • Some mild swelling within the first few hours after injury.
  • Unstable knee with a sense that it will “give out.”


A physical exam of the knee will often diagnosis a MCL tear. X-rays should be done to rule out any fractures. An MRI can be done to confirm the exam findings, and to evaluate associated injuries such as meniscus tears.


Treatment is an initial period of ice and compression to reduce swelling and pain. Crutches and a brace locking the knee straight is important. This will allow the MCL to heal in the appropriate position. MCL tears rarely require surgery, but if the MRI shows an associated injury, surgery may be needed.

Physical therapy should be started after about a month in the knee immobilizer. After six weeks of therapy, and full motion and strength has returned, a return to sports is permitted. Occasionally, the MCL is only sprained and therapy is usually not necessary; in this situation, a return sports can be achieved in three to six weeks from when the injury occurred. If there is no improvement with this program, tsurgery may be an option to restore stability and reduce pain. The MCL usually needs to be reconstructed or replaced, but a repair of the tear, if done early enough, can sometimes be successful.