A MCL injury is a sprain or tear to the medial collateral ligament on the inside of the knee. It most commonly happens when there is a sudden force to the outside of the knee. MCL injuries are common in contact sports and skiing.

MCL injuries are classified based on their severity into 3 grades: Grade 1 (mild) to Grade 3 (a compete tear). Often MCL injuries will occur in combination with injury to other structures in the knee joint.

The MCL provides stability to the inside of the knee joint. The MCL attaches to the bottom of the thigh bone (femur), crosses the knee joint and attaches to the top of the tibia (shin). It is a thickened band of ligament which also has deep fibres attaching to the meniscus deep in the knee.


An injury to the MCL can be caused by:

  • a force to the outside of the knee while it is slightly bent e.g. a heavy tackle in rugby
  • a twisting force to the knee while the knee is slightly bent What do I feel?
  • Pain and tenderness over the inside aspect of the knee
  • Swelling may be present
  • Some instability and loss of function in knee (if tear is large) What can I do?
  • RICE (Rest, Ice, Compression and Elevation)
  • See a physiotherapist for rehabilitation and exercises

Because of the varying grades of MCL injury, it is very important to get comprehensive assessment and treatment from a physiotherapist. For moderate to severe injuries, rehabilitation may take twelve weeks. For mild to moderate strains, return to play may take four to six weeks. Your physiotherapist will guide you in a graduated return to play once the injury has healed correctly.