The medial collateral ligament (MCL) runs from the inner side (medial side) of the femur (thigh bone) to the inner (medial side) of the tibia (lower leg bone). It prevents the knee from opening on the inside when struck from the outside of the knee joint. The MCL lies on the outside of the joint capsule and has a good blood supply that contributes to its good healing potential.
The lateral collateral ligament (LCL) runs from the outer side (lateral side) of the femur (thigh bone) to the top of the fibula (the smaller of the two lower leg bones). It prevents the knee from opening on the outer side when struck from the inner side of the knee joint. The LCL is thinner and when completely disrupted often requires surgical repair.« Back to Glossary Index