Overview

The medial collateral ligament, commonly called the “MCL”, is on the inner side of your knee, connecting to the femur and to the tibia. The MCL stabilizes your knee by working with the lateral collateral ligament (LCL) to prevent excessive side-to-side movement of your knee joint. The medial collateral ligament helps keep the upper and lower leg aligned properly.

Causes

Your medial collateral ligament can be injured when your knee is pushed sideways toward the inner side of your body. A hard blow to the outer side of your knee is the most common cause.  This sideways movement can stretch the MCL, tear some of its fibers, or even rupture the ligament completely.

Symptoms

An MCL injury causes pain and swelling of the inner side of your knee. Your knee may feel stiff, unstable, and weak.  It may lock or catch when you walk.  Some people feel foot numbness or weakness after an MCL injury.

Treatment

Most MCL strains can be treated with rest, ice, a knee brace, and physical therapy.  Many MCL tears heal without surgery by using these same treatments over a longer period of time.  MCL ruptures require surgery.