The lateral collateral ligament, or LCL, is the thin band of tissue running along the outside of the knee that connects the thighbone to the fibula.
Like the MCL, the lateral collateral ligament’s main function is to keep the knee stable as it moves through its full arc of motion. The main cause of LCL injuries is direct force to the inside of the knee. This puts pressure on the outside of the knee and causes the ligament to stretch or tear.
The symptoms of a torn or sprained LCL may include swelling or stiffness in the knee, pain or soreness on the outside of the knee, or an overall feeling like the knee is going to give out.