The lateral collateral ligament is the ligament that fixes the knee joint and is located near the midpoint of the lateral side of the knee, the upper end is connected to the femur, which is the thigh bone, and the lower end is connected to the head of the fibula, which is the lateral calf bone. The main function of the lateral collateral ligament is to connect the thigh bone to the calf bone and to prevent the knee joint from protruding outward and from turning inward, which in layman’s terms means preventing the entire lower limb from becoming O-shaped. The lateral collateral ligament is less likely to be injured than the medial collateral ligament. Most of these injuries are caused by a strong force on the inside of the knee, which causes the entire knee to deform outward, causing excessive force on the lateral collateral ligament and resulting in injury or even ligament rupture.