If the lateral collateral ligament is torn, the following symptoms can occur: First, pain at the injury site, which can be heard as a popping sound at the time of the tear, while severe pain occurs. Second, swelling, there can be a small amount of bleeding after the collateral ligament injury, which can then appear as localized ecchymosis, resulting in symptoms of swelling, and can also appear as bruised ecchymosis, which is due to localized bleeding seeping into the subcutis, resulting in bruised ecchymosis. Thirdly, joint movement may be limited due to pain and swelling. Tearing of the lateral collateral ligament often leads to an increase in the angle of the joint when it is turned inward, resulting in lateral instability of the knee joint. If there is instability of the joint and the MRI shows a complete rupture of the ligament, surgery is required.