In most cases with a history of trauma to the knee joint from sudden valgus or rotational forces, after a ligament rupture, there is generally significant swelling of the medial aspect of the knee joint, localized severe pain, subcutaneous bruising, and bruising. The knee joint is one of the most complex and injury-prone parts of the body, relying on ligaments and muscles to maintain its stability. The ligaments are like a tough band that holds the two bones together and prevents instability from misalignment between the two bones. If an external force causes the knee to rotate or flex excessively more than the ligament can withstand, then damage to the ligament can result. The knee has four sets of ligaments: the anterior cruciate ligament, the posterior cruciate ligament, the medial collateral ligament, and the lateral collateral ligament. Knee instability brought about by ligament damage must be treated promptly, otherwise the wear and tear of the articular cartilage caused by the instability of the joint will predispose to osteoarthritis over time, seriously affecting the life of the joint. It is caused by a history of trauma and is more common in adolescents, more in men than in women, and most common in athletes. When injured, the sound of a ruptured ligament can sometimes be heard, and soon the pain is so severe that the person can no longer continue to exercise or work. Swelling, pressure and blood accumulation at the knee joint, spasm of the knee muscles, the patient is afraid to move the knee, and the knee joint is in a forced position, either straight or flexed. There are obvious pressure points at the rupture of the lateral collateral ligament of the knee and sometimes the curled up severed end of the ligament is felt.