Ligaments are important static stabilizing factors of the knee joint, and their main function is to limit and guide. When the stress on the ligament exceeds its yield point, which is the mark of complete rupture, it is often torn and may still maintain the continuity of the general shape, but the tension that maintains the stability of the joint is lost, resulting in vertical instability. If the violence is more severe and the knee joint is extremely displaced, the continuity of the ligament shape may be lost, and it may be completely ruptured, which is often manifested as complex instability. In the acute stage, the patient's knee joint is swollen and painful, and the protective muscles are tense. Positive signs are difficult to find, and early diagnosis is difficult; in the late stage, patients often show varying degrees of knee instability. Unstable knee joints are prone to repeated injuries, and the shear stress on the meniscus and articular cartilage increases, causing meniscus damage, aggravated articular cartilage degeneration, and secondary traumatic arthritis. Although there are many methods for late ligament reconstruction, the long-term efficacy is good or bad, but none of them can completely restore the anatomical and physiological functions of the original ligament. Therefore, early correct diagnosis and treatment of knee ligament injuries are very important.