The anterior cruciate ligament is an important stabilizing structure of the knee joint, which not only stabilizes the knee anteriorly and posteriorly, but also stabilizes it internally and externally and rotates it. Patients often ask me if a ruptured ACL can be treated conservatively. For this question we have to look at two aspects: 1. A partial tear of the cruciate ligament (I-II°) has no obvious knee instability subjectively or on manual examination by an experienced sports medicine physician. Knee instability is mainly manifested as walking flicker, down stairs injured leg can not eat strength, can not do fast running and jumping and other movements. If there is no such condition, you can usually choose conservative treatment. Ren Yizhong, Department of Joint and Sports Medicine Surgery, Second Affiliated Hospital of Inner Mongolia Medical University 2. Complete rupture of the cruciate ligament (II-III°) This condition can lead to knee instability, which can lead to the following problems: ① Secondary meniscus tear. When the cruciate ligament is just injured, 20 out of 100 people will have a meniscus tear. If surgery is delayed for a long time, 40 out of 100 people will have a torn meniscus after 6 months, 60 out of 100 people will have a torn meniscus after one year, and 80 people will have a torn meniscus after two years. , ② Secondary cartilage injury. After the ACL rupture, on the surface walking and some non-strenuous activities can be done, but compared with the good leg, the affected leg in the process of activity because the femur and tibia and with the patella between the wear and tear has been greater than the healthy leg, joint degeneration accelerated a lot. (iii) Secondary serious injury: After a cruciate ligament rupture, it can lead to repeated injuries to the knee joint because of knee instability. In repeated injuries, because there is no protection from the ACL, it may lead to other ligament injuries and even knee dislocation. The effectiveness of surgical treatment for multiple ligament ruptures will have to be compromised. ④Secondary joint laxity: ACL rupture can lead to joint laxity, which in turn stretches the normal structures even more, and so on in a vicious circle, which can lead to the knee becoming even looser over time. Therefore, surgery is recommended. For the timing of surgical treatment, it is generally better to try to take 0 – 3 months after the injury, so that complications can be avoided.