The anterior cruciate ligament of the knee is an important stabilizing structure of the knee joint, which has not only anterior and posterior stabilizing effects, but also internal and external stabilizing and rotational stabilizing effects. Once ruptured, it can lead to instability of the knee joint, which can lead to the following problems: 1. Secondary meniscal tears. When the cruciate ligament is just injured, 20 out of 100 people will have a torn meniscus. 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. That is, if surgery is delayed for 2 years, 60 out of 100 patients with a torn ACL will have their meniscus hitched in. 2. Secondary cartilage injury. After 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 of 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. 3, secondary serious injury: after the rupture of the cruciate ligament, because of the instability of the knee joint, it can lead to repeated injuries to the knee joint. In repeated injuries, because there is no protection from the ACL, it may lead to other ligament injuries and even knee dislocation. The effect of surgical treatment for multiple ligament ruptures will have to be discounted. 4, secondary joint laxity: ACL rupture will lead to joint laxity, and the lax joint will pull the normal structure even looser, so the vicious cycle will lead to the knee joint becoming even looser over time.