Can a rupture of the ACL heal on its own? Can it be repaired if it does not heal on its own? In fact, the chances of an ACL rupture healing on its own are very low. And even if the ligament does heal on its own, it is very difficult to grow back to its original position and its ability to maintain the stability of the knee joint is greatly diminished. In addition, the ACL is located in the center of the knee joint, and there is a large cavity in the knee joint that contains a large amount of joint fluid. When the ACL is ruptured, the body perceives the ruptured ligament as a foreign body and therefore initiates an immune response, and within about 2-3 months after the injury, the joint effusion absorbs and eliminates the ruptured ligament. In other words, the ruptured ACL has no environment for self-repair. Therefore, after ACL rupture, conservative treatment is basically ineffective, and surgery is the only effective treatment at present. So, what kind of surgery is needed after an ACL rupture? Can the ruptured ligament be surgically sewn up? The answer is no. There are reports in the literature of early surgery to sew up the ruptured ligament, however, through long-term observation, the efficacy of this surgery is very poor, for reasons that may be related to the absorption of the ruptured ligament by the body as mentioned above. Currently, repair surgery is only considered when the anterior cruciate ligament is ruptured at the inferior stop and the rupture is accompanied by a bone mass. In general, ACL reconstruction surgery is often required when a rupture of the body part of the ligament occurs. ACL reconstruction surgery, as the name implies, involves replacing the injured ligament with another tendon graft, such as an autologous tendon, an allograft tendon or an artificial ligament, to restore stability to the knee joint. For patients who have missed the optimal time for surgery, early surgery can also reduce the risk of secondary knee injury, and even in some patients who have had a ligament rupture for more than 10 years and have bone spurs in the knee joint, ACL reconstruction surgery can be valuable. In elderly patients without significant joint instability, surgery is not recommended; patients who have had a ligament rupture for many years, with very severe cartilage damage and deformed joints, are not the best candidates for ligament reconstruction surgery either.