During ACL reconstruction surgery, other tendons are needed to replace the ruptured ligament. So, what are such replacements? How should I choose? Currently, there are three types of ligament substitutes used for ACL reconstruction: autologous tendon, allograft tendon and artificial ligament. So, how to choose between the three alternatives: autologous tendon, allograft tendon and artificial ligament? Generally speaking, autologous tendon is mainly used as a substitute for ACL reconstruction surgery; allograft tendon is rarely used in China due to problems related to allograft rejection, sterilization and preservation, and organ donation; artificial ligament may be the future development trend, but at present, the surgical effect is not ideal due to technology and process level. Thus, autologous tendon is the most widely used graft in clinical practice. So, when using autologous tendon as a substitute in surgery, will the location being taken be affected? The answer is almost never. This is because when an autologous tendon is surgically taken, it is often a semitendinosus or thin femoral tendon from the N cord muscle (the N cord is a group of muscles rather than a single muscle). Half of the semitendinosus is tendon and the other half is muscle; the tendon is removed during surgery and there is still muscle to maintain normal function. In addition, a study found that 1 to 2 years after ACL reconstruction, a review of ultrasound and MRI can reveal that the removed semitendinosus tendon may also partially regenerate. Therefore, the function of the original site will not be affected too much. It is important to know that besides ACL reconstruction, many other surgeries also take the tendon here for treatment. In addition, in addition to the N cord tendon, other autologous tendons such as the patellar tendon and quadriceps tendon can also be used for ACL reconstruction surgery. However, due to the problems of secondary trauma associated with the use of other tendons, they are generally not preferred. Only when revision surgery is required, or when multiple ligament injuries are involved, should the use of other tendons be considered simultaneously. In other words, the N-cord tendon is currently the preferred tendon for ACL reconstruction. In addition, the use of single- or double-bundle reconstruction in ACL reconstruction is also a concern for patients. Theoretically, double-bundle reconstruction can indeed better restore the stability of the joint. However, the current clinical results and literature reports show that double-bundle reconstruction does not have obvious advantages, but rather increases the difficulty and prolongs the operation time, and even causes double the trauma and generates double the cost. Moreover, with the improvement of clinical surgical techniques and bone tract drilling methods, single-bundle reconstruction surgery can now also well ensure the rotational stability and anterior stability of the knee joint, and achieve good clinical results. Therefore, the mainstream method of ACL reconstruction surgery is still single-bundle reconstruction.