Patients with cruciate ligament tears usually cannot heal themselves, as follows. A partial tear of the cruciate ligament, with only a small portion of the ligament attached, also cannot heal itself, and the partially ruptured part of the ligament will atrophy and be absorbed by the body, and the joint stability will decrease, so surgery is required. A complete tear of the cruciate ligament, in which the severed end of the ligament detaches, cannot heal itself without contact and can only be reconstructed surgically. Therefore, after the patient tears the cruciate ligament, even with conservative treatment, it will not heal itself, and only the joint pain and swelling symptoms will be relieved, and the joint function cannot be guaranteed, so surgery is needed. After the surgical treatment, rehabilitation training is needed to restore the stability and range of motion of the joint, as well as to restore the strength and power of the muscles.