1.Data and Methods 1.1 Clinical data The data were selected from 24 patients with ACL injury admitted to our hospital between August 2004 and January 2009.All the cases were diagnosed before surgery and were selected for ACL reconstruction with autograft or artificial ligament according to the indications of LARS ligament use, combined with doctors’ recommendation and patients’ wishes. All cases were diagnosed before surgery, and according to the indications for the use of LARS ligament, combined with the doctor’s recommendation and the patients’ wishes, they chose to have ACL reconstruction with autograft or artificial ligament.There were 11 cases in the LARS artificial ligament group. There were 11 cases in the LARS artificial ligament group. 10 cases were male and 1 case was female; age ranged from 25 to 52 years old, and the average age was 39.5 years old. ACL reconstruction with two semitendinosus-femoral thin tendon (ST-G) was used as a control group for the same period of time, and there were 13 cases in total. There were 10 males and 3 females, aged 19-55 years, with a mean age of 36.7 years. All of them had car accident injuries (14 cases) and sports injuries (10 cases). 1.2 Indications of LARS ligament surgery Young patients with acute-phase injuries, especially athletes who want to return to the sports field as soon as possible; elderly patients who want to regain the ability to play sports (except osteoporosis and osteoarthritis patients); professional athletes with chronic injuries who want to continue their sports careers; autologous or allogeneic material transplantation failed cases; and those who have the ability to pay for the rapid recovery. 1.3 Surgical methods (LARS ligament cases) 1.3.1 Treatment of intra-articular ligament remnants Unlike traditional ACL reconstruction, LARS ligament reconstruction needs to preserve the length of the cruciate ligament remnants or the synovial structure outside the ligament as much as possible. 1.3.2 Establishment of tibial bone channel ACL tibial bone locator positioning, take the guide pin through the locator positioning, withdraw the locator, LARS special flat head hollow drill (7.5mm diameter) along the guide pin to drill out the bone channel and clean the bone channel. 1.3.3 Establishment of femoral bone channel The ACL femoral bone locator was positioned in the reverse direction through the tibial tunnel, and the ligament equidistant point was searched for at the femoral end of the ligament, and the guiding needle was positioned in the reverse direction to open up the femur, and the femur was pierced out subcutaneously, and the locator was withdrawn, and the skin of the lateral thigh was incised along the guiding needle, and the LARS special 3-layer trocars were inserted in order to separate the soft tissues. The LARS flat head hollow drill (7.5mm diameter) was used to drill along the guiding needle from the outside inward toward the joint cavity to establish the femoral channel and clean the channel, and the channel guiding cannula was placed along the guiding needle. 1.3.4 Ligament installation The LARS guide wire was inserted through the guide cannula from the femoral tunnel, and then from the tibial tunnel, and the LARS artificial ligament was pulled out of the bone canal from the bottom up. Under direct arthroscopic vision, the length of the free fibers of the ligament in the joint cavity was adjusted, and the fibers of the artificial ligament were rotated outward to adjust the degree of rotation of the free fibers. The femoral end was fixed with LARS titanium screws from the outside to the inside, the artificial ligament was tightened, the knee joint was extended and flexed for 20 times to adjust the ligament tension evenly, the knee was flexed at 90°, and the tibial end was fixed with the titanium screws extruded. Cut the residual artificial ligament with a blade for the tibial end and a LARS ligament cutter for the femoral end. 1.4 Rehabilitation program 1.4.1 The LARS artificial ligament group carried out the quadriceps functional exercise as early as possible after the operation; 2 weeks of wearing a brace to support the crutches to walk with weight; 1 week after the operation, the flexion of the knee joint reaches 90 degrees; the fourth week after the operation, the patient can resume the office work; 4 weeks to 2 months after the operation to gradually resume the daily activities, 2 months after the operation can be riding a bicycle; 2-4 months after the operation to resume the movement, and began to trot or jogging. 1.4.2 In the autologous tendon transplantation group, on the first postoperative day, ankle pump exercise was performed, and isometric contraction of quadriceps muscle in knee-extension position was performed; from 1 to 4 weeks, weight-bearing walking with crutches was performed; from 3d to 1 week after the operation, knee flexion was up to 90°; on the fourth postoperative week, the patients could return to the office work; from 4 weeks to 6 months after the operation, they could resume their daily activities, and could ride a bicycle after 4 months; from 6 to 8 months after the operation, they resumed their exercise and started trotting or jogging. 1.5 The average follow-up time after surgery was 15 months (6-30 months). The postoperative time of each patient was recorded as the time of getting down from the floor with the help of crutches, the time of walking with the help of crutches, the time of resumption of exercise, and whether there was any postoperative knee joint effusion, swelling, or pain and discomfort. Joint laxity was evaluated by KT-2000. The Lysholm score, Tegner, and IKDC scores of the perioperative patients were recorded during the follow-up period, including the preoperative period and 3, 6, and 12 months after the operation, for three times.