OBJECTIVE: To investigate 75 cases of anterior and posterior cruciate ligament injuries after arthroscopic application of LARS artificial ligament separately or simultaneously 18 cases of anterior and posterior cruciate ligament injuries were reconstructed when LARS artificial ligament was used as the reconstruction material. Postoperative follow-up ranged from 10 to 42 months, and the function of the affected knee was assessed using the International Knee Documentation Committee Ligament Criteria Evaluation Scale (IKDC) and the Lysholm Knee Function Scale, and anterior and posterior knee laxity was examined by KT-1000. RESULTS: Reconstruction of the anterior cruciate ligament, posterior cruciate ligament, and both anterior and posterior cruciate ligaments resulted in statistically significant differences between the preoperative Lysholm knee function scores and IKDC scores and postoperative scores in all patients. Conclusion: Arthroscopic application of LARS artificial ligament to reconstruct anterior cruciate or posterior cruciate ligament, or both anterior and posterior cruciate ligaments of the knee, is a minimally invasive, safe and effective surgical method for the treatment of knee cruciate ligament injury with good recent efficacy. From August 2004 to April 2007, 37 cases of anterior cruciate ligament injury were treated, of which 27 were male and 10 were female; 17 were left knee and 20 were right knee; 20 cases of posterior cruciate ligament injury were treated, of which 16 were male and 4 were female; 9 were left knee and 11 were right knee. 18 cases of simultaneous anterior and posterior cruciate ligament injury were treated, of which 16 were male and 2 were female; 5 were left knee and 2 were right knee. There were 18 cases of simultaneous anterior and posterior cruciate ligament injuries, 16 in men and 2 in women; 5 in the left knee and 13 in the right. In all knee cruciate ligament injuries, the age ranged from 17 to 48 years old, with an average of 27.5 years old; the mechanism of injury: 15 cases of car accidents, 9 cases of heavy object crushing injuries, and 51 cases of sports injuries. All patients were diagnosed with anterior or posterior cruciate ligament injury, or both anterior and posterior cruciate ligaments, by MRI examination and physical examination before surgery. The postoperative follow-up ranged from 10 to 42 months, with an average of 29.4 months. 2. Surgical methods: (1) Reconstruction of the anterior cruciate ligament Establishment of tibial bone tract: ACL with tibial locator. Accessed through an anteromedial (AM) incision, the apical bulb is placed against the posterior cruciate ligament and the tip is placed on the tibial spine. The tip of the guide rod is placed 2 cm medial to the tibial tuberosity, and an incision of approximately 5 mm in length is made to place the locator, and the Kirschner needle is passed through the guide rod into the joint cavity to form the bone tract, the locator is withdrawn, and the bone tract is formed and cleaned with an electric drill. Creation of the femoral osseous tract: The radius is calculated using a femoral locator with a 140 degree arc of the condyle. The tip is hooked at the highest point of the posterior aspect of the femoral epicondyle through the AM incision into the joint cavity, and then the locator is adjusted to the calculated radius value. A Kirschner needle is taken through the locator to penetrate the femur from the anterolateral aspect of the femur. The locator is removed, an incision is made in the anterolateral thigh skin, and the trocar is inserted in a small to large set outside the keratoplasty needle, and a drill is used from the lateral thigh to form the femoral bone channel along the keratoplasty needle into the joint cavity and clean the bone channel. The femoral and tibial osteochannels were passed through a long catheter in the knee in the flexed position, and a guide wire was used to guide the LARS artificial ligament through, so that the free fiber portion of the artificial ligament entered the osteochannel by 1 mm at each end. the artificial ligament was moderately externally rotated, and the degree of rotation of the free fiber was adjusted to make it loose and tight to facilitate the growth of autologous tissue. The screws were fixed in the tibiofemoral tract [1]. (2) Reconstruction of the posterior cruciate ligament The tibiofemoral tract was established: a tibial locator with an elbow entered through the AM incision and extended along the posterior aspect of the anterior cruciate ligament to the posterior aspect of the tibia via the posterior cruciate ligament above, with the tip 1 to 2 cm below the tibial plateau. the guide bar was parallel to the tibial plateau, and a Kirschner pin was inserted into the guide bar and tapped into the bone for fixation. A skin incision is made anterior to the calf and the LARS tip drill is inserted through the accessory hole and drilled into the tibial bone tract. the LARS guide wire is passed through the bone tract in the guide bar and out through the locator end. The locator is removed and the guide wire is passed through the anterior calf skin incision into the bone tract and out through the AM incision via the articular cavity. Establishment of the femoral osseous tract: The anterolateral femoral bundle localization point is located 1.5 cm medial to the midline of the intercondylar groove and 1 cm posterior to the articular surface. The localization point of the posterior medial femoral bundle was located 1.5 cm medial to the midline of the intercondylar groove and 1 cm posterior to the articular surface 1 cm anteriorly, and was penetrated through the anterolateral (AL) incision with a Kirschner needle at each of the two localization points of the posterior cruciate ligament of the medial femoral condyle. A LARS 6mm caliber flat-tipped drill was selected to drill the femoral bone tract along the Kirschner needle, and a skin incision was made at the corresponding site on the medial thigh. A catheter was placed from the skin incision into the femoral tract (note that the catheter should not be inserted into the joint cavity to avoid tissue damage), and the guide wire was passed through the femoral tract via the catheter and passed out of the AM incision under the arthroscope. The LARS artificial ligament was fixed in the same way as the anterior cruciate ligament reconstruction [2, 3]. (3) Simultaneous reconstruction of anterior and posterior cruciate ligaments If the anterior and posterior cruciate ligaments are reconstructed simultaneously under arthroscopy, the posterior cruciate ligament should be reconstructed first, and it should be noted that the tension of the posterior cruciate ligament cannot act on the anterior cruciate ligament. Therefore, it is important not to overdo it when correcting posterior tibial dislocation, which leads to overkill [4]. Before performing posterior cruciate ligament tibial end fixation, it is important to confirm that the posterior edge of the femoral condyle is not anterior to the posterior edge of the tibial plateau when the knee is flexed at 90°. The use of fluoroscopy or intraoperative radiographs may be considered to ensure that the two condyles overlap. A line parallel to the posterior tibial cortex is drawn from the posterior edge of the femoral condyle. If the tibial plateau is anterior to this line, the posterior cruciate ligament tension must be relaxed and this line should be flush with the posterior edge of the tibial plateau, which can then be fixed. The anterior cruciate ligament can be reconstructed only if the posterior cruciate ligament is reconstructed and the knee has returned to its central position. 3. Postoperative management and rehabilitation Postoperative management: routine anti-inflammatory, rehydration and swelling treatment for 3 to 5 days. Start functional exercise after anesthesia awakening. Firstly, encourage patients to start isometric contraction of lower limb muscles. Straight leg raising exercise was started around the 3rd day after surgery to strengthen the quadriceps muscle strength, 150 to 200 times per day. Active flexion and extension exercises were performed 2 to 3 weeks after surgery, and after two weeks, walking with the help of crutches, partial weight-bearing, and strengthening of resistance ankle plantarflexion or forefoot standing exercises. After 4 weeks postoperatively, the native sensation of the limb can be gradually restored by riding a stationary bicycle, and after 4 to 6 weeks, the patient can walk with full weight-bearing under the crutches. 2 to 3 months later, the patient can continue to exercise to increase the stability of the knee joint, while continuing to enhance resistance muscle training and native sensation training, and at the same time, he can carry out daily work, life, and even resume general sports. For patients with special occupations such as athletes, competitive sports can be performed gradually after four months postoperatively, depending on the postoperative recovery [5]. 4. Follow-up 69 of 75 patients were followed up, with 3 cases lost in the ACL group, 2 cases lost in the posterior cruciate ligament group, and 1 case lost in the anterior-posterior cruciate ligament group. The patients were followed up for 10 to 42 months after surgery to find out the symptoms of the affected knee, knee mobility and stability, the degree of functional limitation of the knee during daily activities and sports, and the changes in mobility after surgery. The International Knee Documentation Committee Ligament Criteria Evaluation Scale (IKDC) and Lysholm Knee Function Rating Scale were used to assess the function of the affected knee, and anterior and posterior knee laxity was examined by KT-1000. 5. Statistical analysis The data data in the study were expressed as ＋S The SPSS10.0 statistical software was applied for statistical analysis, and the paired t-test was used for measurement data, and the chi-square test was used for count data. II. Results ACL group: all patients had disappearance of knee instability symptoms, negative anterior drawer test, good joint function, and extension and flexion of O0 to (120±4.45). According to the Lysholm knee score method, the mean score improved from (44.6±1.36) preoperatively to (82.8±2.46) postoperatively, and the difference between the two was significant (t test t=2.882 P