To observe the clinical efficacy of arthroscopic reconstruction of the anterior cruciate ligament of the knee by applying Transfix fixation on the femoral side and Interference screw on the tibial side combined with portal nail fixation of the autologous N cord tendon or allograft tendon. Rupture of the anterior cruciate ligament (ACL) is a common knee injury, and arthroscopic ACL reconstruction is now a routine procedure with proven efficacy. The choice of graft and fixation method during surgery is an important factor affecting the prognosis. As the two most commonly used ligament grafts in clinical practice, the autologous doubledsemitendinosusandgracilis tendon (DSTG) has early healing, easy access, no immune response, and has been shown to have better mechanical properties than normal ACL and bone-patellar tendon Bone has better mechanical properties than normal ACL and bone-patellar tendon; while allograft tendon has the advantages of sufficient source, no donor complications and short operation time. Recent improvements in graft fixation methods and materials have also improved the success rate of ACL reconstruction using the N cord tendon. In patients with ACL rupture of the knee, single bundle reconstruction of the ACL was performed using the resorbable femoral transverse nail (Bio-Transfix) and resorbable tibial interface screw (Bio-Interference) combined with portal nail provided by ARTHREX, USA, in which good recent results were achieved using autologous DSTG and allograft tendons. The development of tendon fixation techniques in the past 10 years, especially the application of femoral transverse nail fixation and tibial end interface screw combined with portal nail fixation, has improved the success rate of ACL reconstruction surgery with N cord tendon graft; meanwhile, because the four semitendinosus and thin femoral tendons have similar elastic modulus to ACL, their strength is about 250%-300% of normal ACL, and they have certain advantages in restoring knee joint stability. advantages. Therefore, the N cord tendon is gradually becoming the first choice for grafts in most ACL reconstructive surgeries. However, some postoperative complications, such as knee laxity, bone tunnel enlargement, and fixation failure, have also occurred. In the present group of cases, 2-4 mm intercondylar fossa enlargement was performed during ACL reconstruction surgery, which facilitated the observation of the true posterior margin of the intercondylar fossa, thus avoiding surgical failure due to inaccurate positioning of the femoral end, and no postoperative injury of the intercondylar fossa with graft impingement was observed during the postoperative follow-up. No significant increase in postoperative bleeding was observed due to the effective hemostasis of the cancellous bone surface after shaping. Studies on tendon bone healing showed that:3 months postoperatively, the tendon bone contact area was osteolysed and replaced by fibrovascular tissue, and the lamellar bone was partially covered by uncalcified bone-like tissue to stimulate ligamentous fixation; 6 months postoperatively, the fibrous interface was continuously covered by bone-like tissue contact and Sharpey fibers were formed; 10 months postoperatively, the healing process reached maturity; thus, the time to tendon bone healing was determined to be 10 to 12 months. Therefore, 3, 6, and 12 months postoperatively were used as important time points to guide rehabilitation exercises. Until the tendon graft heals with the bone tract and develops sufficient strength, the most important factor determining joint stability is the fixation technique of the graft rather than the graft itself. Currently, in ACL reconstructive surgery with the N-cord tendon as the graft, the tibial side is mostly fixed in the tract with absorbable or titanium interface screws, and the tendon ends are reinforced outside the tract with portal nails or screw washers; on the femoral side, different surgeons have different options, and the main methods of fixation include cross-over nails, interface screws, button plates, and suture pins. GiuseppeMilano et al. chose different fixation methods on porcine knee specimens: interface screws (Bioscrew), expansion fixation (Rigidfix), extracortical suspension fixation (EndoButton-CL), and transverse nail suspension fixation (TransfixandBio-Transfix), and performed a biomechanical device on The reliability of lateral femoral fixation with the transverse nail was confirmed by the comparison of 1000 cycles of loading tests, which showed that the transverse nail was significantly higher than the other groups in terms of maximum breaking load force as well as fixation strength and stiffness. In terms of safety, NicolasPujol et al. applied a transverse penetrating nail (TransFix) to 20 freshly frozen cadaveric knees through the tibial tunnel (GroupI) and the anteromedial knee approach (GroupII) to position and drive the transverse nail, respectively. Postoperative anatomic comparison revealed no medically induced injury in GroupI, whereas GroupII showed lateral collateral knee ligament (LCL) injury in half of the cases, and the mean length of the transverse nail entry point from the LCL was significantly less than that of GroupI. Therefore, insertion of a femoral locator through the tibial tunnel to shape the bone tunnel and position the transverse nail is recommended, which is consistent with the present surgical approach. Although lateral femoral transverse nail fixation is a reliable and safe fixation technique, there are still some specific intraoperative complications, and YongSeukLee et al. reported that during the vertical pulling of the four femoral tendons into the femoral bone tunnel using a steel guide wire, the tendons could not be fully entered due to excessive resistance of the bone tunnel, resulting in the rupture of the tendons or the guide wire when the transverse nail was inserted, so it is recommended that Nam-HongChoi et al. reported a case in which the tendon of four strands was pulled vertically into the femoral tunnel using a steel guidewire and the guidewire was crossed and twisted, resulting in a rupture of the cut tendon during the final stage of guidewire tensioning. It is recommended that the braided sutures at both ends of the tendon be tightened with uniform force during the final stage of guide wire tensioning, even under arthroscopic surveillance. MichailKokkinakis et al. reported three cases of iliotibial bundle friction syndrome due to protrusion of the tail of a transverse nail, which disappeared after removal of the tail of the transverse nail with a firm tendon-bone union, thus emphasizing the importance of using the scale on the transverse nail percussion device to confirm the depth of nail insertion and of using the finger to touch the tail of the nail to determine the burial depth. This emphasizes the importance of using the scale on the transverse nail strikers to confirm the depth of nail entry and touching the nail tail with the finger to determine the burial into the bone cortex. The authors’ experience was to use an intraoperative arthroscopic lens to slide along the steel guide wire and directly observe whether the tail of the nail was buried in the bone cortex. In our group, 36 patients were selected for ACL reconstruction using allograft tendons, and no adverse effects such as infection and rejection occurred after surgery. Compared with patients using autologous tendons, there were no differences in Lachman test, ADT, IKDC and Lysholm scores, except for a shorter operative time, which is consistent with many previous reports in the literature. Also, animal experiments showed that there were no significant differences in the gross observations, histological examinations, and biomechanical tests between the allograft tendon and the autologous tendon before and at 2, 4, and 8 weeks after transplantation, indicating that the allograft tendon and the autologous tendon have similar structures and healing processes. Although arthroscopic allograft tendon reconstruction of knee ACL is effective and can avoid the complications associated with the extraction of autologous tendon, it should be selected according to the patient’s condition and subjective requirements because it increases the medical burden on the patient. Lateral femoral transverse nailing (Transfix) fixation and tibial lateral interface screws combined with portal nail fixation for single bundle reconstruction of the ACL of the knee have positive near-term efficacy, reliable graft fixation, and safe surgical operation. Reconstruction with both autologous and allogeneic tendons has good clinical results, but further follow-up is needed for medium- and long-term results.