Abstract:Abstract: Objective?To evaluate the application of 3D printing technology printed the knee joint model to assist the arthroscopic reconstruction of the anterior cruciate ligament, and find the optimal region for the reconstruction of the femoral tunnel.?Methods?30 patients who were diagnosed as “anterior cruciate ligament injury” by clinical physical examination, MRI examination and knee arthroscopy from June 2018 to February 2019. The knee joint was cleaned and three-dimensional reconstruction was performed. The knee joint model was established and the femur and tibia in the model were established and make 3D printing. The whole model was firmly placed on the lower limb continuous passive motion training machine, from 0° to the 120° flexion position, and the reading in the displacement sensor display was observed by its movement every 10° to calculate the length change.?Results?The change in length measured at point A was (9.70 ± 0.66) mm, the coefficient of variation was 2.13, the change in length measured at point B was (8.86 ± 1.45) mm, the coefficient of variation was 3.98, and the change in length of point C was (8.90 ± 1.27) mm, the coefficient of variation is 3.75, the length of the D point is (9.40 ± 0.62) mm, the coefficient of variation is 2.04, the length of the E point is (9.90 ± 0.65) mm, and the coefficient of variation is 2.14.?Conclusion?For the measurement of 30 different tunnels of knee joints in patients with anterior cruciate ligament injury, we found that the triangles surrounded by the three points A, D and E are the isometric length of the articular anterior cruciate ligament based on the consensus of the tibial tunnel. The arthroscopic reconstruction of the anterior cruciate ligament in the area surrounded by the three points can achieve the isometric length and is an optimal area for surgical reconstruction.