The spatial three-dimensional positional relationship between the posterior cruciate ligament tibial insertion and the posterior septum: an anatomical study

Background: The posterior cruciate ligament (PCL) tibial insertion and posterior septum are important factors affecting the success rate of posterior cruciate ligament reconstruction(PCLR). The purpose of this study was to accurately quantify the anatomical features and relationship of the PCL tibial insertion and posterior septum. Methods Twelve cadaveric human knees were dissected to investigate the PCL and posterior septum. First, the anatomical localization of the PCL, tibial insertion and posterior septum were observed from the medial and lateral sides of the knee joint using a U-shaped capsulotomy. Second, the border length and insertion of the PCL tibial insertion were measured with a soft ruler, and a tibial tunnel was created within the anatomical footprint of the PCL while preserving the integrity of the posterior septum, and the ratio of tunnel exit to PCL tibial insertion was calculated. Finally, HE staining was performed to evaluation the blood vessels content in the posterior septum. Results The PCL and its tibial insertion were located medial to the posterior septum in all specimens, and the inferior border of the inserion is adjacent to the posterior capsule reflexion and above the shipboard-like structure. The PCL tibial insertion had a right-angle trapezoidal-like structure with narrow superior and wide inferior sides. The superior and inferior sides of the insertion were approximately (8.8 ± 1.7) and (13.4 ± 3.2) mm, respectively, and the medial and lateral sides were approximately (11.5 ± 1.2) and (12.1 ± 0.3) mm, with an area of approximately (123.3 ± 31.4) mm². Compared to the posterior capsule, the posterior septum contained abundant blood vessels. Conclusion The PCL in the posterior compartment of the knee follows the posterior septum and is located entirely medial to the posterior septum, and the inferior border of the PCL tibial inserion is adjacent to the posterior capsule reflexion and above the shipboard-like structure. It is feasible to create an effective tibial tunnel within the tibial footprint of the PCL while preserving the posterior septum.