Correlation Between the Posterior Tibial Slope, Proximal Tibial Angle, Distal Femoral Angle, and Femoral Intercondylar Notch Morphology and Posterior Cruciate Ligament Injury

Background : Posterior cruciate ligament (PCL) injury is one of the common sports-related injuries of the knee joint, often leading to instability, pain, and functional impairment of the knee. In recent years, studies have found that certain anatomical factors, such as the posterior tibial slope angle and the morphology of the femoral intercondylar notch, are correlated with the occurrence of PCL injury. However, systematic research on the correlation between these factors and PCL injury is still limited, and there is currently no definitive or unified conclusion. Moreover, the potential correlation between the proximal tibial angle and the distal femoral angle with PCL injury remains an unexplored area. Purpose ：The aim of this study was to investigate the exact correlation between the posterior tibial slope angle and femoral intercondylar notch morphology with PCL injury by quantifying relevant anatomical indices. Additionally, this study further explored the correlation between the proximal tibial angle and the distal femoral angle with PCL injury, in order to provide a theoretical basis for the clinical early identification of high-risk populations for PCL injury and the development of personalized treatment plans. Methods : This study employed a retrospective analysis method, including patients who visited our hospital due to knee injuries from 2021 to 2024 and were diagnosed with isolated PCL injury via MRI. All patients underwent reconstruction surgery under knee arthroscopy. Meanwhile, patients without PCL injury during the same period were selected as the control group. Through imaging, the posterior tibial slope angle, proximal tibial angle, distal femoral angle, and the width, height, and angle of the femoral intercondylar notch were measured and assessed in both the case and control groups. Subsequently, univariate and multivariate logistic regression analyses, as well as other correlation analysis methods, were used to statistically analyze the correlation between each anatomical index and PCL injury, in order to clarify their potential associations. Results : This study included a total of 169 participants, comprising 80 patients with isolated PCL injury (case group) accounting for 47.34%, and 89 controls without PCL injury accounting for 52.66%. There were no statistically significant differences between the two groups in terms of age, gender, BMI, or side affected (P > 0.05), indicating comparability between the groups. In terms of anatomical parameter measurements, the mean posterior tibial slope angle in the PCL injury group was 7.81 ± 3.59°, significantly lower than that in the control group was 11.06 ± 4.07° (t = 5.46, P < 0.001). Additionally, the femoral intercondylar angle was significantly smaller in the case group compared with the control group (Z = -2.40, P < 0.05). However, no statistically significant differences were observed between the two groups in bicondylar width, intercondylar notch width index (NWI), intercondylar notch depth, intercondylar notch width, proximal tibial angle, or distal femoral angle (P > 0.05).Further ROC curve analysis revealed that a posterior tibial slope angle of ≤6.5° had predictive value for PCL injury, with an AUC of 0.734 (95% CI: 0.659–0.809), sensitivity of 43.8%, and specificity of 92.1%. Moreover, a femoral intercondylar angle of ≤49.5° also had some predictive value for PCL injury, with an AUC of 0.607 (95% CI: 0.522–0.693), sensitivity of 50%, and specificity of 69.7%. Conclusion : Compared with the control group, the posterior tibial slope angle and femoral intercondylar angle were significantly decreased in the PCL injury group. The risk of PCL injury was significantly increased when the posterior tibial slope angle was ≤6.5° and the femoral intercondylar angle was ≤49.5°. Therefore, corresponding preventive and intervention plans should be developed for these factors to reduce the incidence of PCL injury.