Anatomical risk factor analysis of posterior cruciate ligament tibial avulsion fracture in adults

Abstract

BACKGROUND: The anatomical morphology of the distal femur and proximal tibia has an important influence on the movement of the tibiofemoral joint, and its role in anterior cruciate ligament injury has been well described. However, the research on the anatomical risk factors of posterior cruciate ligament tibial avulsion fracture is still limited, and no unified consensus has been formed. OBJECTIVE: To investigate the anatomical risk factors for posterior cruciate ligament tibial avulsion fracture. METHODS: The medical records of 53 patients who underwent surgical treatment for posterior cruciate ligament tibial avulsion fracture from March 2021 to September 2024 were retrospectively collected as the posterior cruciate ligament avulsion group (32 males and 21 females), and the data of 53 subjects without posterior cruciate ligament injury in the same period were included as the posterior cruciate ligament normal group (24 males and 29 females). The intercondylar notch width, femoral condyle width, intercondylar notch width index, intercondylar notch height, intercondylar notch shape index, intercondylar notch angle, Blumensaat's line inclination angle, medial tibial posterior slope, and lateral tibial posterior slope were measured and calculated in Magnetic Resonance Imaging to analyze the differences in the anatomical data of the two groups. Binary logistic regression analysis was used to determine the independent risk factors and to establish a risk factor model by receiver operating characteristic curve. RESULTS AND CONCLUSION: (1) The intercondylar notch width index, intercondylar notch shape index, intercondylar notch angle, and medial tibial posterior slope in the posterior cruciate ligament avulsion group were significantly smaller than those in the posterior cruciate ligament normal group (P < 0.05); there were no significant differences in intercondylar notch width, femoral condyle width, intercondylar notch height, Blumensaat's line inclination angle, and lateral tibial posterior slope between the two groups (P > 0.05). (2) Binary logistic regression found that intercondylar notch width index was associated with posterior cruciate ligament tibial avulsion fracture. (3) It is suggested that compared with those with normal posterior cruciate ligament, patients with posterior cruciate ligament tibial avulsion fracture have smaller intercondylar notch width index, intercondylar notch shape index, intercondylar notch angle, and medial tibial posterior slope; intercondylar notch width index is an independent risk factor for posterior cruciate ligament tibial avulsion fracture.

1. Introduction

The posterior cruciate ligament (PCL) originates from the lateral aspect of the medial femoral condyle, passes through the intercondylar notch, and inserts on the posterior aspect of the tibial plateau. It is a crucial structure for maintaining knee stability, being twice as strong as the anterior cruciate ligament (ACL), and it limits excessive posterior translation of the tibia during knee flexion [1-2]. PCL injuries account for 3%-20% of all knee injuries, and PCL tibial avulsion fracture is a specific type of PCL injury [3]. If not promptly diagnosed and treated, it can lead to subsequent meniscal, cartilage, and arthritic changes [4-6]. When the proximal tibia is subjected to direct posterior force or knee hyperextension, the PCL tension exceeds its tolerance, resulting in PCL injury or even avulsion of the bony attachment [7-8].

Among the potential risk factors for PCL tibial avulsion fracture, the anatomical morphology of the intercondylar notch and tibial plateau remains controversial. Van Kuijk et al. [5] used X-ray to establish a knee anatomical model and found that patients with PCL injury had a narrower and sharper intercondylar notch and a flatter tibial eminence. Conversely, Liu et al. [9] concluded based on MRI that a narrow intercondylar notch does not lead to PCL injury. The proximal tibia is equally important for maintaining tibiofemoral joint stability. Previous studies have shown that the tibial posterior slope is associated with ACL and PCL injuries. During movement, an increased tibial posterior slope increases the risk of ACL injury [10-11]. In contrast, a larger tibial posterior slope effectively limits posterior tibial translation, while a decreased slope increases PCL stress and the risk of PCL injury [12-14].

The anatomical morphology of the distal femur and proximal tibia significantly influences tibiofemoral joint motion, and its role in ACL injury has been well described. However, research on the anatomical risk factors for PCL tibial avulsion fracture is still limited, and no unified consensus has been reached [15-16]. Therefore, this study aims to investigate the anatomical risk factors for PCL tibial avulsion fracture, including intercondylar notch width, femoral condyle width, intercondylar notch width index (NWI), intercondylar notch height, intercondylar notch shape index, intercondylar notch angle, Blumensaat's line inclination angle, medial tibial posterior slope, and lateral tibial posterior slope.