A novel 3DCT-based classification for posterior cruciate ligament tibial avulsion fractures

Objective: The Meyers and McKeever (MM) classification is widely used for posterior cruciate ligament (PCL) tibial avulsion fractures; however, it fails to comprehensively reflect fracture characteristics and morphology due to its exclusive reliance on plain radiographs, which may result in suboptimal treatment decisions. Computed tomography (CT) scanning and three-dimensional computed tomography (3DCT) reconstruction can provide a more detailed visualization of articular fracture configurations, enabling the development of effective treatment strategies. Therefore, we developed a novel classification system for PCL tibial avulsion fractures based on fracture characteristics on 3DCT images, systematically evaluated and compared classification accuracy and reliability with the MM classification. Methods: Patients aged 18 years or older who underwent plain radiographs and CT examinations that confirmed PCL tibial avulsion fractures from June 2020 to Jan 2025 were included. A novel 3DCT-based classification system was established by considering three key fracture characteristics: fracture displacement degree, fracture line numbers, and fracture involvement regions. To verify the reliability and accuracy of the novel 3DCT-based and MM classification systems, intra- and inter-rater reliability assessments were performed. Additionally, the consistency and discrepancy in fracture patterns between the two classification systems were systematically described. Results: Ultimately, 53 patients (40 males and 13 females) with PCL tibial avulsion fractures were enrolled in the final study (mean age 42.9, range 22-65). The novel 3DCT-based classification system consisted of four principles and seven categories. The intra-rater reliability of the MM classification demonstrated substantial agreement, whereas the 3DCT-based classification exhibited perfect agreement. The inter-rater reliability of both classifications displayed substantial agreement, and the novel classification had higher reliability values. In addition, approximately 22.6% of non-displaced fracture types, along with some type II and III fractures identified through radiographs, exhibited differing fracture characteristics when evaluated using 3DCT. Conclusion: The novel 3DCT-based classification is more reliable, simplified, and intuitive than the MM classification. This novel classification system allows for a more accurate description of these fractures and reduces the risk of misdiagnosis based on radiographs. Additionally, it provides valuable guidance for preoperative planning and the selection of appropriate treatment strategies.