The pivotal role of the coronal fracture line for a new three-dimensional CT-based fracture classification of bicondylar proximal tibial fractures

Classical fracture classifications (AO/OTA, Schatzker) are commonly used to characterize bicondylar proximal tibial fractures. However, none of these classifications allows for a treatment algorithm. The aim of our study was to use 3D appearance of these fractures in CT imaging to improve the clinical value of the classification. 3D appearance of 81 CT scans of bicondylar proximal tibial fractures were systematically analyzed and were classified in 3 subtypes, based on the fracture lines orientation. The novel classification was compared for reliability and for clinical relevance with AO and Schatzker classification. A total of 159 fracture lines were identified which were most frequently oriented in sagittal (89/159), and in coronal (41/159) direction. Based on the orientation of the major fracture lines three fracture types were defined. A special emphasis was drawn to the coronal fracture line of the medial plateau leading to a surgical treatment algorithm. Interobserver reliability was analyzed for all 81 patients resulting in an excellent reliability of К=0.936 for the 3D classification scheme compared to К=0.720 for the AO/OTA, К=0.785 for the Schatzker classification. Correlations with clinical parameters were only observed for the 3D classification. The presented classification scheme based on the 3D geometry of bicondylar proximal tibial fractures demonstrates a good reliability of clinical relevance.