Two-dimensional and three-dimensional computed tomography for the classification and characterisation of tibial plateau fractures

Abstract

Background Complex tibial plateau fractures can be difficult to characterise on plain radiographs and two-dimensional computed tomography (2D CT). The present study evaluated whether three-dimensional computed tomography (3D CT) reconstructions can improve the reliability of complex tibial plateau fracture characterisation and classification. Methods Forty-five consecutive intra-articular fractures of the tibial plateau were evaluated by six independent observers for classification according to standard systems and for the presence of six characteristics: (1) posteromedial shear fracture; (2) coronal plane fracture; (3) lateral condylar impaction; (4) medial condylar impaction; (5) tibial spine involvement; and (6) separation of tibial tubercle necessitating fixation. Two rounds of characterisation and classification were performed: the first classification after a combination of plain radiographs and 2D CT and the second one after 3D CT information were added. Results 3D CT improved the average ‘inter’-observer reliability of the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) classification ( κ2D = 0.536, 95% confidence interval (CI): 0.481–0.591 vs. κ3D = 0.545, 95% CI: 0.478–0.612), the Hohl and Moore classification ( κ2D = 0.668, 95% CI: 0.605–0.732 vs. κ3D = 0.746, 95% CI: 0.605–0.732) and of the Schatzker classification ( κ2D = 0.545, 95% CI: 0.494–0.596 vs. κ3D = 0.596, 95% CI: 0.538–0.654). ‘Intra’-observer reliability also improved non-significantly for all systems after the addition of 3D CT for individual observers. 3D CT did improve the ‘intra’-observer reliability for the identification of the following fracture characteristics: coronal plane fracture (average κ2D = 0.700, interquartile range (IQR): 0.551–0.820 vs. average κ3D = 0.774, IQR: 0.692–0.847); lateral condylar impaction (average, κ2D = IQR: 0.675–0.901 to 1.000 vs. average, κ3D = 0.785, IQR 0.737–0.807); medial condylar impaction (average κ2D = 0.631, IQR: 0.537–0.670 vs. κ3D = 0.719, IQR: 0.679–0.895); tibial spine involvement average ( κ2D = 0.621, IQR 0.545–0.678 vs. average κ3D = 0.705, IQR: 0.652–0.794); separation of tibial tubercle necessitating fixation (average κ2D = 0.332, IQR: 0.080–0.574 vs. average κ3D = 0.441, IQR: 0.325–0.681). The only improvement that was found to be statistically significant was for recognition of medial condylar impaction as the IQR did not overlap. 3D CT had limited influence on average ‘inter’-observer reliability for the recognition of all specific fracture characteristics ( κ2D = 0.488 vs. κ3D = 0.485, both moderate agreement for all fracture characteristics) but showed a non-significant improvement of the recognition of coronal plane fractures (fair to moderate; κ2D = 0.398, 95% CI: 0.273–0.523 to κ3D = 0.418, 95% CI: 0.262–0.574) and recognition of impaction of the lateral condyle ( κ2D = 0.614, 95% CI: 0.467–0.760 to κ3D = 0.693, 95% CI: 0.538–0.849). Conclusions The added value of 3D CT after 2D CT is limited and does not significantly improve reliability of characterisation and classification of tibial plateau fractures.