Newly Designed Plates For Lateral Tibial Plateau Fracture And Its Finite Element Analysis

BACKGROUND: Tibial plateau fractures,one intra-articular fracture,are of great challenge to treat.This study aimed to evaluate the morphological characteristics of tibial plateau fractures based on the Schatzker classification.Then the plate-screw models for lateral tibia plateau were designed according to the morphological characteristics and the“Rafting” theories with further study if the novel plates can provide sufficient fixation strength for lateral tibial plateau fracture.METHOD: The retrospective study reviewed a total 186 cases of tibial plateau fractures in Xinhua Hospital.The morphologic characteristics of different Schatzker types of tibial plateau fractures was clarified based on CT scanning and three-dimensional(3D)reconstruction by measuring the fracture line angles(FLA),mapping the most common zones of depression,and measuring the depression depth.Then the plate-screw models for lateral tibia plateau were designed according to the morphological characteristics.And the fracture models were created according to fracture line angle(FLA).The plate-screw systems were then placed in the right place simulating fracture fixation models for finite element analysis(FEA).RESULT: Schatzker type I and II fractures had three morphological subtypes respectively: single anterolateral fracture,single posterolateral fracture,and complex fracture(the anterolateral and posterolateral complex).Schatzker type IV fractures were also divided into three subtypes: single posteromedial fracture,single anteromedial fracture,and the whole medial plateau fracture.For various Schatzker types and subtypes of fracture,fracture depression clustered and occurred at different locations of the tibial plateau.A significant difference was observed in the depression depth among the different Schatzker types(P < 0.01),especially between Schatzker type III and other types.There was no difference in the depression depth among the subtypes of Schatzker type II,whereas the difference was significant between the two subtypes of Schatzker type IV.The maximum RDs achieved in the present study were far below 2 mm.In all the tests,the maximum von Mises stress of the implants was 53.240 MPa,which was far smaller than the maximum resistance of 795 MPa.The displacement and stresses in the fixation complexes increased with the axial force.The equivalent displacement or stress map of each fixation under different axial forces showed similar distributing characteristics.The motion characteristics of the three models differed,and the max-shear stress of trabecula increased with the axial load.CONCLUSION: Schatzker type I,II,and IV fractures could be divided into three corresponding subtypes by FLA.The location and depression depth of different Schatzker types of fractures were highly variable.Proper preoperative planning,operative approach,and fixation method should be selected based on the morphological characteristics of individual types of plateau fractures.The two novel plates developed in the present study can fix well lateral tibial plateau fractures involving anterolateral fragment and posterolateral fragments.Motions after ORIF should be advised to decrease the risk of trabecular microfracture.