The Biomechanical Evaluation of Plate Matching and Ideal Screw Trajectories on Internal Fixation of Tibial Plateau Fractures: A Finite Element Analysis

Abstract

This study was aimed to compare the biomechanical characteristics between the personalized plate system and the existing plate system in the internal fixation of tibial plateau fractures, and to explore the biomechanical advantages of the personalized plate system with matching plate and optimized screw trajectories in the internal fixation of tibial plateau fractures. Schatzker classification I tibial plateau fractures were reconstructed using Unigraphics NX 8.5 software. Four groups of finite element models of Schatzker classification I tibial plateau fractures were simulated. Four kinds of implants were instrumented into the models, including the locking plate with mismatched anatomical shape and non-optimized screw trajectories (group A), the locking plate with mismatched anatomical shape but optimized screw trajectories (group B), the locking plate with matched anatomical shape but non-optimized screw trajectories (group C), and the locking plate with matched anatomical shape and optimized screw trajectories (group D). Loads of compression, rotation and varus-valgus were applied to a reference point coupled of the articular surface of tibial plateau. The biomechanical properties of different fixation methods contain deformation and stress index were compared to explore the influence of matching plate and optimized screw trajectories. As shown in the results, the three improved internal fixation groups (Group B, C and D) can effectively reduce the displacement of internal fixation and fracture end. Compared with group A, the reduction rates of deformation comprehensive index in group B, group C and group D were 0.94%, 0.22%, and 3.23%, respectively, the effect of reducing displacement in group D was the most obvious. On the contrary, the change rates of stress comprehensive index in the improved groups(Group B, C and D) were higher than group A, but the stresses increase were within the safe range. Compared with group A, the increase rates of stress comprehensive index in group B, group C and group D were 115.27%%, 32.77%, and 58.89%, respectively. The stress increase rate of group C was the lowest, followed by Group D. Base on the above results, we believe that matched plate and optimized screw trajectories group can obtain better fixation effect. Combined with the comprehensive stress and deformation index, it can be seen that the fixation effect is the best when plate matching and screw trajectories optimization for the Schatzker classification I tibial plateau fractures. And the influence of screw factor is more important than anatomical matching plate.