A Novel Design of a Plate for Posterolateral Tibial Plateau Fractures Through Traditional Anterolateral Approach

Biomechanical performance of a newly designed plate for treating posterolateral tibial plateau fractures was compared with three traditional internal fixation devices using finite element analysis (FEA) and biomechanical experiments. Forty synthetic tibias were used to create posterolateral shearing tibial fracture models, which were randomly assigned to groups A-D. The fragments were fixed with two 6.5-mm lag screws (group A), the newly designed plate (group B), a 3.5-mm lateral locking plate (group C), and a posterolateral buttress plate (group D). In the biomechanical experiment, vertical displacement of the posterolateral fragments was measured under axial loads of 500-1500 N. In the FEA, vertical displacement of the posterolateral fragments and stress distribution and maximum stress of each internal fixation were measured under axial loads of 250-750 N. Biomechanically, collective ranges of vertical displacements in the four groups were 0.356 +/- 0.089-1.055 +/- 0.023 mm at 500 N axial load, 0.651 +/- 0.062-1.525 +/- 0.03 mm at 1000 N, and 0.903 +/- 0.077-1.796 +/- 0.04 mm at 1500 N. Differences between the four groups were statistically significant (P < 0.05), except for groups B and C at 1500 N. FEA showed that collective ranges of vertical displacements in the four groups were 0.290-1.425 mm at of 250 N axial load, 0.580-1.680 mm at 500 N, 1.067-1.818 mm at 750 N. Maximum stress of groups A-D were, respectively, 321.940, 132.660, 100.383, and 321.940 MPa under 250 N axial load. Maximum stress of all four internal fixations increased, and the overall trends at 500 and 750 N were consistent with that at 250 N. Posterior, straight fixation was the most reliable. Fixation with the lag screw was least reliable. The new plate and 3.5-mm lateral locking plate exhibited similar control over fragment displacement. The newly designed plate was stable and reliable, indicating its suitability for clinical application.