Design And Finite Element Biomechanical Test Of A New Lateral Tibial Platform Plate

Objective:1.Design a new anatomical plate of the lateral tibial plateau that can be used to fix fractures of the anterolateral and posterolateral tibial plateau simultaneously.2.Three-dimensional modeling and finite element analysis software were used to establish three-dimensional finite element models of the new lateral plate of the tibial plateau,the posteroal T-plate,the traditional lateral L-plate and the posterolateral fracture of the tibial plateau.Different loads were applied to the models to simulate the force on the knee joint of the human body under different movements.The results of simulation analysis compare the effectiveness and mechanical distribution characteristics of different internal fixation methods.3.The new plate model,the lateral L-plate model and the artificial tibia model were used to simulate the internal fixation of the posterolateral plateau fracture.The universal tester was used to apply loads to the model,and the fixation effects of the two were compared through the displacement results of the posterolateral plateau fracture block.Method:1.CT scan results of a healthy adult knee joint were collected,and 3D reconstruction and finite element analysis software such as Mimics 21.0,Geomagic Wrap 2021,Solid Works 2017,ANSYS Workbench 19.2 were used.A new type of steel plate was designed to take into account both the anterolateral and posterolateral platforms,and the traditional L-shaped steel plate and the posteroal T-shaped steel plate were reconstructed.Three internal fixation methods were loaded and analyzed,and the maximum displacement,failure load and stress distribution of each model were measured to compare the mechanical characteristics of each model.2.Six pairs of artificial tibial models of the same model were selected and divided into two groups.The fracture models were constructed with a pendulum saw,and the two groups of models were fixed with new plates and L-plates respectively.According to the results of finite element simulation analysis,three points that may appear obvious displacements were marked on the fracture blocks and tibia of the two groups of models.Pressure tests were carried out on the models to measure the displacement of fracture blocks,and the load when the displacement of fracture blocks was greater than 2mm was defined as failure load.All the collected measurement data were tested by statistical methods to analyze the effectiveness of the two internal fixation methods.Results:1.The designed new plate can fix the posterolateral fracture block of the tibial plateau well and take into account the treatment of the anterolateral plateau fracture.2.Finite element analysis results: The displacement and stress distribution of60 KG adult knee joints at 500 N,1000N and 1500 N were successfully simulated and calculated.Under 500 N load,the maximum displacements of fracture blocks were0.0431 mm for the new plate,0.0432 mm for the posteroal T-plate and 0.0474 mm for the lateral L-plate.The maximum equivalent stress is 13.145 MPa for the new steel plate,8.529 MPa for the posteroal T-plate and 13.329 MPa for the outer L-plate.Under1000 N loading,the maximum displacements of fracture blocks were 0.0873 mm for the new plate,0.0856 mm for the posteroal T-plate and 0.0943 mm for the lateral L-plate.The maximum equivalent stress is 25.799 MPa for the new steel plate,17.133 MPa for the posteroal T-plate and 24.377 MPa for the lateral L-plate.Under1500 N load,the maximum displacements of fracture blocks were 0.1306 mm for the new plate,0.1207 mm for the posteroal T-plate and 0.1410 mm for the lateral L-plate.The maximum equivalent stresses were 38.070 MPa for the new steel plate,25.703 MPa for the posteroal T-plate and 36.175 MPa for the lateral L-plate.The displacement and equivalent stress of the three internal fixation models increase gradually with the increase of load,but they are smaller than the failure displacement of internal fixation and the yield strength of plate screws.The area of stress concentration is mainly the junction of bone and internal fixation and the turning point of the internal fixation shape,which are also the positions where internal fixation is prone to failure.The experimental results are similar to the common fracture and withdrawal of plate screws in clinical practice.3.Biomechanical test results: The fracture internal fixation models of the new plate and the lateral L-plate were respectively loaded.The displacement of the fracture block of the new plate group was 0.628±0.036 mm and that of the lateral L-plate was 0.888±0.023 mm under 500 N load.Under 1000 N loading,the displacement of fracture block in the new plate group was 0.948±0.025 mm and that of the lateral L-plate was 1.357±0.038 mm.Under 1500 N load,the displacement of fracture block of the new plate group was 1.655±0.057 mm,and that of the lateral L-plate was 1.965±0.060 mm.The failure loads of the two models were 2048±31N new steel plate and 1568±12N outer L-plate,respectively.Conclusion : In this study,a new type of lateral tibial plateau plate was successfully designed by using 3D reconstruction and finite element analysis software,and its fixation effect was verified by biomechanical tests to be more reliable than the currently commonly used lateral L-plate.Moreover,the plate can fix the anterolateral tibia and posterolateral tibia platform at the same time,so as to better fit the shape of the tibia and reduce the intraoperative damage to the knee joint structure.