The Three-dimensional Finite Element Model And Biomechanical Analysis Of The New Locking Anterolateral Plate For Distal Tibial

Objective:The biomechanical properties of the new distal tibial anterolateral locking plate and the L-shaped distal tibial anterolateral locking plate in the treatment of distal tibial fractures were compared through finite element analysis and biomechanical test experiments,so as to provide a theoretical basis for the future application of the new distal tibial anterolateral locking plate in clinic.Methods:1.Based on the CT scanning data of lower limbs in normal adults,a three-dimensional finite element model of Rüedi-Allg?wer III Pilon fracture(equivalent to OA43/C3 distal tibial fracture,intra-articular fracture)was established by using relevant software.Then,the new distal tibial anterolateral locking plate and L-shaped distal tibial anterolateral locking plate were used to assemble and fix the fracture model.The finite element software Ansys was used to load the two groups of fracture-assembly models with different axial forces and torsional forces,respectively.The magnitude and distribution of stress and fracture displacement of the two models under different loads were compared.2.Twelve synthetic tibial models were selected and made into a 1cm transverse bone defect 25mm-35 mm from the distal tibial articular surface to simulate tibial OA43/A3 fractures(extra-articular fractures).The 12 fracture models were randomly divided into two groups.The new distal tibial anterolateral locking plate(observation group)and L-shaped distal tibial anterolateral locking plate(control group)were used for the same reduction and fixation of the fracture model.All models were tested on the same mechanical tester.Two groups of steel plate-fracture solid models were subjected to non-destructive biomechanical tests by applying axial load with the maximum value of 1 000 N,torsional load with the maximum torque of5 N·m and cyclic axial load with the maximum value of 100 N–800 N(dynamic compression fatigue test).The axial stiffness and maximum torsional angle of the two groups of steel plates and whether the test could pass the dynamic compression fatigue test were compared.Result:1.Compared with L-plate fracture assembly model,the overall bearing stress,tibial bearing stress and displacement of fracture block are relatively small,and the internal fixation bearing stress is relatively large.The internal fixation stress of the two groups of models is mainly around the distal tibial fracture line,The stress distribution of the new type distal tibial plate is more uniform.Compared with L-plate fracture assembly model,the overall bearing stress and internal fixation bearing stress of the new type steel plate fracture assembly model are larger,while the tibia bearing stress and fracture block displacement are relatively small.The new steel plate stress is concentrated at the intersection of the steel plate head body,and the stress distribution near the fracture line of the distal end of the plate is relatively small,The stress concentration of L-shaped steel plate is more obvious,and the stress concentration is more obvious.2.In the axial load static compression test,the results showed that the steel plate compression stiffness of the observation group(638.16 ± 166.56 N / mm)was higher than that of the control group(339.69 ± 43.56 N / mm),and the difference was statistically significant(P < 0.05).Static radial torsion test results showed that the maximum torsion angle of the new distal tibial plate in the observation group(5.88 ± 0.48 °)was lower than that of the L-shaped plate in the control group(6.56 ± 0.53 °),and the difference was statistically significant(P < 0.05).The two groups of steel plates passed the sine load dynamic fatigue test with the loading size of 100 N – 800 N,the frequency of 5 Hz,and the continuous repetition of 1million cycles,and there was no sign of steel plate fracture.Conlution:In the treatment of complex distal tibial fractures,the new distal tibial plate has stronger anti-compression and anti-torsion ability than the L-shaped distal tibial plate.The stress distribution of the tibia,internal fixation system and fracture surface is more reasonable,and the displacement of the fracture block is smaller.Therefore,it can be considered that the new distal tibial plate is more suitable for distal tibial fractures and has better biomechanical properties than the traditional lateral L-shaped plate fixation,which can provide certain biomechanical basis for future clinical application.