Theestablishment Of Three-dimensional Finite Elemental Model Of Anatomical Specialized Two-egment Adjustiable Spinal Repair System And Finite Element Analysis Of Biomechanics

Objective:To establish a three-dimensional finite element model(FEM)of anatomical specialized two-segment adjustable spinal repair system with three-dimensional software and make a comparison with titanium mesh prosthesis replacement model.To analyze the effect of new prosthesis on segmental range of motion(ROM)and the distribution of stress,strain and displacement and to make a preliminary biomech-anical analysis.Methods:A spine specimen(L1-L6)of a fresh adult porcine was select as the research object with the removal of paraspinal muscles and the Preserved of ligaments and bone structure integrallty.X-ray was used to exclude the disease of trauma,cancer and other degeneration diseases.Thin slice CT scan was also performed and standard DICOM data was acquired.The finite element models of both the new cage and the titanium mesh prosthesis was constructed by the combination of software package Mimics v16.0,Magics v16.0,3-matic,Catia v5r20 and Abaqus 6.51.A new prosthesis replacement physical model was established,and the pedicle screw rigid fixation was performed based on the model of adult porcine spine specimens.The validity of the three-dimensional finite element method is verified by the load displacement experiment.ROMs of surgical intervention segment and adjacent segment lumbar were calculated after being subjected to moments 10.0Nm and 500 N preload and generating flexion,extension,lateral bending and axial rotation as well as the distribution of stress,strain,and displacement on intervertebral disc prosthesis.Result:1.A three-dimensional finite element model of two-segment adjustable anatomic repair system were established,including(412519)nodes,and(1668026)elements.titanium mesh implant three dimensional finite element model was also buid.2.The effect on the surgical segment : ROM of new prosthesis model decreased by 70% compared with the normal spinal model,The overall stability were good,there is no significant difference between the two model.3.The two stage prosthesis can better fit the upper and lower vertebral endplate,disperse stress,the maximum stress value of 30 MPa,titanium mesh showed a significant stress concentration trend,about 500 Mpa,both strains were 0.001,no significant difference.4.The contact stress between the prosthesis and the upper and lower endplate was similar to that of 13.2MPa and 11.7MPa,respectively5.In the two stage,the stress of the prosthesis is concentrated at the base and the cap at both ends,while the stress of the titanium mesh is concentrated at the gap junctionConclusions:1.The reconstructed model of spine defect prosthesis was established with realistic appearance and geometry in keeping with the physical and the model was validated by the three-dimensional finite element model,which could be used on biomechanics test.2.The two stage adjustable anatomic prosthesis reconstruction system and titanium mesh reconstruction system can meet the needs of reconstruction,and restore the immediate stability after operation,there is no significant difference between the two.3.The two-stage adjustable anatomical prosthesis can be anatomically fit to the upper and lower vertebral contact surfaces,which can better distribute the stress,reduce the stress concentration and promote the integration of the bone interface.The contact area between the titanium mesh prosthesis and the endplate is small,the stress concentration is more concentrated,and the stress shielding is easy to occur.Both strains are within the normal range,and no obvious yield sign can be found.