Objectives:To compare the biomechanical characteristics of 3D-printed titanium alloy artificial vertebral bodies(AVB)with standard,self-stabilizing,and truss structures in spinal reconstruction after total en bloc spondylectomy(TES).Methods:A finite element model of the normal spine was constructed based on the CT data of the T10-L2 segments of a healthy adult male and was subsequently validated.The defect after vertebral column resection was simulated by removing the T12 vertebra,and three types of 3D-printed titanium alloy AVBs were implanted:standard(cylindrical),self-stabilizing(with two pairs of screws at the upper and lower ends),and truss(with bilateral ring holes for screw-rod connection).A 200N axial load and a 7.5N·m torque were applied using Abaqus software to simulate flexion,extension,lateral bending,and rotation movements.The overall stiffness of the"vertebra-prosthesis-vertebra"composite structure,the stress distributions on the posterior column connecting rod,the endplate,and the fusion device were analyzed.Results:The range of motion of the T10-L2 normal spinal finite element model established in this study was consistent with previous literature reports,therefore validating the model.Stiffness analysis showed that the displacement difference among the standard,truss,and self-stabilizing AVBs under the same load was 0.1mm,with the self-stabilizing structure AVB exhibiting the smallest displacement;The truss structure had smaller displacement in left-right bending.Stress analysis results indicated that the posterior column connecting rods of the three kinds of morphological AVBs bore the maximum Von Mises stress(174.90-175.00MPa)during rotation.Compared with the standard structure,the truss structure reduced the mid-segment stress of the posterior column connecting rod by 18.5％-24.3％during flexion-extension and lateral bending.Endplate stress analysis revealed that the maximum Von Mises stress on the endplate occurred during flexion,with values of 32.54MPa,30.76MPa,and 24.37MPa for the standard,truss,and self-stabilizing structures,respectively.The self-stabilizing structure reduced endplate stress by 14％-30％compared with the other two structures.Analysis of the internal fixation system showed that the cage stress of the self-stabilizing AVB was significantly lower than that of the standard and truss structures:reduced by 57％and 61％in flexion;52％-62％and 59％-64％in lateral bending;and 61％-62％and 46％-61％in rotation,respectively.Conclusions:Compared to the standard structure,the truss structure AVB reduces the stress concentration of the posterior column connecting rod through a multi-segment stress dispersion mechanism.The self-stabilizing structure AVB enhances the stability of the prosthesis-vertebral body interface through screw fixation.

Objectives:To compare the biomechanical characteristics of 3D-printed titanium alloy artificial vertebral bodies(AVB)with standard,self-stabilizing,and truss structures in spinal reconstruction after total en bloc spondylectomy(TES).Methods:A finite element model of the normal spine was constructed based on the CT data of the T10-L2 segments of a healthy adult male and was subsequently validated.The defect after vertebral column resection was simulated by removing the T12 vertebra,and three types of 3D-printed titanium alloy AVBs were implanted:standard(cylindrical),self-stabilizing(with two pairs of screws at the upper and lower ends),and truss(with bilateral ring holes for screw-rod connection).A 200N axial load and a 7.5N·m torque were applied using Abaqus software to simulate flexion,extension,lateral bending,and rotation movements.The overall stiffness of the"vertebra-prosthesis-vertebra"composite structure,the stress distributions on the posterior column connecting rod,the endplate,and the fusion device were analyzed.Results:The range of motion of the T10-L2 normal spinal finite element model established in this study was consistent with previous literature reports,therefore validating the model.Stiffness analysis showed that the displacement difference among the standard,truss,and self-stabilizing AVBs under the same load was 0.1mm,with the self-stabilizing structure AVB exhibiting the smallest displacement;The truss structure had smaller displacement in left-right bending.Stress analysis results indicated that the posterior column connecting rods of the three kinds of morphological AVBs bore the maximum Von Mises stress(174.90-175.00MPa)during rotation.Compared with the standard structure,the truss structure reduced the mid-segment stress of the posterior column connecting rod by 18.5％-24.3％during flexion-extension and lateral bending.Endplate stress analysis revealed that the maximum Von Mises stress on the endplate occurred during flexion,with values of 32.54MPa,30.76MPa,and 24.37MPa for the standard,truss,and self-stabilizing structures,respectively.The self-stabilizing structure reduced endplate stress by 14％-30％compared with the other two structures.Analysis of the internal fixation system showed that the cage stress of the self-stabilizing AVB was significantly lower than that of the standard and truss structures:reduced by 57％and 61％in flexion;52％-62％and 59％-64％in lateral bending;and 61％-62％and 46％-61％in rotation,respectively.Conclusions:Compared to the standard structure,the truss structure AVB reduces the stress concentration of the posterior column connecting rod through a multi-segment stress dispersion mechanism.The self-stabilizing structure AVB enhances the stability of the prosthesis-vertebral body interface through screw fixation.