3-dimensional Finite-element Study On Anterior Transpedicular Screw Fixation System Of The Subaxial Cervical Spine

Objective Using3-dimensional finite-element analysis to compare the biomechanicalproperties of models reconstructed by the anterior cervical pedicle screw fixation system(Anterior Cervical Transpedicular Screw, ACTPS) and the cervical anterior screw platesystem (Anterior Cervical Locked-plate, ACLP) after2levels corpectomy, and provide atheoretical evidence for clinical application.Methods CT data (C1-T1) was collected from a28years old male volunteer.The3-dimensional nonlinear subaxial cervical (C3-C7) intact model was established and analyzedby Mimics11.0, Rapidform XOR3, Hypermesh10.0, CATIA5V19, ANSYS14.0softwares. The axial force of75N and moment couple of1N·m was loaded on the upper surface of C3,made the model movement in flexion extension, lateral bending, rotatingdirection,respectively.Then,recorded the range of motion (ROM),and compared the results with the in vitrobiomechanical experimental data of Panjabi and Moroney.ACTPS and ACLP internal fixation model were established.The ROM of the two modelswere calculated by ANSYS software. The Von Mises stress distribution and maximum stressvalue of ACTPS group and ACLP group were recorded and analyzed,to compare the ROMof the two internal fixation models with intact model.Results There were85,832elements and23,612nodes in the intact model of subaxialcervical spine (C3-C7) be established in this experiment, and the ROM of intact modelvalidated with the reported cadaveric experimental data of Panjabi and Moroney.In ACTPS model group, the stress was been well-distributed relatively, but in ACLPmodel group, the stress concentrated on the interface between screw and the titanium plate.There were obvious differences of the maximum stress value of the two groups. The ROM ofACTPS group of fixed segments was smaller than ACLP group, adjacent segment ROMshowed no significant difference.Compared with the intact group, the ROM in flexionextension, lateral flexion, rotation direction was decreased respectively about25°,20°and8°,adjacent segment ROM of C3/4was correspondingly compensated about0.3°,3°and0.1°.Conclusion ACTPS system has better biomechanical stability than the ACLP vertebralscrew system, it suitable for reconstruction stability of2levels or more than2levels afteranterior cervical decompression, especially for the cases of poor bone quality or anteriorcervical revision.Meanwhile, the risk of fracture is lower than the ACLP system.