A finite element model of C1 lateral mass-C2 intralaminar screw-rod fixation and its biomechanical analysis

English Keywords:Axis  Lamina  Finite element analysis  Biomechanics

English Abstract:

  【Abstract】 Objective：To establish an anatomic detailed finite element model of C1-C2 complex and investigate the biomechanical features of intralaminar C2 screws.Method：The coordinate data of the cervical vertebrae were obtained from the CT scan images of a healthy Chinese male adult volunteer.Visualization Toolkit（VTK） software was used to preprocess and establish the geometry model of the C1-C2 cervical spine.The geometry model was meshed by ABAQUS software.Some material parameters were defined from other available material parameters by using proportion and function scale method.The changes of theoretical stress in different positions of atlas were analyzed when the skull was in neutral position，flexion/extension，right and left lateral bending，axial rotation and anterior-posterior（AP） translation.Result：The model of C1-C2 complex consisted of 183363 nodes and 116082 elements.The data indicated that C1 lateral mass-C2 intralaminar screw-rod fixation significantly reduced the C1-C2 motion in flexion/extension，lateral bending and axial rotation compared to the intact cases.The results showed that there was concentration of stress at the upper bone-screw interface and the inferior transition area between rod and screw in extension.Stress concentration in flexion occurred in both the upper rod-screw transition area and bone-screw interface. In rotation the inferior conjunction of screw-rod presented stress convergence，the stress of the screw system was well-distributed.Conclusion：The finite element model of the atlantoaxial spine realistically simulates the atlantoaxial motion，which can simulate the natural condition and facilitate the further biomechanical research.