[Establishment of finite element model of anterior cervical transpedicular system for reconstruction of cervical stability after subtotal resection of two segments of lower cervical spine].

Objective: To establish the fixation model of anterior cervical transpedicular system (ACTPS) after subtotal resection of two segments of lower cervical spine(C ₃ -C ₇ ) in order to provide a finite element modeling method for anterior cervical reconstruction.
Methods: The CT data of the cervical segment (C ₁ -T ₁ ) of a 30-year-old adult healthy male volunteer was collected. Used Mimics 10.0, Rapidform XOR3, HyperMesh 10.0, CATIA5V19 and ANSYS 14.0 to establish the three-dimensional nonlinear complete model of lower cervical spine(C ₃ -C ₇ ) as the intact group. The number of units and nodes of the complete model were recorded. After the effectiveness of the complete model was verified, the C ₅ and C ₆ vertebral subtotal resection was performed, and the ACTPS model was established as the ACTPS group. The axial force of 75 N and moment couple of 1N·m was loaded on the upper surface of C ₃ in intact group and ACTPS group, the range of motion(ROM)and stress distribution in states of flexion extension, lateral flexion, rotation was compared between two groups.
Results: There were 85 832 elements and 23 612 nodes in the complete model of lower cervical spine(C ₃ -C ₇ ) which was established in this experiment. The stress distribution of ACTPS internal fixation model was relatively uniform. Comparing with the intact group, the overall range of motion in ACTPS group was decreased in flexion extension, lateral flexion and rotation directions, and the corresponding compensation of adjacent C _3,4 segment was increased slightly.
Conclusion: The stress distribution of ACTPS fixation system is uniform, there is no stress concentration area at the joint of screw and titanium plate, and the fracture risk of internal fixation is low. It is suitable for stability reconstruction after anterior decompression of two or more cervical segments.