Abstract:

Objective　To analyze through the mouth atlanto-axial vertebral anterior plate fixation in finite element for the development of the segmental anterior fixation surgery and to provide the reference of inner plant improvement.　Methods　One case, male, 36 years old, 64 kg weight was randomly selected in January 2014 in our hospital, whom was excluded of the skull-atlanto-axial vertebral disease. The patient received scanning with a thickness of 0.625 mm; Image data were rebuilt in the Mimics16.01 software and Pro/ENGINEER4.0 software was used to rebuild the atlanto-axial vertebral anterior plate. After reconstruction of steel screw 3D model according to the classic through the mouth,the model was imported into Mimics16.01 and the model surface was meshed and material assigned. The model was then imported into Ansys14.0, and was forced 80 N vertical loading. The surface was applied 15 Nm torque to simulate three-motion state example, forward bends, stretch, side-bending. The stress and deformation of screw and rod were measured. Results　Atlanto-axial vertebral three-dimensional reconstruction model were divided into 39842 individual grid and the model was loaded. The stress of upper screw root in bend was biggest (62.34 ±5.52) Mpa (F=73.23, P<0.05, the difference was statistically significant).A screw of the root and the top, lateral stress was the largest, respectively were (78.42±5.5.14) Mpa (F=112.32, P<0.05);(95.48±7.12)Mpa (F= 62.32, P<0.05), the difference had statistical significance; Under three different motion state and a screw root stress, Upper screw root stress in bending forward was greater than the lower (forward bends, stretch and lateral bending state , t value were 12.2, 9.23, 22.98, P<0.05, differences were statistically significant), and in the lateral current screw root stress was greater than the upper; In the same movement state, the top was greater than the root, the differences were statistically significant (forward bends, stretch and lateral bending state after t value were 23.14, 22.01, 8.13, P<0.05).　Conclusion Through the mouth atlanto-axial vertebra fixed system stress distribution was more reasonable, could withstand normal atlanto-axial after vertebral motion bearing stress, but the postoperative patients should reduce the proneness and lateral movement to lower the risk of fatigue fracture fixation system.

Key words: Atlant vertebrea, Axial vertebrea, Internofixation, FEA, Biomechanical analysis