Finite element analysis of transoral anterior atlantoaxial plate fixation in a teenager

doi:10.3969/j.issn.2095-4344.1336

Abstract

Abstract:

BACKGROUND: Compared with other vertebral bodies, atlantoaxial vertebra has unique anatomical and functional differences. If atlantoaxial vertebra is damaged, traditional posterior fixation cannot achieve the desired effect, as the main load-bearing part of atlantoaxial vertebra is anterior and middle columns, so more effective fixation methods need to be explored.

OBJECTIVE: To investigate the mechanical parameters of transoral anterior atlantoaxial fixation plate by finite element analysis, in order to provide information for application and improvement of the fixation system for this age group.

METHODS: Imaging data were collected from one randomly selected patient (male, 12 years of age, 52 kg, with non-skull base atlantoaxial disease) who met the experimental criteria and underwent imaging in the Second Affiliated Hospital of Inner Mongolia Medical University since February 2016. Imaging data were reconstructed using Mimics 16.01 software. The plate for anterior atlantoaxial fixation was designed with Pro/ENGINEER 4.0 software according to the atlantoaxial anatomical diameters of the patient. The reconstructed three-dimensional model of the plate and screws was introduced into Mimics 16.01 and registered according to the requirements of a typical transoral anterior approach, followed by surface and volume mesh generation and material assignment. A 60-N load was applied vertically and a 15 N • m moment was applied at the surface to simulate anterior flexion, posterior extension, and lateral bending. Stresses at the screws and rods were measured. This study was approved by the Ethics Committee of Inner Mongolia Medical University on January 24, 2017 (approval number: 20170124).

RESULTS AND CONCLUSION: A total of 14 541 volume meshes and 5 247 nodes were generated on the three-dimensional atlantoaxial reconstruction mode. At the root of the upper screw, the maximum stress was observed in anterior flexion (54.21 ± 4.32 MPa, F=69.15, P < 0.05). At both the root and the tip of the lower screw, the maximum stress was observed in lateral bending, both presenting significant differences (root: 69.22 ± 4.12 MPa, F=89.34, P < 0.05; tip: 87.15 ± 6.57 MPa, F=57.23, P < 0.05). In anterior flexion and posterior extension, the stress was higher at the upper than the lower screw roots (P < 0.05); and in lateral bending, the stress was higher at the lower than the upper screw roots. In anterior flexion, posterior extension, and lateral bending, the stress was higher at the tip than the root of the lower screw, all presenting significant differences (P < 0.05). The transoral anterior atlantoaxial plate fixation system has a reasonable stress distribution in the adolescent and can withstand the stress of normal atlantoaxial movements.

Key words: adolescent, atlas, axis, internal fixation, finite element analysis, clinical applied anatomy, biomechanics, stress distribution

CLC Number:

R456|R681.5|R318

Zhang Bin, Li Zhijun, Ning Pengfei, Liu Ying, Cao Li, Zhang Fengying, Li Xiaohe. Finite element analysis of transoral anterior atlantoaxial plate fixation in a teenager[J]. Chinese Journal of Tissue Engineering Research, 2019, 23(28): 4535-4540.

Figures/Tables 2

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