Biomechanical study of arlas-axis components pull-out strength following artificial atlanto-odontoid joint arthroplasty

Abstract

Objective To investigate the arias-axis components pull-out strength following artifi-cial atlanto-odontoid joint arthroplasty and evaluate its biomechanical performance. Methods Ten sets of artificial atlanto-odontoid joint used in adults' bony specimens were selected for biomechanical test in MTS858 Mini Bionix machine including the arias-axis components pull-out strength. Results F-maxs were (894.36±102.30) N in the atlas components, and (1227.59±143.35) N in axis components respec-tively. The screw length of atlas components was (20.69±1.43) mm, and that of axis components was (24.03±1.31) mm. The yield length of atlas and axis components was (1.51±0.11) and (1.0.12) mm respectively. There was statistically significant difference between pull-out strength of the atlas-axis components and the screw length of the atlas-axis components (P 0.05). A statistically sig-nificant positive correlation was observed between pull-out strength of the arias-axis components and the screw length of the atlas-axis components (r1=0.880). There was statistically significant positive correla-tion between pull-out strength of the atlas-axis components and the yield length of the atlas-axis compo-nents (r2=0.606). Conclusion The atlas-axis components had excellent biomechanical performance of pull-out strength. The screws of atlas components should be implanted unicortically. The screws of axis components should be implanted bicortically. Screw path length is one of the important factors influencing the arias-axis components pull-out strength. Key words: Biomechanics; Atlanto-edontoid joint; Artificial joint; Atlanto-axial joint; Replacement