Finite element analysis of anteroposterior integration fixation by posterolateral nail-stick system for thoracolumbar disorders / 中国组织工程研究

ABSTRACT

BACKGROUND:Currently thoracolumbar fixation techniques have its advantages and disadvantages, it is necessary to explore a new internal fixation to fix the spine effectively and conveniently. OBJECTIVE:To establish thoracolumbar (T12-L2) three-dimensional finite element model and observe the effect of anteroposterior integration fixation by posterolateral nail-stick system on thoracolumbar stability. METHODBased on the CT scan data of normal human T12-L2 segments, we used Geomagic 11.0, Ug 7.0, Hypermesh 10.0, Abaqus 6.9.1 software to establish a three-dimensional finite element model of T12-L2 segments. Subsequently we established nail-stick system posterior fixation, anterior fixation, posterolateral anteroposterior integration fixation model. T12 segment was given 500 N preload and 7.5 N·m torque, to simulate thoracolumbar flexion, extension, lateral bending and rotation. The average rigidity of fixed segments under different conditions were observed. RESULTS AND CONCLUSION:Three fixation models showed a higher average rigidity than normal model under different conditions. The average rigidity in anteroposterior integration fixation by posterolateral nail-stick system was increased by 13%, 28%, 11%, 17%and 9%, compared with simple posterior fixation under the conditions such as anterior flexion, lateral bending and lateral rotation, respectively. Under the posterior extension, the average rigidity was reduced by 6%than the posterior fixation. Compared with the anterior fixation, the average rigidity in anteroposterior integration fixation by posterolateral nail-stick system was reduced by 15%, 10%, and 14%under the conditions of anterior flexion and lateral bending. While the average rigidity was higher than anterior flexion under the posterior extension and lateral rotation, increasing 5%, 12%and 2%. The anteroposterior integration fixation by posterolateral nail-stick system can improve the stability of fixed segments, and the stability is higher than anterior fixation at posterior extension and lateral rotation, while higher than posterior fixation in anterior flexion, lateral bending and lateral rotation. So it is a potential fixation method.