Three-dimensional Finite Element Method Analysis Anterior And Posterior Approach Internal Fixation In Thoracolumbar Burst Fractures

Objective: (1) To establish the three-dimensional finite element model of T12-L2 segment of normal spine for further biomechanics investigation; (2) To investigate the stability of anterior approach internal fixation with titanium mesh implants/screw and posterior approach internal fixation with pedicle screw; (3) To investigate the stress distribution of internal fixation fused with anterior and posterior approach, in order to reduce or avoid the complication of internal fixation failure.Methods: In this study, a detailed T12-L2 three-dimensional nonlinear finite element model of a normal man aged 20 was established with the aid of two software Geomagic Studio and ANASYS which can derive a nonlinear finite element model from CT images. The model was validated in contrast to the biomechanical behaviors of cadaver spine. Based on the normal model, the destabilized model, the interbody, posterolateral and the circumferential fusions models were built up. After loadings employed on all models and the Von Miss stress, we recorded the angular motions of fused segment and the Von Mises stress.Results: (1) The finite element model of T12-L2 was built up and validated. (2) Both internal fixations in anterior and posterior approach can gain valid stability in reconstruction of L1 segment burst fracture. (3) The stability of anterior approach internal fixation is superior to the posterior fixation. In flexion, extension, flexor, reversing, and vertical loading, MS in T12 plane of anterior fixation group is less than the MS of Posterior fixation group, statistically significant difference (p <0.01). The highest Von Mises stress of internal fixation in anterior approach was recorded in the titanium mesh implants and titanium connecting rods. The highest Von Mises stress of internal fixation in posterior approach was recorded in the connection of pedicle screws and connecting rods.Conclusions:Both internal fixations in anterior and posterior approach can gain valid stability in reconstruction of L1 segment burst fracture. The stability of anterior approach internal fixation is higher than posterior approach internal fixation.