Oblique Lateral Interbody Fusion Combined With Different Internal Fixations in The Treatment of Degenerative Lumbar Spine Disease: A Finite Element Analysis

Abstract

Little is known about the biomechanical performance of various internal fixations in oblique lumbar interbody fusion (OLIF). In this study, finite element (FE) analysis was used to describe the biomechanical findings of various different internal fixations to compare and explore the stability of each fixation.METHODS: Six validated FE models of the L3-S1 segment were reconstructed from computed tomography images, including (1) an intact model, (2)a stand-alone (SA) model with no instrument (3) a unilateral pedicle screw model (UPS), (4) a unilateral pedicle screw contralateral translaminar facet screw model (UPS-CTLFS), (5) a bilateral pedicle screw (BPS) model, and (6) a cortical bone trajectory screw (CBT).Three-dimensional model was performed by computed tomography data, and 150N static force and 10N.m moments in different directions were applied to the models to analyze the validation of the models in comparison with previous studies. Models of the OLIF cage was created with three-dimensional scanning to improve the accuracy of the FE analysis. Range of motion (ROM) of the surgical segment stresses, stress of the cage, and stress of fixation were evaluated in the different models.RESULTS:ROM increased from least to greatest as follows: BPS, UPS-CTFS, CBT, UPS, SA. The SA group had the greatest ROM and the SA group had the greatest ROM and stresses on the CAGE. The ROM of the BPS and UPS-CTFS was not significantly different for all motion loadings. Compared with the other three models, the BPS model had lower stresses in internal fixation for all loading conditions and the CBT screw internal fixation had the highest stresses for different loads Compared with the other groups.CONCLUSIONSThe BPS model provided the best biomechanical stability for OLIF. The SA model was relatively less stable. The UPS-CFTS group reduced the ROM of the fusion segments, but the stresses on the internal fixation and CAGE were relatively higher in the UPS-CFTS Compared with the BPS group; and the CBT group had lower ROM in flexion and extension Compared with the BPS, but its ROM in rotation and lateral flexion was relatively higher. The stability of the CBT was poorer than that of the BPS and LPS-CTFS groups. The stress on the CAGE and internal fixation was greater in the CBT group.

Biomechanical characteristics of 2 different posterior fixation methods of bilateral pedicle screws: A finite element analysis

“…[49] Although this difference in stress does not have a decisive impact on the operation, the long-term stress concentration will lead to fracture of pedicle screws due to fatigue, which will bring a series of potential risks after the operation, which is not conducive to the stability of the entire internal fixation system. [50,51] The intervertebral disc is an important load center and buffer structure for spinal function. It plays a key role in the spinal movement, bearing, and transmission of various loads.…”

“…[49] Although this difference in stress does not have a decisive impact on the operation, the long-term stress concentration will lead to fracture of pedicle screws due to fatigue, which will bring a series of potential risks after the operation, which is not conducive to the stability of the entire internal fixation system. [50,51]…”

Research progress of finite element analysis in lumbar fusion surgery for lumbar degenerative diseases

“…However, Tempe [53] et al found that sinking the fusion apparatus was a common complication of stand-alone OLIF in long-term postoperative follow-up. Through biomechanical analysis by the FEM, Shuyi ZHANG [54] et al found that stand-alone OLIF mobility and the stress of the fusion apparatus were large, which might be a reason for fusion sinking. Sheng jia Huang [55]et al through the FEM analysis, that stand-alone OLIF technology significantly reduces the activity in all directions, and the technology has a certain stability.…”