scholarly journals Influence of Different Fixed System in Osteoporotic Lumbar Vertebrae in Fusion：A 3D Finite Element Analysis

2021 ◽  
Author(s):  
Han Ye ◽  
Wu Jincheng ◽  
Wang Xiaodong ◽  
Gao Wenshan ◽  
Sun Shaosong ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pedicle Screw ◽  
Maximum Stress ◽  
Pedicle Screws ◽  
Cement Augmentation ◽  
Normal Model ◽  
Element Analysis ◽  
Normal Bone ◽  
Flexion Extension

Abstract Background：Posterior lumbar interbody fusion(PLIF) is the most common surgical method for lumbar fusion surgery, and pedicle screws（PS）can provide effective fixation strength in normal bone. However, pedicle screws are prone to loosening in osteoporotic patients. cortical bone trajectory (CBT) screw fixation and cement augmentation pedicle screw（CAPS） fixation are often used to reduce the risk of loosening. Although several studies are reported that the pullout strength of CBT screws or CAPS screws are higher than PS，There are no relevant studies on different internal fixation stress analysis. The purpose of this study was to compare the stresses of different fixation methods and analyze the stresses of different internal fixation systems through finite element analysis.Methods: Five finite element models were established and tested by simulating PLIF surgery at L4/5. They included: (1) normal model (2) osteoporosis model (3) pedicle screw model; (4) cement augmentation pedicle screw（CAPS）model; (5) cortical bone trajectory (CBT) model. The range of motion (ROM), stress of fusion cage and screw-rod system of different models were analyzed by simulating flexion, extension, left bending, right bending, left rotation and right rotation movements through software.Results: The ROM of the osteoporosis model was increased compared with the normal bone, and the osteoporosis was increased by 5.3%, 17.6%, 11.5%, 11.3%, 7.5%, and 8.3% compared with the normal model during flexion, extension, left bending, right bending, left rotation, and right rotation. After fixation, the ROM decreased, but the difference was not significant between the different fixation models. The stress of the screw-rods is the minimum one in the CAPS group. the PS group is the middle one, and stress of the CBT group is max. The cage stress is the minimum in the CAPS group which is slightly smaller than the cage stress in the PS group. the cage stress was the max in the CBT group.Conclusion: PLIF can decrease the ROM of lumbar vertebra and fusion segment in osteoporosis, but different fixation methods have little effect on ROM. However, there was a great difference in the stress of implant, with the least stress in the CAPS group, the second in the PS group, and the greatest stress in the CBT. The same is true for Cage stress. At the same time, the maximum stress zone to occur at the screw-rod junction, while the maximum stress of cage occurs at the position in contact with the endplate. The study has guiding significance for clinical practice.

The Benefits of Cement Augmentation of Pedicle Screw Fixation Are Increased in Osteoporotic Bone: A Finite Element Analysis

2014 ◽  
Vol 2 (4) ◽  
pp. 248-259 ◽  
Author(s):  
Wenhai Wang ◽  
George R. Baran ◽  
Hitesh Garg ◽  
Randal R. Betz ◽  
Missoum Moumene ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Cement Augmentation ◽  
Osteoporotic Bone ◽  
Element Analysis

Biomechanical comparison of stand-alone and bilateral pedicle screws fixation for oblique lumbar inter-body fusion surgery – a finite element analysis

2019 ◽  
Author(s):  
guofang Fang ◽  
yunzhi lin ◽  
wenggang cui ◽  
lili guo ◽  
shihao Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screws ◽  
Element Model ◽  
Axial Rotation ◽  
Pedicle Screw Fixation ◽  
Element Analysis ◽  
Intact Group ◽  
Flexion Extension

Abstract Objectives: The aim of this study was to evaluate the biomechanical stability and safety in patients undergoing oblique lumbar inter-body fusion (OLIF) surgery with stand-alone (SA) and Bilateral pedicle screw fixation (BPSF). Methods: A finite element model of L4-L5 spinal unit was established and validated. Based on the validated model technique, function surgical models corresponding to SA, BPSF were created. Simulations employing the models were performed to investigate the OLIF surgery. A bending moment of 7.5 Nm and a 500 N follower load were applied to the models in flexion, extension, axial rotation and lateral bending. Finite element(FE) models were developed to compare the biomechanics of the intact group, SA, BPSF group. Results: Compared with the Range of motion (ROM) of the intact lumbar model, SA model decreased by 79.5% in flexion, 54.2% in extension, BPSF model decreased by 86.4% in flexion, 70.8% in extension. Compared with the BPSF, the maximum stresses of L4 inferior endplate (IEP) and L5 superior endplate (SEP) increased significantly in SA model, L4 IEP increased to 49.7MPa in extension, L5 SEP increased to 47.7MPa in flexion. Conclusions: OLIF surgery with BPSF could reduce the max stresses of the endplate which may reduce cage sedimentation incidence. However, OLIF surgery with SA could not provide enough rigidity for the fusion segment in osteoporosis patients which may increase the cage sedimentation incidence. Keywords: OLIF; Pedicle screw fixation; spinal fusion; finite element

Biomechanical Comparison of Posterior Lumbar Interbody Fusion and Transforaminal Lumbar Interbody Fusion by Finite Element Analysis

2012 ◽  
Vol 72 (1) ◽  
pp. ons21-ons26 ◽  
Author(s):  
Hao Xu ◽  
Hao Tang ◽  
Xuemei Guan ◽  
Fugui Jiang ◽  
Neng Xu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Range Of Motion ◽  
Pedicle Screw ◽  
Interbody Fusion ◽  
Posterior Lumbar Interbody Fusion ◽  
Transforaminal Lumbar Interbody Fusion ◽  
Lumbar Interbody Fusion ◽  
Element Analysis ◽  
Flexion Extension

Abstract Background: The transforaminal lumbar interbody fusion (TLIF) procedure may reduce many of the risks and limitations associated with posterior lumbar interbody fusion (PLIF). However, little is known about the biomechanical difference between PLIF and TLIF. Objective: To determine the biomechanical difference between PLIF and TLIF by finite-element analysis. Methods: Three validated finite-element models of L3-5 lumbar segment were created (intact model, PLIF model, and TLIF model). To analyze the biomechanics of these models, flexion, extension, rotation, and lateral bending moments of 7.5 N-m with a compressive preload of 400 N were imposed on the superior surfaces of the L3 vertebral body. Results: The range of motion at the L4-5 level of the PLIF and TLIF models decreased for all loading cases, compared with the intact model. Differences in the range of motion between PLIF and TLIF were not significant at less than 1 degree for all loading cases. The stress of the cage was found to be high in the PLIF model at the cageendplate interface under all loading conditions. The stress exerted on the pedicle screw was greater in TLIF than PLIF. Particularly in flexion loading, the stress experienced by the pedicle screw in the TLIF model was 70.7% greater than that in the PLIF model. Conclusion: The TLIF procedure increases the approximate biomechanical stability and reduces stress at the cage-endplate interface, except for a slight increase in screw stress. Clinically, the TLIF procedure may reduce many of the risks and limitations associated with PLIF and offer a useful alternative to the PLIF procedure.

Selection of suitable pedicle screw for degenerated cortical and cancellous bone of human lumbar spine: A finite element study

2020 ◽  
pp. 039139882096448
Author(s):  
Pushpdant Jain ◽  
David Chua Sing Ngie ◽  
Soh Fong Lim ◽  
Bee Huah Lim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pedicle Screw ◽  
Cancellous Bone ◽  
Body Movement ◽  
Pedicle Screws ◽  
Element Analysis ◽  
Moment Conditions ◽  
Bone Screw ◽  
Selection Of

Pedicular arthrodesis is the traditional procedure in terms of increase in the biomechanical stability with higher fixation rate. The current work aims to identify the effect of three spinal pedicle screws considering cortical and cancellous degeneracy condition. Lumbar section L2-L3 is utilized and various load and moment conditions were applied to depict the various biomechanical parameters for selection of suitable screw. Three dimensional model is considered in finite element analysis to identify the various responses of pedicle screw at bone screw juncture. Computed tomography (CT) images of a healthy male were considered to generate the finite element vertebral model. Generated intact model was further utilized to develop the other implanted models of degenerated cortical and cancellous bone models. The three fused instrumented models with different cortical and cancellous degeneracy conditions were analyzed in finite element analysis. The results were obtained as stress pattern at bone screw boundary and intervertebral disc stress. FE simulated results represents significant changes in the von Mises stress due to various load and moment conditions on degenerated bones during different body movement conditions. Results have shown that among all pedicle screws, the 6.0 mm diameter screw reflects very less stress values at the juncture. Multiple results on biomechanical aspects obtained during the FE study can be considered to design a new stabilization device and may be helpful to plan surgery of critical sections.

scholarly journals Influence of cement-augmented pedicle screws with different volumes of polymethylmethacrylate in osteoporotic lumbar vertebrae over the adjacent segments: A 3D finite element analysis

2020 ◽  
Author(s):  
Hui-zhi Guo ◽  
Shun-cong Zhang ◽  
Dan-qing Guo ◽  
Yan-huai Ma ◽  
Kai yuan ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pedicle Screw ◽  
Thoracolumbar Spine ◽  
Lumbar Vertebrae ◽  
Pedicle Screws ◽  
Adjacent Segment Degeneration ◽  
Adjacent Segment ◽  
Element Analysis ◽  
Adjacent Segments

Abstract Background: Polymethylmethacrylate (PMMA) is commonly used for cement-augmented pedicle screw instrumentation (CAPSI) to improve the fixation stability and reduce the risk of screw loosening in the osteoporotic thoracolumbar spine. Biomechanical researches have shown that various dose of cement (1-3ml) can be injected to enhance screw stability. To date, there have been no studies on the relationship between adjacent segment degeneration and the volume of PMMA. This study aimed to explore the influence of CAPSI with different volumes of PMMA in osteoporotic lumbar vertebrae over adjacent segments by using finite element analysis.Methods: Seven different finite element models were reconstructed and simulated under different loading conditions, including (1) an intact model, (2) three single-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml), and (3) three double-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml). To improve the accuracy of the finite element analysis, the models of the injectable pedicle screw and bone cement were created by using a three-dimensional scanning machine and the CAPSI patient’s CT data, respectively. The range of motion (ROM), the stress of intervertebral discs, and the stress of facet in the adjacent segment were comparatively analysed among the different models.Results: The ROMs of the different segments were compared with experimental data, with good agreement under the different load conditions. Compared with the intact model, the ROM, disc stresses, and facet stress in adjacent segments were found to be higher in the six operative models. Otherwise, with a larger volume of PMMA injected, the ROM, disc stresses, and facet stress slightly increased at the adjacent segment. However, the differences among the augmented models were insignificant for all loading cases.Conclusions: CAPSI could increase the incidence of disk degeneration in the adjacent segment, while within a certain range, different volumes of PMMA provided an approximate impact over the adjacent segment degeneration.

scholarly journals Influence of cement-augmented pedicle screws with different volumes of polymethylmethacrylate in osteoporotic lumbar vertebrae over the adjacent segments: A 3D finite element analysis

2020 ◽  
Author(s):  
Hui-zhi Guo ◽  
Shun-cong Zhang ◽  
Dan-qing Guo ◽  
Yan-huai Ma ◽  
Kai yuan ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pedicle Screw ◽  
Thoracolumbar Spine ◽  
Lumbar Vertebrae ◽  
Pedicle Screws ◽  
Adjacent Segment Degeneration ◽  
Adjacent Segment ◽  
Element Analysis ◽  
Adjacent Segments

Abstract Background: Polymethylmethacrylate (PMMA) is commonly used for cement-augmented pedicle screw instrumentation (CAPSI) to improve the fixation stability and reduce the risk of screw loosening in the osteoporotic thoracolumbar spine. Biomechanical researches have shown that various dose of cement (1-3ml) can be injected to enhance screw stability. To date, there have been no studies on the relationship between adjacent segment degeneration and the volume of PMMA. This study aimed to explore the influence of CAPSI with different volumes of PMMA in osteoporotic lumbar vertebrae over adjacent segments by using finite element analysis.Methods: Seven different finite element models were reconstructed and simulated under different loading conditions, including (1) an intact model, (2) three single-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml), and (3) three double-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml). To improve the accuracy of the finite element analysis, the models of the injectable pedicle screw and bone cement were created by using a three-dimensional scanning machine and the CAPSI patient’s CT data, respectively. The range of motion (ROM), the stress of intervertebral discs, and the stress of facet in the adjacent segment were comparatively analyzed among the different models.Results: The ROMs of the different segments were compared with experimental data, with good agreement under the different load conditions. Compared with the intact model, the ROM, disc stresses, and facet stress in adjacent segments were found to be higher in the six operative models. Otherwise, with a larger volume of PMMA injected, the ROM, disc stresses, and facet stress slightly increased at the adjacent segment. However, the differences among the augmented models were insignificant for all loading cases.Conclusions: CAPSI could increase the incidence of disk degeneration in the adjacent segment, while within a certain range, different volumes of PMMA provided an approximate impact over the adjacent segment degeneration.

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