Modelling tri-cortical pedicle screw fixation in thoracic vertebrae under osteoporotic condition: A finite element analysis based on computed tomography

2020 ◽  
Vol 187 ◽  
pp. 105035
Author(s):  
Wencan Zhang ◽  
Junyong Zhao ◽  
Le Li ◽  
Chenxiao Yu ◽  
Yuefeng Zhao ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Thoracic Vertebrae ◽  
Element Analysis

scholarly journals Treatment of Thoracolumbar Fractures Through Different Short Segment Pedicle Screw Fixation Techniques: A Finite Element Analysis

2020 ◽  
Vol 12 (2) ◽  
pp. 601-608
Author(s):  
Tie‐nan Wang ◽  
Bao‐lin Wu ◽  
Rui‐meng Duan ◽  
Ya‐shuai Yuan ◽  
Ming‐jia Qu ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Thoracolumbar Fractures ◽  
Short Segment ◽  
Element Analysis ◽  
Fixation Techniques

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

scholarly journals Retropharyngeal Reduction Plate for Treatment of Irreducible Atlantoaxial Dislocation: A Cadaveric Test and Finite Element Analysis

2020 ◽  
Author(s):  
Yukun Du ◽  
Zhao Meng ◽  
Jianyi Li ◽  
Zheng Zhao ◽  
Xiangyang Wang ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Atlantoaxial Dislocation ◽  
Element Analysis ◽  
Irreducible Atlantoaxial Dislocation ◽  
Plate System ◽  
Fixation System

Abstract Background: Clinical studies have shown that irreducible atlantoaxial dislocation (IAAD) can achieve reduction, decompression, fixation and fusion by transoral, posterior, and other traditional approaches. The present study aims to introduced a newly designed reduction plate through the retropharyngeal approach and evaluate its feasibility by cadaveric test and finite element analysis.Methods: A cadaveric specimen and a 45-year-old postoperative female patient diagnosed with IAAD who underwent the traditional posterior fixation were enrolled in this scientific study. The retropharyngeal approach involved placing the reduction plate into a cadaveric specimen’s cervical spine. Spiral CT thinly scanning (0.05 mm) from the base of the occipital bone to C7 vertebrae was performed and reconstructed for three-dimensional (3D) finite element analysis using Mimics software based on the Dicom data of two different fixations. Biomechanical distribution was compared between two fixations under different stress conditions, including flexion, extension, bending and rotation, respectively.Results: There was no significant difference in maximum stress between the retropharyngeal reduction plate system and the posterior atlantoaxial pedicle screw fixation system during flexion. Under states of extension, bending and rotation, the maximum stress of the reduction plate system was significantly lower than that of the posterior atlantoaxial pedicle screw fixation system. Both of the maximum stresses between two fixations were far lower than the maximum yield strength (795-827 MPa) and ultimate strength (860-896 MPa) of the titanium alloys. There was no significantly stress concentration between retropharyngeal reduction plate system and the posterior atlantoaxial pedicle screw fixation system under different movement.Conclusions: The cadaveric test showed that it is feasible to place the reduction plate using the retropharyngeal approach. The finite element analysis indicated that the retropharyngeal reduction plate system may provide relatively reliable fixation compared with traditional posterior fixation. A new choice of designing a surgical plan for treating atlantoaxial dislocation is presented.

scholarly journals The effect of denosumab on pedicle screw fixation: a prospective 2-year longitudinal study using finite element analysis

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Soji Tani ◽  
Koji Ishikawa ◽  
Yoshifumi Kudo ◽  
Koki Tsuchiya ◽  
Akira Matsuoka ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Elderly Patients ◽  
Pedicle Screw ◽  
Screw Fixation ◽  
Pedicle Screw Fixation ◽  
Pullout Strength ◽  
Mineral Density ◽  
Element Analysis ◽  
Denosumab Treatment

Abstract Background Pedicle screw loosening is a major complication following spinal fixation associated with osteoporosis in elderly. However, denosumab is a promising treatment in patients with osteoporosis. The effect of denosumab on pedicle screw fixation is unknown. Therefore, we investigated whether denosumab treatment improves pedicle screw fixation in elderly patients with osteoporosis. Methods This was a 2-year prospective open-label study. From February 2015 to January 2016, we included 21 patients with postmenopausal osteoporosis who received initial denosumab treatment. At baseline, 12 months, and 24 months, we measured volumetric bone mineral density (BMD) using quantitative computed tomography (QCT) and performed CT-based finite element analysis (FEA). Finite element models of L4 vertebrae were created to analyze the bone strength and screw fixation. Results BMD increased with denosumab treatment. FEA revealed that both pullout strength of pedicle screws and compression force of the vertebra increased significantly at 12 and 24 months following denosumab treatment. Notably, pullout strength showed a stronger correlation with three-dimensional volumetric BMD around pedicle screw placement assessed by QCT (r = 0.83, at 24 months) than with two-dimensional areal BMD assessed by dual energy X-ray absorptiometry (r = 0.35, at 24 months). Conclusion To our knowledge, this is the first study to reveal that denosumab treatment achieved strong pedicle screw fixation with an increase in BMD around the screw assessed by QCT and FEA; therefore, denosumab could be useful for osteoporosis treatment during spinal surgery in elderly patients with osteoporosis.

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

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