BIOMECHANICAL ANALYSIS OF INTERBODY AND POSTEROLATERAL FUSION WITH TRANSPEDICULAR SCREW FIXATION FOR SPONDYLOLISTHESIS: A FINITE ELEMENT STUDY

2008 ◽  
Vol 20 (03) ◽  
pp. 145-151 ◽  
Author(s):  
Heng-Liang Liu ◽  
Ming-Tsung Sun ◽  
Chun-Li Lin ◽  
Hsin-Yi Cheng ◽  
Kou-Chen Wei ◽  
...  
Keyword(s):  
Finite Element ◽  
Interbody Fusion ◽  
Screw Fixation ◽  
Posterolateral Fusion ◽  
Fe Model ◽  
Functional Spinal Unit ◽  
Transpedicular Screw ◽  
Flexion Extension ◽  
Computer Aided ◽  
Transpedicular Screw Fixation

This study investigates and compares the mechanical response of interbody and posterolateral fusion along with the transpedicular screw fixation for the degenerative spondylolisthesis under different load conditions using finite element (FE) analysis. Image processing, computer aided design (CAD), and computer aided engineering techniques were applied to build a three-dimensional model of a functional spinal unit (L4–L5) with transpedicular screw fixation for the posterolateral fusion FE model. Additionally, the intervertebral disc was replaced by two cages to represent the interbody fusion FE model. A unit moment of 1 Nm was applied on the top of L4 in different directions to simulate the flexion, extension, lateral bending, and axial rotation, respectively. The lower of L5 was fixed in all directions for constraint. The simulated results revealed that using cages obviously decreased (13%–58%) the stress imposed upon the instrumentations. The stress concentration occurred at the locking nut on the transpedicular screw head, the middle part of the bone plate, and the thread of transpedicular screw near the head. These findings were comparable to clinical observations. With the limited data, our results suggested interbody fusion in combination with transpedicular screw fixation demonstrated less stress on the instrumentations than the posterolateral fusion with only transpedicular screw fixation.

scholarly journals Screws Fixation for Oblique Lateral Lumbar Interbody Fusion (OL-LIF): A Finite Element Study

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Qinjie Ling ◽  
Huanliang Zhang ◽  
Erxing He
Keyword(s):  
Finite Element ◽  
Cortical Bone ◽  
Vertebral Body ◽  
Interbody Fusion ◽  
Screw Fixation ◽  
Fe Model ◽  
Lumbar Interbody Fusion ◽  
Maximum Displacement ◽  
Lateral Lumbar Interbody Fusion ◽  
Functional Spinal Unit

Background. The combination of screw fixation and cage can provide stability in lumbar interbody fusion (LIF), which is an important technique to treat lumbar degeneration diseases. As the narrow surface cage is developed in oblique lateral lumbar interbody fusion (OL-LIF), screw fixation should be improved at the same time. We used the finite element (FE) method to investigate the biomechanics response by three different ways of screw fixation in OL-LIF. Methods. Using a validated FE model, OL-LIF with 3 different screw fixations was simulated, including percutaneous transverterbral screw (PTVS) fixation, percutaneous cortical bone trajectory screw (PCBTS) fixation, and percutaneous transpedical screw (PPS) fixation. Range of motion (ROM), vertebral body displacement, cage displacement, cage stress, cortical bone stress, and screw stress were compared. Results. ROM in FE models significantly decreased by 84-89% in flexion, 91-93% in extension, 78-89% in right and left lateral bending, and 73-82% in right and left axial rotation compared to the original model. The maximum displacement of the vertebral body and the cage in six motions except for the extension of model PTVS was the smallest among models. Meanwhile, the model PTVS had the higher stress of screw-rods system and also the lowest stress of cage. In all moments, the maximum stresses of the cages were lower than their yield stress. Conclusions. Three screw fixations can highly restrict the surgical functional spinal unit (FSU). PTVS provided the better stability than the other two screw fixations. It may be a good choice for OL-LIF.

scholarly journals Biomechanical Evaluation of Anterolateral Screw Fixation for Oblique Lumbar Interbody Fusion Surgery – A Finite Element Analysis

2020 ◽  
Author(s):  
gufang Fang ◽  
SG Chen ◽  
wda zhuang ◽  
WH Huang ◽  
Hongxun Sang
Keyword(s):  
Finite Element ◽  
Interbody Fusion ◽  
Screw Fixation ◽  
Upper Body ◽  
Lumbar Interbody Fusion ◽  
Element Analysis ◽  
Flexion Extension ◽  
Cage Subsidence ◽  
Oblique Lumbar Interbody Fusion ◽  
Maximum Stresses

Abstract Background: The most common complication of oblique lumbar interbody fusion (OLIF) is cage subsidence. OLIF combined with internal fixation could help decrease the cage subsidence and increase the fusion rate. The aim of this study was to evaluate the biomechanical feasibility and safety in the patients undergoing OLIF surgery with anterolateral screw fixation (ASF). Methods: Based on our previous validated model , L4-L5 functional surgical models corresponding to the ASF and Bilateral pedicle screw fixation(BPSF) methods were created. A 500 N compression force was applied to the superior surface of the model to represent the upper body weight, and a 7.5 Nm moment was applied to simulate the six movement directions of the lumbar spinal model: flexion/extension, right/left lateral bending and right/left axial rotation. Finite element (FE) models were developed to compare the biomechanics of the ASF and BPSF groups. Results: Compared to the range of motion (ROM) of the intact lumbar model, that of the ASF model was decreased by 82.0% in flexion, 60.0% in extension, and the BPSF model was decreased by 86.7% in flexion, 77.3% in extension. Compared to the BPSF model, the maximum stresses of the L4 inferior endplate (IEP) and L5 superior endplate (SEP) were greatly increased in the ASF model; The contact surface between vertebrae and screw (CSVS) in the ASF model produced nearly100% more stresses than the BPSF model in all moment .Conclusions: OLIF surgery with ASF could not reduce the maximum stresses on the endplate and CSVS, which may be a potential risk factor for cage subsidence and screw loosening.

scholarly journals Stress-strain distribution in intact L4-L5 vertebrae under the influence of physiological movements: A finite element (FE) investigation

2021 ◽  
Vol 1206 (1) ◽  
pp. 012024
Author(s):  
Devismita Sanjay ◽  
Neeraj Kumar ◽  
Souptick Chanda
Keyword(s):  
Finite Element ◽  
Strain Distribution ◽  
Analysis Data ◽  
Fe Model ◽  
Loading Conditions ◽  
Compression Load ◽  
Tetrahedral Elements ◽  
Functional Spinal Unit ◽  
Flexion Extension

Abstract This study is aimed at finding the stress and strain distribution in functional spinal unit of L4-L5 occurring due to physiological body movements under five loading conditions, namely compression, flexion, extension, lateral bending and torsion. To this purpose, 3D finite element (FE) model has been generated using 4-noded unstructured tetrahedral elements considered both for bones and intervertebral disc, and 1D tension-only spring elements for ligaments. The analyses were performed for a compression load of 500 N and for other load cases, a moment of 10 N-m along with a preload of 500 N was applied. The model was validated against in-vitro experimental data obtained from literature and FE analysis data for a range of motion (RoM) corresponding to various loading conditions. The highest stress was predicted in the case of torsion though the angular deformation was highest in case of flexion.

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