Biomechanical Analysis of a Long-Segment Fusion in a Lumbar Spine—A Finite Element Model Study

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Raghu N. Natarajan ◽  
Kei Watanabe ◽  
Kazuhiro Hasegawa
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Posterior Instrumentation ◽  
Spinal Instrumentation ◽  
Element Model ◽  
Biomechanical Analysis ◽  
Spinal Stabilization ◽  
Rod System ◽  
Fixation Techniques ◽  
Materials Used

Examine the biomechanical effect of material properties, geometric variables, and anchoring arrangements in a segmental pedicle screw with connecting rods spanning the entire lumbar spine using finite element models (FEMs). The objectives of this study are (1) to understand how different variables associated with posterior instrumentation affect the lumbar spine kinematics and stresses in instrumentation, (2) to compare the multidirectional stability of the spinal instrumentation, and (3) to determine how these variables contribute to the rigidity of the long-segment fusion in a lumbar spine. A lumbar spine FEM was used to analyze the biomechanical effects of different materials used for spinal rods (TNTZ or Ti or CoCr), varying diameters of the screws and rods (5 mm and 6 mm), and different fixation techniques (multilevel or intermittent). The results based on the range of motion and stress distribution in the rods and screws revealed that differences in properties and variations in geometry of the screw-rod moderately affect the biomechanics of the spine. Further, the spinal screw-rod system was least stable under the lateral bending mode. Stress analyzes of the screws and rods revealed that the caudal section of the posterior spinal instrumentation was more susceptible to high stresses and hence possible failure. Although CoCr screws and rods provided the greatest spinal stabilization, these constructs were susceptible to fatigue failure. The findings of the present study suggest that a posterior instrumentation system with a 5-mm screw-rod diameter made of Ti or TNTZ is advantageous over CoCr instrumentation system.

scholarly journals Development of a Detailed Volumetric Finite Element Model of the Spine to Simulate Surgical Correction of Spinal Deformities

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Mark Driscoll ◽  
Jean-Marc Mac-Thiong ◽  
Hubert Labelle ◽  
Stefan Parent
Keyword(s):  
Finite Element ◽  
Intervertebral Disc ◽  
Finite Element Model ◽  
Ex Vivo ◽  
Spinal Instrumentation ◽  
Element Model ◽  
Patient Data ◽  
Biomechanical Analysis ◽  
Published Data

A large spectrum of medical devices exists; it aims to correct deformities associated with spinal disorders. The development of a detailed volumetric finite element model of the osteoligamentous spine would serve as a valuable tool to assess, compare, and optimize spinal devices. Thus the purpose of the study was to develop and initiate validation of a detailed osteoligamentous finite element model of the spine with simulated correction from spinal instrumentation. A finite element of the spine from T1 to L5 was developed using properties and geometry from the published literature and patient data. Spinal instrumentation, consisting of segmental translation of a scoliotic spine, was emulated. Postoperative patient and relevant published data of intervertebral disc stress, screw/vertebra pullout forces, and spinal profiles was used to evaluate the models validity. Intervertebral disc and vertebral reaction stresses respected publishedin vivo,ex vivo, andin silicovalues. Screw/vertebra reaction forces agreed with accepted pullout threshold values. Cobb angle measurements of spinal deformity following simulated surgical instrumentation corroborated with patient data. This computational biomechanical analysis validated a detailed volumetric spine model. Future studies seek to exploit the model to explore the performance of corrective spinal devices.

scholarly journals Biomechanical analysis of a newly developed interspinous process device conjunction with interbody cage based on a finite element model

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243771
Author(s):  
In-Suk Bae ◽  
Koang-Hum Bak ◽  
Hyoung-Joon Chun ◽  
Je Il Ryu ◽  
Sung-Jae Park ◽  
...  
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Finite Element Model ◽  
Element Model ◽  
Axial Rotation ◽  
Biomechanical Analysis ◽  
Interbody Cage ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Interspinous Process Device

Purpose This study aimed to investigate the biomechanical effects of a newly developed interspinous process device (IPD), called TAU. This device was compared with another IPD (SPIRE) and the pedicle screw fixation (PSF) technique at the surgical and adjacent levels of the lumbar spine. Materials and methods A three-dimensional finite element model analysis of the L1-S1 segments was performed to assess the biomechanical effects of the proposed IPD combined with an interbody cage. Three surgical models—two IPD models (TAU and SPIRE) and one PSF model—were developed. The biomechanical effects, such as range of motion (ROM), intradiscal pressure (IDP), disc stress, and facet loads during extension were analyzed at surgical (L3-L4) and adjacent levels (L2-L3 and L4-L5). The study analyzed biomechanical parameters assuming that the implants were perfectly fused with the lumbar spine. Results The TAU model resulted in a 45%, 49%, 65%, and 51% decrease in the ROM at the surgical level in flexion, extension, lateral bending, and axial rotation, respectively, when compared to the intact model. Compared to the SPIRE model, TAU demonstrated advantages in stabilizing the surgical level, in all directions. In addition, the TAU model increased IDP at the L2-L3 and L4-L5 levels by 118.0% and 78.5% in flexion, 92.6% and 65.5% in extension, 84.4% and 82.3% in lateral bending, and 125.8% and 218.8% in axial rotation, respectively. Further, the TAU model exhibited less compensation at adjacent levels than the PSF model in terms of ROM, IDP, disc stress, and facet loads, which may lower the incidence of the adjacent segment disease (ASD). Conclusion The TAU model demonstrated more stabilization at the surgical level than SPIRE but less stabilization than the PSF model. Further, the TAU model demonstrated less compensation at adjacent levels than the PSF model, which may lower the incidence of ASD in the long term. The TAU device can be used as an alternative system for treating degenerative lumbar disease while maintaining the physiological properties of the lumbar spine and minimizing the degeneration of adjacent segments.

Rolling Resistance Calculation Procedure Using the Finite Element Method

2019 ◽  
Vol 48 (3) ◽  
pp. 224-248
Author(s):  
Pablo N. Zitelli ◽  
Gabriel N. Curtosi ◽  
Jorge Kuster
Keyword(s):  
Finite Element ◽  
Energy Dissipation ◽  
Rolling Resistance ◽  
Element Model ◽  
The Finite Element Method ◽  
Temperature Changes ◽  
Rubber Compounds ◽  
Different Temperatures ◽  
Materials Used ◽  
Account Temperature

ABSTRACT Tire engineers are interested in predicting rolling resistance using tools such as numerical simulation and tests. When a car is driven along, its tires are subjected to repeated deformation, leading to energy dissipation as heat. Each point of a loaded tire is deformed as the tire completes a revolution. Most energy dissipation comes from the cyclic loading of the tire, which causes the rolling resistance in addition to the friction force in the contact patch between the tire and road. Rolling resistance mainly depends on the dissipation of viscoelastic energy of the rubber materials used to manufacture the tires. To obtain a good rolling resistance, the calculation method of the tire finite element model must take into account temperature changes. It is mandatory to calibrate all of the rubber compounds of the tire at different temperatures and strain frequencies. Linear viscoelasticity is used to model the materials properties and is found to be a suitable approach to tackle energy dissipation due to hysteresis for rolling resistance calculation.

scholarly journals Biomechanical characteristics of tibio-femoral joint after partial medial meniscectomy in different flexion angles: a finite element analysis

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xiaohui Zhang ◽  
Shuo Yuan ◽  
Jun Wang ◽  
Bagen Liao ◽  
De Liang
Keyword(s):  
Finite Element ◽  
Articular Cartilage ◽  
Finite Element Model ◽  
Medial Meniscus ◽  
Lateral Meniscus ◽  
Element Model ◽  
Magnetic Resonance Images ◽  
Biomechanical Analysis ◽  
Joint Stress ◽  
Tibiofemoral Joint

Abstract Background Recent studies have pointed out that arthroscopy, the commonly-used surgical procedure for meniscal tears, may lead to an elevated risk of knee osteoarthritis (KOA). The biomechanical factors of KOA can be clarified by the biomechanical analysis after arthroscopic partial meniscectomy (APM). This study aimed to elucidate the cartilage stress and meniscus displacement of the tibiofemoral joint under flexion and rotation loads after APM. Methods A detailed finite element model of the knee bone, cartilage, meniscus, and major ligaments was established by combining computed tomography and magnetic resonance images. Vertical load and front load were applied to simulate different knee buckling angles. At the same time, by simulating flexion of different degrees and internal and external rotations, the stresses on tibiofemoral articular cartilage and meniscus displacement were evaluated. Results Generally, the contact stress on both the femoral tibial articular cartilage and the meniscus increased with the increased flexion degree. Moreover, the maximum stress on the tibial plateau gradually moved backward. The maximum position shift value of the lateral meniscus was larger than that of the medial meniscus. Conclusion Our finite element model provides a realistic three-dimensional model to evaluate the influence of different joint range of motion and rotating tibiofemoral joint stress distribution. The decreased displacement of the medial meniscus may explain the higher pressure on the knee components. These characteristics of the medial tibiofemoral joint indicate the potential biomechanical risk of knee degeneration.

Biomechanical Effect of Lumbar Disc Degeneration Under Flexion/Extension: A Finite Element Model Study

2007 ◽  
Author(s):  
Lissette M. Ruberté ◽  
Raghu Natarajan ◽  
Gunnar B. J. Andersson
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Finite Element Model ◽  
Disc Degeneration ◽  
Pathological Condition ◽  
Lumbar Disc ◽  
Element Model ◽  
Adjacent Segment ◽  
Lumbar Disc Degeneration ◽  
Flexion Extension

Degenerative disc disease (DDD) is a progressive pathological condition observed in 60 to 80% of the population [1]. It involves changes in both the biochemistry and morphology of the intervertebral disc and is associated with chronic low back pain, sciatica and adult scoliosis [2,3]. The most accepted theory of the effects of DDD on the kinematics of the spine is that proposed by Kirkaldy-Willis and Farfan which states that the condition initiates as a temporary dysfunction, followed by instability and then re-stabilization as the disease progresses [4]. Although there is no clear relationship between disc degeneration and the mechanical behavior of the lumbar spine, abnormal motion patterns either in the form of increased motion or erratic motion have been reported from studies on human cadaveric motion segments [5,6]. To date however no study has looked at how disc degeneration affects the adjacent segment mechanics. IN vivo testing is difficult for these purposes given that specimens are generally obtained from people at the later stages of life and consequently often display multiple pathologies. A finite element model is a viable alternative to study the mechanics of the segments adjacent to the diseased disc. It is hypothesized that moderate degeneration at one level will alter the kinematics of the whole lumbar spine.

Investigation of Lumbosacral Spine Anatomical Variation Effect on Load-Partitioning Under Follower Load Using Geometrically Personalized Finite Element Model

2014 ◽  
Author(s):  
Sadegh Naserkhaki ◽  
Jacob L. Jaremko ◽  
Greg Kawchuk ◽  
Samer Adeeb ◽  
Marwan El-Rich
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Anatomical Variation ◽  
Load Sharing ◽  
Element Model ◽  
Collagen Fibers ◽  
Spinal Curvature ◽  
Lumbosacral Spine ◽  
Follower Load ◽  
Spinal Load

The spinal load sharing and mechanical stresses developed in the spine segments due to mechanical loads are dependent on the unique spinal anatomy (geometry and posture). Variation in spinal curvature alters the load sharing of the lumbar spine as well as the stiffness and stability of the passive tissues. In this paper, effects of lumbar spine curvature variation on spinal load sharing under compressive Follower Load (FL) are investigated numerically. 3D nonlinear Finite Element (FE) models of three ligamentous lumbosacral spines are developed based on personalized geometries; hypo-lordotic (Hypo-L), normal (Normal-L) and hyper-lordotic (Hyper-L) cases. Analysis of each model is performed under Follower Load and developed stress in the discs and forces in the collagen fibers are investigated. Stresses on the discs vary in magnitude and distribution depending on the degree of lordosis. A straight hypo-lordotic spine shows stresses more equally distributed among discs while a highly curved hyper-lordotic spine has stresses concentrated at lower discs. Stresses are uniformly distributed in each disc for Hypo-L case while they are concentrated posteriorly for Hyper-L case. Also, the maximum force in collagen fibers is developed in the Hyper-L case. These differences might be clinically significant related to back pain.

A Biomechanical Model of Lumbar Spine

2000 ◽  
Author(s):  
Subramanya Uppala ◽  
Robert X. Gao ◽  
Scott Cowan ◽  
K. Francis Lee
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Biomechanical Model ◽  
Element Model ◽  
Fe Model ◽  
Flexion Extension ◽  
Cortical Shell ◽  
Three Dimensional Finite Element

Abstract The strength and stability of the lumbar spine are determined not only by the bone and muscles, but also by the visco-elastic structures and the interplay between the different components of the spine, such as ligaments, capsules, annulus fibrosis, and articular cartilage. In this paper we present a non-linear three-dimensional Finite Element model of the lumbar spine. Specifically, a three-dimensional FE model of the L4-5 one-motion segment/2 vertebrae was developed. The cortical shell and the cancellous bone of the vertebral body were modeled as 3D isoparametric eight-nodal elements. Finite element models of spinal injuries with fixation devices are also developed. The deformations across the different sections of the spine are observed under the application of axial compression, flexion/extension, and lateral bending. The developed FE models provided input to both the fixture design and experimental studies.

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