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Gruber G, Nicolini LF, Ribeiro M, Lerchl T, Wilke HJ, Jaramillo HE, Senner V, Kirschke JS, Nispel K. Comparative FEM study on intervertebral disc modeling: Holzapfel-Gasser-Ogden vs. structural rebars. Front Bioeng Biotechnol 2024; 12:1391957. [PMID: 38903189 PMCID: PMC11188472 DOI: 10.3389/fbioe.2024.1391957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 04/29/2024] [Indexed: 06/22/2024] Open
Abstract
Introduction: Numerical modeling of the intervertebral disc (IVD) is challenging due to its complex and heterogeneous structure, requiring careful selection of constitutive models and material properties. A critical aspect of such modeling is the representation of annulus fibers, which significantly impact IVD biomechanics. This study presents a comparative analysis of different methods for fiber reinforcement in the annulus fibrosus of a finite element (FE) model of the human IVD. Methods: We utilized a reconstructed L4-L5 IVD geometry to compare three fiber modeling approaches: the anisotropic Holzapfel-Gasser-Ogden (HGO) model (HGO fiber model) and two sets of structural rebar elements with linear-elastic (linear rebar model) and hyperelastic (nonlinear rebar model) material definitions, respectively. Prior to calibration, we conducted a sensitivity analysis to identify the most important model parameters to be calibrated and improve the efficiency of the calibration. Calibration was performed using a genetic algorithm and in vitro range of motion (RoM) data from a published study with eight specimens tested under four loading scenarios. For validation, intradiscal pressure (IDP) measurements from the same study were used, along with additional RoM data from a separate publication involving five specimens subjected to four different loading conditions. Results: The sensitivity analysis revealed that most parameters, except for the Poisson ratio of the annulus fibers and C01 from the nucleus, significantly affected the RoM and IDP outcomes. Upon calibration, the HGO fiber model demonstrated the highest accuracy (R2 = 0.95), followed by the linear (R2 = 0.89) and nonlinear rebar models (R2 = 0.87). During the validation phase, the HGO fiber model maintained its high accuracy (RoM R2 = 0.85; IDP R2 = 0.87), while the linear and nonlinear rebar models had lower validation scores (RoM R2 = 0.71 and 0.69; IDP R2 = 0.86 and 0.8, respectively). Discussion: The results of the study demonstrate a successful calibration process that established good agreement with experimental data. Based on our findings, the HGO fiber model appears to be a more suitable option for accurate IVD FE modeling considering its higher fidelity in simulation results and computational efficiency.
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Affiliation(s)
- Gabriel Gruber
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine and Health, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Luis Fernando Nicolini
- Department of Mechanical Engineering, Federal University of Santa Maria, Av. Santa Maria, Brazil
| | - Marx Ribeiro
- Department for Orthopedics, Trauma and Reconstructive Surgery, University Hospital RWTH Aachen, Aachen, Germany
- Department of Mechanical Engineering, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Tanja Lerchl
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine and Health, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- Associate Professorship of Sport Equipment and Sport Materials, School of Engineering and Design, Technical University of Munich, Garching, Germany
| | - Hans-Joachim Wilke
- Institute of Orthopaedic Research and Biomechanics, Trauma Research Centre Ulm, University of Ulm, Ulm, Germany
| | | | - Veit Senner
- Associate Professorship of Sport Equipment and Sport Materials, School of Engineering and Design, Technical University of Munich, Garching, Germany
| | - Jan S. Kirschke
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine and Health, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Kati Nispel
- Department of Diagnostic and Interventional Neuroradiology, School of Medicine and Health, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
- Associate Professorship of Sport Equipment and Sport Materials, School of Engineering and Design, Technical University of Munich, Garching, Germany
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Dong R, Zhu S, Cheng X, Gao X, Wang Z, Wang Y. Study on the biodynamic characteristics and internal vibration behaviors of a seated human body under biomechanical characteristics. Biomech Model Mechanobiol 2024:10.1007/s10237-024-01849-z. [PMID: 38671153 DOI: 10.1007/s10237-024-01849-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 04/07/2024] [Indexed: 04/28/2024]
Abstract
To provide reference and theoretical guidance for establishing human body dynamics models and studying biomechanical vibration behavior, this study aimed to develop and verify a computational model of a three-dimensional seated human body with detailed anatomical structure under complex biomechanical characteristics to investigate dynamic characteristics and internal vibration behaviors of the human body. Fifty modes of a seated human body were extracted by modal method. The intervertebral disc and head motions under uniaxial white noise excitation (between 0 and 20 Hz at 1.0, 0.5 and 0.5 m/s2 r.m.s. for vertical, fore-aft and lateral direction, respectively) were computed by random response analysis method. It was found that there were many modes of the seated human body in the low-frequency range, and the modes that had a great impact on seated human vibration were mainly distributed below 13 Hz. The responses of different positions of the spine varied greatly under the fore-aft and lateral excitation, but the maximum stress was distributed in the lumbar under different excitations, which could explain why drivers were prone to lower back pain after prolonged driving. Moreover, there was a large vibration coupling between the vertical and fore-aft direction of an upright seated human body, while the vibration couplings between the lateral and other directions were very small. Overall, the study could provide new insights into not only the overall dynamic characteristics of the human body, but also the internal local motion and biomechanical characteristics under different excitations.
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Affiliation(s)
- RuiChun Dong
- School of Mechanical Engineering, Shandong University of Technology, Zibo, 255000, People's Republic of China.
| | - Shuai Zhu
- School of Mechanical Engineering, Shandong University of Technology, Zibo, 255000, People's Republic of China
| | - Xiang Cheng
- School of Mechanical Engineering, Shandong University of Technology, Zibo, 255000, People's Republic of China
| | - Xiang Gao
- School of Mechanical Engineering, Shandong University of Technology, Zibo, 255000, People's Republic of China
| | - ZhongLong Wang
- School of Mechanical Engineering, Shandong University of Technology, Zibo, 255000, People's Republic of China
| | - Yi Wang
- School of Chemical Engineering, University of Birmingham, Birmingham, B15 2TT, UK
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Ardatov O, Pachaleva J, Aleksiuk V, Maknickas A, Uzieliene I, Vaiciuleviciute R, Bernotiene E. Modeling the Effect of Annulus Fibrosus Stiffness on the Stressed State of a Vertebral L1 Body and Nucleus Pulposus. Bioengineering (Basel) 2024; 11:305. [PMID: 38671727 PMCID: PMC11047532 DOI: 10.3390/bioengineering11040305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/28/2024] Open
Abstract
The investigation examines the transference of stiffness from intervertebral discs (IVDs) to the lumbar body of the L1 vertebra and the interactions among adjacent tissues. A computational model of the vertebra was developed, considering parameters such as cortical bone thickness, trabecular bone elasticity, and the nonlinear response of the nucleus pulposus to external loading. A nonlinear dynamic analysis was performed, revealing certain trends: a heightened stiffness of the annulus fibrosus correlates with a significant reduction in the vertebral body's ability to withstand external loading. At a supplied displacement of 6 mm, the vertebra with a degenerative disc reached its yielding point, whereas the vertebrae with a healthy annulus fibrosus exhibited a strength capacity exceeding 20%. The obtained findings and proposed methodology are potentially useful for biomedical engineers and clinical specialists in evaluating the condition of the annulus fibrosus and predicting its influence on the bone components of the spinal system.
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Affiliation(s)
- Oleg Ardatov
- Faculty of Mechanics, Vilnius Gediminas Technical University, LT-10223 Vilnius, Lithuania;
| | - Jolita Pachaleva
- Department of Regenerative Medicine, State Research Institute Centre for Innovative Medicine, LT-08410 Vilnius, Lithuania; (J.P.); (V.A.); (I.U.); (R.V.); (E.B.)
| | - Viktorija Aleksiuk
- Department of Regenerative Medicine, State Research Institute Centre for Innovative Medicine, LT-08410 Vilnius, Lithuania; (J.P.); (V.A.); (I.U.); (R.V.); (E.B.)
| | - Algirdas Maknickas
- Faculty of Mechanics, Vilnius Gediminas Technical University, LT-10223 Vilnius, Lithuania;
| | - Ilona Uzieliene
- Department of Regenerative Medicine, State Research Institute Centre for Innovative Medicine, LT-08410 Vilnius, Lithuania; (J.P.); (V.A.); (I.U.); (R.V.); (E.B.)
| | - Raminta Vaiciuleviciute
- Department of Regenerative Medicine, State Research Institute Centre for Innovative Medicine, LT-08410 Vilnius, Lithuania; (J.P.); (V.A.); (I.U.); (R.V.); (E.B.)
| | - Eiva Bernotiene
- Department of Regenerative Medicine, State Research Institute Centre for Innovative Medicine, LT-08410 Vilnius, Lithuania; (J.P.); (V.A.); (I.U.); (R.V.); (E.B.)
- Faculty of Fundamental Sciences, Vilnius Gediminas Technical University, LT-10221 Vilnius, Lithuania
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Remus R, Selkmann S, Lipphaus A, Neumann M, Bender B. Muscle-driven forward dynamic active hybrid model of the lumbosacral spine: combined FEM and multibody simulation. Front Bioeng Biotechnol 2023; 11:1223007. [PMID: 37829567 PMCID: PMC10565495 DOI: 10.3389/fbioe.2023.1223007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 09/05/2023] [Indexed: 10/14/2023] Open
Abstract
Most spine models belong to either the musculoskeletal multibody (MB) or finite element (FE) method. Recently, coupling of MB and FE models has increasingly been used to combine advantages of both methods. Active hybrid FE-MB models, still rarely used in spine research, avoid the interface and convergence problems associated with model coupling. They provide the inherent ability to account for the full interplay of passive and active mechanisms for spinal stability. In this paper, we developed and validated a novel muscle-driven forward dynamic active hybrid FE-MB model of the lumbosacral spine (LSS) in ArtiSynth to simultaneously calculate muscle activation patterns, vertebral movements, and internal mechanical loads. The model consisted of the rigid vertebrae L1-S1 interconnected with hyperelastic fiber-reinforced FE intervertebral discs, ligaments, facet joints, and force actuators representing the muscles. Morphological muscle data were implemented via a semi-automated registration procedure. Four auxiliary bodies were utilized to describe non-linear muscle paths by wrapping and attaching the anterior abdominal muscles. This included an abdominal plate whose kinematics was optimized using motion capture data from upper body movements. Intra-abdominal pressure was calculated from the forces of the abdominal muscles compressing the abdominal cavity. For the muscle-driven approach, forward dynamics assisted data tracking was used to predict muscle activation patterns that generate spinal postures and balance the spine without prescribing accurate spinal kinematics. During calibration, the maximum specific muscle tension and spinal rhythms resulting from the model dynamics were evaluated. To validate the model, load cases were simulated from -10° extension to +30° flexion with weights up to 20 kg in both hands. The biomechanical model responses were compared with in vivo literature data of intradiscal pressures, intra-abdominal pressures, and muscle activities. The results demonstrated high agreement with this data and highlight the advantages of active hybrid modeling for the LSS. Overall, this new self-contained tool provides a robust and efficient estimation of LSS biomechanical responses under in vivo similar loads, for example, to improve pain treatment by spinal stabilization therapies.
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Affiliation(s)
- Robin Remus
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
| | - Sascha Selkmann
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
| | - Andreas Lipphaus
- Biomechanics Research Group, Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
| | - Marc Neumann
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
| | - Beate Bender
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
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5
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Hao J, Tang X, Jiang N, Wang H, Jiang J. Biomechanical stability of oblique lateral interbody fusion combined with four types of internal fixations: finite element analysis. Front Bioeng Biotechnol 2023; 11:1260693. [PMID: 37818236 PMCID: PMC10561304 DOI: 10.3389/fbioe.2023.1260693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 09/04/2023] [Indexed: 10/12/2023] Open
Abstract
Objective: Using finite element analysis to identify the optimal internal fixation method for oblique lateral lumbar interbody fusion (OLIF), providing guidance for clinical practice. Methods: A finite element model of the L4 - L5 segment was created. Five types of internal fixations were simulated in the generated L4-L5 finite element (FE) model. Then, six loading scenarios, i.e., flexion, extension, left-leaning, right-leaning, rotate left, and rotate right, were simulated in the FE models with different types of fixations. The biomechanical stability of the spinal segment after different fixations was investigated. Results: Regarding the range of motion (ROM) of the fused segment, OLIF + Bilateral Pedicle Screws (BPS) has a maximum ROM of 1.82° during backward bending and the smallest ROM in all directions of motion compared with other models. In terms of the von Mises stress distribution on the cage, the average stress on every motion direction of OLIF + BPS is about 17.08MPa, and of OLIF + Unilateral Vertebral Screw - Pedicle Screw (UVS-PS) is about 19.29 MPa. As for the von Mises stress distribution on the internal fixation, OLIF + BPS has the maximum internal fixator stress in left rotation (31.85 MPa) and OLIF + Unilateral Pedicle Screw (UPS) has the maximum internal fixator stress in posterior extension (76.59 MPa). The data of these two models were smaller than those of other models. Conclusion: OLIF + BPS provides the greatest biomechanical stability, OLIF + UPS has adequate biomechanical stability, OLIF + UVS-PS is inferior to OLIF + UPS synthetically, and OLIF + Double row vertical screw (DRVS) and Individual OLIF (IO) do not present significant obvious advantages.
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Affiliation(s)
- Jiayu Hao
- Department of Spine Surgery, Dalian Municipal Central Hospital, Dalian University of Technology, Dalian, China
| | - XianSheng Tang
- Department of Engineering Mechanics, Dalian University of Technology, Dalian, China
| | - Nizhou Jiang
- Department of Spine Surgery, Dalian Municipal Central Hospital, Dalian University of Technology, Dalian, China
| | - Hong Wang
- Department of Spine Surgery, Dalian Municipal Central Hospital, Dalian University of Technology, Dalian, China
| | - Jian Jiang
- Department of Spine Surgery, Dalian Municipal Central Hospital, Dalian University of Technology, Dalian, China
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6
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Dong R, Tang S, Cheng X, Wang Z, Zhang P, Wei Z. Influence of foot excitation and shin posture on the vibration behavior of the entire spine inside a seated human body. Comput Methods Biomech Biomed Engin 2023:1-16. [PMID: 37668064 DOI: 10.1080/10255842.2023.2252956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 07/28/2023] [Accepted: 08/17/2023] [Indexed: 09/06/2023]
Abstract
Due to ethical issues and simplification of traditional biomechanical models, experimental methods and traditional computer methods were difficult to quantify the effects of foot excitation and shin posture on vibration behavior of the entire spine inside a seated human body under vertical whole-body vibration. This study developed and verified different three-dimensional (3D) finite element (FE) models of seated human body with detailed anatomical structure under the biomechanical characteristics to predict vibration behavior of the entire spine inside a seated human body with different foot excitation (with and without vibration) and shin posture (vertical and tilt posture). Random response analysis was performed to study the transmissibility of the entire spine to seat under vertical white noise excitation between 0 and 20 Hz at 0.5 m/s2 r.m.s. The results showed that although the foot excitation could reduce the fore-aft transmissibility in the cervical spine (23% reduction), it could significantly increase that in the lumbar spine (52% increase), which resulted in complex alternating stresses at lumbar spine and made the lumbar spine more vulnerable to injury in long-term vibration environment. Moreover, the shin tilt posture made the maximum fore-aft transmissibility in the lumbar spine move to the upper lumbar spine. The study provided new insights into the influence of foot excitation and shin posture on the vibration behavior of the entire spine inside a seated human body. Foot excitation exposed the lumbar spine to complex alternating stresses and made it more vulnerable to injury in long-term whole body vibration.
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Affiliation(s)
- RuiChun Dong
- School of Mechanical Engineering, Shandong University of Technology, Zibo, P.R. China
| | - ShengJie Tang
- School of Mechanical Engineering, Shandong University of Technology, Zibo, P.R. China
| | - Xiang Cheng
- School of Mechanical Engineering, Shandong University of Technology, Zibo, P.R. China
| | - ZongLiang Wang
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, P.R. China
| | - PeiBiao Zhang
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, P.R. China
| | - Zheng Wei
- School of Mechanical Engineering, Shandong University of Technology, Zibo, P.R. China
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Mordechai HS, Aharonov A, Sharon SE, Bonshtein I, Simon C, Sivan SS, Sharabi M. Toward a mechanically biocompatible intervertebral disc: Engineering of combined biomimetic annulus fibrosus and nucleus pulposus analogs. J Biomed Mater Res A 2023; 111:618-633. [PMID: 36815687 DOI: 10.1002/jbm.a.37519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 02/09/2023] [Accepted: 02/11/2023] [Indexed: 02/24/2023]
Abstract
Intervertebral disc (IVD) degeneration and accompanying lower back pain impose global medical and societal challenges, affecting over 600 million people worldwide. The IVD complex fibrocartilaginous structure is responsible for the spine biomechanical function. The nucleus pulposus (NP), composed of swellable glycosaminoglycan (GAG), transfers compressive loads to the surrounding fiber-reinforced annulus fibrosus (AF) lamellae, which stretches under tension. Together, these substructures allow the IVD to withstand extremely high and complex loads. Key to mimic the complete disc must consider the properties of its substructures. This study presents three novel substructures-a biomimetic silk-reinforced composite lamella for the AF, a GAG analog for the NP, and a novel biomimetic combined AF-NP construct. The biomimetic AF demonstrates nonlinear, hyperelastic, and anisotropic behavior similar to the native human AF, while the NP analog demonstrates mechanical behavior similar to the human NP. The synergized biomimetic AF-NP demonstrates similar behavior to the unconfined NP, with significantly increased deformations indicating improved performance. Validation of the AF-NP construct mechanics using a finite element model yields results compatible with native human IVD under various physiological loadings. The ability of our AF-NP construct to mimic the native IVD offers a revolutionary concept for the potential development of a fully functional IVD.
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Affiliation(s)
- Haim S Mordechai
- Department of Mechanical Engineering & Mechatronics, Ariel University, Ariel, Israel
| | - Adi Aharonov
- Department of Mechanical Engineering & Mechatronics, Ariel University, Ariel, Israel
| | - Smadar E Sharon
- Department of Mechanical Engineering & Mechatronics, Ariel University, Ariel, Israel
| | - Iris Bonshtein
- Department of Biotechnology Engineering, Braude College of Engineering, Karmiel, Israel
| | - Chen Simon
- Department of Biotechnology Engineering, Braude College of Engineering, Karmiel, Israel
| | - Sarit S Sivan
- Department of Biotechnology Engineering, Braude College of Engineering, Karmiel, Israel
| | - Mirit Sharabi
- Department of Mechanical Engineering & Mechatronics, Ariel University, Ariel, Israel
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8
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Biomechanical and clinical studies on lumbar spine fusion surgery: a review. Med Biol Eng Comput 2023; 61:617-634. [PMID: 36598676 DOI: 10.1007/s11517-022-02750-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 12/22/2022] [Indexed: 01/05/2023]
Abstract
Low back pain is associated with degenerative disc diseases of the spine. Surgical treatment includes fusion and non-fusion types. The gold standard is fusion surgery, wherein the affected vertebral segment is fused. The common complication of fusion surgery is adjacent segment degeneration (ASD). The ASD often leads to revision surgery, calling for a further fusion of adjacent segments. The existing designs of nonfusion type implants are associated with clinical problems such as subsidence, difficulty in implantation, and the requirement of revision surgeries. Various surgical approaches have been adopted by the surgeons to insert the spinal implants into the affected segment. Over the years, extensive biomechanical investigations have been reported on various surgical approaches and prostheses to predict the outcomes of lumbar spine implantations. Computer models have been proven to be very effective in identifying the best prosthesis and surgical procedure. The objective of the study was to review the literature on biomechanical studies for the treatment of lumbar spinal degenerative diseases. A critical review of the clinical and biomechanical studies on fusion spine surgeries was undertaken. The important modeling parameters, challenges, and limitations of the current studies were identified, showing the future research directions.
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9
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Kassab-Bachi A, Ravikumar N, Wilcox RK, Frangi AF, Taylor ZA. Contribution of Shape Features to Intradiscal Pressure and Facets Contact Pressure in L4/L5 FSUs: An In-Silico Study. Ann Biomed Eng 2023; 51:174-188. [PMID: 36104641 PMCID: PMC9831962 DOI: 10.1007/s10439-022-03072-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 08/27/2022] [Indexed: 02/01/2023]
Abstract
Finite element models (FEMs) of the spine commonly use a limited number of simplified geometries. Nevertheless, the geometric features of the spine are important in determining its FEM outcomes. The link between a spinal segment's shape and its biomechanical response has been studied, but the co-variances of the shape features have been omitted. We used a principal component (PCA)-based statistical shape modelling (SSM) approach to investigate the contribution of shape features to the intradiscal pressure (IDP) and the facets contact pressure (FCP) in a cohort of synthetic L4/L5 functional spinal units under axial compression. We quantified the uncertainty in the FEM results, and the contribution of individual shape modes to these results. This parameterisation approach is able to capture the variability in the correlated anatomical features in a real population and sample plausible synthetic geometries. The first shape mode ([Formula: see text]) explained 22.6% of the shape variation in the subject-specific cohort used to train the SSM, and had the largest correlation with, and contribution to IDP (17%) and FCP (11%). The largest geometric variation in ([Formula: see text]) was in the annulus-nucleus ratio.
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Affiliation(s)
- Amin Kassab-Bachi
- grid.9909.90000 0004 1936 8403Institute of Medical and Biological Engineering (iMBE), School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT UK ,grid.9909.90000 0004 1936 8403Centre for Computational Imaging & Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds, Leeds, LS2 9BW UK
| | - Nishant Ravikumar
- grid.9909.90000 0004 1936 8403Centre for Computational Imaging & Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds, Leeds, LS2 9BW UK
| | - Ruth K. Wilcox
- grid.9909.90000 0004 1936 8403Institute of Medical and Biological Engineering (iMBE), School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT UK
| | - Alejandro F. Frangi
- grid.9909.90000 0004 1936 8403Centre for Computational Imaging & Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds, Leeds, LS2 9BW UK ,grid.9909.90000 0004 1936 8403Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds, LS2 9JT UK
| | - Zeike A. Taylor
- grid.9909.90000 0004 1936 8403Institute of Medical and Biological Engineering (iMBE), School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT UK ,grid.9909.90000 0004 1936 8403Centre for Computational Imaging & Simulation Technologies in Biomedicine (CISTIB), School of Computing, University of Leeds, Leeds, LS2 9BW UK
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Nicolini LF, Beckmann A, Laubach M, Hildebrand F, Kobbe P, Mello Roesler CRD, Fancello EA, Markert B, Stoffel M. An experimental-numerical method for the calibration of finite element models of the lumbar spine. Med Eng Phys 2022; 107:103854. [DOI: 10.1016/j.medengphy.2022.103854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 05/18/2022] [Accepted: 07/18/2022] [Indexed: 11/27/2022]
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11
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Comparison of the biomechanical performance of three spinal implants for treating the wedge-shaped burst fractures. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2022. [DOI: 10.1016/j.medntd.2021.100109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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12
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Fasser MR, Kuravi R, Bulla M, Snedeker JG, Farshad M, Widmer J. A novel approach for tetrahedral-element-based finite element simulations of anisotropic hyperelastic intervertebral disc behavior. Front Bioeng Biotechnol 2022; 10:1034441. [PMID: 36582835 PMCID: PMC9792499 DOI: 10.3389/fbioe.2022.1034441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/21/2022] [Indexed: 12/14/2022] Open
Abstract
Intervertebral discs are microstructurally complex spinal tissues that add greatly to the flexibility and mechanical strength of the human spine. Attempting to provide an adjustable basis for capturing a wide range of mechanical characteristics and to better address known challenges of numerical modeling of the disc, we present a robust finite-element-based model formulation for spinal segments in a hyperelastic framework using tetrahedral elements. We evaluate the model stability and accuracy using numerical simulations, with particular attention to the degenerated intervertebral discs and their likely skewed and narrowed geometry. To this end, 1) annulus fibrosus is modeled as a fiber-reinforced Mooney-Rivlin type solid for numerical analysis. 2) An adaptive state-variable dependent explicit time step is proposed and utilized here as a computationally efficient alternative to theoretical estimates. 3) Tetrahedral-element-based FE models for spinal segments under various loading conditions are evaluated for their use in robust numerical simulations. For flexion, extension, lateral bending, and axial rotation load cases, numerical simulations reveal that a suitable framework based on tetrahedral elements can provide greater stability and flexibility concerning geometrical meshing over commonly employed hexahedral-element-based ones for representation and study of spinal segments in various stages of degeneration.
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Affiliation(s)
- Marie-Rosa Fasser
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Ramachandra Kuravi
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, Zurich, Switzerland.,Engineering Division, Lawrence Berkeley National Lab, Berkeley, CA, United States
| | | | - Jess G Snedeker
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.,Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland
| | - Mazda Farshad
- Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland
| | - Jonas Widmer
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
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Sun PD, Zhang XX, Zhang YW, Wang Z, Wu XY, Wu YC, Yu XL, Gan HR, Liu XD, Ai ZZ, He JY, Dong XP. Stress analysis of the thoracolumbar junction in the process of backward fall: An experimental study and finite element analysis. Exp Ther Med 2021; 22:1117. [PMID: 34504571 PMCID: PMC8383768 DOI: 10.3892/etm.2021.10551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 04/21/2020] [Indexed: 11/05/2022] Open
Abstract
The aim of the present study was to evaluate the biomechanical mechanism of injuries of the thoracolumbar junction by the methods of a backward fall simulation experiment and finite element (FE) analysis (FEA). In the backward fall simulation experiment, one volunteer was selected to obtain the contact force data of the sacrococcygeal region during a fall. Utilizing the fall data, the FEA simulation of the backward fall process was given to the trunk FE model to obtain the stress status of local bone structures of the thoracolumbar junction during the fall process. In the fall simulation test, the sacrococcygeal region of the volunteer landed first; the total impact time was 1.14±0.58 sec, and the impact force was up to 4,056±263 N. The stress of thoracic (T)11 was as high as 42 MPa, that of the posterior margin and the junction of T11 was as high as 70.67 MPa, and that of the inferior articular process and the superior articular process was as high as 128 MPa. The average stress of T12 and the anterior margin of lumbar 1 was 25 MPa, and that of the endplate was as high as 21.7 MPa, which was mostly distributed in the back of the endplate and the surrounding cortex. According to the data obtained from the fall experiment as the loading condition of the FE model, the backward fall process can be simulated to improve the accuracy of FEA results. In the process of backward fall, the front edge of the vertebral body and the root of vertebral arch in the thoracolumbar junction are stress concentration areas, which have a greater risk of injury.
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Affiliation(s)
- Pei-Dong Sun
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China.,Department of Human Anatomy, Southern Medical University, Guangdong Key Laboratory of Medical Biomechanics, Guangzhou, Guangdong 510515, P.R. China
| | - Xiao-Xiang Zhang
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Yuan-Wei Zhang
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Zhe Wang
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Xiao-Yu Wu
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Yan-Chao Wu
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Xing-Liang Yu
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Hao-Ran Gan
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Xiang-Dong Liu
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Zi-Zheng Ai
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Jian-Ying He
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
| | - Xie-Ping Dong
- Department of Orthopedics, Jiangxi Provincial People's Hospital Affiliated to Nanchang University, Nanchang, Jiangxi 330006, P.R. China
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Fan W, Zhao D, Guo LX. A finite element model of the human lower thorax to pelvis spinal segment: Validation and modal analysis. Biomed Mater Eng 2021; 32:267-279. [PMID: 33998527 DOI: 10.3233/bme-196017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Several finite element (FE) models have been developed to study the effects of vibration on human lumbar spine. However, the authors know of no published results so far that have proposed computed tomography-based FE models of whole lumbar spine including the pelvis to conduct dynamic analysis. OBJECTIVE To create and validate a three-dimensional ligamentous FE model of the human lower thorax to pelvis spinal segment (T12-Pelvis) and provide a detailed simulation environment to investigate the dynamic characteristics of the lumbar spine under whole body vibration (WBV). METHODS The T12-Pelvis model was generated based on volume reconstruction from computed tomography scans and validated against the published experimental data. FE modal analysis was implemented to predict dynamic characteristics associated with the first-order vertical resonant frequency and vibration mode of the model with upper body mass of 40 kg under WBV. RESULTS It was found that the current FE model was validated and corresponded closely with the published data. The obtained results from the modal analysis indicated that the first-order vertical resonant frequency of the T12-Pelvis model was 6.702 Hz, and the lumbar spine mainly performed vertical motion with a small anteroposterior motion. It was also found that shifting the upper body mass centroid onwards or rearwards from the normal upright sitting posture reduced the vertical resonant frequency. CONCLUSIONS These findings may be helpful to better understand vibration response of the human spine, and provide important information to minimize injury and discomfort for these WBV-exposed occupational groups.
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Affiliation(s)
- Wei Fan
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, China
| | - Dan Zhao
- Liaoning University of Traditional Chinese Medicine, Shenyang, China.,Liaoning Special Education Teachers College, Shenyang, China
| | - Li-Xin Guo
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, China
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15
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Kandil K, Zaïri F, Messager T, Zaïri F. A microstructure-based model for a full lamellar-interlamellar displacement and shear strain mapping inside human intervertebral disc core. Comput Biol Med 2021; 135:104629. [PMID: 34274895 DOI: 10.1016/j.compbiomed.2021.104629] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/02/2021] [Accepted: 07/02/2021] [Indexed: 12/30/2022]
Abstract
The determinant role of the annulus fibrosus interlamellar zones in the intervertebral disc transversal and volumetric responses and hence on their corresponding three-dimensional conducts have been only revealed and appreciated recently. Their consideration in disc modeling strategies has been proven to be essential for the reproduction of correct local strain and displacement fields inside the disc especially in the unconstrained directions of the disc. In addition, these zones are known to be the starting areas of annulus fibrosus circumferential tears and disc delamination failure mode, which is often judged as one of the most dangerous disc failure modes that could evolve with time leading to disc hernia. For this latter reason, the main goal of the current contribution is to incorporate physically for the first time, the interlamellar zones, at the scale of a complete human lumbar intervertebral disc, in order to allow a correct local vision and replication of the different lamellar-interlamellar interactions and an identification of the interlamellar critical zones. By means of a fully tridimensional chemo-viscoelastic constitutive model, which we implemented into a finite element code, the physical, mechanical and chemical contribution of the interlamellar zones is added to the disc. The chemical-induced volumetric response is accounted by the model for both the interlamellar zones and the lamellae using experimentally-based fluid kinetics. Computational simulations are performed and critically discussed upon different simple and complex physiological movements. The disc core and the interlamellar zones are numerically accessed, allowing the observation of the displacement and shear strain fields that are compared to direct MRI experiments from the literature. Important conclusions about the correct lamellar-interlamellar-nucleus interactions are provided thanks to the developed model. The critical interlamellar spots with the highest delamination potentials are defined, analyzed and related to the local kinetics and microstructure.
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Affiliation(s)
- Karim Kandil
- ICAM Site de Lille, 6 Rue Auber, 59016, Lille, France; Univ. Lille, IMT Lille Douai, Univ. Artois, JUNIA, ULR 4515 - LGCgE, Laboratoire de Génie Civil et géo-Environnement, 59000, Lille, France
| | - Fahmi Zaïri
- Univ. Lille, IMT Lille Douai, Univ. Artois, JUNIA, ULR 4515 - LGCgE, Laboratoire de Génie Civil et géo-Environnement, 59000, Lille, France.
| | - Tanguy Messager
- Univ. Lille, Unité de Mécanique de Lille (EA 7572 UML), 59000, Lille, France
| | - Fahed Zaïri
- Ramsay Générale de Santé, Hôpital Privé Le Bois, 59000, Lille, France
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16
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Lu Y, Cheng L, Zhu H. Influence of nucleotomy on the load sharing in the spinal facet joint under the loading scenarios of different human postures. Med Eng Phys 2021; 93:35-41. [PMID: 34154773 DOI: 10.1016/j.medengphy.2021.05.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 03/02/2021] [Accepted: 05/25/2021] [Indexed: 10/21/2022]
Abstract
One-in-five people suffer from chronic low back pain (LBP). The incidence of this disease has doubled since 1950s and affects not only the elderly, but also the young population. However, the mechanism of LBP is still unknown. A possible location where the LBP may develop is the facet joint and it has been revealed that the intervertebral disc (IVD) nucleotomy may be a trigger for LBP. The aim of the present study was to investigate the influence of IVD nucleotomy on the load sharing in the spinal facet joint under the loading scenarios of different postures. Finite element (FE) models of the intact and nucleotomised L4 - L5 spinal segments were generated from the clinical CT images. Seven human postures, including upright, 5° extension, 5° flexion, ± 6° lateral bending and ± 2° axial rotation, were simulated. The resultant forces in the fact joint were compared between the intact and the nucleotomised cases. It was revealed that the IVD nucleotomy significantly increased the forces in the facet joints under the loading scenarios of upright, 5° extension and 5° flexion. The IVD nucleotomy increased the force in the ipsilateral facet joint but decreased the force on the contralateral side under the loading scenarios of ± 2° axial rotation. However, the IVD nucleotomy made little influence on the resultant forces in both facet joints in the postures of ± 6° lateral bending. In conclusion, the IVD nucleotomy can cause an increase in the overall force in the facet joint, and thus may serve as a possible explanation for the LBP and a main contributing factor for the pain complaints.
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Affiliation(s)
- Yongtao Lu
- Department of Engineering Mechanics, Dalian University of Technology, Dalian 116024, China; State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China; DUT-BSU Joint Institute, Dalian University of Technology, Dalian, China.
| | - LiangLiang Cheng
- Affiliated Zhongshan Hospital of Dalian University, Dalian 116001, China.
| | - Hanxing Zhu
- School of Engineering, Cardiff University, Queen's Buildings, the Parade, CF24 3AA Cardiff, UK
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17
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Remus R, Lipphaus A, Neumann M, Bender B. Calibration and validation of a novel hybrid model of the lumbosacral spine in ArtiSynth-The passive structures. PLoS One 2021; 16:e0250456. [PMID: 33901222 PMCID: PMC8075237 DOI: 10.1371/journal.pone.0250456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 04/07/2021] [Indexed: 12/04/2022] Open
Abstract
In computational biomechanics, two separate types of models have been used predominantly to enhance the understanding of the mechanisms of action of the lumbosacral spine (LSS): Finite element (FE) and musculoskeletal multibody (MB) models. To combine advantages of both models, hybrid FE-MB models are an increasingly used alternative. The aim of this paper is to develop, calibrate, and validate a novel passive hybrid FE-MB open-access simulation model of a ligamentous LSS using ArtiSynth. Based on anatomical data from the Male Visible Human Project, the LSS model is constructed from the L1-S1 rigid vertebrae interconnected with hyperelastic fiber-reinforced FE intervertebral discs, ligaments, and facet joints. A mesh convergence study, sensitivity analyses, and systematic calibration were conducted with the hybrid functional spinal unit (FSU) L4/5. The predicted mechanical responses of the FSU L4/5, the lumbar spine (L1-L5), and the LSS were validated against literature data from in vivo and in vitro measurements and in silico models. Spinal mechanical responses considered when loaded with pure moments and combined loading modes were total and intervertebral range of motions, instantaneous axes and centers of rotation, facet joint contact forces, intradiscal pressures, disc bulges, and stiffnesses. Undesirable correlations with the FE mesh were minimized, the number of crisscrossed collagen fiber rings was reduced to five, and the individual influences of specific anatomical structures were adjusted to in vitro range of motions. Including intervertebral motion couplings for axial rotation and nonlinear stiffening under increasing axial compression, the predicted kinematic and structural mechanics responses were consistent with the comparative data. The results demonstrate that the hybrid simulation model is robust and efficient in reproducing valid mechanical responses to provide a starting point for upcoming optimizations and extensions, such as with active skeletal muscles.
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Affiliation(s)
- Robin Remus
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
- * E-mail:
| | - Andreas Lipphaus
- Biomechanics Research Group, Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
| | - Marc Neumann
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
| | - Beate Bender
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
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18
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Development of a multiscale model of the human lumbar spine for investigation of tissue loads in people with and without a transtibial amputation during sit-to-stand. Biomech Model Mechanobiol 2020; 20:339-358. [PMID: 33026565 DOI: 10.1007/s10237-020-01389-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 09/19/2020] [Indexed: 01/14/2023]
Abstract
Quantification of lumbar spine load transfer is important for understanding low back pain, especially among persons with a lower limb amputation. Computational modeling provides a helpful solution for obtaining estimates of in vivo loads. A multiscale model was constructed by combining musculoskeletal and finite element (FE) models of the lumbar spine to determine tissue loading during daily activities. Three-dimensional kinematic and ground reaction force data were collected from participants with ([Formula: see text]) and without ([Formula: see text]) a unilateral transtibial amputation (TTA) during 5 sit-to-stand trials. We estimated tissue-level load transfer from the multiscale model by controlling the FE model with intervertebral kinematics and muscle forces predicted by the musculoskeletal model. Annulus fibrosis stress, intradiscal pressure (IDP), and facet contact forces were calculated using the FE model. Differences in whole-body kinematics, muscle forces, and tissue-level loads were found between participant groups. Notably, participants with TTA had greater axial rotation toward their intact limb ([Formula: see text]), greater abdominal muscle activity ([Formula: see text]), and greater overall tissue loading throughout sit-to-stand ([Formula: see text]) compared to able-bodied participants. Both normalized (to upright standing) and absolute estimates of L4-L5 IDP were close to in vivo values reported in the literature. The multiscale model can be used to estimate the distribution of loads within different lumbar spine tissue structures and can be adapted for use with different activities, populations, and spinal geometries.
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19
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Influence of different postures under vertical impact load on thoracolumbar burst fracture. Med Biol Eng Comput 2020; 58:2725-2736. [PMID: 32880092 DOI: 10.1007/s11517-020-02254-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 08/23/2020] [Indexed: 10/23/2022]
Abstract
Clinical studies have extensively shown that burst fractures can cause severe and long-term neurological deficits. However, the mechanism of burst fracture is not clear, and the influence of different spinal postures on burst fracture is still unidentified. The study aimed at investigating the influence of different postures under vertical impact load on thoracolumbar burst fracture. A detailed nonlinear finite element model of T12-L2 segment was developed to investigate these problems. In this work, a rigid ball was used to vertically impact the finite element spinal segment, which emulated the process of burst fracture as in experimental condition. During the process, amounting to 9 different postures (normal, flexion, extension, right/left lateral bending of 8°, right/left axial rotation of 4° and 8°) were studied. Totally five failure modes were observed. Six different parameters, including vertebral height, vertebral bulge, interpedicular widening, vertebral kyphotic angle, posterior vertebral body angle, and joint facet contact force, were observed to evaluate the corresponding severity of burst fracture. Burst fracture in extension was the severest, and the loss of vertebral height in flexion was the most. The different postures in these simulations changed the morphology of intervertebral disc and facet joints force, resulting in different types of fracture.
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20
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Biswas JK, Dey S, Karmakar SK, Roychowdhury A, Datta S. Design of Patient Specific Spinal Implant (Pedicle Screw Fixation) using FE Analysis and Soft Computing Techniques. Curr Med Imaging 2020; 16:371-382. [PMID: 32410539 DOI: 10.2174/1573405614666181018122538] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 07/31/2018] [Accepted: 08/09/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND This work uses genetic algorithm (GA) for optimum design of patient specific spinal implants (pedicle screw) with varying implant diameter and bone condition. The optimum pedicle screw fixation in terms of implant diameter is on the basis of minimum strain difference from intact (natural) to implantation at peri-prosthetic bone for the considered six different peri-implant positions. METHODS This design problem is expressed as an optimization problem using the desirability function, where the data generated by finite element analysis is converted into an artificial neural network (ANN) model. The finite element model is generated from CT scan data. Thereafter all the ANN predictions of the microstrain in six positions are converted to unitless desirability value varying between 0 and 1, which is then combined to form the composite desirability. Maximization of the composite desirability is done using GA where composite desirability should be made to go up as close as possible to 1. If the composite desirability is 1, then all 'strain difference values in 6 positions' are 0. RESULTS The optimum solutions obtained can easily be used for making patient-specific spinal implants.
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Affiliation(s)
- Jayanta Kumar Biswas
- Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711103, India.,Department of Mechanical Engineering, JIS College of Engineering, Kalyani, Nadia-741235, India
| | - Swati Dey
- Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711103, India
| | - Santanu Kumar Karmakar
- Deparment of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711103, India
| | - Amit Roychowdhury
- Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711103, India
| | - Shubhabrata Datta
- Department of Mechanical Engineering, SRM Institute of Science and Technology, Kattankulathur - 603203, Tamil Nadu, India
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21
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Anitha DP, Baum T, Kirschke JS, Subburaj K. Effect of the intervertebral disc on vertebral bone strength prediction: a finite-element study. Spine J 2020; 20:665-671. [PMID: 31841703 DOI: 10.1016/j.spinee.2019.11.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/23/2019] [Accepted: 11/25/2019] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Osteoporotic vertebral fractures (OVFs) are a prevalent skeletal condition in the elderly but the mechanism behind these fractures remain unclear due to the complex biomechanical interplay between spinal segments such as the vertebra and intervertebral discs (IVDs). PURPOSE To investigate the biomechanical influence of IVDs by (1) comparing finite element (FE)-predicted failure load with experimentally measured failure load of functional spinal units (FSUs) and (2) comparing this correlation with those of FE-predicted failure load and bone mineral density (BMD) of the single central vertebra with experimentally measured failure load. STUDY DESIGN A computational biomechanical analysis. PATIENT SAMPLE Ten thoracic FSUs consisting of a central vertebra, the adjacent IVDs, and the upper and lower halves of the adjacent vertebrae were harvested from formalin-fixed human donors (4 males, 6 females; mean age of 82±9 years). OUTCOME MEASURES The outcome measures included the prediction of vertebral strength and determination of BMD in FSUs and the single central vertebra and the correlation of both measures with experimentally measured vertebral strength of the FSUs. METHODS The FSUs underwent clinical multidetector computed tomography (MDCT) (spatial resolution: 250×250×600 μm3). BMD was determined for the FSUs from the MDCT images of the central vertebrae. FE-predicted failure load was calculated in the single central vertebra of the FSUs alone and the entire FSUs. Experimentally measured failure load of the FSUs was determined in a uniaxial biomechanical test. RESULTS BMD of the central vertebrae correlated significantly with experimentally measured failure load (R2=0.66, p<.02), whereas FE-predicted failure load of the central vertebra showed no significant correlation with experimentally measured failure load (p=.07). However, FE-predicted failure load of FSUs best predicted experimentally measured failure load of FSUs (R2=0.93, p<.0001). CONCLUSIONS This study demonstrated that routine clinical MDCT images can be an accurate and feasible tool for prediction of OVFs using patient-specific FE analysis of FSU models. CLINICAL SIGNIFICANCE Improved management of OVFs is essential amidst current clinical challenges. Implementation of a vertebral strength assessment tool could result in more accurate prediction of osteoporotic fracture risk and aid clinicians with better targeted early treatment strategies.
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Affiliation(s)
- D Praveen Anitha
- Engineering Product Development (EPD) Pillar, Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372
| | - Thomas Baum
- Department of Neuroradiology, Klinikum rechts der Isar, Technische Universitaet Muenchen, Muenchen, Germany
| | - Jan S Kirschke
- Department of Neuroradiology, Klinikum rechts der Isar, Technische Universitaet Muenchen, Muenchen, Germany
| | - Karupppasamy Subburaj
- Engineering Product Development (EPD) Pillar, Singapore University of Technology and Design (SUTD), 8 Somapah Road, Singapore 487372.
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22
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Areias B, Caetano SC, Sousa LC, Parente M, Jorge RN, Sousa H, Gonçalves JM. Numerical simulation of lateral and transforaminal lumbar interbody fusion, two minimally invasive surgical approaches. Comput Methods Biomech Biomed Engin 2020; 23:408-421. [PMID: 32189515 DOI: 10.1080/10255842.2020.1734579] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The present study aims to compare spinal stability after two different minimally invasive techniques, the lateral lumbar interbody fusion (LLIF) and the transforaminal lumbar interbody fusion (TLIF) approaches. Two nonlinear three-dimensional finite element (FE) models of the L4-L5 functional spinal unit (FSU) were subjected to the loads that usually act on the lumbar spine. Findings show that the LLIF approach yields better results for torsion load case, due to the larger surface area of the implant. For extension, flexion and lateral bending loads, the TLIF approach presents smaller displacements probably due to the anterior placement of the cage and to the smaller damaged area of the annulus fibrosus.
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Affiliation(s)
- B Areias
- INEGI/DEMec, Faculdade de Engenharia da Universidade do Porto, Porto, Portugal
| | - S C Caetano
- MEB, Faculdade de Engenharia da Universidade do Porto, Porto, Portugal
| | - L C Sousa
- INEGI/DEMec, Faculdade de Engenharia da Universidade do Porto, Porto, Portugal
| | - M Parente
- INEGI/DEMec, Faculdade de Engenharia da Universidade do Porto, Porto, Portugal
| | - R N Jorge
- INEGI/DEMec, Faculdade de Engenharia da Universidade do Porto, Porto, Portugal
| | - H Sousa
- Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
| | - J M Gonçalves
- Hospital da Luz Arrábida, Vila Nova de Gaia, Portugal
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23
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Fidalgo DS, Areias B, Sousa LC, Parente M, Jorge RN, Sousa H, Gonçalves JM. Minimally invasive transforaminal and anterior lumbar interbody fusion surgery at level L5-S1. Comput Methods Biomech Biomed Engin 2020; 23:384-395. [PMID: 32096422 DOI: 10.1080/10255842.2020.1731482] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
This paper presents a finite element analysis to investigate the biomechanical changes caused by transforaminal (TLIF) and anterior lumbar interbody fusion (ALIF) at the L5-S1 level, applying two different implants: T_PAL (TLIF) and SynFix (ALIF). The main objective is to determine which one is more stable for patients. Numerical simulations of segmental motion show that, in the early postoperative phase, displacements and rotation angles obtained in ALIF are greater than the corresponding ones obtained in TLIF, as well as the principal stress values on the ligaments. So, TLIF performed with T_PAL is more stable than ALIF, especially during the recovery phase.
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Affiliation(s)
- D S Fidalgo
- INEGI/DEMec, FEUP, Universidade do Porto, Porto, Portugal
| | - B Areias
- INEGI/DEMec, FEUP, Universidade do Porto, Porto, Portugal
| | - L C Sousa
- INEGI/DEMec, FEUP, Universidade do Porto, Porto, Portugal
| | - M Parente
- INEGI/DEMec, FEUP, Universidade do Porto, Porto, Portugal
| | - R N Jorge
- INEGI/DEMec, FEUP, Universidade do Porto, Porto, Portugal
| | - H Sousa
- Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
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24
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Comparison of Biomechanical Performance of Five Different Treatment Approaches for Fixing Posterior Pelvic Ring Injury. JOURNAL OF HEALTHCARE ENGINEERING 2020; 2020:5379593. [PMID: 32076495 PMCID: PMC6996702 DOI: 10.1155/2020/5379593] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 11/18/2019] [Accepted: 01/06/2020] [Indexed: 12/03/2022]
Abstract
Background A large number of pelvic injuries are seriously unstable, with mortality rates reaching 19%. Approximately 60% of pelvic injuries are related to the posterior pelvic ring. However, the selection of a fixation method for a posterior pelvic ring injury remains a challenging problem for orthopedic surgeons. The aim of the present study is to investigate the biomechanical performance of five different fixation approaches for posterior pelvic ring injury and thus provide guidance on the choice of treatment approach in a clinical setting. Methods A finite element (FE) model, including the L3-L5 lumbar vertebrae, sacrum, and full pelvis, was created from CT images of a healthy adult. Tile B and Tile C types of pelvic fractures were created in the model. Five different fixation methods for fixing the posterior ring injury (PRI) were simulated: TA1 (conservative treatment), TA2 (S1 screw fixation), TA3 (S1 + S2 screw fixation), TA4 (plate fixation), and TA5 (modified triangular osteosynthesis). Based on the fixation status (fixed or nonfixed) of the anterior ring and the fixation method for PRI, 20 different FE models were created. An upright standing loading scenario was simulated, and the resultant displacements at the sacroiliac joint were compared between different models. Results When TA5 was applied, the resultant displacements at the sacroiliac joint were the smallest (1.5 mm, 1.6 mm, 1.6 mm, and 1.7 mm) for all the injury cases. The displacements induced by TA3 and TA2 were similar to those induced by TA5. TA4 led to larger displacements at the sacroiliac joint (2.3 mm, 2.4 mm, 4.8 mm, and 4.9 mm), and TA1 was the worst case (3.1 mm, 3.2 mm, 6.3 mm, and 6.5 mm). Conclusions The best internal fixation method for PRI is the triangular osteosynthesis approach (TA5), followed by S1 + S2 screw fixation (TA3), S1 screw fixation (TA2), and plate fixation (TA4).
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Guo LX, Li WJ. Finite element modeling and static/dynamic validation of thoracolumbar-pelvic segment. Comput Methods Biomech Biomed Engin 2019; 23:69-80. [DOI: 10.1080/10255842.2019.1699543] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Li-Xin Guo
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, China
| | - Wu-Jie Li
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, China
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Haj-Ali R, Wolfson R, Masharawi Y. A patient specific computational biomechanical model for the entire lumbosacral spinal unit with imposed spondylolysis. Clin Biomech (Bristol, Avon) 2019; 68:37-44. [PMID: 31158588 DOI: 10.1016/j.clinbiomech.2019.05.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/31/2019] [Accepted: 05/13/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND A biomechanical model of the lumbosacral spinal unit between L1-S1 was developed to investigate the behavior of normal and select pathological states. Our aims were to generate predictive structural models for mechanical deformation including critical stresses in the spine components and to investigate the probability of subsequent lumbar spine fractures in the presence of unilateral spondylolysis. METHODS A non-linear three-dimensional finite element pathology-free model of the L1-S1 lumbosacral unit was generated using patient-specific computerized tomography scans and calibrated by comparing it to experimental data of a range of motion modes consisting of flexion, extension, left and right lateral bending, and left and right axial rotation. Unilateral and bilateral pars defects were created on the isthmus of L5 to simulate spondylolysis. FINDINGS Results showed that under flexion, left lateral bending and right axial rotation, stresses were higher on the contralateral L5 pars-interarticularis, whereas, no significant changes occurred on the left-right isthmus of the L2-L4 and S1. Significant changes in the range of motion compared to the pathology-free model were observed in bilateral spondylolysis not only adjacent to the pars defect area but also in other lumbar spine levels. INTERPRETATION The proposed pathology-free lumbosacral unit model showed good correlation with experimental tests for all loading cases. In unilateral spondylolysis, a subsequent pars defect was observed within the same vertebra. The overall modeling approach can be used to study different pathological states.
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Affiliation(s)
- Rami Haj-Ali
- Faculty of Engineering, Tel-Aviv University, 6997801 Tel Aviv, Israel
| | - Roza Wolfson
- Faculty of Engineering, Tel-Aviv University, 6997801 Tel Aviv, Israel
| | - Youssef Masharawi
- The Spinal Research Laboratory, Department of Physical Therapy, the Stanley Steyer School of Health Professions, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Ramat Aviv, 6997801, Israel.
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Sharabi M, Wertheimer S, Wade KR, Galbusera F, Benayahu D, Wilke HJ, Haj-Ali R. Towards intervertebral disc engineering: Bio-mimetics of form and function of the annulus fibrosus lamellae. J Mech Behav Biomed Mater 2019; 94:298-307. [DOI: 10.1016/j.jmbbm.2019.03.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/19/2019] [Accepted: 03/20/2019] [Indexed: 12/11/2022]
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Lu Y, Zhu Y, Krause M, Huber G, Li J. Evaluation of the capability of the simulated dual energy X-ray absorptiometry-based two-dimensional finite element models for predicting vertebral failure loads. Med Eng Phys 2019; 69:43-49. [PMID: 31147202 DOI: 10.1016/j.medengphy.2019.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 03/11/2019] [Accepted: 05/19/2019] [Indexed: 11/17/2022]
Abstract
Prediction of the vertebral failure load is of great importance for the prevention and early treatment of bone fracture. However, an efficient and effective method for accurately predicting the failure load of vertebral bones is still lacking. The aim of the present study was to evaluate the capability of the simulated dual energy X-ray absorptiometry (DXA)-based finite element (FE) model for predicting vertebral failure loads. Thirteen dissected spinal segments (T11/T12/L1) were scanned using a HR-pQCT scanner and then were mechanically tested until failure. The subject-specific three-dimensional (3D) and two-dimensional (2D) FE models of T12 were generated from the HR-pQCT scanner and the simulated DXA images, respectively. Additionally, the areal bone mineral density (aBMD) and areal bone mineral content (aBMC) of T12 were calculated. The failure loads predicted by the simulated DXA-based 2D FE models were more moderately correlated with the experimental failure loads (R2 = 0.66) than the aBMC (R2 = 0.61) and aBMD (R2 = 0.56). The 2D FE models were slightly outperformed by the HR-pQCT-based 3D FE models (R2 = 0.71). The present study demonstrated that the simulated DXA-based 2D FE model has better capability for predicting the vertebral failure loads than the densitometric measurements but is outperformed by the 3D FE model. The 2D FE model is more suitable for clinical use due to the low radiation dose and low cost, but it remains to be validated by further in vitro and in vivo studies.
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Affiliation(s)
- Yongtao Lu
- Department of Engineering Mechanics, Dalian University of Technology, No. 2 Linggong Road, 116024 Dalian, China; State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, No. 2 Linggong Road, 116024 Dalian, China.
| | - Yifan Zhu
- Department of Engineering Mechanics, Shanghai Jiaotong University, No. 800 Dongchuan Road, 20024 Shanghai, China
| | - Matthias Krause
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20251 Hamburg, Germany
| | - Gerd Huber
- Institute of Biomechanics, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
| | - Junyan Li
- Department of Design Engineering and Mathematics, School of Science and Technology, Middlesex University, The Burroughs, Hendon, NW4 4BT London, UK
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Is there any advantage of using stand-alone cages? A numerical approach. Biomed Eng Online 2019; 18:63. [PMID: 31113423 PMCID: PMC6530002 DOI: 10.1186/s12938-019-0684-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 05/14/2019] [Indexed: 11/17/2022] Open
Abstract
Background Segment fusion using interbody cages supplemented with pedicle screw fixation is the most common surgery for the treatment of low back pain. However, there is still much controversy regarding the use of cages in a stand-alone fashion. The goal of this work is to numerically compare the influence that each surgery has on lumbar biomechanics. Methods A non-linear FE model of the whole lumbar spine was developed to compare between two types of cages (OLYS and NEOLIF) with and without supplementary fixation. The motion of the whole spine was analysed and the biomechanical environment of the adjacent segments to the operated one was studied. Moreover, the risk of subsidence of the cages was qualitatively evaluated. Results A great ROM reduction occurred when supplementary fixation was used. This stiffening increased the stresses at the adjacent levels. It might be hypothesised that the overloading of these segments could be related with the clinically observed adjacent disc degeneration. Meanwhile, the stand-alone cages allowed for a wider movement, and therefore, the influence of the surgery on adjacent discs was much lower. Regarding the risk of subsidence, the contact pressure magnitude was similar for both intervertebral cage designs and near the value of the maximum tolerable pressure of the endplates. Conclusions A minimally invasive posterior insertion of an intervertebral cage (OLYS or NEOLIF) was compared using a stand-alone design or adding supplementary fixation. The outcomes of these two techniques were compared, and although stand-alone cage may diminish the risk of disease progression to the adjacent discs, the spinal movement in this case could compromise the vertebral fusion and might present a higher risk of cage subsidence.![]() Electronic supplementary material The online version of this article (10.1186/s12938-019-0684-8) contains supplementary material, which is available to authorized users.
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Kamal Z, Rouhi G, Arjmand N, Adeeb S. A stability-based model of a growing spine with adolescent idiopathic scoliosis: A combination of musculoskeletal and finite element approaches. Med Eng Phys 2019; 64:46-55. [DOI: 10.1016/j.medengphy.2018.12.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 12/15/2018] [Accepted: 12/31/2018] [Indexed: 10/27/2022]
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Sharabi M, Levi-Sasson A, Wolfson R, Wade KR, Galbusera F, Benayahu D, Wilke HJ, Haj-Ali R. The Mechanical Role of the Radial Fiber Network Within the Annulus Fibrosus of the Lumbar Intervertebral Disc: A Finite Elements Study. J Biomech Eng 2018; 141:2709746. [DOI: 10.1115/1.4041769] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Indexed: 11/08/2022]
Abstract
The annulus fibrosus (AF) of the intervertebral disc (IVD) consists of a set of concentric layers composed of a primary circumferential collagen fibers arranged in an alternating oblique orientation. Moreover, there exists an additional secondary set of radial translamellar collagen fibers which connects the concentric layers, creating an interconnected fiber network. The aim of this study was to investigate the mechanical role of the radial fiber network. Toward that goal, a three-dimensional (3D) finite element model of the L3–L4 spinal segment was generated and calibrated to axial compression and pure moment loading. The AF model explicitly recognizes the two heterogeneous networks of fibers. The presence of radial fibers demonstrated a pronounced effect on the local disc responses under lateral bending, flexion, and extension modes. In these modes, the radial fibers were in a tensile state in the disc region that subjected to compression. In addition, the circumferential fibers, on the opposite side of the IVD, were also under tension. The local stress in the matrix was decreased in up to 9% in the radial fibers presence. This implies an active fiber network acting collectively to reduce the stresses and strains in the AF lamellae. Moreover, a reduction of 26.6% in the matrix sideways expansion was seen in the presence of the radial fibers near the neutral bending axis of the disc. The proposed biomechanical model provided a new insight into the mechanical role of the radial collagen fibers in the AF structure. This model can assist in the design of future IVD substitutes.
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Affiliation(s)
- Mirit Sharabi
- The Fleischman Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Aviad Levi-Sasson
- The Fleischman Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Roza Wolfson
- The Fleischman Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Kelly R. Wade
- Institute of Orthopaedic Research and Biomechanics, University of Ulm, Ulm 89081, Germany
| | - Fabio Galbusera
- Institute of Orthopaedic Research and Biomechanics, University of Ulm, Ulm 89081, Germany
- IRCCS Galeazzi Orthopaedic Institute, Milan 20161, Italy
| | - Dafna Benayahu
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Hans-Joachim Wilke
- Institute of Orthopaedic Research and Biomechanics, University of Ulm, Ulm 89081, Germany
| | - Rami Haj-Ali
- Professor The Fleischman Faculty of Engineering, School of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel e-mail:
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Calvo-Echenique A, Cegoñino J, Chueca R, Pérez-Del Palomar A. Stand-alone lumbar cage subsidence: A biomechanical sensitivity study of cage design and placement. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2018; 162:211-219. [PMID: 29903488 DOI: 10.1016/j.cmpb.2018.05.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 05/02/2018] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND AND OBJECTIVE Spinal degeneration and instability are commonly treated with interbody fusion cages either alone or supplemented with posterior instrumentation with the aim to immobilise the segment and restore intervertebral height. The purpose of this work is to establish a tool which may help to understand the effects of intervertebral cage design and placement on the biomechanical response of a patient-specific model to help reducing post-surgical complications such as subsidence and segment instability. METHODS A 3D lumbar functional spinal unit (FSU) finite element model was created and a parametric model of an interbody cage was designed and introduced in the FSU. A Drucker-Prager Cap plasticity formulation was used to predict plastic strains and bone failure in the vertebrae. The effect of varying cage size, cross-sectional area, apparent stiffness and positioning was evaluated under 500 N preload followed by 7.5 Nm multidirectional rotation and the results were compared with the intact model. RESULTS The most influential cage parameters on the FSU were size, curvature congruence with the endplates and cage placement. Segmental stiffness was higher when increasing the cross-sectional cage area in all loading directions and when the cage was anteriorly placed in all directions but extension. In general, the facet joint forces were reduced by increasing segmental stiffness. However, these forces were higher than in the intact model in most of the cases due to the displacement of the instantaneous centre of rotation. The highest plastic deformations took place at the caudal vertebra under flexion and increased for cages with greater stiffness. Thus, wider cages and a more anteriorly placement would increase the volume of failed bone and, therefore, the risk of subsidence. CONCLUSIONS Cage geometry plays a crucial role in the success of lumbar surgery. General considerations such as larger cages may be applied as a guideline, but parameters such as curvature or cage placement should be determined for each specific patient. This model provides a proof-of-concept of a tool for the preoperative evaluation of lumbar surgical outcomes.
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Affiliation(s)
- Andrea Calvo-Echenique
- Group of Biomaterials Aragón Institute of Engineering Research (I3A) Department of Mechanical Engineering, University of Zaragoza, Spain
| | - José Cegoñino
- Group of Biomaterials Aragón Institute of Engineering Research (I3A) Department of Mechanical Engineering, University of Zaragoza, Spain
| | - Raúl Chueca
- Group of Biomaterials Aragón Institute of Engineering Research (I3A) Department of Mechanical Engineering, University of Zaragoza, Spain
| | - Amaya Pérez-Del Palomar
- Group of Biomaterials Aragón Institute of Engineering Research (I3A) Department of Mechanical Engineering, University of Zaragoza, Spain.
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Biswas JK, Rana M, Majumder S, Karmakar SK, Roychowdhury A. Effect of two-level pedicle-screw fixation with different rod materials on lumbar spine: A finite element study. J Orthop Sci 2018; 23:258-265. [PMID: 29113764 DOI: 10.1016/j.jos.2017.10.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 09/23/2017] [Accepted: 10/19/2017] [Indexed: 11/29/2022]
Abstract
BACKGROUND Pedicle-screw-rod fixation system is very popular surgical remedy for degenerative disc disease. It is important to observe load vs. spinal motion characteristic for better understanding of clinical problems and treatment of spinal instability associated with low-back pain. OBJECTIVE The objective of this study is to understand the effect [range of motion (ROM) and intervertebral foramen height] of pedicle-screw fixation with three rod materials on lumbar spine under three physiological loading conditions. METHOD A three-dimensional finite element (FE) model of lumbar to sacrum (L1-S) vertebrae with pedicle-screw-rod fixation at L3-L5 level is developed. Three rod materials [titanium alloy (Ti6Al4V), ultra-high molecular weight poly ethylene (UHMWPE) and poly-ether-ether-ketone (PEEK)] are used for two-level fixation and the FE models are simulated for axial rotation, lateral bending and flexion-extension under ±10 Nm moment and 500 N compressive load and compared with the intact (natural) model. RESULT & DISCUSSION For axial rotation, lateral bending and flexion, ROM increased 2.8, 4.5 and 1.83 times respectively for UHMWPE, and 3.7, 7.2 and 2.15 times respectively for PEEK in comparison to Ti6Al4V. As ROM is 49, 29 and 31% of the intact model during axial rotation, lateral bending and flexion respectively, PEEK rod produced better motion flexibility than Ti6Al4V and UHMWPE rod. Foramen height increased insignificantly by 2.21% for the PEEK rod with respect to the intact spine during flexion. For the PEEK rod, maximum stress of 40 MPa during axial rotation is much below the yield stress of 98 MPa. CONCLUSION Ti6Al4V pedicle-screw-rod fixation system highly restricted the ROM of the spine, which is improved by using UHMWPE and PEEK, having lower stiffness. The foramen height did not vary significantly for any implant materials. In terms of ROM and maximum stress, PEEK rod may be considered for a better implant design to get better ROM and thus mobility.
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Affiliation(s)
- Jayanta Kumar Biswas
- Dept. of Aerospace Engineering & Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
| | - Masud Rana
- Dept. of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
| | - Santanu Majumder
- Dept. of Aerospace Engineering & Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
| | - Santanu Kumar Karmakar
- Dept. of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India
| | - Amit Roychowdhury
- Dept. of Aerospace Engineering & Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah, 711103, India.
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Dong RC, Guo LX. Human body modeling method to simulate the biodynamic characteristics of spine in vivo with different sitting postures. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2017; 33:e2876. [PMID: 28264145 DOI: 10.1002/cnm.2876] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/16/2017] [Accepted: 02/26/2017] [Indexed: 06/06/2023]
Abstract
The aim of this study is to model the computational model of seated whole human body including skeleton, muscle, viscera, ligament, intervertebral disc, and skin to predict effect of the factors (sitting postures, muscle and skin, buttocks, viscera, arms, gravity, and boundary conditions) on the biodynamic characteristics of spine. Two finite element models of seated whole body and a large number of finite element models of different ligamentous motion segments were developed and validated. Static, modal, and transient dynamic analyses were performed. The predicted vertical resonant frequency of seated body model was in the range of vertical natural frequency of 4 to 7 Hz. Muscle, buttocks, viscera, and the boundary conditions of buttocks have influence on the vertical resonant frequency of spine. Muscle played a very important role in biodynamic response of spine. Compared with the vertical posture, the posture of lean forward or backward led to an increase in stress on anterior or lateral posterior of lumbar intervertebral discs. This indicated that keeping correct posture could reduce the injury of vibration on lumbar intervertebral disc under whole-body vibration. The driving posture not only reduced the load of spine but also increased the resonant frequency of spine.
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Affiliation(s)
- Rui-Chun Dong
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China
| | - Li-Xin Guo
- School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China
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The Effects of Physiological Biomechanical Loading on Intradiscal Pressure and Annulus Stress in Lumbar Spine: A Finite Element Analysis. JOURNAL OF HEALTHCARE ENGINEERING 2017; 2017:9618940. [PMID: 29065672 PMCID: PMC5592017 DOI: 10.1155/2017/9618940] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/10/2017] [Accepted: 07/24/2017] [Indexed: 01/21/2023]
Abstract
The present study was conducted to examine the effects of body weight on intradiscal pressure (IDP) and annulus stress of intervertebral discs at lumbar spine. Three-dimensional finite element model of osseoligamentous lumbar spine was developed subjected to follower load of 500 N, 800 N, and 1200 N which represent the loads for individuals who are normal and overweight with the pure moments at 7.5 Nm in flexion and extension motions. It was observed that the maximum IDP was 1.26 MPa at L1-L2 vertebral segment. However, the highest increment of IDP was found at L4-L5 segment where the IDP was increased to 30% in flexion and it was more severe at extension motion reaching to 80%. Furthermore, the maximum annulus stress also occurred at the L1-L2 segment with 3.9 MPa in extension motion. However, the highest increment was also found at L4-L5 where the annulus stress increased to 17% in extension motion. Based on these results, the increase of physiological loading could be an important factor to the increment of intradiscal pressure and annulus fibrosis stress at all intervertebral discs at the lumbar spine which may lead to early intervertebral disc damage.
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Calvo-Echenique A, Cegoñino J, Correa-Martín L, Bances L, Palomar APD. Intervertebral disc degeneration: an experimental and numerical study using a rabbit model. Med Biol Eng Comput 2017; 56:865-877. [DOI: 10.1007/s11517-017-1738-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 10/09/2017] [Indexed: 11/25/2022]
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Alkalay RN, Harrigan TP. Mechanical assessment of the effects of metastatic lytic defect on the structural response of human thoracolumbar spine. J Orthop Res 2016; 34:1808-1819. [PMID: 26748564 DOI: 10.1002/jor.23154] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 12/29/2015] [Indexed: 02/04/2023]
Abstract
To investigate the effects of a clinical lytic defect on the structural response of human thoracolumbar functional spinal unit. A novel CT-compatible mechanical test system was used to image the deformation of a T12-L1 motion segment and measure the change in strain response under compressive loads ranging from 50 to 750 N. A lytic lesion (LM) with cortex involvement (33% by volume) was introduced to the upper vertebral body and the CT experiments were repeated. Finite element models, established from the CT volumes, were used to investigate the defect's effects on the structural response and the state of principal and shear stresses within the affected and adjacent vertebrae. The lytic lesion resulted in severe loss of the vertebral structural competence, resulting in significant, non-linear, and asymmetric increase in the experimentally measured strains and computed stresses within both vertebrae (p < 0.01). At the cortex, the tensile strains were significantly increased, while compressive strains significantly decreased, (p < 0.05). Both the vertebral bone and cortex regions adjacent to the defect showed significant increase in computed compressive, tensile, and shear stresses (p < 0.01). Changes in stress and strain distribution within the affected and adjacent vertebral bone and the experimentally observed bulging and buckling of the vertebral cortices suggested that initiation of catastrophic vertebral failure may occur under load magnitudes encountered in daily living. Although the effect of LM on the global deformation of the spine was well-predicted, our results show that FE predictions of local strain changes must be carefully assessed for clinical relevance. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1808-1819, 2016.
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Affiliation(s)
- Ron N Alkalay
- Center for Advanced Orthopedic Studies, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Avenue, Boston, Massachusetts, 02215.
| | - Timothy P Harrigan
- Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road Laurel, Maryland, 20723
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Automated finite element meshing of the lumbar spine: Verification and validation with 18 specimen-specific models. J Biomech 2016; 49:2669-2676. [DOI: 10.1016/j.jbiomech.2016.05.025] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 05/23/2016] [Accepted: 05/25/2016] [Indexed: 11/18/2022]
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Mengoni M, Vasiljeva K, Jones AC, Tarsuslugil SM, Wilcox RK. Subject-specific multi-validation of a finite element model of ovine cervical functional spinal units. J Biomech 2016; 49:259-66. [DOI: 10.1016/j.jbiomech.2015.12.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 10/26/2015] [Accepted: 12/03/2015] [Indexed: 01/03/2023]
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Campbell JQ, Petrella AJ. An Automated Method for Landmark Identification and Finite-Element Modeling of the Lumbar Spine. IEEE Trans Biomed Eng 2015; 62:2709-16. [DOI: 10.1109/tbme.2015.2444811] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Geometrical aspects of patient-specific modelling of the intervertebral disc: collagen fibre orientation and residual stress distribution. Biomech Model Mechanobiol 2015; 15:543-60. [DOI: 10.1007/s10237-015-0709-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 07/17/2015] [Indexed: 10/23/2022]
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Cegoñino J, Calvo-Echenique A, Pérez-del Palomar A. Influence of different fusion techniques in lumbar spine over the adjacent segments: A 3D finite element study. J Orthop Res 2015; 33:993-1000. [PMID: 25676778 DOI: 10.1002/jor.22854] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 02/03/2015] [Indexed: 02/04/2023]
Abstract
The most conventional technique to treat the intervertebral disc degeneration consists on fusing the affected segment with a posterior screw fixation and sometimes with the insertion of a cage in the intersomatic space. However, this kind of surgeries had controversial results in the adjacent discs. The aim of this work was to prove the stabilization of the spine and the decompression of the disc and to analyze the influence over the adjacent segments. With this purpose, four different models were built and simulated under different loading conditions. The stabilization of the spine was ensured by the screw fixation which reduced dramatically the relative motion in the affected segment. On the other hand, the pore pressure showed a high fall in the operated models proving the decompression of the neural structures. In the adjacent segments, the ROM increased up to 50% in the upper disc and 70% in the lower one. The pore pressure and principal stresses also increased after both surgeries. The observed results suggested that the fusion procedure could trigger a cascade degeneration effect over the adjacent discs, while it is also seen that cage insertion helps to maintain disc height in a better way than screw fixation only.
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Affiliation(s)
- José Cegoñino
- Group of Biomaterials, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
| | - Andrea Calvo-Echenique
- Group of Biomaterials, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
| | - Amaya Pérez-del Palomar
- Group of Biomaterials, Aragón Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza, Spain
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Momeni Shahraki N, Fatemi A, Goel VK, Agarwal A. On the Use of Biaxial Properties in Modeling Annulus as a Holzapfel-Gasser-Ogden Material. Front Bioeng Biotechnol 2015; 3:69. [PMID: 26090359 PMCID: PMC4453479 DOI: 10.3389/fbioe.2015.00069] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 04/30/2015] [Indexed: 11/17/2022] Open
Abstract
Besides the biology, stresses and strains within the tissue greatly influence the location of damage initiation and mode of failure in an intervertebral disk. Finite element models of a functional spinal unit (FSU) that incorporate reasonably accurate geometry and appropriate material properties are suitable to investigate such issues. Different material models and techniques have been used to model the anisotropic annulus fibrosus, but the abilities of these models to predict damage initiation in the annulus and to explain clinically observed phenomena are unclear. In this study, a hyperelastic anisotropic material model for the annulus with two different sets of material constants, experimentally determined using uniaxial and biaxial loading conditions, were incorporated in a 3D finite element model of a ligamentous FSU. The purpose of the study was to highlight the biomechanical differences (e.g., intradiscal pressure, motion, forces, stresses, strains, etc.) due to the dissimilarity between the two sets of material properties (uniaxial and biaxial). Based on the analyses, the biaxial constants simulations resulted in better agreements with the in vitro and in vivo data, and thus are more suitable for future damage analysis and failure prediction of the annulus under complex multiaxial loading conditions.
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Affiliation(s)
- Narjes Momeni Shahraki
- Mechanical, Industrial and Manufacturing Engineering Department, University of Toledo , Toledo, OH , USA ; Engineering Center for Orthopaedic Research Excellence, University of Toledo , Toledo, OH , USA
| | - Ali Fatemi
- Mechanical, Industrial and Manufacturing Engineering Department, University of Toledo , Toledo, OH , USA
| | - Vijay K Goel
- Engineering Center for Orthopaedic Research Excellence, University of Toledo , Toledo, OH , USA ; Bioengineering Department, University of Toledo , Toledo, OH , USA
| | - Anand Agarwal
- Engineering Center for Orthopaedic Research Excellence, University of Toledo , Toledo, OH , USA ; Bioengineering Department, University of Toledo , Toledo, OH , USA
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Clouthier AL, Hosseini HS, Maquer G, Zysset PK. Finite element analysis predicts experimental failure patterns in vertebral bodies loaded via intervertebral discs up to large deformation. Med Eng Phys 2015; 37:599-604. [PMID: 25922211 DOI: 10.1016/j.medengphy.2015.03.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 01/14/2015] [Accepted: 03/22/2015] [Indexed: 11/28/2022]
Abstract
Vertebral compression fractures are becoming increasingly common. Patient-specific nonlinear finite element (FE) models have shown promise in predicting yield strength and damage pattern but have not been experimentally validated for clinically relevant vertebral fractures, which involve loading through intervertebral discs with varying degrees of degeneration up to large compressive strains. Therefore, stepwise axial compression was applied in vitro on segments and performed in silico on their FE equivalents using a nonlocal damage-plastic model including densification at large compression for bone and a time-independent hyperelastic model for the disc. The ability of the nonlinear FE models to predict the failure pattern in large compression was evaluated for three boundary conditions: healthy and degenerated intervertebral discs and embedded endplates. Bone compaction and fracture patterns were predicted using the local volume change as an indicator and the best correspondence was obtained for the healthy intervertebral discs. These preliminary results show that nonlinear finite element models enable prediction of bone localisation and compaction. To the best of our knowledge, this is the first study to predict the collapse of osteoporotic vertebral bodies up to large compression using realistic loading via the intervertebral discs.
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Affiliation(s)
- Allison L Clouthier
- Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014 Bern, Switzerland.
| | - Hadi S Hosseini
- Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014 Bern, Switzerland.
| | - Ghislain Maquer
- Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014 Bern, Switzerland.
| | - Philippe K Zysset
- Institute for Surgical Technology and Biomechanics, University of Bern, Stauffacherstrasse 78, 3014 Bern, Switzerland.
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Maquer G, Schwiedrzik J, Huber G, Morlock MM, Zysset PK. Compressive strength of elderly vertebrae is reduced by disc degeneration and additional flexion. J Mech Behav Biomed Mater 2015; 42:54-66. [DOI: 10.1016/j.jmbbm.2014.10.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 10/29/2014] [Accepted: 10/31/2014] [Indexed: 01/03/2023]
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Maquer G, Laurent M, Brandejsky V, Pretterklieber ML, Zysset PK. Finite element based nonlinear normalization of human lumbar intervertebral disc stiffness to account for its morphology. J Biomech Eng 2014; 136:061003. [PMID: 24671515 DOI: 10.1115/1.4027300] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Indexed: 11/08/2022]
Abstract
Disc degeneration, usually associated with low back pain and changes of intervertebral stiffness, represents a major health issue. As the intervertebral disc (IVD) morphology influences its stiffness, the link between mechanical properties and degenerative grade is partially lost without an efficient normalization of the stiffness with respect to the morphology. Moreover, although the behavior of soft tissues is highly nonlinear, only linear normalization protocols have been defined so far for the disc stiffness. Thus, the aim of this work is to propose a nonlinear normalization based on finite elements (FE) simulations and evaluate its impact on the stiffness of human anatomical specimens of lumbar IVD. First, a parameter study involving simulations of biomechanical tests (compression, flexion/extension, bilateral torsion and bending) on 20 FE models of IVDs with various dimensions was carried out to evaluate the effect of the disc's geometry on its compliance and establish stiffness/morphology relations necessary to the nonlinear normalization. The computed stiffness was then normalized by height (H), cross-sectional area (CSA), polar moment of inertia (J) or moments of inertia (Ixx, Iyy) to quantify the effect of both linear and nonlinear normalizations. In the second part of the study, T1-weighted MRI images were acquired to determine H, CSA, J, Ixx and Iyy of 14 human lumbar IVDs. Based on the measured morphology and pre-established relation with stiffness, linear and nonlinear normalization routines were then applied to the compliance of the specimens for each quasi-static biomechanical test. The variability of the stiffness prior to and after normalization was assessed via coefficient of variation (CV). The FE study confirmed that larger and thinner IVDs were stiffer while the normalization strongly attenuated the effect of the disc geometry on its stiffness. Yet, notwithstanding the results of the FE study, the experimental stiffness showed consistently higher CV after normalization. Assuming that geometry and material properties affect the mechanical response, they can also compensate for one another. Therefore, the larger CV after normalization can be interpreted as a strong variability of the material properties, previously hidden by the geometry's own influence. In conclusion, a new normalization protocol for the intervertebral disc stiffness in compression, flexion, extension, bilateral torsion and bending was proposed, with the possible use of MRI and FE to acquire the discs' anatomy and determine the nonlinear relations between stiffness and morphology. Such protocol may be useful to relate the disc's mechanical properties to its degree of degeneration.
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Zahari SN, Abd Latif MJ, Kadir MRA. The influence of preload application for vertebra segment in finite element modelling. 2014 IEEE CONFERENCE ON BIOMEDICAL ENGINEERING AND SCIENCES (IECBES) 2014. [DOI: 10.1109/iecbes.2014.7047485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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Finite element analyses of human vertebral bodies embedded in polymethylmethalcrylate or loaded via the hyperelastic intervertebral disc models provide equivalent predictions of experimental strength. J Biomech 2014; 47:2512-6. [DOI: 10.1016/j.jbiomech.2014.04.015] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/07/2014] [Accepted: 04/07/2014] [Indexed: 11/24/2022]
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Park WM, Kim K, Kim YH. Biomechanical analysis of two-step traction therapy in the lumbar spine. ACTA ACUST UNITED AC 2014; 19:527-33. [PMID: 24913413 DOI: 10.1016/j.math.2014.05.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 04/09/2014] [Accepted: 05/09/2014] [Indexed: 11/25/2022]
Abstract
Traction therapy is one of the most common conservative treatments for low back pain. However, the effects of traction therapy on lumbar spine biomechanics are not well known. We investigated biomechanical effects of two-step traction therapy, which consists of global axial traction and local decompression, on the lumbar spine using a validated three-dimensional finite element model of the lumbar spine. One-third of body weight was applied on the center of the L1 vertebra toward the superior direction for the first axial traction. Anterior translation of the L4 vertebra was considered as the second local decompression. The lordosis angle between the superior planes of the L1 vertebra and sacrum was 44.6° at baseline, 35.2° with global axial traction, and 46.4° with local decompression. The fibers of annulus fibrosus in the posterior region, and intertransverse and posterior longitudinal ligaments experienced stress primarily during global axial traction, these stresses decreased during local decompression. A combination of global axial traction and local decompression would be helpful for reducing tensile stress on the fibers of the annulus fibrosus and ligaments, and intradiscal pressure in traction therapy. This study could be used to develop a safer and more effective type of traction therapy.
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Affiliation(s)
- Won Man Park
- Department of Mechanical Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do 446-701, Republic of Korea
| | - Kyungsoo Kim
- Department of Applied Mathematics, Kyung Hee University, Yongin-si, Gyeonggi-do 446-701, Republic of Korea
| | - Yoon Hyuk Kim
- Department of Mechanical Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do 446-701, Republic of Korea.
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50
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Dreischarf M, Zander T, Shirazi-Adl A, Puttlitz CM, Adam CJ, Chen CS, Goel VK, Kiapour A, Kim YH, Labus KM, Little JP, Park WM, Wang YH, Wilke HJ, Rohlmann A, Schmidt H. Comparison of eight published static finite element models of the intact lumbar spine: predictive power of models improves when combined together. J Biomech 2014; 47:1757-66. [PMID: 24767702 DOI: 10.1016/j.jbiomech.2014.04.002] [Citation(s) in RCA: 232] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/01/2014] [Accepted: 04/01/2014] [Indexed: 10/25/2022]
Abstract
Finite element (FE) model studies have made important contributions to our understanding of functional biomechanics of the lumbar spine. However, if a model is used to answer clinical and biomechanical questions over a certain population, their inherently large inter-subject variability has to be considered. Current FE model studies, however, generally account only for a single distinct spinal geometry with one set of material properties. This raises questions concerning their predictive power, their range of results and on their agreement with in vitro and in vivo values. Eight well-established FE models of the lumbar spine (L1-5) of different research centers around the globe were subjected to pure and combined loading modes and compared to in vitro and in vivo measurements for intervertebral rotations, disc pressures and facet joint forces. Under pure moment loading, the predicted L1-5 rotations of almost all models fell within the reported in vitro ranges, and their median values differed on average by only 2° for flexion-extension, 1° for lateral bending and 5° for axial rotation. Predicted median facet joint forces and disc pressures were also in good agreement with published median in vitro values. However, the ranges of predictions were larger and exceeded those reported in vitro, especially for the facet joint forces. For all combined loading modes, except for flexion, predicted median segmental intervertebral rotations and disc pressures were in good agreement with measured in vivo values. In light of high inter-subject variability, the generalization of results of a single model to a population remains a concern. This study demonstrated that the pooled median of individual model results, similar to a probabilistic approach, can be used as an improved predictive tool in order to estimate the response of the lumbar spine.
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Affiliation(s)
- M Dreischarf
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany.
| | - T Zander
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - A Shirazi-Adl
- Division of Applied Mechanics, Department of Mechanical Engineering, École Polytechnique, Montréal, Quebec, Canada
| | - C M Puttlitz
- Orthopaedic Bioengineering Research Laboratory, Colorado State University, USA
| | - C J Adam
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - C S Chen
- Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei, Taiwan
| | - V K Goel
- Departments of Bioengineering and Orthopaedic Surgery, Colleges of Engineering and Medicine, University of Toledo, USA
| | - A Kiapour
- Departments of Bioengineering and Orthopaedic Surgery, Colleges of Engineering and Medicine, University of Toledo, USA
| | - Y H Kim
- Department of Mechanical Engineering, Kyung Hee University, Yongin 446-701, Republic of Korea
| | - K M Labus
- Orthopaedic Bioengineering Research Laboratory, Colorado State University, USA
| | - J P Little
- Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - W M Park
- Department of Mechanical Engineering, Kyung Hee University, Yongin 446-701, Republic of Korea
| | - Y H Wang
- Department of Physical Therapy and Assistive Technology, National Yang-Ming University, Taipei, Taiwan
| | - H J Wilke
- Institute of Orthopaedic Research and Biomechanics, Ulm, Germany
| | - A Rohlmann
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - H Schmidt
- Julius Wolff Institute, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany; Institute of Orthopaedic Research and Biomechanics, Ulm, Germany
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