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intervertebral-discs
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Transient Diffusion of Drugs into the Intervertebral Disc using Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Parnianpour, Mohammad (Supervisor) ; Hoviattalab, Maryam (Supervisor) ; Shirazi Adl, Abolfazl (Co-Advisor)
Abstract
In this study, transient diffusion of drug into the intervertebral disc is considered. The amount of Diffused drug from the blood into the intervertebral disc of dog is measured and concentration of drug is calculated for each region of the intervertebral disc including nucleus pulpous, inner annulus fibroses and outer annulus fibroses. Using finite element method, it is shown that the amount of drug diffusion into the intervertebral disc is affected by some parameters such as the type of drug, dose if drug and endplate calcification. This research is done in two parts: In first part, diffusion of drug (sulphate) into the dog intervertebral disc is investigated to compare the obtained...
Poly (Vinyl Alcohol) Hydrogel/Nano-diamond as a Replacement for the Nucleus Pulposus
, M.Sc. Thesis Sharif University of Technology ; Frounchi, Masoud (Supervisor) ; Dadbin, Susan (Supervisor)
Abstract
The nucleus pulposus, which is a part of intervertebral disc, is normally hydrated and gel-like to maintain normal biomechanical functions of the disc through intradiscal pressures. In a degenerated disc, however, water content of nucleus is significantly reduced, resulting in an abnormal stress state of the annulus. Surgical interventions cannot restore the biomedical function to vertebral segment. One approach to restore the normal biomechanics of an intervertebral disc is to replace the nucleus with a prosthetic material which leads to a restoration of the behavior of the disc. The mechanical behavior of poly(vinyl alcohol) and nanodiamond hydrogel may provide a material suitable for...
Biomechanical Modeling of Flexible-bar and Investigating of Muscle Forces and Compression Forces on Discs in Lumbar Region During of Rehabilitation Exercises
, M.Sc. Thesis Sharif University of Technology ; Parnianpour, Mohammad (Supervisor) ; Asghari, Mohsen (Supervisor)
Abstract
A single-degree-of-freedom model is considered for flexible exercise bars based on the lumped-element approach. By considering the side segment of a flexible exercise bar as a cantilever beam with an equivalent mass at the free end, its free-vibration response and forced one under excitation of the grip of the flexible bar is written parametrically. Some experiments are performed on a specific flexible bar to obtain numerical values for the parameters in the model to have it quantitatively known. In the next step, simulation of the model results in the response of the flexible bar under a considered excitation. The response is imported into a multi-segment musculoskeletal software, AnyBody,...
An Investigation on Neck Injury Due to Head Impact in Road Accidents Considering Hyperviscoelastic Properties of Soft Tissues
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor)
Abstract
Neck fracture caused by impacts on the head and neck during road accidents annually imposes a great cost to the people hospitals and the economy of country. Most of these accidents, regardless of cartilaginous injury causes sudden pressure to the spinal cord so it seems necessary to understand the biomechanical response of the neck and the mechanism of injury to reduce costs. Many computational models related to the neck injury have been developed recently. The aim of this project is to investigate the effect of frontal and rear impacts to the head and neck during road accidents. There are many researches have used elastic property for tissues but a little portion of research in this field...
Development and Validation of Biomechanical Model for Calculation of Moment into the Intervertebral L5-S1 Disc and the amount of NIOSH Permissible Limit Load During Lifting Activity
, M.Sc. Thesis Sharif University of Technology ; Parnianpor, Mohammad (Supervisor) ; Narimani, Roya (Supervisor)
Abstract
Lifting is considered a major risk to people's health in life, particularly to the workers. Appropriate wearable tools for measuring the individual’s kinematic and kinetic movement are required for examining and analyzing the lifting activity to prevent injury in the workplace. Different wearable systems have been developed to calculate the force applied on the foot sole to analyze movement in various areas of gait analysis, occupational biomechanics, sports, and other areas. The accuracy and precision of these systems need to be tested before application in any of these areas. In this study, 3 subjects performed five different activities of symmetrical lifting by placing Pedar insoles in...
Estimation of spinal loads using a detailed finite element model of the L4-L5 lumbar segment derived by medical imaging kinematics; A feasibility study
, Article World Congress on Medical Physics and Biomedical Engineering, WC 2018, 3 June 2018 through 8 June 2018 ; Volume 68, Issue 2 , 2018 , Pages 791-795 ; 16800737 (ISSN) ; Arjmand, N ; Sharif University of Technology
Springer Verlag
2018
Abstract
Low back pain is the most prevalent orthopedic disorder and the first main cause of poor working functionality in developed as wells as many developing countries. In Absence of noninvasive in vivo measurement approaches, biomechanical models are used to estimate mechanical loads on human joints during physical activities. To estimate joint loads via musculoskeletal models, the calculation of muscle forces are of importance. It is however difficult to estimate muscle forces as the number of muscles, i.e. unknown parameters, is far more than the existing degrees of freedom; the system is highly redundant. Therefore, in this study, instead of muscle forces estimation, their effects (i.e.,...
A computational dynamic finite element simulation of the thoracic vertebrae under blunt loading: spinal cord injury
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 41, Issue 2 , 2019 ; 16785878 (ISSN) ; Razaghi, R ; Ebrahimi, S ; Karimi, A ; Sharif University of Technology
Springer Verlag
2019
Abstract
Spinal cord is a long, thin, tubular bundle of nervous tissue located in the vertebral column. Since the spinal cord is one of the most crucial pathways for information connecting of the central nervous system, it has to stay safe under any blunt impact loading, i.e., accident, punch, gunshot, burst, etc. Therefore, it is important to investigate the possible injuries that may occur in the vertebral column, especially the spinal cord, as a result of blunt loading. However, due to various experimental limitations, numerical modelling, specifically finite element (FE) models, has been beneficial in predicting the injury to the spinal cord. This study, thus, aimed at predicting the stresses and...
Adjacent segments biomechanics following lumbar fusion surgery: a musculoskeletal finite element model study
, Article European Spine Journal ; Volume 31, Issue 7 , 2022 , Pages 1630-1639 ; 09406719 (ISSN) ; Arjmand, N ; Shirazi-Adl, A ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Purpose: This study exploits a novel musculoskeletal finite element (MS-FE) spine model to evaluate the post-fusion (L4–L5) alterations in adjacent segment kinetics. Methods: Unlike the existing MS models with idealized representation of spinal joints, this model predicts stress/strain distributions in all passive tissues while organically coupled to a MS model. This generic (in terms of musculature and material properties) model uses population-based in vivo vertebral sagittal rotations, gravity loads, and an optimization algorithm to calculate muscle forces. Simulations represent individuals with an intact L4–L5, a preoperative severely degenerated L4–L5 (by reducing the disc height by ~...
A regenerative approach towards recovering the mechanical properties of degenerated intervertebral discs: Genipin and platelet-rich plasma therapies
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 231, Issue 2 , 2017 , Pages 127-137 ; 09544119 (ISSN) ; Wang, J. L ; Abdollahi, M ; Hsu, Y. C ; Parnianpour, M ; Khalaf, K ; Sharif University of Technology
SAGE Publications Ltd
2017
Abstract
Degenerative disc disease, associated with discrete structural changes in the peripheral annulus and vertebral endplate, is one of the most common pathological triggers of acute and chronic low back pain, significantly depreciating an individual's quality of life and instigating huge socioeconomic costs. Novel emerging therapeutic techniques are hence of great interest to both research and clinical communities alike. Exogenous crosslinking, such as Genipin, and platelet-rich plasma therapies have been recently demonstrated encouraging results for the repair and regeneration of degenerated discs, but there remains a knowledge gap regarding the quantitative degree of effectiveness and...
Biomechanical effects of lumbar fusion surgery on adjacent segments using musculoskeletal models of the intact, degenerated and fused spine
, Article Scientific Reports ; Volume 11, Issue 1 , 2021 ; 20452322 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
Nature Research
2021
Abstract
Adjacent segment disorders are prevalent in patients following a spinal fusion surgery. Postoperative alterations in the adjacent segment biomechanics play a role in the etiology of these conditions. While experimental approaches fail to directly quantify spinal loads, previous modeling studies have numerous shortcomings when simulating the complex structures of the spine and the pre/postoperative mechanobiology of the patient. The biomechanical effects of the L4–L5 fusion surgery on muscle forces and adjacent segment kinetics (compression, shear, and moment) were investigated using a validated musculoskeletal model. The model was driven by in vivo kinematics for both preoperative (intact or...
Prediction of the thorax/pelvis orientations and L5–S1 disc loads during various static activities using neuro-fuzzy
, Article Journal of Mechanical Science and Technology ; Volume 34, Issue 8 , 7 August , 2020 , Pages 3481-3485 ; ISSN: 1738494X ; Sayyaadi, H ; Arjmand, N ; Sharif University of Technology
Korean Society of Mechanical Engineers
2020
Abstract
Spinal posture including thorax/pelvis orientations as well as loads on the intervertebral discs are crucial parameters in biomechanical models and ergonomics to evaluate the risk of low back injury. In vivo measurement of spinal posture toward estimation of spine loads requires the common motion capture techniques and laboratory instruments that are costly and time-consuming. Hence, a closed loop algorithm including an artificial neural network (ANN) and fuzzy logic is proposed here to predict the L5–S1 segment loads and thorax/pelvis orientations in various 3D reaching activities. Two parts namely a fuzzy logic strategy and an ANN from this algorithm; the former, developed based on the...
A model for flexi-bar to evaluate intervertebral disc and muscle forces in exercises
, Article Medical Engineering and Physics ; Volume 38, Issue 10 , 2016 , Pages 1076-1082 ; 13504533 (ISSN) ; Nikkhoo, M ; Ashouri, S ; Asghari, M ; Parnianpour, M ; Khalaf, K ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
This study developed and validated a lumped parameter model for the FLEXI-BAR, a popular training instrument that provides vibration stimulation. The model which can be used in conjunction with musculoskeletal-modeling software for quantitative biomechanical analyses, consists of 3 rigid segments, 2 torsional springs, and 2 torsional dashpots. Two different sets of experiments were conducted to determine the model's key parameters including the stiffness of the springs and the damping ratio of the dashpots. In the first set of experiments, the free vibration of the FLEXI-BAR with an initial displacement at its end was considered, while in the second set, forced oscillations of the bar were...
Biomechanical response of intact, degenerated and repaired intervertebral discs under impact loading – Ex-vivo and In-Silico investigation
, Article Journal of Biomechanics ; Volume 70 , March , 2018 , Pages 26-32 ; 00219290 (ISSN) ; Wang, J. L ; Parnianpour, M ; El-Rich, M ; Khalaf, K ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Understanding the effect of impact loading on the mechanical response of the intervertebral disc (IVD) is valuable for investigating injury mechanisms and devising effective therapeutic modalities. This study used 24 porcine thoracic motion segments to characterize the mechanical response of intact (N = 8), degenerated (Trypsin-denatured, N = 8), and repaired (Genepin-treated, N = 8) IVDs subject to impact loading. A meta-model analysis of poroelastic finite element simulations was used in combination with ex-vivo creep and impact tests to extract the material properties. Forward analyses using updated specimen-specific FE models were performed to evaluate the effect of impact duration. The...
On the modeling of human intervertebral disc annulus fibrosus: Elastic, permanent deformation and failure responses
, Article Journal of Biomechanics ; Volume 102 , 2020 ; Shirazi Adl, A ; Baghani, M ; Eskandari, A. H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
As a primary load-resisting component, annulus fibrosus (AF) maintains structural integrity of the entire intervertebral disc. Experiments have demonstrated that permanent deformation and damage take place in the tissue under mechanical loads. Development of an accurate model to capture the complex behaviour of AF tissue is hence crucial in disc model studies. We, therefore, aimed to develop a non-homogenous model to capture elastic, inelastic and failure responses of the AF tissue and the entire disc model under axial load. Our model estimations satisfactorily agreed with results of existing uniaxial (along fiber, circumferential and axial directions) and biaxial tissue-level tests. The...
A novel coupled musculoskeletal finite element model of the spine – Critical evaluation of trunk models in some tasks
, Article Journal of Biomechanics ; Volume 119 , 2021 ; 00219290 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Spine musculoskeletal (MS) models make simplifying assumptions on the intervertebral joint degrees-of-freedom (rotational and/or translational), representation (spherical or beam-like joints), and properties (linear or nonlinear). They also generally neglect the realistic structure of the joints with disc nuclei/annuli, facets, and ligaments. We aim to develop a novel MS model where trunk muscles are incorporated into a detailed finite element (FE) model of the ligamentous T12-S1 spine thus constructing a gold standard coupled MS-FE model. Model predictions are compared under some tasks with those of our earlier spherical joints, beam joints, and hybrid (uncoupled) MS-FE models. The coupled...
Novel force–displacement control passive finite element models of the spine to simulate intact and pathological conditions; comparisons with traditional passive and detailed musculoskeletal models
, Article Journal of Biomechanics ; Volume 141 , 2022 ; 00219290 (ISSN) ; Ebrahimkhani, M ; Arjmand, N ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Passive finite element (FE) models of the spine are commonly used to simulate intact and various pre- and postoperative pathological conditions. Being devoid of muscles, these traditional models are driven by simplistic loading scenarios, e.g., a constant moment and compressive follower load (FL) that do not properly mimic the complex in vivo loading condition under muscle exertions. We aim to develop novel passive FE models that are driven by more realistic yet simple loading scenarios, i.e., in vivo vertebral rotations and pathological-condition dependent FLs (estimated based on detailed musculoskeletal finite element (MS-FE) models). In these novel force–displacement control FE models,...
Disc size markedly influences concentration profiles of intravenously administered solutes in the intervertebral disc: A computational study on glucosamine as a model solute
, Article European Spine Journal ; Vol. 23, issue. 4 , April , 2014 , p. 715-723 ; Shirazi-Adl, A ; Parnianpour, M ; Urban, J. P. G ; Sharif University of Technology
Abstract
Purpose: Tests on animals of different species with large differences in intervertebral disc size are commonly used to investigate the therapeutic efficacy of intravenously injected solutes in the disc. We hypothesize that disc size markedly affects outcome. Methods: Here, using a small non-metabolized molecule, glucosamine (GL) as a model solute, we calculate the influence of disc size on transport of GL into rat, rabbit, dog and human discs for 10 h post intravenous-injection. We used transient finite element models and considered an identical GL supply for all animals. Results: Huge effects of disc size on GL concentration profiles were found. Post-injection GL concentration in the rat...
Material property identification of artificial degenerated intervertebral disc models - comparison of inverse poroelastic finite element analysis with biphasic closed form solution
, Article Journal of Mechanics ; Volume 29, Issue 4 , 2013 , Pages 589-597 ; 17277191 (ISSN) ; Hsu, Y. C ; Haghpanahi, M ; Parnianpour, M ; Wang, J. L ; Sharif University of Technology
2013
Abstract
ABSTRACT Disc rheological parameters regulate the mechanical and biological function of intervertebral disc. The knowledge of effects of degeneration on disc rheology can be beneficial for the design of new disc implants or therapy. We developed two material property identification protocols, i.e., inverse poroelas-tic finite element analysis, and biphasic closed form solution. These protocols were used to find the material properties of intact, moderate and severe degenerated porcine discs. Comparing these two computational protocols for intact and artificial degenerated discs showed they are valid in defining bi-phasic/poroelastic properties. We found that enzymatic agent disrupts the...
A meta-model analysis of a finite element simulation for defining poroelastic properties of intervertebral discs
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 227, Issue 6 , 2013 , Pages 672-682 ; 09544119 (ISSN) ; Hsu, Y. C ; Haghpanahi, M ; Parnianpour, M ; Wang, J. L ; Sharif University of Technology
2013
Abstract
Finite element analysis is an effective tool to evaluate the material properties of living tissue. For an interactive optimization procedure, the finite element analysis usually needs many simulations to reach a reasonable solution. The metamodel analysis of finite element simulation can be used to reduce the computation of a structure with complex geometry or a material with composite constitutive equations. The intervertebral disc is a complex, heterogeneous, and hydrated porous structure. A poroelastic finite element model can be used to observe the fluid transferring, pressure deviation, and other properties within the disc. Defining reasonable poroelastic material properties of the...
Relative performances of artificial neural network and regression mapping tools in evaluation of spinal loads and muscle forces during static lifting
, Article Journal of Biomechanics ; Volume 46, Issue 8 , 2013 , Pages 1454-1462 ; 00219290 (ISSN) ; Ekrami, O ; Shirazi Adl, A ; Plamondon, A ; Parnianpour, M ; Sharif University of Technology
2013
Abstract
Two artificial neural networks (ANNs) are constructed, trained, and tested to map inputs of a complex trunk finite element (FE) model to its outputs for spinal loads and muscle forces. Five input variables (thorax flexion angle, load magnitude, its anterior and lateral positions, load handling technique, i.e., one- or two-handed static lifting) and four model outputs (L4-L5 and L5-S1 disc compression and anterior-posterior shear forces) for spinal loads and 76 model outputs (forces in individual trunk muscles) are considered. Moreover, full quadratic regression equations mapping input-outputs of the model developed here for muscle forces and previously for spine loads are used to compare the...