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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...
Fabrication Patient-Specific Drill Guide Templates for Cervical Pedicle Screw Placement
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor) ; Parnianpour, Mohammad (Supervisor) ; Azimi, Parisa (Co-Supervisor)
Abstract
One of the most common spinal surgeries involves spinal fusion or vertebral fixation, which is used to treat various conditions such as intervertebral disc disease, scoliosis (lateral deviation of the spinal column), fractures, infections, or the presence of tumors in the spinal column. In this surgical procedure, the use of pedicle screws and titanium rods prevents motion and friction between two vertebrae. Screws may enter the vertebrae in the wrong position and angle, causing bone weakening, rupture of nerve roots or blood vessels, weakness or lack of sensation in some parts of the body, spinal cord injury, and in severe cases, paralysis of the patient. For this reason, fusion surgery is...
Simulation of movement in three-dimensional musculoskeletal human lumbar spine using directional encoding-based neurocontrollers
, Article Journal of Biomechanical Engineering ; Vol. 136, issue. 9 , 2014 ; Vossoughi, G ; Boroushaki, M ; Parnianpour, M ; Sharif University of Technology
Abstract
Despite development of accurate musculoskeletal models for human lumbar spine, the methods for prediction of muscle activity patterns in movements lack proper association with corresponding sensorimotor integrations. This paper uses the directional information of the Jacobian of the musculoskeletal system to orchestrate adaptive critic-based fuzzy neural controller modules for controlling a complex nonlinear redundant musculoskeletal system. The proposed controller is used to control a 3D 3-degree of freedom (DOF) musculoskeletal model of trunk, actuated by 18 muscles. The controller is capable of learning to control from sensory information, without relying on pre-assumed model parameters....
Lumbopelvic rhythm during forward and backward sagittal trunk rotations: Combined in vivo measurement with inertial tracking device and biomechanical modeling
, Article Clinical Biomechanics ; Vol. 29, issue. 1 , 2014 , pp. 7-13 ; ISSN: 02680033 ; Arjmand, N ; Shirazi-Adl, A ; Parnianpour, M ; Sharif University of Technology
Abstract
Background The ratio of total lumbar rotation over pelvic rotation (lumbopelvic rhythm) during trunk sagittal movement is essential to evaluate spinal loads and discriminate between low back pain and asymptomatic population. Methods Angular rotations of the pelvis and lumbar spine as well as their sagittal rhythm during forward flexion and backward extension in upright standing of eight asymptomatic males are measured using an inertial tracking device. The effect of variations in the lumbopelvic ratio during trunk flexion on spinal loads is quantified using a detailed musculoskeletal model. Findings The mean of peak voluntary flexion rotations of the thorax, pelvis, and lumbar was 121 (SD...
Analysis of different material theories used in a FE model of a lumbar segment motion
, Article Acta of Bioengineering and Biomechanics ; Volume 15, Issue 2 , 2013 , Pages 33-41 ; 1509409X (ISSN) ; Nikkhoo, M ; Haghpanahi, M ; Parnianpour, M ; Sharif University of Technology
2013
Abstract
In this study, a nonlinear poroelastic model of intervertebral disc as an infrastructure was developed. Moreover, a new element was defined consisting a disc (Viscoelastic Euler Beam Element) and a vertebra (Rigid Link) as a unit element. Using the new element, three different viscoelastic finite element models were prepared for lumbar motion segment (L4/L5). Prolonged loading (short-term and long-term creep) and cyclic loading were applied to the models and the results were compared with results of in vivo tests. Simplification of the models by using the new element leads to reduction of the runtime of the models in dynamic analyses to few minutes without losing the accuracy in the results
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...
Dynamic responses of intervertebral disc during static creep and dynamic cyclic loading: A parametric Poroelastic finite element analysis
, Article Biomedical Engineering - Applications, Basis and Communications ; Volume 25, Issue 1 , 2013 ; 10162372 (ISSN) ; Haghpanahi, M ; Parnianpour, M ; Wang, J. L ; Sharif University of Technology
2013
Abstract
Low back pain is a common reason for activity limitation in people younger than 45 years old, and was proved to be associated with heavy physical works, repetitive lifting, impact, stationary work postures and vibrations. The study of load transferring and the loading condition encountered in spinal column can be simulated by finite element models. The intervertebral disc is a structure composed of a porous material. Many physical models were developed to simulate this phenomenon. The confounding effects of poroelastic properties and loading conditions on disc mechanical responses are, nevertheless, not cleared yet. The objective of this study was to develop an axisymmetric poroelastic...
Predictive equations for lumbar spine loads in load-dependent asymmetric one- and two-handed lifting activities
, Article Clinical Biomechanics ; Volume 27, Issue 6 , 2012 , Pages 537-544 ; 02680033 (ISSN) ; Plamondon, A ; Shirazi Adl, A ; Parnianpour, M ; Larivière, C ; Sharif University of Technology
2012
Abstract
Background: Asymmetric lifting activities are associated with low back pain. Methods: A finite element biomechanical model is used to estimate spinal loads during one- and two-handed asymmetric static lifting activities. Model input variables are thorax flexion angle, load magnitude as well as load sagittal and lateral positions while response variables are L4-L5 and L5-S1 disc compression and shear forces. A number of levels are considered for each input variable and all their possible combinations are introduced into the model. Robust yet user-friendly predictive equations that relate model responses to its inputs are established. Findings: Predictive equations with adequate...
An improved multi-joint EMG-assisted optimization approach to estimate joint and muscle forces in a musculoskeletal model of the lumbar spine
, Article Journal of Biomechanics ; Volume 44, Issue 8 , 2011 , Pages 1521-1529 ; 00219290 (ISSN) ; Arjmand, N ; Plamondon, A ; Shirazi Adl, A ; Larivière, C ; Sharif University of Technology
Abstract
Muscle force partitioning methods and musculoskeletal system simplifications are key modeling issues that can alter outcomes, and thus change conclusions and recommendations addressed to health and safety professionals. A critical modeling concern is the use of single-joint equilibrium to estimate muscle forces and joint loads in a multi-joint system, an unjustified simplification made by most lumbar spine biomechanical models. In the context of common occupational tasks, an EMG-assisted optimization method (EMGAO) is modified in this study to simultaneously account for the equilibrium at all lumbar joints (M-EMGAO). The results of this improved approach were compared to those of its...
Predictive equations to estimate spinal loads in symmetric lifting tasks
, Article Journal of Biomechanics ; Volume 44, Issue 1 , Jan , 2011 , Pages 84-91 ; 00219290 (ISSN) ; Plamondon, A ; Shirazi Adl, A ; Larivière, C ; Parnianpour, M ; Sharif University of Technology
2011
Abstract
Response surface methodology is used to establish robust and user-friendly predictive equations that relate responses of a complex detailed trunk finite element biomechanical model to its input variables during sagittal symmetric static lifting activities. Four input variables (thorax flexion angle, lumbar/pelvis ratio, load magnitude, and load position) and four model responses (L4-L5 and L5-S1 disc compression and anterior-posterior shear forces) are considered. Full factorial design of experiments accounting for all combinations of input levels is employed. Quadratic predictive equations for the spinal loads at the L4-S1 disc mid-heights are obtained by regression analysis with adequate...
Effect of body weight on spinal loads in various activities: A personalized biomechanical modeling approach
, Article Journal of Biomechanics ; Volume 48, Issue 2 , 2015 , Pages 276-282 ; 00219290 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Epidemiological studies are divided over the causative role of body weight (BW) in low back pain. Biomechanical modeling is a valuable approach to examine the effect of changes in BW on spinal loads and risk of back pain. Changes in BW have not been properly simulated by previous models as associated alterations in model inputs on the musculature and moment arm of gravity loads have been neglected. A detailed, multi-joint, scalable model of the thoracolumbar spine is used to study the effect of BW (varying at five levels, i.e., 51, 68, 85, 102, and 119kg) on the L5-S1 spinal loads during various static symmetric activities while scaling moment arms and physiological cross-sectional areas of...
Comparative evaluation of six quantitative lifting tools to estimate spine loads during static activities
, Article Applied Ergonomics ; Volume 48 , 2015 , Pages 22-32 ; 00036870 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Plamondon, A ; Schmidt, H ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Different lifting analysis tools are commonly used to assess spinal loads and risk of injury. Distinct musculoskeletal models with various degrees of accuracy are employed in these tools affecting thus their relative accuracy in practical applications. The present study aims to compare predictions of six tools (HCBCF, LSBM, 3DSSPP, AnyBody, simple polynomial, and regression models) for the L4-L5 and L5-S1 compression and shear loads in twenty-six static activities with and without hand load. Significantly different spinal loads but relatively similar patterns for the compression (R2>0.87) were computed. Regression models and AnyBody predicted intradiscal pressures in closer agreement with...
Control of lumbar spine flexion-extension movement by PD controller and feedback linearization method
, Article ICCAS 2010 - International Conference on Control, Automation and Systems, 27 October 2010 through 30 October 2010 ; 2010 , Pages 2024-2029 ; 9781424474530 (ISBN) ; Vossughi, G. R ; Parnianpour, M ; Sharif University of Technology
Abstract
The role of motor control in development of low back pain is subject of many researches both in theoretical and experimental fields. In this work flexion-extension movement of lumbar spine have been controlled by three different methods, including feedback linearization (FBL), PD control and their combinations. The model involves 7 links: 1 link for pelvis, 5 links for lumbar vertebrae and 1 link for trunk. Torque actuators have been used on each joint to make them follow desired trajectory. In linear control method, equations of motion have been linearized with respect to upright position and then control signals have been applied in the direction of eigenvectors. Robustness of each method...
How does the central nervous system address the kinetic redundancy in the lumbar spine? Three-dimensional isometric exertions with 18 Hill-model-based muscle fascicles at the L4-L5 level
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 224, Issue 3 , 2010 , Pages 487-501 ; 09544119 (ISSN) ; Khalaf, K ; Nassajian, M. R ; Nasseroleslami, B ; Parnianpour, M ; Sharif University of Technology
2010
Abstract
The human motor system is organized for execution of various motor tasks in a different and flexible manner. The kinetic redundancy in the human musculoskeletal system is a significant property by which the central nervous system achieves many complementary goals. An equilibrium-based biomechanical model of isometric three-dimensional exertions of trunk muscles has been developed. Following the definition and role of the uncontrolled manifold, the kinetic redundancy concept is explored in mathematical terms. The null space of the kinetically redundant system when a certain joint moment and/or stiffness are needed is derived and discussed. The aforementioned concepts have been illustrated,...
Trunk coordination in healthy and chronic nonspecific low back pain subjects during repetitive flexion-extension tasks: Effects of movement asymmetry, velocity and load
, Article Human Movement Science ; Volume 45 , 2016 , Pages 182-192 ; 01679457 (ISSN) ; Sanjari, M. A ; Chehrehrazi, M ; Kahrizi, S ; Parnianpour, M ; Sharif University of Technology
Elsevier
Abstract
Multiple joint interactions are critical to produce stable coordinated movements and can be influenced by low back pain and task conditions. Inter-segmental coordination pattern and variability were assessed in subjects with and without chronic nonspecific low back pain (CNSLBP). Kinematic data were collected from 22 CNSLBP and 22 healthy volunteers during repeated trunk flexion-extension in various conditions of symmetry, velocity, and loading; each at two levels. Sagittal plane angular data were time normalized and used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify lumbar-pelvis and...
A novel approach to evaluate abdominal coactivities for optimal spinal stability and compression force in lifting
, Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 12, Issue 6 , 2009 , Pages 735-745 ; 10255842 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Parnianpour, M ; Sharif University of Technology
Abstract
A novel optimisation algorithm is developed to predict coactivity of abdominal muscles while accounting for both trunk stability via the lowest buckling load (Pcr) and tissue loading via the axial compression (Fc). A nonlinear multi-joint kinematics-driven model of the spine along with the response surface methodology are used to establish empirical expressions for Pcr and Fc as functions of abdominal muscle coactivities and external load magnitude during lifting in upright standing posture. A two-component objective function involving Fc and Pcr is defined. Due to opposite demands, abdominal coactivities that simultaneously maximise Pcr and minimise Fc cannot exist. Optimal solutions are...
Subject-specific 2D/3D image registration and kinematics-driven musculoskeletal model of the spine
, Article Journal of Biomechanics ; Volume 57 , 2017 , Pages 18-26 ; 00219290 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Farahmand, F ; Sharif University of Technology
Abstract
An essential input to the musculoskeletal (MS) trunk models that estimate muscle and spine forces is kinematics of the thorax, pelvis, and lumbar vertebrae. While thorax and pelvis kinematics are usually measured via skin motion capture devices (with inherent errors on the proper identification of the underlying bony landmarks and the relative skin-sensor-bone movements), those of the intervening lumbar vertebrae are commonly approximated at fixed proportions based on the thorax-pelvis kinematics. This study proposes an image-based kinematics measurement approach to drive subject-specific (musculature, geometry, mass, and center of masses) MS models. Kinematics of the thorax, pelvis, and...
Goal equivalent manifold analysis of task performance in non-specific LBP and healthy subjects during repetitive trunk movement; effect of load, velocity, symmetry
, Article Human Movement Science ; Volume 51 , 2017 , Pages 72-81 ; 01679457 (ISSN) ; Sanjari, M. A ; Mokhtarinia, H. R ; Jamshidi, A. A ; Maroufi, N ; Parnianpour, M ; Sharif University of Technology
Abstract
Motor abundance allows reliability of motor performance despite its variability. The nature of this variability provides important information on the flexibility of control strategies. This feature of control may be affected by low back pain (LPB) and trunk flexion/extension conditions. Goal equivalent manifold (GEM) analysis was used to quantify the ability to exploit motor abundance during repeated trunk flexion/extension in healthy individuals and people with chronic non-specific LBP (CNSLBP). Kinematic data were collected from 22 healthy volunteers and 22 CNSLBP patients during metronomically timed, repeated trunk flexion/extension in three conditions of symmetry, velocity, and loading;...
Kinematic analysis of dynamic lumbar motion in patients with lumbar segmental instability using digital videofluoroscopy
, Article European Spine Journal ; Volume 18, Issue 11 , 2009 , Pages 1677-1685 ; 09406719 (ISSN) ; Maroufi, N ; Behtash, H ; Zekavat, H ; Parnianpour, M ; Sharif University of Technology
2009
Abstract
The study design is a prospective, case-control. The aim of this study was to develop a reliable measurement technique for the assessment of lumbar spine kinematics using digital video fluoroscopy in a group of patients with low back pain (LBP) and a control group. Lumbar segmental instability (LSI) is one subgroup of nonspecific LBP the diagnosis of which has not been clarified. The diagnosis of LSI has traditionally relied on the use of lateral functional (flexion-extension) radiographs but use of this method has proven unsatisfactory. Fifteen patients with chronic low back pain suspected to have LSI and 15 matched healthy subjects were recruited. Pulsed digital videofluoroscopy was used...
Subject-specific loads on the lumbar spine in detailed finite element models scaled geometrically and kinematic-driven by radiography images
, Article International Journal for Numerical Methods in Biomedical Engineering ; Volume 35, Issue 4 , 2019 ; 20407939 (ISSN) ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
Wiley-Blackwell
2019
Abstract
Traditional load-control musculoskeletal and finite element (FE) models of the spine fail to accurately predict in vivo intervertebral joint loads due mainly to the simplifications and assumptions when estimating redundant trunk muscle forces. An alternative powerful protocol that bypasses the calculation of muscle forces is to drive the detailed FE models by image-based in vivo displacements. Development of subject-specific models, however, both involves the risk of extensive radiation exposures while imaging in supine and upright postures and is time consuming in terms of the reconstruction of the vertebrae, discs, ligaments, and facets geometries. This study therefore aimed to introduce a...