Loading...
Search for:
spinal-loads
0.006 seconds
Total 28 records
The Effects of Vibrations Transferred to Vehicle Occupants on Spinal Loads as Function of Pelvic-lumbar Orientation, Posture, Seat Specifications and Seat Back Inclination Using FEM
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor) ; Parnianpour, Mohammad (Supervisor)
Abstract
Due to adverse health problems with lumbar spine among professional drivers associated with exposure to whole body vibration (WBV), studying the effect of vibrations and parameters influencing WBV is of great importance. This study aims to simulate whole body vibration for a ground vehicle occupant and calculate loads that lumbar spine tolerate during harmonic sinusoidal vibrations. Moreover, this study determines the effect of lumbar spine angle, seat specifications (angles and materials), and vibration frequency on the results. To this end, a detailed viscoelastic lumbar spine (L1-S1) has been modeled using FE method which has been replaced with the simplified spine model in HYBRID III...
A Development on the Musculoskeletal Modeling of the Spine Using Image- based Kinematics to Predict Intervertebral Loads
, Ph.D. Dissertation Sharif University of Technology ; Farahmand, Farzam (Supervisor) ; Arjmand, Navid (Supervisor)
Abstract
pain is one of the most common musculoskeletal (MS) disorders and the most important cause of functional disability in developed and developing countries. Several studies showed that the most important factor in development of the low back pain is loads and stresses in different parts of the spine. While non-invasive measurement of these internal loads and stresses, as a tool to estimate the risk of injury, is very difficult and costly, biomechanical models of the spine are the best meansfor analyzing the risk of injury in various in-vivo activities. In order to develop a spine model, it is necessary to measure the kinematics of the vertebrae for the specified activity. In previous studies,...
A Comparative Study between Available Lifting Tools for Assessment of Risk of Back Injuries
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor)
Abstract
Epidemiological studies have identified manual material handling and lifting as risk factors in occupational low back pain (LBP). There are many lifting analysis tools to estimate the risk of injury during a specific lifting task. One for using these tools, needs to know the limitations of each tool and be noticed where a tool cannot be used. The purpose of this study is to compare different biomechanical models of lumbar spine and find out their characteristics.Five models are chosen for this study which are: the University of Michigan’s Static Strength Prediction Program ( ) software, the revised Hand-Calculation Back Compressive Force (HCBCF) equation, the simple polynomial equation of...
A Novel Stability-based EMG-assisted Model of the Lumbar Spine to Estimate Trunk Muscle Forces and Spinal Loads in Various Static Activities
, M.Sc. Thesis Sharif University of Technology ; Arjmand, Navid (Supervisor)
Abstract
The spine like every other mechanical pillar, is exposed to buckling and loss of stability. While existing biomechanical models emphasize the pressure force on the disk as the main cause of injury, there is also a possibility of local buckling phenomenon in vertebral discs. Because of the prevalence and high cost of lower back pain, it is essential to evaluate the forces carried by disks and lumbar muscles during occupational activities more accurately. In this regard, hybrid EMG-assisted optimization (EMGAO) approaches are most common methods for estimation of spinal loads. These models, not only use EMG data to be physiologically creditable, but also satisfy equilibrium requirements at all...
An optimization-based method for prediction of lumbar spine segmental kinematics from the measurements of thorax and pelvic kinematics
, Article International Journal for Numerical Methods in Biomedical Engineering ; July , 2015 , Volume 31, Issue 12 ; 20407939 (ISSN) ; Arjmand, N ; Bazrgari, B ; Sharif University of Technology
Wiley-Blackwell
2015
Abstract
Given measurement difficulties, earlier modeling studies have often used some constant ratios to predict lumbar segmental kinematics from measurements of total lumbar kinematics. Recent imaging studies suggested distribution of lumbar kinematics across its vertebrae changes with trunk rotation, lumbar posture, and presence of load. An optimization-based method is presented and validated in this study to predict segmental kinematics from measured total lumbar kinematics. Specifically, a kinematics-driven biomechanical model of the spine is used in a heuristic optimization procedure to obtain a set of segmental kinematics that, when prescribed to the model, were associated with the minimum...
Epidemiological and biomechanical evaluation of airline baggage handling
, Article International Journal of Occupational Safety and Ergonomics ; Volume 22, Issue 2 , 2016 , Pages 218-227 ; 10803548 (ISSN) ; Aref, S ; Mardani, M ; Haddad, O ; Parnianpour, M ; Sharif University of Technology
Taylor and Francis Ltd
Abstract
Objectives. Musculoskeletal disorders (MSDs) are prevalent among airline baggage handlers due to manual materials handling. In this study, the Nordic musculoskeletal questionnaire (NMQ), the revised National Institute for Occupational Safety and Health (NIOSH) lifting equation, and the University of Michigan 3D Static Strength Prediction Program™ (3DSSPP) were used to analyze MSDs among baggage handlers. Methods. The NMQ was filled out by 209 baggage handlers and 46 arbitrarily selected baggage handlers were evaluated using the NIOSH method and 3DSSPP. Results. The obtained results showed that the most common MSDs occurred in the lower back region. The next risky regions included knees,...
Subject-specific biomechanics of trunk: musculoskeletal scaling, internal loads and intradiscal pressure estimation
, Article Biomechanics and Modeling in Mechanobiology ; Volume 15, Issue 6 , 2016 , Pages 1699-1712 ; 16177959 (ISSN) ; Shirazi Adl, A ; Arjmand, N ; El Ouaaid, Z ; Plamondon, A ; Sharif University of Technology
Springer Verlag
Abstract
Development of a subject-specific computational musculoskeletal trunk model (accounting for age, sex, body weight and body height), estimation of muscle forces and internal loads as well as subsequent validation by comparison with measured intradiscal pressure in various lifting tasks are novel, important and challenging. The objective of the present study is twofold. First, it aims to update and personalize the passive and active structures in an existing musculoskeletal kinematics-driven finite element model. The scaling scheme used an existing imaging database and biomechanical principles to adjust muscle geometries/cross-sectional-areas and passive joint geometry/properties in accordance...
The validity and inter-rater reliability of a video-based posture-matching tool to estimate cumulative loads on the lower back
, Article Journal of Biomedical Physics and Engineering ; Volume 12, Issue 4 , 2022 , Pages 417-430 ; 22517200 (ISSN) ; Abdoli Eramaki, M ; Arjmand, N ; Abouhossein, A ; Zakerian, S. A ; Sharif University of Technology
Shriaz University of Medical Sciences
2022
Abstract
Background: Low back pain (LBP) is known as one of the most common workrelated musculoskeletal disorders. Spinal cumulative loads (CLs) during manual material handling (MMH) tasks are the main risk factors for LBP. However, there is no valid and reliable quantitative lifting analysis tool available for quantifying CLs among Iranian workers performing MMH tasks. Objective: This study aimed to investigate the validity and inter-rater reliability of a posture-matching load assessment tool (PLAT) for estimating the L5-S1 static cumulative compression (CC) and shear (CS) loads based on predictive regression equations. Material and Methods: This experimental study was conducted among six...
Sex-Dependent estimation of spinal loads during static manual material handling activities—combined in vivo and in silico analyses
, Article Frontiers in Bioengineering and Biotechnology ; Volume 9 , 2021 ; 22964185 (ISSN) ; Arjmand, N ; Pan, F ; Zander, T ; Schmidt, H ; Sharif University of Technology
Frontiers Media S.A
2021
Abstract
Manual material handling (MMH) is considered as one of the main contributors to low back pain. While males traditionally perform MMH tasks, recently the number of females who undertake these physically-demanding activities is also increasing. To evaluate the risk of mechanical injuries, the majority of previous studies have estimated spinal forces using different modeling approaches that mostly focus on male individuals. Notable sex-dependent differences have, however, been reported in torso muscle strength and anatomy, segmental mass distribution, as well as lifting strategy during MMH. Therefore, this study aimed to use sex-specific models to estimate lumbar spinal and muscle forces during...
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...
Comparison of trunk muscle forces, spinal loads and stability estimated by one stability- and three EMG-assisted optimization approaches
, Article Medical Engineering and Physics ; Volume 37, Issue 8 , 2015 , Pages 792-800 ; 13504533 (ISSN) ; Arjmand, N ; Shirazi-Adl, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Various hybrid EMG-assisted optimization (EMGAO) approaches are commonly used to estimate muscle forces and joint loads of human musculoskeletal systems. Use of EMG data and optimization enables the EMGAO models to account for inter- and intra-individual variations in muscle recruitments while satisfying equilibrium requirements. Due to implications in ergonomics/prevention and rehabilitation/treatment managements of low-back disorders, there is a need to evaluate existing approaches. The present study aimed to compare predictions of three different EMGAO and one stability-based optimization (OPT) approaches for trunk muscle forces, spinal loads, and stability. Identical measured...
Trunk musculoskeletal response in maximum voluntary exertions: a combined measurement-modeling investigation
, Article Journal of Biomechanics ; Volume 70 , March , 2018 , Pages 124-133 ; 00219290 (ISSN) ; El Ouaaid, Z ; Shirazi Adl, A ; Plamondon, A ; Arjmand, N ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Maximum voluntary exertion (MVE) tasks quantify trunk strength and maximal muscle electromyography (EMG) activities with both clinical and biomechanical implications. The aims here are to evaluate the performance of an existing trunk musculoskeletal model, estimate maximum muscle stresses and spinal forces, and explore likely differences between males and females in maximum voluntary exertions. We, therefore, measured trunk strength and EMG activities of 19 healthy right-handed subjects (9 females and 10 males) in flexion, extension, lateral and axial directions. MVEs for all subjects were then simulated in a subject-specific trunk musculoskeletal model, and estimated muscle activities were...
Effect of whole-body vibration and sitting configurations on lumbar spinal loads of vehicle occupants
, Article Computers in Biology and Medicine ; Volume 107 , 2019 , Pages 292-301 ; 00104825 (ISSN) ; Naserkhaki, S ; Parnianpour, M ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Whole-body vibration (WBV) has been identified as one of the serious risk factors leading to spinal disorders, particularly in professional drivers. Although the influential factors in this area have been investigated epidemiologically, finite element (FE) modeling can efficiently help us better understand the problem. In this study, a modified HYBRID III dummy FE model which was enhanced by detailed viscoelastic discs in the lumbar region was utilized to simulate the effect of WBV on lumbar spine loads. Spinal responses to the vertical sinusoidal vibrations of a generic seat were obtained and spinal injury risk factors were calculated. Effects of variation of excitation frequencies, three...
Comparison of different lifting analysis tools in estimating lower spinal loads – Evaluation of NIOSH criterion
, Article Journal of Biomechanics ; Volume 112 , 2020 ; Shirazi Adl, A ; Plamondon, A ; Arjmand, N ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Excessive loads on the human spine is recognized as a risk factor for back injuries/pain. Various lifting analysis tools such as musculoskeletal models, regression equations and NIOSH (National Institute for Occupational Safety and Health) lifting equation (NLE) have been proposed to evaluate and mitigate associated risks during manual material handling activities. Present study aims to compare predicted spinal loads from 5 different lifting analysis tools as well as to critically evaluate the NIOSH recommended weight limit (RWL). Spinal loads were estimated under different symmetric/asymmetric lifting tasks in which hand-load mass at each task was set based on RWL from NLE. Estimated...
Subject-specific regression equations to estimate lower spinal loads during symmetric and asymmetric static lifting
, Article Journal of Biomechanics ; Volume 102 , 2020 ; Shirazi Adl, A ; El Ouaaid, Z ; Plamondon, A ; Arjmand, N ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Workplace safety assessment, personalized treatment design and back pain prevention programs require accurate subject-specific estimation of spinal loads. Since no noninvasive method can directly estimate spinal loads, easy-to-use regression equations that are constructed based on the results of complex musculoskeletal models appear as viable alternatives. Thus, we aim to develop subject-specific regression equations of L4-L5 and L5-S1 shear and compression forces during various symmetric/asymmetric tasks using a nonlinear personalized finite element musculoskeletal trunk model. Kinematics and electromyography (EMG) activities of 19 young healthy subjects were collected during 64 different...
Comparisons of lumbar spine loads and kinematics in healthy and non-specific low back pain individuals during unstable lifting activities
, Article Journal of Biomechanics ; Volume 144 , 2022 ; 00219290 (ISSN) ; Arjmand, N ; Kahrizi, S ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Evaluation of spinal loads in patients with low back pain (LBP) is essential to prevent further lumbar disorders. Many studies have investigated the relationship between lifting task variables and lumbar spine loads during manual lifting activities. The nature of the external load (stable versus unstable loads) is an important variable that has received less attention. Therefore, the present study aimed to measure trunk kinematics and estimate compressive-shear loads on the lumbar spine under lifting a 120 N stable load and 120 ± 13.63 N sensual unstable load in 16 healthy and 16 non-specific LBP individuals during lifting activities. The maximal lumbar loads were estimated using a...
A rigid thorax assumption affects model loading predictions at the upper but not lower lumbar levels
, Article Journal of Biomechanics ; Volume 49, Issue 13 , 2016 , Pages 3074-3078 ; 00219290 (ISSN) ; Ferguson, S. J ; Arjmand, N ; Sharif University of Technology
Elsevier Ltd
Abstract
A number of musculoskeletal models of the human spine have been used for predictions of lumbar and muscle forces. However, the predictive power of these models might be limited by a commonly made assumption; thoracic region is represented as a single lumped rigid body. This study hence aims to investigate the impact of such assumption on the predictions of spinal and muscle forces. A validated thoracolumbar spine model was used with a flexible thorax (T1–T12), a completely rigid one or rigid with thoracic posture updated at each analysis step. The simulations of isometric forward flexion up to 80°, with and without a 20 kg hand load, were performed, based on the previously measured...
Sagittal range of motion of the thoracic spine using inertial tracking device and effect of measurement errors on model predictions
, Article Journal of Biomechanics ; Volume 49, Issue 6 , 2016 , Pages 913-918 ; 00219290 (ISSN) ; Arjmand, N ; Sharif University of Technology
Elsevier Ltd
Abstract
Range of motion (ROM) of the thoracic spine has implications in patient discrimination for diagnostic purposes and in biomechanical models for predictions of spinal loads. Few previous studies have reported quite different thoracic ROMs. Total (T1-T12), lower (T5-T12) and upper (T1-T5) thoracic, lumbar (T12-S1), pelvis, and entire trunk (T1) ROMs were measured using an inertial tracking device as asymptomatic subjects flexed forward from their neutral upright position to full forward flexion. Correlations between body height and the ROMs were conducted. An effect of measurement errors of the trunk flexion (T1) on the model-predicted spinal loads was investigated. Mean of peak voluntary total...
Estimation of loads on human lumbar spine: A review of in vivo and computational model studies
, Article Journal of Biomechanics ; Volume 49, Issue 6 , 2016 , Pages 833-845 ; 00219290 (ISSN) ; Shirazi Adl, A ; Arjmand, N ; Rohlmann, A ; Schmidt, H ; Wolff Institut, Julius ; Sharif University of Technology
Elsevier Ltd
Abstract
Spinal loads are recognized to play a causative role in back disorders and pain. Knowledge of lumbar spinal loads is required in proper management of various spinal disorders, effective risk prevention and assessment in the workplace, sports and rehabilitation, realistic testing of spinal implants as well as adequate loading in in vitro studies. During the last few decades, researchers have used a number of techniques to estimate spinal loads by measuring in vivo changes in the intradiscal pressure, body height, or forces and moments transmitted via instrumented vertebral implants. In parallel, computational models have been employed to estimate muscle forces and spinal loads under various...
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...