Search for: biomechanical-phenomena
0.007 seconds
Total 47 records

    Comparison of the trunk-pelvis and lower extremities sagittal plane inter-segmental coordination and variability during walking in persons with and without chronic low back pain

    , Article Human Movement Science ; Volume 52 , 2017 , Pages 55-66 ; 01679457 (ISSN) Ebrahimi, S ; Kamali, F ; Razeghi, M ; Haghpanah, S. A ; Sharif University of Technology
    Elsevier B.V  2017
    Inter-segmental coordination can be influenced by chronic low back pain (CLBP). The sagittal plane lower extremities inter-segmental coordination pattern and variability, in conjunction with the pelvis and trunk, were assessed in subjects with and without non-specific CLBP during free-speed walking. Kinematic data were collected from 10 non-specific CLBP and 10 non-CLBP control volunteers while the subjects were walking at their preferred speed. Sagittal plane time-normalized segmental angles and velocities were used to calculate continuous relative phase for each data point. Mean absolute relative phase (MARP) and deviation phase (DP) were derived to quantify the trunk-pelvis and bilateral... 

    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) Nikkhoo, M ; Wang, J. L ; Abdollahi, M ; Hsu, Y. C ; Parnianpour, M ; Khalaf, K ; Sharif University of Technology
    SAGE Publications Ltd  2017
    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... 

    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) Chehrehrazi, M ; Sanjari, M. A ; Mokhtarinia, H. R ; Jamshidi, A. A ; Maroufi, N ; Parnianpour, M ; Sharif University of Technology
    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;... 

    Biomechanical simulation of eye-airbag impacts during vehicle accidents

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 232, Issue 7 , 2018 , Pages 699-707 ; 09544119 (ISSN) Shirzadi, H ; Zohoor, H ; Naserkhaki, S ; Sharif University of Technology
    SAGE Publications Ltd  2018
    Airbags are safety devices in vehicles effectively suppressing passengers’ injuries during accidents. Although there are still many cases of eye injuries reported due to eye-airbag impacts in recent years. Biomechanical approaches are now feasible and can considerably help experts to investigate the issue without ethical concerns. The eye-airbag impact–induced stresses/strains in various components of the eye were found to investigate the risk of injury in different conditions (impact velocity and airbag pressure). Three-dimensional geometry of the eyeball, fat and bony socket as well as the airbag were developed and meshed to develop a finite element model. Nonlinear material properties of... 

    The effect of functional bracing on the arthrokinematics of anterior cruciate ligament injured knees during lunge exercise

    , Article Gait and Posture ; Volume 63 , 2018 , Pages 52-57 ; 09666362 (ISSN) Jalali, M ; Farahmand, F ; Esfandiarpour, F ; Golestanha, S. A ; Akbar, M ; Eskandari, A ; Mousavi, S. E ; Sharif University of Technology
    Elsevier B.V  2018
    Background: Functional knee braces are extensively used for partially and completely torn anterior cruciate ligament (ACL) patients and those who have undergone ACL graft reconstruction, in order to support the healing ACL, improve the joint's functional stability, and restore the normal joint kinematics. Research question: Does wearing braces alter the arthrokinematics of the ACL deficient knees during lung exercise? Methods: For ten male unilateral ACL deficient subjects, 3D knee models were reconstructed from CT images, acquired in rest position. Sagittal plane fluoroscopy was then performed throughout a complete cycle of lunge in braced and non-braced conditions. The 3D kinematics of the... 

    Design, construction, and evaluation of “sensor lock”: an electromechanical stance control knee joint

    , Article Disability and Rehabilitation: Assistive Technology ; Volume 13, Issue 3 , 2018 , Pages 226-233 ; 17483107 (ISSN) Arazpour, M ; Ahmadi Bani, M ; Baniasad, M ; Samadian, M ; Golchin, N ; Sharif University of Technology
    Taylor and Francis Ltd  2018
    Background and aim: Most currently-available stance control knee ankle foot orthoses (SCKAFOs) still need full knee extension to lock the knee joint, and they are still noisy, bulky, and heavy. Therefore, the aim of this study was to design, construct, and evaluate an original electromechanical SCKAFO knee joint that could feasibly solve these problems, and thus address the problems of current stance control knee joints with regards to their structure, function, cosmesis, and cost. Method: Ten able-bodied (AB) participants and two (knee ankle foot orthosis) KAFO users were recruited to participate in the study. A custom SCKAFO with the same set of components was constructed for each... 

    Role and significance of trunk and upper extremity muscles in walker-assisted paraplegic gait: a case study

    , Article Topics in Spinal Cord Injury Rehabilitation ; Volume 24, Issue 1 , 2018 , Pages 18-27 ; 10820744 (ISSN) Baniasad, M ; Farahmand, F ; Arazpour, M ; Zohoor, H ; Sharif University of Technology
    Thomas Land Publishers Inc  2018
    Background and Purpose: Understanding the role and significance of trunk and upper extremity muscles in paraplegic gait can help in designing more effective assistive devices for these patients and also provides valuable information for improving muscle strengthening programs. Methods: In a patient with a spinal cord injury (SCI) who could walk independently (rating scale of ambulatory capacity, 9) with the aid of bilateral ankle-foot orthosis and a walker, the kinematics, kinetics and electromyographic (EMG) activities of 16 muscles from the trunk and upper and lower extremities were recorded during gait. The onset, cessation, and duration of the EMG signal were associated with the 4 phases... 

    Lower extremity kinematic analysis in male athletes with unilateral anterior cruciate reconstruction in a jump-landing task and its association with return to sport criteria

    , Article BMC Musculoskeletal Disorders ; Volume 20, Issue 1 , 2019 ; 14712474 (ISSN) Norouzi, S ; Esfandiarpour, F ; Mehdizadeh, S ; Yousefzadeh, N. K ; Parnianpour, M ; Sharif University of Technology
    BioMed Central Ltd  2019
    Background: Return to sport (RTS) criteria are widely being used to identify anterior cruciate ligament reconstructed (ACLR) athletes ready to return to sportive activity and reduce risk of ACL re-injury. However, studies show a high rate of ACL re-injury in athletes who passed RTS criteria. This indicates that the current RTS criteria might not be sufficient to determine return to sport time in ACLR athletes. Previous studies have reported a close association between altered lower limb kinematics and ACL re-injury. However, it is not clear how lower extremity kinematics differs between ACLR athletes who passed the RTS-criteria and who failed. This study compared lower extremity kinematics... 

    Phenomenological tissue fracture modeling for an Endoscopic Sinus and Skull Base Surgery training system based on experimental data

    , Article Medical Engineering and Physics ; Volume 68 , 2019 , Pages 85-93 ; 13504533 (ISSN) Sadeghnejad, S ; Farahmand, F ; Vossoughi, G ; Moradi, H ; Mousa Sadr Hosseini, S ; Sharif University of Technology
    Elsevier Ltd  2019
    The ideal simulator for Endoscopic Sinus and Skull Base Surgery (ESSS)training must be supported by a physical model and provide repetitive behavior in a controlled environment. Development of realistic tissue models is a key part of ESSS virtual reality (VR)-based surgical simulation. Considerable research has been conducted to address haptic or force feedback and propose a phenomenological tissue fracture model for sino-nasal tissue during surgical tool indentation. Mechanical properties of specific sino-nasal regions of the sheep head have been studied in various indentation and relaxation experiments. Tool insertion at different indentation rates into coronal orbital floor (COF)tissue is... 

    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) Dehghan Hamani, I ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
    Wiley-Blackwell  2019
    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... 

    Improvement of upper limb motor control and function after competitive and noncompetitive volleyball exercises in chronic stroke survivors: a randomized clinical trial

    , Article Archives of Physical Medicine and Rehabilitation ; Volume 100, Issue 3 , 2019 , Pages 401-411 ; 00039993 (ISSN) Mandehgary Najafabadi, M ; Azad, A ; Mehdizadeh, H ; Behzadipour, S ; Fakhar, M ; Taghavi Azar Sharabiani, P ; Parnianpour, M ; Taghizadeh, G ; Khalaf, K ; Sharif University of Technology
    W.B. Saunders  2019
    Objectives: To investigate the effects of competitive and noncompetitive volleyball exercises on the functional performance and motor control of the upper limbs in chronic stroke survivors. Design: Randomized clinical trial. Setting: Outpatient rehabilitation center. Participants: Chronic stroke survivors (N=48). Interventions: Participants were randomly assigned to competitive (n=16) or noncompetitive (n=16) volleyball exercise groups (60min/d volleyball exercise+30min/d traditional rehabilitation, 3d/wk for 7wk) and control group (n=16). Main Outcome Measures: Reach and grasp motor control measures were evaluated through kinematic analysis. Functional outcomes were assessed via Motor... 

    Hypersensitivity of trunk biomechanical model predictions to errors in image-based kinematics when using fully displacement-control techniques

    , Article Journal of Biomechanics ; Volume 84 , 2019 , Pages 161-171 ; 00219290 (ISSN) Eskandari, A. H ; Arjmand, N ; Shirazi Adl, A ; Farahmand, F ; Sharif University of Technology
    Elsevier Ltd  2019
    Recent advances in medical imaging techniques have allowed pure displacement-control trunk models to estimate spinal loads with no need to calculate muscle forces. Sensitivity of these models to the errors in post-imaging evaluation of displacements (reported to be ∼0.4–0.9° and 0.2–0.3 mm in vertebral displacements) has not yet been investigated. A Monte Carlo analysis was therefore used to assess the sensitivity of results in both musculoskeletal (MS) and passive finite element (FE) spine models to errors in measured displacements. Six static activities in upright standing, flexed, and extended postures were initially simulated using a force-control hybrid MS-FE model. Computed vertebral... 

    Assessing the role of Ca2+ in skeletal muscle fatigue using a multi-scale continuum model

    , Article Journal of Theoretical Biology ; Volume 461 , 2019 , Pages 76-83 ; 00225193 (ISSN) Karami, M ; Calvo, B ; Zohoor, H ; Firoozbakhsh, K ; Grasa, J ; Sharif University of Technology
    Academic Press  2019
    The Calcium ion Ca2+ plays a critical role as an initiator and preserving agent of the cross-bridge cycle in the force generation of skeletal muscle. A new multi-scale chemo-mechanical model is presented in order to analyze the role of Ca2+ in muscle fatigue and to predict fatigue behavior. To this end, a cross-bridge kinematic model was incorporated in a continuum based mechanical model, considering a thermodynamic compatible framework. The contractile velocity and the generated active force were directly related to the force-bearing states that were considered for the cross-bridge cycle. In order to determine the values of the model parameters, the output results of an isometric simulation... 

    A three-dimensional statistical volume element for histology informed micromechanical modeling of brain white matter

    , Article Annals of Biomedical Engineering ; Volume 48, Issue 4 , 2020 , Pages 1337-1353 Hoursan, H ; Farahmand, F ; Ahmadian, M. T ; Sharif University of Technology
    Springer  2020
    This study presents a novel statistical volume element (SVE) for micromechanical modeling of the white matter structures, with histology-informed randomized distribution of axonal tracts within the extracellular matrix. The model was constructed based on the probability distribution functions obtained from the results of diffusion tensor imaging as well as the histological observations of scanning electron micrograph, at two structures of white matter susceptible to traumatic brain injury, i.e. corpus callosum and corona radiata. A simplistic representative volume element (RVE) with symmetrical arrangement of fully alligned axonal fibers was also created as a reference for comparison. A... 

    Rigid-bar loading on pregnant uterus and development of pregnant abdominal response corridor based on finite element biomechanical model

    , Article International Journal for Numerical Methods in Biomedical Engineering ; Volume 36, Issue 1 , January , 2020 Irannejad Parizi, M ; Ahmadian, M. T ; Mohammadi, H ; Sharif University of Technology
    Wiley-Blackwell  2020
    During pregnancy, traumas can threaten maternal and fetal health. Various trauma effects on a pregnant uterus are little investigated. In the present study, a finite element model of a uterus along with a fetus, placenta, amniotic fluid, and two most effective ligament sets is developed. This model allows numerical evaluation of various loading on a pregnant uterus. The model geometry is developed based on CT-scan data and validated using anthropometric data. Applying Ogden hyper-elastic theory, material properties of uterine wall and placenta are developed. After simulating the “rigid-bar” abdominal loading, the impact force and abdominal penetration are investigated. Findings are compared... 

    Differences in muscle synergies between healthy subjects and transfemoral amputees during normal transient-state walking speed

    , Article Gait and Posture ; Volume 76 , February , 2020 , Pages 98-103 Mehryar, P ; Shourijeh, M. S ; Rezaeian, T ; Khandan, A. R ; Messenger, N ; O'Connor, R ; Farahmand, F ; Dehghani Sanij, A ; Sharif University of Technology
    Elsevier B. V  2020
    Background: Lower limb amputation is a major public health issue globally, and its prevalence is increasing significantly around the world. Previous studies on lower limb amputees showed analogous complexity implemented by the neurological system which does not depend on the level of amputation. Research question: What are the differences in muscle synergies between healthy subjects (HS) and transfemoral amputees (TFA) during self-selected normal transient-state walking speed? Methods: thirteen male HS and eleven male TFA participated in this study. Surface electromyography (sEMG) data were collected from HS dominant leg and TFA intact limb. Concatenated non-negative matrix factorization... 

    Design optimization of an above-knee prosthesis based on the kinematics of gait

    , Article 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'08, Vancouver, BC, 20 August 2008 through 25 August 2008 ; 2008 , Pages 4274-4277 ; 9781424418152 (ISBN) Pejhan, S ; Farahmand, F ; Parnianpour, M ; Sharif University of Technology
    A dynamic model of an above-knee prosthesis during the complete gait cycle was developed. The model was based on a two-dimensional multi-body mechanical system and included a hydraulic and an elastic controller for the knee and a kinematical driver controller for the prosthetic ankle. The equations of motion were driven using Lagrange method. Simulation of the foot contact was conducted using a two-point penetration contact model. The knee elastic and hydraulic controller units, the knee extension stop, and the kinematical driver controller of the ankle were represented by a spring and a dashpot, a nonlinear spring, and a torsional spring-damper within a standard prosthetic configuration.... 

    Effects of an exercise therapy targeting knee kinetics on pain, function, and gait kinetics in patients with knee osteoarthritis: A randomized clinical trial

    , Article Adapted Physical Activity Quarterly ; Volume 38, Issue 3 , 2021 , Pages 377-395 ; 07365829 (ISSN) Bokaeian, H. R ; Esfandiarpour, F ; Zahednejad, S ; Kouhzad Mohammadi, H ; Farahmand, F ; Sharif University of Technology
    Human Kinetics Publishers Inc  2021
    In this study, the effects of an exercise therapy comprising yoga exercises and medial-thrust gait (YogaMT) on lower-extremity kinetics, pain, and function in patients with medial knee osteoarthritis were investigated. Fifty-nine patients were randomly allocated to three treatment groups: (a) the YogaMT group practiced yoga exercises and medial thrust gait, (b) the knee-strengthening group performed quadriceps-and hamstring-strengthening exercises, and (c) the treadmill walking group practiced normal treadmill walking in 12 supervised sessions. The adduction and flexion moments of the hip, knee, and ankle; pain intensity; and 2-min walking test were assessed before and after treatment and at... 

    Can the body slope of interference screw affect initial stability of reconstructed anterior cruciate ligament?: An in-vitro investigation

    , Article BMC Musculoskeletal Disorders ; Volume 22, Issue 1 , 2021 ; 14712474 (ISSN) Daneshvarhashjin, N ; Chizari, M ; Mortazavi, J ; Rouhi, G ; Sharif University of Technology
    BioMed Central Ltd  2021
    Background: Superior biomechanical performance of tapered interference screws, compared with non-tapered screws, with reference to the anterior cruciate ligament (ACL) reconstruction process, has been reported in the literature. However, the effect of tapered interference screw’s body slope on the initial stability of ACL is poorly understood. Thus, the main goal of this study was to investigate the effect of the interference screw’s body slope on the initial stability of the reconstructed ACL. Methods: Based on the best screw-bone tunnel diameter ratios in non-tapered screws, two different tapered interference screws were designed and fabricated. The diameters of both screws were equal to... 

    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) Ebrahimkhani, M ; Arjmand, N ; Shirazi Adl, A ; Sharif University of Technology
    Nature Research  2021
    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...