Search for: models--anatomic
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    Accuracy of Kinect's skeleton tracking for upper body rehabilitation applications

    , Article Disability and Rehabilitation: Assistive Technology ; Vol. 9, issue. 4 , 2014 , pp. 344-352 ; ISSN: 17483107 Mobini, A ; Behzadipour, S ; Saadat Foumani, M ; Sharif University of Technology
    Games and their use in rehabilitation have formed a new and rapidly growing area of research. A critical hardware component of rehabilitation programs is the input device that measures the patients' movements. After Microsoft released Kinect, extensive research has been initiated on its applications as an input device for rehabilitation. However, since most of the works in this area rely on a qualitative determination of the joints' movements rather than an accurate quantitative one, detailed analysis of patients' movements is hindered. The aim of this article is to determine the accuracy of the Kinect's joint tracking. To fulfill this task, a model of upper body was fabricated. The... 

    Novel methodology in design of custom-made hip prosthesis

    , Article Innovative Developments in Design and Manufacturing - Advanced Research in Virtual and Rapid Prototyping, 6 October 2009 through 10 October 2009, Leiria ; 2010 , Pages 117-126 ; 9780415873079 (ISBN) Abbaszadeh, F ; Rahmati, S ; Farahmand, F ; Fatollahzadeh, R ; Sharif University of Technology
    Medical applications of rapid prototyping have an increasing trend, making the future of RP more and more promising. These applications may include design, development, and manufacture of medical devices and instrumentation, as well as implant design, anatomical modeling, surgical planning, surgical implants, and prosthesis fabrication. This paper provides a new methodology for customized hip prosthesis that could provide high accuracy of femoral canal reconstruction via 3D modeling of prosthesis stem, 3D modeling of prosthesis neck, and facilitating the communication between the designer and surgeon. Combining RP technologies and rapid tooling with this novel custom-made hip prosthesis,... 

    Stiffness of knee-spanning external fixation systems for traumatic knee dislocations: A biomechanical study

    , Article Journal of Orthopaedic Trauma ; Volume 24, Issue 11 , Nov , 2010 , Pages 693-696 ; 08905339 (ISSN) Mercer, D ; Firoozbakhsh, K ; Prevost, M ; Mulkey, P ; Decoster, T. A ; Schenck, R ; Sharif University of Technology
    Objective: The purpose of this study was to compare the relative stiffness of four common external fixation (XF) configurations used to span and stabilize the knee after knee dislocation. Methods: Synthetic composite femora and tibiae connected with cords were used to simulate a knee. Four configurations of external fixation were tested: anterior femoral pins with monotube (XF1), anterolateral femoral pins with monotube (XF2), anterolateral femoral pins with two connecting rods (XF3), and hinged ring fixator (XF4). Six specimens of each configuration were loaded nondestructively in varus/valgus, anterior-to- posterior shear, flexion/extension, axial compression, internal/external torsion,... 

    Statistical construction of a Japanese male liver phantom for internal radionuclide dosimetry

    , Article Radiation Protection Dosimetry ; Volume 141, Issue 2 , 2010 , Pages 140-148 ; 01448420 (ISSN) Babapour Mofrad, F ; Aghaeizadeh Zoroofi, R ; Abbaspour Tehrani Fard, A ; Akhlaghpoor, S ; Hori, M ; Chen, Y. W ; Sato, Y ; Sharif University of Technology
    A computational framework is presented, based on statistical shape modelling, for construction of race-specific organ models for internal radionuclide dosimetry and other nuclear-medicine applications. This approach was applied to the construction of a Japanese liver phantom, using the liver of the digital Zubal phantom as the template and 35 liver computed tomography (CT) scans of male Japanese individuals as a training set. The first step was the automated object-space registration (to align all the liver surfaces in one orientation), using a coherent-point-drift maximum-likelihood alignment algorithm, of each CT scan-derived manually contoured liver surface and the template Zubal liver... 

    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... 

    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) Gohari, E ; Nikkhoo, M ; Haghpanahi, M ; Parnianpour, M ; Sharif University of Technology
    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  

    A computer model for evaluating the osteotomy parameters of Chiari pelvic osteotomy

    , Article International Orthopaedics ; Volume 34, Issue 3 , 2010 , Pages 329-333 ; 03412695 (ISSN) Karami, M ; Gouran Savadkoohi, D ; Ghadirpoor, A ; Rahimpoor, S ; Azghani, M ; Farahmand, F ; Sharif University of Technology
    This study was conducted to evaluate the effect of the various osteotomy parameters on the biomechanical aspects of the hip joint on a computerised model. The data of the radiographs and a three-dimensional (3D) CT scan of six patients with coverage deficient hip joint were used to construct a 3D computer model. Then Chiari type osteotomies were simulated using various heights, angles and fibrocartilage thicknesses. A new angle called the mid acetabular center edge (MACE) angle was defined in a mid coronal CT cut. The optimum displacement for obtaining the maximum coverage averaged 73%. The angle and height of the osteotomy had a significant effect on the MACE angle (P value∈<∈0. 01). Our... 

    Developmental model of an automatic production of the human bronchial tree based on L-system

    , Article Computer Methods and Programs in Biomedicine ; Volume 132 , 2016 , Pages 1-10 ; 01692607 (ISSN) Davoodi, A ; Boozarjomehry, R. B ; Sharif University of Technology
    Elsevier Ireland Ltd  2016
    Background and objective: The human lungs exchange air with the external environment via the conducting airways. The application of an anatomically accurate model of the conducting airways can be helpful for simulating gas exchange and fluid distribution throughout the bronchial tree in the lung. Methods: In the current study, Lindenmayer system (L-system) has been formulated to generate the bronchial tree structure in a human lung. It has been considered that the structure of the bronchial tree is divided into two main segments: 1) The central airways (from the trachea to segmental bronchi) and 2) the dichotomous structure (from segmental bronchi to terminal bronchioles). Two sets of... 

    A non-linear mass-spring model for more realistic and efficient simulation of soft tissues surgery

    , Article Medicine Meets Virtual Reality 16 - Parallel, Combinatorial, Convergent: NextMed by Design, MMVR 2008, Long Beach, CA, 30 January 2008 through 1 February 2008 ; Volume 132 , 2008 , Pages 23-25 ; 09269630 (ISSN); 9781586038229 (ISBN) Basafa, E ; Farahmand, F ; Vossoughi, G ; Sharif University of Technology
    IOS Press  2008
    An extension to the classical mass-spring model for more realistic simulation of soft tissues for surgery simulation was proposed. The conventional equations of mass-spring model were generalized for non-linear springs, and model parameters were tuned using experimental data. Results show that the proposed model is fast and interactive, and also demonstrate the typical nonlinear and visco-elastic behaviors of soft tissues well. © 2008 The authors. All rights reserved  

    Prediction of shape and internal structure of the proximal femur using a modified level set method for structural topology optimisation

    , Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 15, Issue 8 , 2012 , Pages 835-844 ; 10255842 (ISSN) Bahari, M. K ; Farahmand, F ; Rouhi, G ; Movahhedy, M. R ; Sharif University of Technology
    A computational framework was developed to simulate the bone remodelling process as a structural topology optimisation problem. The mathematical formulation of the Level Set technique was extended and then implemented into a coronal plane model of the proximal femur to simulate the remodelling of internal structure and external geometry of bone into the optimal state. Results indicated that the proposed approach could reasonably mimic the major geometrical and material features of the natural bone. Simulation of the internal bone remodelling on the typical gross shape of the proximal femur, resulted in a density distribution pattern with good consistency with that of the natural bone. When... 

    A novel distributed model of the heart under normal and congestive heart failure conditions

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 227, Issue 4 , 2013 , Pages 362-372 ; 09544119 (ISSN) Ravanshadi, S ; Jahed, M ; Sharif University of Technology
    Conventional models of cardiovascular system frequently lack required detail and focus primarily on the overall relationship between pressure, flow and volume. This study proposes a localized and regional model of the cardiovascular system. It utilizes noninvasive blood flow and pressure seed data and temporal cardiac muscle regional activity to predict the operation of the heart under normal and congestive heart failure conditions. The analysis considers specific regions of the heart, namely, base, mid and apex of left ventricle. The proposed method of parameter estimation for hydraulic electric analogy model is recursive least squares algorithm. Based on simulation results and comparison... 

    Feasibility of infrared tracking of beating heart motion for robotic assisted beating heart surgery

    , Article International Journal of Medical Robotics and Computer Assisted Surgery ; Volume 14, Issue 1 , February , 2018 ; 14785951 (ISSN) Mansouri, S ; Farahmand, F ; Vossoughi, G ; Ghavidel, A. A ; Rezayat, M ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    Background: Accurate tracking of the heart surface motion is a major requirement for robot assisted beating heart surgery. Method: The feasibility of a stereo infrared tracking system for measuring the free beating heart motion was investigated by experiments on a heart motion simulator, as well as model surgery on a dog. Results: Simulator experiments revealed a high tracking accuracy (81 μm root mean square error) when the capturing times were synchronized and the tracker pointed at the target from a 100 cm distance. The animal experiment revealed the applicability of the infrared tracker with passive markers in practical heart surgery conditions. Conclusion: With the current technology,... 

    A detailed and validated three dimensional dynamic model of the patellofemoral joint

    , Article Journal of Biomechanical Engineering ; Volume 134, Issue 4 , 2012 ; 01480731 (ISSN) Akbar, M ; Farahmand, F ; Jafari, A ; Foumani, M. S ; Sharif University of Technology
    A detailed 3D anatomical model of the patellofemoral joint was developed to study the tracking, force, contact and stability characteristics of the joint. The quadriceps was considered to include six components represented by 15 force vectors. The patellar tendon was modeled using four bundles of viscoelastic tensile elements. Each of the lateral and medial retinaculum was modeled by a three-bundle nonlinear spring. The femur and patella were considered as rigid bodies with their articular cartilage layers represented by an isotropic viscoelastic material. The geometrical and tracking data needed for model simulation, as well as validation of its results, were obtained from an in vivo... 

    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) Gagnon, D ; Arjmand, N ; Plamondon, A ; Shirazi Adl, A ; Larivière, C ; Sharif University of Technology
    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...