The Experts below are selected from a list of 142455 Experts worldwide ranked by ideXlab platform
Richard E. Debski - One of the best experts on this subject based on the ideXlab platform.
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A Validated, Specimen-Specific Finite Element Model of the Supraspinatus Tendon Mechanical Environment
Journal of biomechanical engineering, 2019Co-Authors: R. Matthew Miller, James Thunes, Volker Musahl, Spandan Maiti, Richard E. DebskiAbstract:Rotator cuff tears are a significant clinical problem previously investigated by unvalidated computational models that either use simplified geometry or isotropic elastic material properties to represent the tendon. The objective of this study was to develop an experimentally validated, finite element model of supraspinatus tendon using specimen-specific geometry and inhomogeneous material properties to predict strains in intact supraspinatus tendon. Three-dimensional tendon surface strains were determined at 60°, 70°, and 90° of glenohumeral abduction for articular and bursal surfaces of supraspinatus tendon during cyclic loading to serve as validation data. A finite element model was developed using the tendon geometry and inhomogeneous material properties to predict surface strains for loading conditions mimicking experimental loading conditions. Experimental strains were directly compared with computational model predictions to validate the model. Overall, the model successfully predicted magnitudes of strains that were within the experimental repeatability of 3% strain of experimental measures on both surfaces of the tendon. Model predictions and experiments showed the largest strains to be located on the articular surface (~8% strain) between the middle and anterior edge of the tendon. Importantly, the reference configuration chosen to calculate strains had a significant effect on strain calculations, and therefore must be defined with an innovative optimization algorithm. This study establishes a rigorously validated, specimen-specific computational model using novel surface strain measurements for use in investigating the function of the supraspinatus tendon and to ultimately predict the propagation of supraspinatus tendon tears based on the tendon's Mechanical Environment.
Moto Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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Mechanical Environment of the supraspinatus tendon: a two-dimensional finite element model analysis.
Journal of shoulder and elbow surgery, 2003Co-Authors: Ikuko Wakabayashi, Eiji Itoi, Yotsugi Shibuya, Hirotaka Sano, Ryuji Sashi, Hiroshi Minagawa, Moto KobayashiAbstract:Abstract We performed 2-dimensional finite element model analysis to estimate the Mechanical Environment of the supraspinatus tendon. The geometric shape of the finite element model was determined by magnetic resonance imaging of a normal human shoulder obtained at 0°, 30°, and 60° of abduction, whereas the histologic location of noncalcified and calcified fibrocartilage was determined from a cadaveric specimen. The supraspinatus tendon was pulled proximally with the force of 10 N at 0°, 53 N at 30°, and 115 N at 60° of abduction. The area of high principal stress maximum was observed on the articular side of the supraspinatus tendon, which shifted toward the insertion as the arm was abducted. High stress concentration on the articular side of the supraspinatus tendon near its insertion during arm elevation may explain the frequent occurrence of rotator cuff tears at this site.
R. Matthew Miller - One of the best experts on this subject based on the ideXlab platform.
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A Validated, Specimen-Specific Finite Element Model of the Supraspinatus Tendon Mechanical Environment
Journal of biomechanical engineering, 2019Co-Authors: R. Matthew Miller, James Thunes, Volker Musahl, Spandan Maiti, Richard E. DebskiAbstract:Rotator cuff tears are a significant clinical problem previously investigated by unvalidated computational models that either use simplified geometry or isotropic elastic material properties to represent the tendon. The objective of this study was to develop an experimentally validated, finite element model of supraspinatus tendon using specimen-specific geometry and inhomogeneous material properties to predict strains in intact supraspinatus tendon. Three-dimensional tendon surface strains were determined at 60°, 70°, and 90° of glenohumeral abduction for articular and bursal surfaces of supraspinatus tendon during cyclic loading to serve as validation data. A finite element model was developed using the tendon geometry and inhomogeneous material properties to predict surface strains for loading conditions mimicking experimental loading conditions. Experimental strains were directly compared with computational model predictions to validate the model. Overall, the model successfully predicted magnitudes of strains that were within the experimental repeatability of 3% strain of experimental measures on both surfaces of the tendon. Model predictions and experiments showed the largest strains to be located on the articular surface (~8% strain) between the middle and anterior edge of the tendon. Importantly, the reference configuration chosen to calculate strains had a significant effect on strain calculations, and therefore must be defined with an innovative optimization algorithm. This study establishes a rigorously validated, specimen-specific computational model using novel surface strain measurements for use in investigating the function of the supraspinatus tendon and to ultimately predict the propagation of supraspinatus tendon tears based on the tendon's Mechanical Environment.
Ikuko Wakabayashi - One of the best experts on this subject based on the ideXlab platform.
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Mechanical Environment of the supraspinatus tendon: three-dimensional finite element model analysis.
Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association, 2008Co-Authors: Nobutoshi Seki, Eiji Itoi, Yotsugi Shibuya, Ikuko Wakabayashi, Hirotaka Sano, Ryuji Sashi, Hiroshi Minagawa, Nobuyuki Yamamoto, Hidekazu Abe, Kazuma KikuchiAbstract:Background We analyzed the Mechanical Environment of the supraspinatus tendon using a three-dimensional finite element model with the software programs MENTAT and MARC.
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Mechanical Environment of the supraspinatus tendon: a two-dimensional finite element model analysis.
Journal of shoulder and elbow surgery, 2003Co-Authors: Ikuko Wakabayashi, Eiji Itoi, Yotsugi Shibuya, Hirotaka Sano, Ryuji Sashi, Hiroshi Minagawa, Moto KobayashiAbstract:Abstract We performed 2-dimensional finite element model analysis to estimate the Mechanical Environment of the supraspinatus tendon. The geometric shape of the finite element model was determined by magnetic resonance imaging of a normal human shoulder obtained at 0°, 30°, and 60° of abduction, whereas the histologic location of noncalcified and calcified fibrocartilage was determined from a cadaveric specimen. The supraspinatus tendon was pulled proximally with the force of 10 N at 0°, 53 N at 30°, and 115 N at 60° of abduction. The area of high principal stress maximum was observed on the articular side of the supraspinatus tendon, which shifted toward the insertion as the arm was abducted. High stress concentration on the articular side of the supraspinatus tendon near its insertion during arm elevation may explain the frequent occurrence of rotator cuff tears at this site.
Marie-hélène Lafage-proust - One of the best experts on this subject based on the ideXlab platform.
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MAP and src kinases control the induction of AP-1 members in response to changes in Mechanical Environment in osteoblastic cells.
Cellular signalling, 2002Co-Authors: Corinne Granet, Christian Alexandre, Alain Guignandon Laurence Vico, Marie-hélène Lafage-proustAbstract:The activating protein-1 (AP-1) complex plays a critical role in bone physiology, including its response to strain. We studied gene expression and nuclear translocation kinetics of the seven AP-1 members, after substrate deformation (Flexcell) or simulated microgravity (Clinostat), in osteoblastic ROS17/2.8 cells. Gene expression and nuclear translocation of all the AP-1 members were induced, under both conditions, with differences in their kinetics, except fosB mRNA in the Clinostat. Downregulation of protein kinase C (PKC) and COX1/2 or inhibition of ERK1/2, p38(MAPK) or src kinases had no major effect on AP-1 mRNA expression in the Flexcell. In contrast, ERK1/2, p38(MAPK) and src kinases treatment blocked nuclear translocation of almost all the AP-1 members in both models, except Fra-1, JunD after deformation and Fra-1, JunB after clinorotation. Thus, changes in the osteoblastic Mechanical Environment induced a dramatic induction of most of the AP-1 members with specific kinetics and involved MAPK and src kinase pathways, which differed whether the cells were stretched or clinorotated.
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MAPK and SRC-Kinases Control EGR-1 and NF-κB Inductions by Changes in Mechanical Environment in Osteoblasts
Biochemical and biophysical research communications, 2001Co-Authors: Corinne Granet, Nadia Boutahar, Laurence Vico, Christian Alexandre, Marie-hélène Lafage-proustAbstract:Abstract Bone loss occurs in microgravity whereas an increase in bone mass is observed after skeletal loading. This tissue adaptation involves changes in osteoblastic proliferation and differentiation whose mechanisms remain largely unknown. In this context, we investigated the expression and the nuclear translocation of Egr-1 and NF-κB, in a simulated microgravity model (clinostat) and in a model of Mechanical strain (Flexcell). We performed RT-PCR and immunocytochemistry analyses at baseline and up to 2 h after stimulation (a mitogenic regimen, 1% stretch, 0.05 Hz, 10 min, or clinorotation 50 rpm, 10 min) in osteoblastic ROS17/2.8 cells. Egr-1 induction as well as NF-κB nuclear translocation were activated by Mechanical changes. PKC downregulation and COX1/2 inhibition did not alter these inductions. In contrast, ERK1/2, p38MAPK and src-kinases pathways were differentially involved in both models. Thus, we demonstrated that changes in the Mechanical Environment induced an activation of Egr-1 and NF-κB with specific kinetics and involved various transduction pathways including MAPKs and src-kinases. These could partially explain the later alterations of proliferation observed.
