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Biomechanics and Modeling in Mechanobiology

Antonio E Forte, Stephen M Gentleman, Daniele Dini
The mechanical characterization of brain tissue is a complex task that scientists have tried to accomplish for over 50 years. The results in the literature often differ by orders of magnitude because of the lack of a standard testing protocol. Different testing conditions (including humidity, temperature, strain rate), the methodology adopted, and the variety of the species analysed are all potential sources of discrepancies in the measurements. In this work, we present a rigorous experimental investigation on the mechanical properties of human brain, covering both grey and white matter...
December 8, 2016: Biomechanics and Modeling in Mechanobiology
F A Braeu, A Seitz, R C Aydin, C J Cyron
Constrained mixture models for soft tissue growth and remodeling have attracted increasing attention over the last decade. They can capture the effects of the simultaneous presence of multiple constituents that are continuously deposited and degraded at in general different rates, which is important to understand essential features of living soft tissues that cannot be captured by simple kinematic growth models. Recently the novel concept of homogenized constrained mixture models was introduced. It was shown that these models produce results which are very similar (and in certain limit cases even identical) to the ones of constrained mixture models based on multi-network theory...
December 5, 2016: Biomechanics and Modeling in Mechanobiology
Rami Haj-Ali, Eyass Massarwa, Jacob Aboudi, Fabio Galbusera, Uwe Wolfram, Hans-Joachim Wilke
A new three-dimensional (3D) multiscale micromechanical model has been suggested as adept at predicting the overall linear anisotropic mechanical properties of a vertebral trabecular bone (VTB) highly porous microstructure. A nested 3D modeling analysis framework spanning the multiscale nature of the VTB is presented herein. This hierarchical analysis framework employs the following micromechanical methods: the 3D parametric high-fidelity generalized method of cells (HFGMC) as well as the 3D sublaminate model...
December 2, 2016: Biomechanics and Modeling in Mechanobiology
H Marouane, A Shirazi-Adl, M Adouni
Musculoskeletal models of the lower extremity make a number of important assumptions when attempting to estimate muscle forces and tibiofemoral compartmental loads in activities such as gait. The knee is commonly idealized as a planar 2D joint in the sagittal plane with no consideration of motions and equilibrium in remaining planes. With muscle forces predicted, the static equilibrium in the frontal plane is then used to estimate compartmental loads neglecting also joint passive resistance and assuming condylar contact centers...
December 2, 2016: Biomechanics and Modeling in Mechanobiology
Liang Zhang, Sri Gowtham Thakku, Meghna R Beotra, Mani Baskaran, Tin Aung, James C H Goh, Nicholas G Strouthidis, Michael J A Girard
We aimed to verify a custom virtual fields method (VFM) to estimate the patient-specific biomechanical properties of human optic nerve head (ONH) tissues, given their full-field deformations induced by intraocular pressure (IOP). To verify the accuracy of VFM, we first generated 'artificial' ONH displacements from predetermined (known) ONH tissue biomechanical properties using finite element analysis. Using such deformations, if we are able to match back the known biomechanical properties, it would indicate that our VFM technique is accurate...
December 1, 2016: Biomechanics and Modeling in Mechanobiology
Kenneth I Aycock, Robert L Campbell, Keefe B Manning, Brent A Craven
Inferior vena cava (IVC) filters are medical devices designed to provide a mechanical barrier to the passage of emboli from the deep veins of the legs to the heart and lungs. Despite decades of development and clinical use, IVC filters still fail to prevent the passage of all hazardous emboli. The objective of this study is to (1) develop a resolved two-way computational model of embolus transport, (2) provide verification and validation evidence for the model, and (3) demonstrate the ability of the model to predict the embolus-trapping efficiency of an IVC filter...
November 30, 2016: Biomechanics and Modeling in Mechanobiology
Sara Salehyar, Qiang Zhu
By using a fully coupled fluid-cell interaction model, we numerically simulate the dynamic process of a red blood cell passing through a slit driven by an incoming flow. The model is achieved by combining a multiscale model of the composite cell membrane with a boundary element fluid dynamics model based on the Stokes flow assumption. Our concentration is on the correlation between the transit time (the time it takes to finish the whole translocation process) and different conditions (flow speed, cell orientation, cell stiffness, cell volume, etc...
November 26, 2016: Biomechanics and Modeling in Mechanobiology
Shukei Sugita, Takeo Matsumoto
Elastin and collagen fibers play important roles in the mechanical properties of aortic media. Because knowledge of local fiber structures is required for detailed analysis of blood vessel wall mechanics, we investigated 3D microstructures of elastin and collagen fibers in thoracic aortas and monitored changes during pressurization. Using multiphoton microscopy, autofluorescence images from elastin and second harmonic generation signals from collagen were acquired in media from rabbit thoracic aortas that were stretched biaxially to restore physiological dimensions...
November 22, 2016: Biomechanics and Modeling in Mechanobiology
Thomas A Metzger, Ted J Vaughan, Laoise M McNamara, Glen L Niebur
Age-related increases in trabecular bone porosity, as seen in osteoporosis, not only affect the strength and stiffness, but also potentially the mechanobiological response of bone. The mechanical interaction between trabecular bone and bone marrow is one source of mechanobiological signaling, as many cell populations in marrow are mechanosensitive. However, measuring the mechanics of this interaction is difficult, due to the length scales and geometric complexity of trabecular bone. In this study, a multi-scale computational scheme incorporating high-resolution, tissue-level, fluid-structure interaction simulations with discrete cell-level models was applied to characterize the potential effects of trabecular porosity and marrow composition on marrow mechanobiology in human femoral bone...
November 22, 2016: Biomechanics and Modeling in Mechanobiology
Xiaogai Li, Håkan Sandler, Svein Kleiven
Despite recent efforts on the development of finite element (FE) head models of infants, a model capable of capturing head responses under various impact scenarios has not been reported. This is hypothesized partially attributed to the use of simplified linear elastic models for soft tissues of suture, scalp and dura. Orthotropic elastic constants are yet to be determined to incorporate the direction-specific material properties of infant cranial bone due to grain fibres radiating from the ossification centres...
November 21, 2016: Biomechanics and Modeling in Mechanobiology
Anastasia Desyatova, Jason MacTaggart, William Poulson, Paul Deegan, Carol Lomneth, Anjali Sandip, Alexey Kamenskiy
Open and endovascular treatments for peripheral arterial disease are notorious for high failure rates. Severe mechanical deformations experienced by the femoropopliteal artery (FPA) during limb flexion and interactions between the artery and repair materials play important roles and may contribute to poor clinical outcomes. Computational modeling can help optimize FPA repair, but these simulations heavily depend on the choice of constitutive model describing the arterial behavior. In this study finite element model of the FPA in the standing (straight) and gardening (acutely bent) postures was built using computed tomography data, longitudinal pre-stretch and biaxially determined mechanical properties...
November 21, 2016: Biomechanics and Modeling in Mechanobiology
Cameron Hoerig, Jamshid Ghaboussi, Michael F Insana
An information-based technique is described for applications in mechanical property imaging of soft biological media under quasi-static loads. We adapted the Autoprogressive method that was originally developed for civil engineering applications for this purpose. The Autoprogressive method is a computational technique that combines knowledge of object shape and a sparse distribution of force and displacement measurements with finite-element analyses and artificial neural networks to estimate a complete set of stress and strain vectors...
November 18, 2016: Biomechanics and Modeling in Mechanobiology
Amirhossein Arzani, Alberto M Gambaruto, Guoning Chen, Shawn C Shadden
Near-wall transport is of utmost importance in connecting blood flow mechanics with cardiovascular disease progression. The near-wall region is the interface for biologic and pathophysiologic processes such as thrombosis and atherosclerosis. Most computational and experimental investigations of blood flow implicitly or explicitly seek to quantify hemodynamics at the vessel wall (or lumen surface), with wall shear stress (WSS) quantities being the most common descriptors. Most WSS measures are meant to quantify the frictional force of blood flow on the vessel lumen...
November 17, 2016: Biomechanics and Modeling in Mechanobiology
Marija Smoljkić, Heleen Fehervary, Philip Van den Bergh, Alvaro Jorge-Peñas, Louis Kluyskens, Steven Dymarkowski, Peter Verbrugghe, Bart Meuris, Jos Vander Sloten, Nele Famaey
Ascending thoracic aortic aneurysms (ATAAs) are a silent disease, ultimately leading to dissection or rupture of the arterial wall. There is a growing consensus that diameter information is insufficient to assess rupture risk, whereas wall stress and strength provide a more reliable estimate. The latter parameters cannot be measured directly and must be inferred through biomechanical assessment, requiring a thorough knowledge of the mechanical behaviour of the tissue. However, for healthy and aneurysmal ascending aortic tissues, this knowledge remains scarce...
November 12, 2016: Biomechanics and Modeling in Mechanobiology
O Röhrle, M Sprenger, S Schmitt
By following the common definition of forward-dynamics simulations, i.e. predicting movement based on (neural) muscle activity, this work describes, for the first time, a forward-dynamics simulation framework of a musculoskeletal system, in which all components are represented as continuous, three-dimensional, volumetric objects. Within this framework, the mechanical behaviour of the entire muscle-tendon complex is modelled as a nonlinear hyperelastic material undergoing finite deformations. The feasibility and the full potential of the proposed forward-dynamics simulation framework is demonstrated on a two-muscle, three-dimensional, continuum-mechanical model of the upper limb...
November 11, 2016: Biomechanics and Modeling in Mechanobiology
Cátia Bandeiras, António Completo
In this work a coupled model of solute transport and uptake, cell proliferation, extracellular matrix synthesis and remodeling of mechanical properties accounting for the impact of mechanical loading is presented as an advancement of a previously validated coupled model for free-swelling tissue-engineered cartilage cultures. Tissue-engineering constructs were modeled as biphasic with a linear elastic solid, and relevant intrinsic mechanical stimuli in the constructs were determined by numerical simulation for use as inputs of the coupled model...
November 5, 2016: Biomechanics and Modeling in Mechanobiology
Karol Daszkiewicz, Ghislain Maquer, Philippe K Zysset
Boundary conditions (BCs) and sample size affect the measured elastic properties of cancellous bone. Samples too small to be representative appear stiffer under kinematic uniform BCs (KUBCs) than under periodicity-compatible mixed uniform BCs (PMUBCs). To avoid those effects, we propose to determine the effective properties of trabecular bone using an embedded configuration. Cubic samples of various sizes (2.63, 5.29, 7.96, 10.58 and 15.87 mm) were cropped from [Formula: see text] scans of femoral heads and vertebral bodies...
October 26, 2016: Biomechanics and Modeling in Mechanobiology
Alexey Kamenskiy, Andreas Seas, Paul Deegan, William Poulson, Eric Anttila, Sylvie Sim, Anastasia Desyatova, Jason MacTaggart
Femoropopliteal artery (FPA) mechanics play a paramount role in pathophysiology and the artery's response to therapeutic interventions, but data on FPA mechanical properties are scarce. Our goal was to characterize human FPAs over a wide population to derive a constitutive description of FPA aging to be used for computational modeling. Fresh human FPA specimens ([Formula: see text]) were obtained from [Formula: see text] predominantly male (80 %) donors 54±15 years old (range 13-82 years). Morphometric characteristics including radius, wall thickness, opening angle, and longitudinal pre-stretch were recorded...
October 22, 2016: Biomechanics and Modeling in Mechanobiology
Jie Gao, John L Williams, Esra Roan
Growth plate chondrocytes are responsible for bone growth through proliferation and differentiation. However, the way they experience physiological loads and regulate bone formation, especially during the later developmental phase in the mature growth plate, is still under active investigation. In this study, a previously developed multiscale finite element model of the growth plate is utilized to study the stress and strain distributions within the cartilage at the cellular level when rapidly compressed to 20 %...
October 21, 2016: Biomechanics and Modeling in Mechanobiology
Jun Qiu, Fang-Fang Li
Mechanical properties of a single cell and its mechanical response under stimulation play an important role in regulating interactions between cell and extracellular matrix and affecting mechanotransduction. Osteocytes exhibit solid-like viscoelastic behavior in response to the interstitial fluid shear resulting from tissue matrix deformation. This study intends to quantitatively describe the mechanical behavior of osteocytes combining in vitro experiment and fluid-structure interaction (FSI) finite element (FE) model...
October 17, 2016: Biomechanics and Modeling in Mechanobiology
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