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Computer Methods in Biomechanics and Biomedical Engineering

C Pizzolato, M Reggiani, L Modenese, D G Lloyd
Real-time estimation of joint angles and moments can be used for rapid evaluation in clinical, sport, and rehabilitation contexts. However, real-time calculation of kinematics and kinetics is currently based on approximate solutions or generic anatomical models. We present a real-time system based on OpenSim solving inverse kinematics and dynamics without simplifications at 2000 frame per seconds with less than 31.5 ms of delay. We describe the software architecture, sensitivity analyses to minimise delays and errors, and compare offline and real-time results...
October 10, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Elizabeth C Clarke, David F Fletcher, Lynne E Bilston
Syringomyelia (a spinal cord cyst) usually develops as a result of conditions that cause cerebrospinal fluid (CSF) obstruction. The mechanism of syrinx formation and enlargement remains unclear, though previous studies suggest that the fluid enters via the perivascular spaces (PVS) of the penetrating arteries of the spinal cord, and that alterations in the CSF pulse timing and pressure could contribute to enhanced PVS inflow. This study uses an idealised computational model of the PVS to investigate the factors that influence peri-arterial fluid flow...
October 7, 2016: Computer Methods in Biomechanics and Biomedical Engineering
K Cao, P Sucosky
Computational characterizations of aortic valve hemodynamics have typically discarded the effects of coronary flow. The objective of this study was to complement our previous fluid-structure interaction aortic valve model with a physiologic coronary circulation model to quantify the impact of coronary flow on aortic sinus hemodynamics and leaflet wall shear stress (WSS). Coronary flow suppressed vortex development in the two coronary sinuses and altered WSS magnitude and directionality on the three leaflets, with the most substantial differences occurring in the belly and tip regions...
October 7, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Yu-Ching Yang, Haw-Long Lee, Win-Jin Chang, Wen-Lih Chen
The aim of this study is to solve an inverse heat conduction problem to estimate the unknown time-dependent laser irradiance and thermal damage in laser-irradiated biological tissue from the temperature measurements taken within the tissue. The dual-phase-lag model is considered in the formulation of heat conduction equation. The inverse algorithm used in the study is based on the conjugate gradient method and the discrepancy principle. The effect of measurement errors and measurement locations on the estimation accuracy is also investigated...
October 6, 2016: Computer Methods in Biomechanics and Biomedical Engineering
M D Gilchrist, D MacManus, J G Murphy, B Pierrat
In order to avoid the numerical difficulties in locally enforcing the incompressibility constraint using the displacement formulation of the Finite Element Method, slight compressibility is typically assumed when simulating the mechanical response of arterial tissue. The current standard method of accounting for slight compressibility of hyperelastic soft tissue assumes an additive decomposition of the strain-energy function into a volumetric and a deviatoric part. This has been shown, however, to be inconsistent with the linear theory and results in cubes retaining their cuboid shape under hydrostatic tension and compression, which seems at variance with the reinforcement of arterial tissue with two families of collagen fibres...
October 6, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Maki Matsuzaki, Yasunori Ayukawa, Nobuo Sakai, Tatsuya Matsuzaki, Yasuyuki Matsushita, Kiyoshi Koyano
A number of finite element analyses (FEAs) for the dental implant were performed without regard for preload and with all interfaces 'fixed-bonded'. The purpose of this study was comparing the stress distributions between the conventional FEA model with all contacting interfaces 'fixed-bonded' (bonded model) and the model with the interfaces of the components in 'contact' with friction simulated as a preloaded implant (contact model). We further verified the accuracy of the result of the FEA using model experiment...
September 28, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Daisuke Tawara, Ken Nagura
Because changes in the mechanical properties of bone are closely related to trabecular bone remodeling, methods that consider the temporal morphological changes induced by adaptive remodeling of trabecular bone are needed to estimate long-term fracture risk and bone quality in osteoporosis. We simulated bone remodeling using simplified and pig trabecular bone models and estimated the morphology of healthy and osteoporotic cases. We then displayed the fracture risk of the remodeled models based on a cumulative histogram from high stress...
September 27, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Naiara Rodriguez-Florez, Alessandra Carriero, Sandra J Shefelbine
This study aimed at using eXtended finite element method (XFEM) to characterize crack growth through bone's intra-cortical pores. Two techniques were compared using Abaqus: (1) void material properties were assigned to pores; (2) multiple enrichment regions with independent crack-growth possibilities were employed. Both were applied to 2D models of transverse images of mouse bone with differing porous structures. Results revealed that assigning multiple enrichment regions allows for multiple cracks to be initiated progressively, which cannot be captured when the voids are filled...
September 22, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Michael E Stender, Richard A Regueiro, Virginia L Ferguson
The changes experienced in synovial joints with osteoarthritis involve coupled chemical, biological, and mechanical processes. The aim of this study was to investigate the consequences of increasing permeability in articular cartilage (AC), calcified cartilage (CC), subchondral cortical bone (SCB), and subchondral trabecular bone (STB) as observed with osteoarthritis. Two poroelastic finite element models were developed using a depth-dependent anisotropic model of AC with strain-dependent permeability and poroelastic models of calcified tissues (CC, SCB, and STB)...
September 16, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Fanan Wei, Haitao Yang, Lianqing Liu, Guangyong Li
Dynamic mechanical behaviour of living cells has been described by viscoelasticity. However, quantitation of the viscoelastic parameters for living cells is far from sophisticated. In this paper, combining inverse finite element (FE) simulation with Atomic Force Microscope characterization, we attempt to develop a new method to evaluate and acquire trustworthy viscoelastic index of living cells. First, influence of the experiment parameters on stress relaxation process is assessed using FE simulation. As suggested by the simulations, cell height has negligible impact on shape of the force-time curve, i...
September 14, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Mingzheng Zhang, Fang Pu, Liqiang Xu, Linlin Zhang, Hang Liang, Deyu Li, Yu Wang, Yubo Fan
Spinal cages are used to create a suitable mechanical environment for interbody fusion in cases of degenerative spinal instability. Due to individual variations in bone structures and pathological conditions, patient-specific cages can provide optimal biomechanical conditions for fusion, strengthening patient recovery. Finite element analysis (FEA) is a valuable tool in the biomechanical evaluation of patient-specific cage designs, but the time- and labor-intensive process of modeling limits its clinical application...
September 14, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Tanvir R Faisal, Nicolay Hristozov, Tamara L Western, Alejandro Rey, Damiano Pasini
Plant petioles can be considered as hierarchical cellular structures, displaying geometric features defined at multiple length scales. Their macroscopic mechanical properties are the cumulative outcome of structural properties attained at each level of the structural hierarchy. This work appraises the compliance of a rhubarb stalk by determining the stalk's bending and torsional stiffness both computationally and experimentally. In our model, the irregular cross-sectional shape of the petiole and the layers of the constituent tissues are considered to evaluate the stiffness properties at the structural level...
September 14, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Sarfaraz Kamangar, Irfan Anjum Badruddin, A Badarudin, N Nik-Ghazali, Kalimuthu Govindaraju, N J Salman Ahmed, T M Yunus Khan
The current study investigates the hyperemic flow effects on heamodynamics parameters such as velocity, wall shear stress in 3D coronary artery models with and without stenosis. The hyperemic flow is used to evaluate the functional significance of stenosis in the current era. Patients CT scan data of having healthy and coronary artery disease was chosen for the reconstruction of 3D coronary artery models. The diseased 3D models of coronary artery shows a narrowing of >50% lumen area. Computational fluid dynamics was performed to simulate the hyperemic flow condition...
September 9, 2016: Computer Methods in Biomechanics and Biomedical Engineering
G David, R M Pedrigi, J D Humphrey
Accommodation of the eyes, the mechanism that allows humans to focus their vision on near objects, naturally diminishes with age via presbyopia. People who have undergone cataract surgery, using current surgical methods and artificial lens implants, are also left without the ability to accommodate. The process of accommodation is generally well known; however the specific mechanical details have not been adequately explained due to difficulties and consequences of performing in vivo studies. Most studies have modeled the mechanics of accommodation under assumptions of a linearly elastic, isotropic, homogenous lens and lens capsule...
September 9, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Shaomin Luo, Cheng Xu, Shu Wang, Yaoke Wen
In the last few decades, various researches focus on the transient pressure in the behind armor blunt trauma. This paper presented a investigation on the transient pressure in the ballistic gelatin behind a soft body armor subjected to the impacting from three ammunitions. Experimental results show that three peaks appear on the pressure-time curves without taking into account the ammunition type and the impact velocity. Furthermore, numerical models of the test were created to compare modelling results to the pressure from the pressure gauges buried in the gelatin block...
August 30, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Anastasios Raptis, Michalis Xenos, Efstratios Georgakarakos, George Kouvelos, Athanasios Giannoukas, Nicos Labropoulos, Miltiadis Matsagkas
Endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms results in redirection of blood through the deployed endograft (EG). Even though EVAR is clinically effective, the absolute flow restoration is not warranted. Our purpose was to compare the physiological with the post-EVAR infrarenal flow conditions. We developed patient-specific models based on computed tomography data of five healthy volunteers and ten patients treated with the Endurant(®) stent-graft system. Wall shear stress (WSS), helicity, pressure and velocity fields were calculated using computational fluid dynamics...
August 22, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Qian Liu, Wanchun Wang, Andrew R Thoreson, Chunfeng Zhao, Weihong Zhu, Pengcheng Dou
Three dimensional finite element models of cam-type FAI with alpha angles of 60°, 70°, 80°, and 90° were created to investigate the cartilage contact mechanics in daily activities. Intra-articular cartilage contact pressures during routine daily activities were assessed and cross-compared with a normal control hip. Alpha angles and hip range of motion were found to have a combined influence on the cartilage contact mechanics in hips with cam-type FAI, thereby resulting in abnormally high pressures and driving the cartilage damage...
August 19, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Sercan Küçükkurt, Gökhan Alpaslan, Ahmet Kurt
OBJECTIVE: In this study, we compared the success of sinus lifting and alternative treatment methods in applying dental implants in cases lacking adequate bone due to pneumatization of the maxillary sinus. METHODS: In a computer environment, 3D models were created using computerized tomography data from a patient. Additionally, implants and abutments were scanned at the macroscopic level, and the resulting images were transferred to the 3D models. Five different models were examined: a control model, lateral sinus lifting (LSL), short dental implant placement (SIP), tilted implant placement (TIP) and distal prosthetic cantilever (DC) use...
August 8, 2016: Computer Methods in Biomechanics and Biomedical Engineering
A Rahbari, H Montazerian, E Davoodi, S Homayoonfar
The main aim of this research is to numerically obtain the permeability coefficient in the cylindrical scaffolds. For this purpose, a mathematical analysis was performed to derive an equation for desired porosity in terms of morphological parameters. Then, the considered cylindrical geometries were modeled and the permeability coefficient was calculated according to the velocity and pressure drop values based on the Darcy's law. In order to validate the accuracy of the present numerical solution, the obtained permeability coefficient was compared with the published experimental data...
August 5, 2016: Computer Methods in Biomechanics and Biomedical Engineering
Yabin Wu, Stephen J Ferguson
Self-lubrication of a diarthrodial joint is largely attributed to interstitial fluid pressurisation. However, the retention of synovial fluid within the intra-articular gap may also contribute to lubrication. Fluid flow in the intra-articular gap between two micro-rough cartilage surfaces was simulated with a three-dimensional numerical model. Representative surface roughness parameters were incorporated and their relative influence on gap flow resistance was quantified. Resistance changes with decreasing gap height were explored...
August 1, 2016: Computer Methods in Biomechanics and Biomedical Engineering
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