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Medical Engineering & Physics

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https://www.readbyqxmd.com/read/30111489/the-effect-of-plaque-eccentricity-on-blood-hemodynamics-and-drug-release-in-a-stented-artery
#1
José A Ferreira, Lino Gonçalves, Jahed Naghipoor, Paula de Oliveira, Timon Rabczuk
Atherosclerosis in the coronary arteries is one of the leading causes of death in the world. Percutaneous coronary interventions (PCI) associated with the implantation of drug eluting stents (DES) is one of the most common forms of revascularization in patients with atherosclerotic coronary artery disease. The use of DES is considered as an effective tool to reduce restenosis after PCI. However despite all the progress made in DES procedures, the rate of restenosis remains relatively high. Mathematical modeling and numerical simulation are believed to play an essential role in identifying zones with a higher risk of in-stent restenosis...
August 12, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30098937/an-interpolation-technique-to-enable-accurate-three-dimensional-joint-kinematic-analyses-using-asynchronous-biplane-fluoroscopy
#2
Mohsen Akbari-Shandiz, Joseph D Mozingo, David R Holmes Iii, Kristin D Zhao
Biplane 2D-3D model-based registration and radiostereometric analysis (RSA) approaches have been commonly used for measuring three-dimensional, in vivo joint kinematics. However, in clinical biplane systems, the x-ray images are acquired asynchronously, which introduces registration errors. The present study introduces an interpolation technique to reduce image registration error by generating synchronous fluoroscopy image estimates. A phantom study and cadaveric shoulder study were used to evaluate the level of improvement in image registration that could be obtained as a result of using our interpolation technique...
August 8, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30098936/the-influence-of-bileaflet-prosthetic-aortic-valve-orientation-on-the-blood-flow-patterns-in-the-ascending-aorta
#3
Utku Gülan, Markus Holzner
We investigate three-dimensional pulsatile aortic flow in the ascending aorta with mechanical prosthetic aortic valve implanted at two different orientations under physiological flow conditions using an anatomically accurate aorta. We perform 3D Particle Tracking Velocimetry measurements to assess the phase averaged and fluctuating velocity patterns as well as the shear stresses. A St Jude Medical prosthetic heart valve is implanted in an anatomically accurate silicone model of an aorta obtained from high resolution magnetic resonance imaging of a healthy proband at two different orientations...
August 8, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30098935/a-spatial-filtering-approach-to-environmental-emotion-perception-based-on-electroencephalography
#4
Yuanyuan Su, Peng Chen, Xueying Liu, Wenchao Li, Zhao Lv
Studies have demonstrated that visual built environments can affect the emotions of individuals, which can be recorded and investigated using electroencephalography (EEG). To study emotional intensity in adolescents exposed to different visual built environments, we proposed an EEG-based spatial filtering method using Independent Component Analysis (ICA). Specifically, to identify effective video stimuli to induce emotions, we first developed a stimulus selection strategy using the normalized valence/arousal space model...
August 8, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30097314/validity-of-the-microsoft-kinect-%C3%A2-in-assessing-spatiotemporal-and-lower-extremity-kinematics-during-stair-ascent-and-descent-in-healthy-young-individuals
#5
Jeonghoon Oh, Christopher Kuenze, Marco Jacopetti, Joseph F Signorile, Moataz Eltoukhy
Stair negotiation is one of the most challenging, yet frequently encountered, locomotor tasks in daily life. This study is the first attempt to investigate the capacity of the Kinect™ sensor to assess stair negotiation spatiotemporal and sagittal plane kinematic variables. The goal of this study was to examine the validity of the Kinect™ v2 sensor in assessing lower extremity kinematics and spatiotemporal parameters in healthy young individuals; and to demonstrate its potential as a low-cost stair gait analysis tool...
August 8, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30097313/estimating-regions-of-interest-on-the-distal-femur
#6
Johan van der Merwe, Dawie J van den Heever, Pieter J Erasmus
We investigated the ability of a statistical shape model to estimate unknown regions of interest related to patient-specific unicompartmental knee replacement design on the distal femur. Generality ranged between 0.67 and 1.03 mm, specificity from 0.79 to 1.07 mm, and leave-one-out root mean square estimation errors from 0.88 to 1.27 mm for different regions. Moderate to strong correlations were established between ground truths and model estimates for local morphological measurements on the medial and lateral condyles...
August 7, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30082204/wear-analysis-of-explanted-conventional-metal-back-polyethylene-glenoid-liners
#7
Gyorgy Kocsis, Charlie J Payne, Angus Wallace, Donal McNally
INTRODUCTION: Glenoid component wear and loosening is the Achilles heel of total shoulder replacement. Analysis of failed, revised implants might give an insight into the causes of component failure. Volumetric assessment of conventional total shoulder replacement glenoid liner wear rate and scanning electron microscopy was accomplished in this study for the purpose. Coherence scanning interferometry (white light scanner) 3D images were acquired. This method requires no physical contact, ionising radiation or extensive surface preparation...
August 3, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30082203/enabling-portable-multiple-line-refreshable-braille-displays-with-electroactive-elastomers
#8
Gabriele Frediani, James Busfield, Federico Carpi
Full-page (multiple-lines), electrically refreshable, portable and affordable Braille displays do not currently exist. There is a need for such an assistive technology, which could be used as the Braille-coded tactile analogue for blind people of the digital tablets used by sighted people. Turning those highly desirable systems into reality requires a radically new technology for Braille dot actuation. Here, we describe standard-sized refreshable Braille dots based on an innovative actuation technology that uses electro-responsive smart materials known as dielectric elastomers...
August 3, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30077486/correlations-between-core-muscle-geometry-pain-intensity-functional-disability-and-postural-balance-in-patients-with-nonspecific-mechanical-low-back-pain
#9
Farahnaz Emami, Amin Kordi Yoosefinejad, Mohsen Razeghi
Patients with low back pain (LBP) have reduced core muscle geometry and impaired postural balance. Impaired trunk control was shown to be associated with poor balance and limited functional mobility in these patients. However, the relationship between muscle geometry and postural balance is unclear. This study aimed to determine the correlation of core muscle geometry with pain intensity, functional disability and postural balance in patients with chronic nonspecific mechanical LBP. Thirty patients aged 20-50 years were enrolled...
August 1, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30077485/a-compliant-aortic-model-for-in-vitro-simulations-design-and-manufacturing-process
#10
Stefania Marconi, Ettore Lanzarone, Guido H W van Bogerijen, Michele Conti, Francesco Secchi, Santi Trimarchi, Ferdinando Auricchio
We design and manufacture a silicone model of the human aorta, able to mimic both the geometrical and the mechanical properties of physiological individuals, with a specific focus on reproducing the compliance. In fact, while the models available in the literature exhibit an unrealistic compliant behavior, though they are detailed from the geometrical viewpoint, here the goal is to provide an accurate compliant tool for in vitro testing the devices that interface with the vascular system. A parametric design of the aortic model is obtained based on the available literature data, and the model is manufactured with a specific silicone mixture using rapid prototyping and molding techniques...
August 1, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30064940/on-a-columbus-egg-for-the-shape-of-asymptomatic-dysplastic-and-impinged-hip-joints
#11
Daniel Simões Lopes, Sara M Pires, Vasco V Mascarenhas, Miguel T Silva, Joaquim A Jorge
Understanding morphological features that characterize normal hip joint is critical and necessary for a more comprehensive definition of pathological presentations, such as femoroacetabular impingement and hip dysplasia. Based on anatomical observations that articular surfaces of synovial joints are better represented by ovoidal shapes than by spheres, the aim of this study is to computationally test this morphological classification for the femoral head and acetabular cavity of asymptomatic, dysplastic and impinged hips by comparing spherical, ellipsoidal and ovoidal shapes...
July 28, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30064939/simple-implantable-wireless-sensor-platform-to-measure-pressure-and-force
#12
John F Drazan, Omar T Abdoun, Michael T Wassick, Reena Dahle, Luke Beardslee, George A Marcus, Nathaniel C Cady, Eric H Ledet
Smart implants have the potential to enable personalized care regimens for patients. However, the integration of smart implants into daily clinical practice is limited by the size and cost of available sensing technology. Passive resonant sensors are an attractive alternative to traditional sensing technologies because they obviate the need for on-sensor signal conditioning or telemetry and are substantially simpler, smaller, less expensive, and more robust than other sensing methods. We have developed a novel simple, passive sensing platform that is adaptable to a variety of applications...
July 28, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30061067/patellar-tendon-buckling-is-altered-with-age
#13
Laura Chernak Slane, Félix Dandois, Stijn Bogaerts, Hilde Vandenneucker, Lennart Scheys
Recent evidence has revealed that the patellar tendon exhibits buckling during passive knee extension, wherein the tendon folds back onto itself. The clinical relevance of such buckling is unclear, but it has been suggested that it serves to protect the patellar tendon from rupture when subjected to a sudden extreme contraction. Although prior evidence suggests buckling occurs universally, it is poorly understood, and may be influenced by age and sex. Healthy adults (n = 41, aged 21-80 years) were recruited to assess age- and sex-based differences in patellar tendon buckling during passive knee extension...
July 27, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30061066/how-a-pilot-hole-size-affects-osteosynthesis-at-the-screw-bone-interface-under-immediate-loading
#14
F Affes, H Ketata, M Kharrat, M Dammak
An inappropriate pilot hole size (PHS) is one of several factors that affects the stiffness of the screw-bone fixation. The present study uses finite element models to investigate the effect of varying the PHS on the biomechanical environment of the screw-bone interface of the fractured bone, after the screw insertion and under the immediate body weight pressure (BWP). Four PHS from 71% up to 85% of the screw external diameter (SED) were considered for analysis. A non linear material behaviour of the bone with ductile damage properties was used in the study...
July 27, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30061065/a-compression-system-for-studying-depth-dependent-mechanical-properties-of-articular-cartilage-under-dynamic-loading-conditions
#15
Amin Komeili, Ziad Abusara, Salvatore Federico, Walter Herzog
The biological activities of chondrocytes are influenced by the mechanical characteristics of their environment. The overall real-time mechanical response of cartilage has been investigated earlier. However, the instantaneous local mechano-biology of cartilage has not been investigated in detail under dynamic loading conditions. In order to address this gap in the literature, we designed a compression testing device and implemented a dual photon microscopy technique with the goal of measuring local mechanical and biological responses of articular cartilage under dynamic loading conditions...
July 27, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30061064/modal-frequency-and-shape-curvature-as-a-measure-of-implant-fixation-a-computer-study-on-the-acetabular-cup
#16
Petr Henyš, Steven Leuridan, Quentin Goossens, Michiel Mulier, Leonard Pastrav, Wim Desmet, Jos Vander Sloten, Kathleen Denis, Lukáš Čapek
Modal parameters are often investigated in order to assess the initial fixation of an implant. Most of studies are focused on the natural frequencies and frequency response function. Usually the femoral stem is tested although the acetabular cup fixation is important as well. The results of implant stability assessment are inconsistent and seem to suggest that frequency as a stability indicator is not sufficiently sensitive. In this study the sensitivity of the modal properties to changes in the bone-implant interface was investigated with the help of the finite element method (FEM)...
July 27, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30057256/a-novel-method-to-measure-rim-deformation-in-uhmwpe-acetabular-liners
#17
Susan Partridge, Paige Buckley, Greg de Boer, Sophie Williams
Fluoroscopy studies of total hip replacement (THR) have shown that the femoral head and acetabular cup can separate in vivo, causing edge loading on the rim of the cup. Pre-clinical testing of THR involves ISO standard motion and loading parameters that are representative of a standard walking gait. However, a requirement for more robust testing of THR has been identified and protocols for edge loading in hip simulators have been developed. This technical note describes a method to measure rim wear and deformation on ultra-high molecular weight polyethylene acetabular liners using 2D contacting profilometry and Matlab® analysis...
July 26, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30017665/biomechanical-characteristics-of-immediately-loaded-and-osseointegration-dental-implants-inserted-into-sika-deer-antler
#18
Yun He, Istabrak Hasan, Ludger Keilig, Dominik Fischer, Luisa Ziegler, Markus Abboud, Gerhard Wahl, Christoph Bourauel
This study aimed to compare biomechanical characteristics of immediately loaded (IL) and osseointegrated (OS) dental implants inserted into Sika deer antler and lay a foundation for developing an alternative animal model for dental implants studies. Two implants per antler were inserted. One implant was loaded immediately via a self-developed loading device; the other was submerged and unloaded as control. IL implants were harvested after different loading periods. The unloaded implants were collected after OS and the shedding of antler...
July 13, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30006003/geometric-surrogates-of-abdominal-aortic-aneurysm-wall-mechanics
#19
Jesús Urrutia, Anuradha Roy, Samarth S Raut, Raúl Antón, Satish C Muluk, Ender A Finol
The maximum diameter criterion is the most important factor in the clinical management of abdominal aortic aneurysms (AAA). Consequently, interventional repair is recommended when an aneurysm reaches a critical diameter, typically 5.0 cm in the United States. Nevertheless, biomechanical measures of the aneurysmal abdominal aorta have long been implicated in AAA risk of rupture. The purpose of this study is to assess whether other geometric characteristics, in addition to maximum diameter, may be highly correlated with the AAA peak wall stress (PWS)...
July 10, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/30001979/intraoperative-bone-defect-measurement-in-the-acetabulum-using-a-navigation-system-the-influence-of-bone-porosity-on-the-digitalization-process
#20
David Putzer, Florian Scholl, Lukas Dankl, Dietmar Dammerer, Martin Thaler, Michael Nogler
The aim of the study was to evaluate how bone porosity affects intraoperative volume measurement of the acetabulum in a plastic bone model study and to validate the measurement method on cadaveric acetabula. Point cloud collection was performed using a navigation system and compared to CT measurements as well as theoretical calculations on sawbones with different porosities and validated on cadaveric specimens. The grade of porosity had a significant influence on the volume measurement. In high porous materials volume calculation (61...
July 9, 2018: Medical Engineering & Physics
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