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Medical Engineering & Physics

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https://www.readbyqxmd.com/read/27913178/estimating-the-material-properties-of-heel-pad-sub-layers-using-inverse-finite-element-analysis
#1
Nafiseh Ahanchian, Christopher J Nester, David Howard, Lei Ren, Daniel Parker
Detailed information about the biomechanical behaviour of plantar heel pad tissue contributes to our understanding of load transfer when the foot impacts the ground. The objective of this work was to obtain the hyperelastic and viscoelastic material properties of heel pad sub-layers (skin, micro-chamber and macro-chamber layers) in-vivo. An anatomically detailed 3D Finite Element model of the human heel was used to derive the sub-layer material properties. A combined ultrasound imaging and motorised platform system was used to compress heel pad and to create input data for the Finite Element model...
November 29, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27913177/effect-of-trunnion-roughness-and-length-on-the-modular-taper-junction-strength-under-typical-intraoperative-assembly-forces
#2
S Y Jauch-Matt, A W Miles, H S Gill
Modular hip implants are at risk of fretting-induced postoperative complications most likely initiated by micromotion between adjacent implant components. A stable fixation between ball head and stem-neck taper is critical to avoid excessive interface motions. Therefore, the aim of this study was to identify the effect of trunnion roughness and length on the modular taper strength under typical intraoperative assembly forces. Custom-made Titanium trunnions (standard/mini taper, smooth/grooved surface finish) were assembled with modular Cobalt-chromium heads by impaction with peak forces ranging from 2kN to 6kN...
November 29, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27913176/rotary-ultrasonic-bone-drilling-improved-pullout-strength-and-reduced-damage
#3
Vishal Gupta, Pulak M Pandey, Vadim V Silberschmidt
Bone drilling is one of the most common operations used to repair fractured parts of bones. During a bone drilling process, microcracks are generated on the inner surface of the drilled holes that can detrimentally affect osteosynthesis and healing. This study focuses on the investigation of microcracks and pullout strength of cortical-bone screws in drilled holes. It compares conventional surgical bone drilling (CSBD) with rotary ultrasonic bone drilling (RUBD), a novel approach employing ultrasonic vibration with a diamond-coated hollow tool...
November 29, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27913175/automated-cta-based-measurements-for-planning-support-of-minimally-invasive-aortic-valve-replacement-surgery
#4
Mustafa A Elattar, Floortje van Kesteren, Esther M Wiegerinck, Ed Vanbavel, Jan Baan, Riccardo Cocchieri, Bas de Mol, Nils R Planken, Henk A Marquering
Minimally invasive aortic valve replacement (mini-AVR) procedures are a valuable alternative to conventional open heart surgery. Currently, planning of mini-AVR consists of selection of the intercostal space closest to the sinotubular junction on preoperative computer tomography images. We developed an automated algorithm detecting the sinotubular junction (STJ) and intercostal spaces for finding the optimal incision location. The accuracy of the STJ detection was assessed by comparison with manual delineation by measuring the Euclidean distance between the manually and automatically detected points...
November 29, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27913174/high-gain-driven-right-leg-circuit-for-dry-electrode-systems
#5
Federico N Guerrero, Enrique Spinelli
This paper presents an improved driven right leg (DRL) circuit compensation together with a practical implementation. The proposed design allows to increase common mode voltage attenuation compared with the widely used dominant pole compensation while maintaining the same proven stability margin and design criteria, and requiring only a modification of its passive feedback network. A sample implementation of the proposed DRL was obtained estimating the values of interference model parameters for a dry electrode measurement system...
November 29, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27889391/review-of-fall-detection-techniques-a-data-availability-perspective
#6
REVIEW
Shehroz S Khan, Jesse Hoey
A fall is an abnormal activity that occurs rarely; however, missing to identify falls can have serious health and safety implications on an individual. Due to the rarity of occurrence of falls, there may be insufficient or no training data available for them. Therefore, standard supervised machine learning methods may not be directly applied to handle this problem. In this paper, we present a taxonomy for the study of fall detection from the perspective of availability of fall data. The proposed taxonomy is independent of the type of sensors used and specific feature extraction/selection methods...
November 23, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27876283/importance-of-trabecular-anisotropy-in-finite-element-predictions-of-patellar-strain-after-total-knee-arthroplasty
#7
A Latypova, D P Pioletti, A Terrier
Patellar fracture and anterior knee pain remain major complications after Total Knee Arthroplasty (TKA). Patient-specific finite element (FE) models should help improve understanding of these complications through estimation of joint and bone mechanics. However, sensitivity of predictions on modeling techniques and approaches is not fully investigated. In particular, the importance of patellar bone anisotropy, usually omitted in FE models, on strain prediction is still unknown. The objective of this study was thus to estimate the influence of modeling patellar trabecular anisotropy on prediction of patellar strain in TKA models...
November 18, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27863910/gabor-frames-for-classification-of-paroxysmal-and-persistent-atrial-fibrillation-episodes
#8
Nuria Ortigosa, Antonio Galbis, Carmen Fernández, Óscar Cano
In this study, we propose a new classification method for early differentiation of paroxysmal and persistent atrial fibrillation episodes, i.e. those which spontaneously or with external intervention will return to sinus rhythm within 7 days of onset from the ones where the arrhythmia is sustained for more than 7 days. Today, clinicians provide patients classification once the course of the arrhythmia has been disclosed. This classification problem is dealt with in this study. We study a sparse representation of surface electrocardiogram signals by means of Gabor frames and afterwards we apply a linear discriminant analysis...
November 15, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27856143/finite-element-modelling-of-the-foot-for-clinical-application-a-systematic-review
#9
REVIEW
Sara Behforootan, Panagiotis Chatzistergos, Roozbeh Naemi, Nachiappan Chockalingam
Over the last two decades finite element modelling has been widely used to give new insight on foot and footwear biomechanics. However its actual contribution for the improvement of the therapeutic outcome of different pathological conditions of the foot, such as the diabetic foot, remains relatively limited. This is mainly because finite element modelling has only been used within the research domain. Clinically applicable finite element modelling can open the way for novel diagnostic techniques and novel methods for treatment planning/optimisation which would significantly enhance clinical practice...
November 15, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27836575/energy-flow-analysis-of-amputee-walking-shows-a-proximally-directed-transfer-of-energy-in-intact-limbs-compared-to-a-distally-directed-transfer-in-prosthetic-limbs-at-push-off
#10
R A Weinert-Aplin, D Howard, M Twiste, H L Jarvis, A N Bennett, R J Baker
Reduced capacity and increased metabolic cost of walking occurs in amputees, despite advances in prosthetic componentry. Joint powers can quantify deficiencies in prosthetic gait, but do not reveal how energy is exchanged between limb segments. This study aimed to quantify these energy exchanges during amputee walking. Optical motion and forceplate data collected during walking at a self-selected speed for cohorts of 10 controls, 10 unilateral trans-tibial, 10 unilateral trans-femoral and 10 bilateral trans-femoral amputees were used to determine the energy exchanges between lower limb segments...
November 8, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27836574/towards-bioreactor-development-with-physiological-motion-control-and-its-applications
#11
Marcus Stoffel, Wolfgang Willenberg, Marzieh Azarnoosh, Nadine Fuhrmann-Nelles, Bei Zhou, Bernd Markert
In biomedical applications bioreactors are used, which are able to apply mechanical loadings under cultivation conditions on biological tissues. However, complex mechanobiological evolutions, such as the dependency between mechanical properties and cell activity, depend strongly on the applied loading conditions. This requires correct physiological movements and loadings in bioreactors. The aim of the present study is to develop bioreactors, in which native and artificial biological tissues can be cultivated under physiological conditions in knee joints and spinal motion segments...
November 8, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27818076/studying-the-magnetic-stimulation-of-nervous-tissues-a-calculation-framework-to-investigate-stimulation-areas
#12
Simona Valentini, Iacopo Portaccio, Dino Accoto
The electromagnetic stimulation of nervous tissue has represented an alternative to electrical stimulation since the 1980s. The growing number of potential applications has led to an increasing interest in the development of modeling tools that can help the design of novel electromagnetic stimulators. In this context, the aim of this paper is to provide a versatile calculation framework to investigate the properties of the electric field generated by a plurality of miniature coils, arranged in cuff configuration...
November 3, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27818075/an-active-simulator-for-neonatal-intubation-design-development-and-assessment
#13
Ilaria Baldoli, Selene Tognarelli, Ferdinando Vangi, Davide Panizza, Rosa T Scaramuzzo, Armando Cuttano, Cecilia Laschi, Arianna Menciassi
This study describes the technical realization and the pre-clinical validation of a instrumented neonatal intubation skill trainer able to provide objective feedback for the improvement of clinical competences required for such a delicate procedure. The Laerdal(®) Neonatal Intubation Trainer was modified by applying pressure sensors on areas that are mainly subject to stress and potential injuries. Punctual Force Sensing Resistors (FSRs) were characterized and fixed on the external side of the airway structure on the dental arches and epiglottis...
November 3, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27816391/the-coupling-between-peripheral-microcirculation-and-slow-breathing
#14
Zehava Ovadia-Blechman, Benjamin Gavish, Danit Levy-Aharoni, David Shashar, Vered Aharonson
Vasomotion (rhythmic changes in arteriolar diameter) is believed to enhance tissue perfusion at low oxygenation levels. We hypothesized that slow breathing and vasomotion may correlate temporally ("coupling"), especially at low oxygenation levels. We paced down spontaneous breathing to about 5 or 6breaths/min in 14 healthy subjects using device-guided breathing (DGB), and continuously monitored respiration, transcutaneous oxygen pressure ("oxygenation"), and skin capillary blood flow ("microflow") using a laser Doppler flowmeter...
November 2, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27816390/biomechanical-analysis-of-combining-head-down-tilt-traction-with-vibration-for-different-grades-of-degeneration-of-the-lumbar-spine
#15
Sicong Wang, Lizhen Wang, Yawei Wang, Chengfei Du, Ming Zhang, Yubo Fan
In recent years, a combination of traction and vibration therapy is usually used to alleviate low back pain (LBP) in clinical settings. Combining head-down tilt (HDT) traction with vibration was demonstrated to be efficacious for LBP patients in our previous study. However, the biomechanics of the lumbar spine during this combined treatment is not well known and need quantitative analysis. In addition, LBP patients have different grades of degeneration of the lumbar spinal structure, which are often age related...
November 2, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27816389/biomechanical-optimization-of-the-angle-and-position-for-surgical-implantation-of-a-straight-short-stem-hip-implant
#16
Gillian E Cook, Saeid Samiezadeh, Zachary Morison, Mina S R Aziz, Habiba Bougherara, Radovan Zdero, Emil H Schemitsch
Conservative hip implants preserve healthy bone for revision surgeries and improve physiological loading; however, they have little supporting biomechanical data with respect to their 3D orientation during implantation. This study endeavored to determine the optimal 3D orientation of a straight short stem hip implant within the proximal femur that would yield a stress distribution most similar to an intact femur. Synthetic femurs were implanted with a stem in one of seven maximum angles or positions and axially loaded, with resultant strain values used to validate a finite element model...
November 2, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27814955/model-dependent-and-model-independent-approaches-for-evaluating-hepatic-fibrosis-in-rat-liver-using-shearwave-dispersion-ultrasound-vibrometry
#17
Haoming Lin, Xinyu Zhang, Yuanyuan Shen, Yi Zheng, Yanrong Guo, Ying Zhu, Xianfen Diao, Tianfu Wang, Siping Chen, Xin Chen
This study assesses gradations of hepatic fibrosis in rat livers using both model-dependent and model-independent approaches. Liver fibrosis was induced in 37 rats using carbon tetrachloride (CCl4); 6 rats served as the controls. Shear wave velocity as a function of frequency, referred to as velocity dispersion, was measured in vitro by an ultrasound elastography method called shearwave dispersion ultrasound vibrometry (SDUV). For the model-dependent approach, the velocity dispersion data were fit to the Voigt model to solve the viscoelastic modulus...
November 1, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27814954/modification-of-the-grood-and-suntay-joint-coordinate-system-equations-for-knee-joint-flexion
#18
Danè Dabirrahmani, Michael Hogg
Since its introduction, the Grood and Suntay Joint Coordinate System (JCS) has been embraced by the International Society of Biomechanics (ISB) and been widely used for biomechanical reporting. There is, however, a limitation in its ability to provide correct flexion values over a wide range of clinically relevant flexion angles. This technical note addresses the limitation of the JCS equations and introduces a new set of equations to overcome this problem.
November 1, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27789226/reducing-temperature-elevation-of-robotic-bone-drilling
#19
Arne Feldmann, Jasmin Wandel, Philippe Zysset
This research work aims at reducing temperature elevation of bone drilling. An extensive experimental study was conducted which focused on the investigation of three main measures to reduce the temperature elevation as used in industry: irrigation, interval drilling and drill bit designs. Different external irrigation rates (0 ml/min, 15 ml/min, 30 ml/min), continuously drilled interval lengths (2 mm, 1 mm, 0.5 mm) as well as two drill bit designs were tested. A custom single flute drill bit was designed with a higher rake angle and smaller chisel edge to generate less heat compared to a standard surgical drill bit...
October 24, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27789225/progress-in-anterior-chamber-angle-imaging-for-glaucoma-risk-prediction-a-review-on-clinical-equipment-practice-and-research
#20
REVIEW
Shinoj V K, Xun Jie Jeesmond Hong, Murukeshan V M, Baskaran M, Aung Tin
The visualization capabilities of various ocular imaging instruments can generally be categorized into photographic (e.g. gonioscopy, Pentacam, RetCam) and optical tomographic (e.g. optical coherence tomography (OCT), photoacoustic (PA) imaging, ultrasound biomicriscopy (UBM)) methods. These imaging instruments allow vision researchers and clinicians to visualize the iridocorneal angle, and are essential in the diagnosis and management of glaucoma. Each of these imaging modalities has particular benefits and associated drawbacks in obtaining repeatable and reliable measurement in the evaluation of the angle...
October 24, 2016: Medical Engineering & Physics
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