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Medical Engineering & Physics

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https://www.readbyqxmd.com/read/28109564/development-of-a-surgical-navigation-system-based-on-3d-slicer-for-intraoperative-implant-placement-surgery
#1
Xiaojun Chen, Lu Xu, Huixiang Wang, Fang Wang, Qiugen Wang, Ron Kikinis
Implant placement has been widely used in various kinds of surgery. However, accurate intraoperative drilling performance is essential to avoid injury to adjacent structures. Although some commercially-available surgical navigation systems have been approved for clinical applications, these systems are expensive and the source code is not available to researchers. 3D Slicer is a free, open source software platform for the research community of computer-aided surgery. In this study, a loadable module based on Slicer has been developed and validated to support surgical navigation...
January 18, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28100406/modeling-of-path-planning-and-needle-steering-with-path-tracking-in-anatomical-soft-tissues-for-minimally-invasive-surgery
#2
Pan Li, Shan Jiang, Dong Liang, Zhiyong Yang, Yan Yu, Wei Wang
Steerable needles can potentially improve the effectiveness of diagnostic and therapeutic procedures, such as biopsy and cancer treatment, by increasing the targeting accuracy and reaching previously inaccessible targets. A discrete potential field algorithm based on three dimensional (3D) anatomical structures is proposed in this paper to plan the needle path in minimally invasive surgery. A 3D kinematic model of needle steering is formulated using Lie group theory. Model parameters are fitted using experimental data acquired via a 2-degree of freedom robotic device and an ultrasound imaging device...
January 16, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28100405/dynamic-hilbert-warping-a-new-measure-of-rr-interval-signals-evaluated-in-the-cognitive-load-estimation
#3
Peyvand Ghaderyan, Ataollah Abbasi
RR interval (RRI) signals represent the time intervals between successive heart R-waves. These signals are influenced by many cognitive and psychological processes. In this study, a new technique based on the combination of empirical mode decomposition and dynamic Hilbert warping (DHW) was proposed to inference cognitive states from measured RRI signals. Moreover, a set of entropic and statistical measures was extracted to characterize the regularity and temporal distribution in the phase spectra and amplitude envelope of the analytic signals...
January 16, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28089224/loading-of-the-medial-meniscus-in-the-acl-deficient-knee-a-multibody-computational-study
#4
Trent M Guess, Swithin Razu
The menisci of the knee reduce tibiofemoral contact pressures and aid in knee lubrication and nourishment. Meniscal injury occurs in half of knees sustaining anterior cruciate ligament injury and the vast majority of tears in the medial meniscus transpire in the posterior horn region. In this study, computational multibody models of the knee were derived from medical images and passive leg motion for two female subjects. The models were validated against experimental measures available in the literature and then used to evaluate medial meniscus contact force and internal hoop tension...
January 11, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28087211/the-effect-of-bone-growth-onto-massive-prostheses-collars-in-protecting-the-implant-from-fracture
#5
Paul Fromme, Gordon W Blunn, William J Aston, Tasneem Abdoola, Jacob Koris, Melanie J Coathup
Limb-sparing distal femoral endoprotheses used in cancer patients have a high risk of aseptic loosening. It had been reported that young adolescent patients have a higher rate of loosening and fatigue fracture of intramedullary stems because the implant becomes undersized as patients grow. Extracortical bone growth into the grooved hydroxyapatite-coated collar had been shown to reduce failure rates. The stresses in the implant and femur have been calculated from Finite Element models for different stages of bone growth onto the collar...
January 10, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28043781/the-application-of-physiological-loading-using-a-dynamic-multi-axis-spine-simulator
#6
Timothy Patrick Holsgrove, Anthony W Miles, Sabina Gheduzzi
In-vitro testing protocols used for spine studies should replicate the in-vivo load environment as closely as possible. Unconstrained moments are regularly employed to test spinal specimens in-vitro, but applying such loads dynamically using an active six-axis testing system remains a challenge. The aim of this study was to assess the capability of a custom-developed spine simulator to apply dynamic unconstrained moments with an axial preload. Flexion-extension, lateral bending, and axial rotation were applied to an L5/L6 porcine specimen at 0...
December 30, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28043780/influence-of-mouth-opening-on-oropharyngeal-humidification-and-temperature-in-a-bench-model-of-neonatal-continuous-positive-airway-pressure
#7
Hendrik S Fischer, Tim L Ullrich, Christoph Bührer, Christoph Czernik, Gerd Schmalisch
Clinical studies show that non-invasive respiratory support by continuous positive airway pressure (CPAP) affects gas conditioning in the upper airways, especially in the presence of mouth leaks. Using a new bench model of neonatal CPAP, we investigated the influence of mouth opening on oropharyngeal temperature and humidity. The model features the insertion of a heated humidifier between an active model lung and an oropharyngeal head model to simulate the recurrent expiration of heated, humidified air. During unsupported breathing, physiological temperature and humidity were attained inside the model oropharynx, and mouth opening had no significant effect on oropharyngeal temperature and humidity...
December 30, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28040435/in-vitro-investigation-of-the-hemodynamic-responses-of-the-cerebral-coronary-and-renal-circulations-with-a-rotary-blood-pump-installed-in-the-descending-aorta
#8
M A Rezaienia, G Paul, E J Avital, S Mozafari, M Rothman, T Korakianitis
This study investigates the hemodynamic responses of the cardiovascular system when a rotary blood pump is operating in the descending aorta, with a focus on the cerebral, coronary and renal autoregulation, using our in-house cardiovascular emulator. Several improvements have been made from our previous studies. A novel coronary system was developed to replicate the native coronary perfusion. Three pinch valves actuated by stepper motors were used to simulate the regional autoregulation systems of the native cerebral, coronary and renal circulations...
December 28, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/28007497/a-novel-method-for-extraction-of-neural-response-from-single-channel-cochlear-implant-auditory-evoked-potentials
#9
Daniel Sinkiewicz, Lendra Friesen, Behnaz Ghoraani
Cortical auditory evoked potentials (CAEP) are used to evaluate cochlear implant (CI) patient auditory pathways, but the CI device produces an electrical artifact, which obscures the relevant information in the neural response. Currently there are multiple methods, which attempt to recover the neural response from the contaminated CAEP, but there is no gold standard, which can quantitatively confirm the effectiveness of these methods. To address this crucial shortcoming, we develop a wavelet-based method to quantify the amount of artifact energy in the neural response...
December 19, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27993478/pharmaceutical-aerosols-deposition-patterns-from-a-dry-powder-inhaler-euler-lagrangian-prediction-and-validation
#10
Ravishekar Ravi Kannan, A J Przekwas, Narender Singh, Renishkumar Delvadia, Geng Tian, Ross Walenga
This study uses Computational Fluid Dynamics (CFD) to predict, analyze and validate the deposition patterns in a human lung for a Budesonide drug delivered from the Novolizer Dry Powder Inhaler device. We used a test case of known deposition patterns to validate our computational Euler Lagrangian-based deposition predictions. Two different lung models are used: (i) a basic ring-less trachea model and (ii) an advanced Human Zygote5 model. Unlike earlier attempts, the current simulations do not include the device in the computational domain...
December 16, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27989384/evaluation-of-predicted-knee-function-for-component-malrotation-in-total-knee-arthroplasty
#11
Valentine Vanheule, Hendrik Pieter Delport, Michael Skipper Andersen, Lennart Scheys, Roel Wirix-Speetjens, Ilse Jonkers, Jan Victor, Jos Vander Sloten
Soft-tissue balancing for total knee arthroplasty (TKA) remains subjective and highly dependent on surgical expertise. Pre-operative planning may support the clinician in taking decisions by integrating subject-specific computer models that predict functional outcome. However, validation of these models is essential before they can be applied in clinical practice. The aim of this study was to evaluate a knee modelling workflow by comparing experimental cadaveric measures to model-based kinematics and ligament length changes...
December 15, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27989383/dynamic-property-changes-in-stapedial-annular-ligament-associated-with-acute-otitis-media-in-the-chinchilla
#12
Brooke M Hitt, Xuelin Wang, Rong Z Gan
Located at the end of the ossicular chain, the stapedial annular ligament (SAL) serves as a closed yet mobile boundary between the cochlear fluid and stapes footplate. It is unclear how SAL properties change with acute otitis media (AOM). This paper reports the measurements of SAL dynamic properties in chinchilla AOM model using dynamic mechanical analyzer (DMA) and frequency-temperature superposition (FTS) principle. AOM was analyzed in two infection groups: 4 days (4D) and 8 days (8D) post induction. SAL specimens were measured using DMA at three temperatures: 5, 25, and 37°C...
December 15, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27988329/wheelchair-pushrim-kinetics-measurement-a-method-to-cancel-inaccuracies-due-to-pushrim-weight-and-wheel-camber
#13
Félix Chénier, Rachid Aissaoui, Cindy Gauthier, Dany H Gagnon
The commercially available SmartWheel(TM) is largely used in research and increasingly used in clinical practice to measure the forces and moments applied on the wheelchair pushrims by the user. However, in some situations (i.e. cambered wheels or increased pushrim weight), the recorded kinetics may include dynamic offsets that affect the accuracy of the measurements. In this work, an automatic method to identify and cancel these offsets is proposed and tested. First, the method was tested on an experimental bench with different cambers and pushrim weights...
December 14, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27986380/evaluation-of-the-magnitude-of-hip-joint-deformation-in-subjects-with-avascular-necrosis-of-the-hip-joint-during-walking-with-and-without-scottish-rite-orthosis
#14
Mohammad Taghi Karimi, Ali Mohammadi, Mohammad Hossein Ebrahimi, Anthony McGarry
The femoral head in subjects with leg calve perthes disease (LCPD) is generally considerably deformed. It is debatable whether this deformation is due to an increase in applied loads, a decrease in bone mineral density or a change in containment of articular surfaces. The aim of this study was to determine the influence of these factors on deformation of the femoral head. Two subjects with LCPD participated in this study. Subject motion and the forces applied on the affected leg were recorded using a motion analysis system (Qualsis(TM)) and a Kistler force plate...
December 13, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27956021/prediction-of-the-drilling-path-to-surgically-pin-the-femoral-neck-from-the-spatial-location-of-pelvic-and-femoral-anatomical-landmarks-a-cadaver-validation-study
#15
V Sholukha, J Panda, P Salvia, B Beyer, M Rooze, S Van Sint Jan
Several clinical applications rely on accurate guiding information when drilling along the femoral neck (e.g., pin insertion in case of neck fracture). Currently, applications rely on real-time X-ray imaging, which results in irradiation issues for the surgeon conducting the operation. The goal of this paper was to develop an X-ray-free method that would allow for a pathway to be drilled between the lateral aspect of the femoral diaphysis (the so-called piercing point), the femoral neck and the head centres...
December 9, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27956020/characterizing-the-reduction-of-stimulation-artifact-noise-in-a-tripolar-nerve-cuff-electrode-by-application-of-a-conductive-shield-layer
#16
Parisa Sabetian, Bita Sadeghlo, Chengran Harvey Zhang, Paul B Yoo
Tripolar nerve cuff electrodes have been widely used for measuring peripheral nerve activity. However, despite the high signal-to-noise ratio levels that can be achieved with this recording configuration, the clinical use of cuff electrodes in closed-loop controlled neuroprostheses remains limited. This is largely attributed to artifact noise signals that contaminate the recorded neural activity. In this study, we investigated the use of a conductive shield layer (CSL) as a means of reducing the artifact noise recorded by nerve cuff electrodes...
December 9, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27939099/effect-of-various-factors-on-pull-out-strength-of-pedicle-screw-in-normal-and-osteoporotic-cancellous-bone-models
#17
Vicky Varghese, Gurunathan Saravana Kumar, Venkatesh Krishnan
Pedicle screws are widely used for the treatment of spinal instability by spine fusion. Screw loosening is a major problem of spine fusion, contributing to delayed patient recovery. The present study aimed to understand the factor and interaction effects of density, insertion depth and insertion angle on pedicle screw pull out strength and insertion torque. A pull out study was carried out on rigid polyurethane foam blocks representing osteoporotic to normal bone densities according to the ASTM-1839 standard...
December 8, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27939098/biomechanical-properties-of-human-t-cells-in-the-process-of-activation-based-on-diametric-compression-by-micromanipulation
#18
Mingming Du, Neena Kalia, Guido Frumento, Frederick Chen, Zhibing Zhang
A crucial step in enabling adoptive T cell therapy is the isolation of antigen (Ag)-specific CD8(+) T lymphocytes. Mechanical changes that accompany CD8(+) T lymphocyte activation and migration from circulating blood across endothelial cells into target tissue, may be used as parameters for microfluidic sorting of activated CD8(+) T cells. CD8(+) T cells were activated in vitro using anti-CD3 for a total of 4 days, and samples of cells were mechanically tested on day 0 prior to activation and on day 2 and 4 post-activation using a micromanipulation technique...
December 8, 2016: Medical Engineering & Physics
https://www.readbyqxmd.com/read/27913178/estimating-the-material-properties-of-heel-pad-sub-layers-using-inverse-finite-element-analysis
#19
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/27913176/rotary-ultrasonic-bone-drilling-improved-pullout-strength-and-reduced-damage
#20
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
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