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Medical Engineering & Physics

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https://www.readbyqxmd.com/read/29229407/inducing-targeted-failure-in-cadaveric-testing-of-3-segment-spinal-units-with-and-without-simulated-metastases
#1
Karlijn H J Groenen, Dennis Janssen, Yvette M van der Linden, Jan G M Kooloos, Jasper Homminga, Nico Verdonschot, Esther Tanck
We propose an experimental setup and protocol able to induce targeted failure of the middle vertebra in 3-segment spinal units and to capture the specimens' deformation in their post-failure state. Sixteen 3-segment spinal units with and without artificial metastases were destructively tested in axial compression using one of two failure criteria; either: (A) A clear drop in force (>10-15% of peak force) (n = 4); or (B) A minimum displacement of 5 mm (n = 12). Subsequently, the specimens were fully fixated in polymethylmethacrylate (PMMA), thereby preserving their post-failure state...
December 8, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29229406/validation-of-single-plane-fluoroscopy-and-2d-3d-shape-matching-for-quantifying-shoulder-complex-kinematics
#2
Rebekah L Lawrence, Arin M Ellingson, Paula M Ludewig
Fluoroscopy and 2D/3D shape-matching has emerged as the standard for non-invasively quantifying kinematics. However, its accuracy has not been well established for the shoulder complex when using single-plane fluoroscopy. The purpose of this study was to determine the accuracy of single-plane fluoroscopy and 2D/3D shape-matching for quantifying full shoulder complex kinematics. Tantalum markers were implanted into the clavicle, humerus, and scapula of four cadaveric shoulders. Biplane radiographs were obtained with the shoulder in five humerothoracic elevation positions (arm at the side, 30°, 60°, 90°, maximum)...
December 8, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29229405/instrumented-socket-inserts-for-sensing-interaction-at-the-limb-socket-interface
#3
Eric C Swanson, Jake B McLean, Katheryn J Allyn, Christian B Redd, Joan E Sanders
The objective of this research was to investigate a strategy for designing and fabricating computer-manufactured socket inserts that were embedded with sensors for field monitoring of limb-socket interactions of prosthetic users. An instrumented insert was fabricated for a single trans-tibial prosthesis user that contained three sensor types (proximity sensor, force sensing resistor, and inductive sensor), and the system was evaluated through a sequence of laboratory clinical tests and two days of field use...
December 8, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29229404/integrated-experimental-and-computational-approach-to-laser-machining-of-structural-bone
#4
Narendra B Dahotre, Soundarapandian Santhanakrishnan, Sameehan S Joshi, Riaz J K Khan, Daniel P Fick, William B Robertson, Raymond K Sheh, Charlie N Ironside
This study describes the fundamentals of laser-bone interaction during bone machining through an integrated experimental-computational approach. Two groups of laser machining parameters identified the effects of process thermodynamics and kinetics on machining attributes at micro to macro. A continuous wave Yb-fiber Nd:YAG laser (wavelength 1070 nm) with fluences in the range of 3.18 J/mm2-8.48 J/mm2 in combination of laser power (300 W-700 W) and machining speed (110 mm/s-250 mm/s) were considered for machining trials...
December 8, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29229403/detection-of-ventricular-premature-beats-based-on-the-pressure-signals-of-a-hemodialysis-machine
#5
Mattias Holmer, Juan Pablo Martínez, Eduardo Gil, Frida Sandberg, Bo Olde, Leif Sörnmo
Monitoring of ventricular premature beats (VPBs), being abundant in hemodialysis patients, can provide information on cardiovascular instability and electrolyte imbalance. In this paper, we describe a method for VPB detection which explores the signals acquired from the arterial and the venous pressure sensors, located in the extracorporeal blood circuit of a hemodialysis machine. The pressure signals are mainly composed of a pump component and a cardiac component. The cardiac component, severely overshadowed by the pump component, is estimated from the pressure signals using an earlier described iterative method...
December 8, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29229402/full-field-strain-distribution-in-multi-vertebra-spine-segments-an-in-vitro-application-of-digital-image-correlation
#6
Marco Palanca, Miguel Marco, Maria Luisa Ruspi, Luca Cristofolini
The biomechanics of the spine is experimentally assessed in terms of range of motion and overall stiffness. Quantification of the surface strain distribution is currently limited either to the vertebrae or the discs, whereas a full-field approach to measure the strain distribution in a multi-vertebra segment is currently missing. The aim of this work was to explore the feasibility of using Digital Image Correlation (DIC) to measure the strain distribution simultaneously on the vertebral bodies and the intervertebral discs of spine segments in different loading configurations...
December 8, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29191409/reducing-the-sensation-of-electrical-stimulation-with-dry-electrodes-by-using-an-array-of-constant-current-sources
#7
Cassandra D Solomons, Martin Slovak, Ben Heller, Anthony T Barker
Hydrogel electrodes are commonly used for functional and other electrical stimulation applications since the hydrogel layer has been shown to considerably reduce the perception of stimulation compared to dry electrodes. However, these hydrogel electrodes must be changed regularly as they dry out or become contaminated with skin cells and sweat products, thus losing their adhesiveness and resistive properties. Dry electrodes are longer lasting but are more uncomfortable due to unequal current distribution (current hogging)...
November 27, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29239748/validation-of-an-alignment-method-using-motion-tracking-system-for-in-vitro-orientation-of-cadaveric-hip-joints-with-reduced-set-of-anatomical-landmarks
#8
Suzan Bsat, Ifaz Haider, Andrew Speirs, Paul Beaulé, Hanspeter Frei
Accurate in-vitro orientation of cadaveric hip joints is challenging due to limited available anatomical landmarks. Published hip joint in-vitro investigations commonly lack details on methods used to achieve reported orientations and the accuracy with which the desired orientation has been achieved. The aim of this study was to develop an accurate method for orienting hip joints with limited anatomical landmarks for in-vitro investigations, and to compare this method against orientation using guiding axes and by visual approximation...
November 25, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29239747/functional-testing-on-engineered-cartilage-to-identify-the-role-played-by-shearing
#9
Ling Wang, Hao Shen, Jichang Nie, Dichen Li, Hongbin Fan, Zhongmin Jin, Chaozong Liu
Compressive loading is crucial for tissue regeneration in cartilage; however, the role played by shearing induced from translational or rotational motion of the knee joint has yet to be identified. This study aims at investigating the effects of in vivo like dynamic load-compression integrated with shearing on tissue regeneration, particularly to identify the role played by shearing induced from rotational motion. Tissue samples fabricated from a calcium alginate hydrogel embedded with chondrocytes were subjected to a dynamic tissue culture...
November 24, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29153539/deviations-in-frequency-and-mode-of-vibration-in-whole-body-vibration-training-devices-with-long-term-and-regular-use
#10
Tobias S Kaeding, Sanam Moghaddamnia, Momme Kück, Lothar Stein
Research regarding whole body vibration training (WBVT) and its practical use may be hindered by the fact that WBVT devices generate frequencies and/or modes of vibration different from their preset adjustments. This research aimed to clarify whether prolonged regular use can generate such deviations in frequency and mode of vibration. Three WBVT devices, each used for approximately 13 months in two research projects, were tested with an accelerometer before start of the 1st study, after four months, and after 13 months (the completion of the 2nd study)...
November 16, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29122452/estimated-landmark-calibration-of-biomechanical-models-for-inverse-kinematics
#11
Ursula Trinler, Richard Baker
Inverse kinematics is emerging as the optimal method in movement analysis to fit a multi-segment biomechanical model to experimental marker positions. A key part of this process is calibrating the model to the dimensions of the individual being analysed which requires scaling of the model, pose estimation and localisation of tracking markers within the relevant segment coordinate systems. The aim of this study is to propose a generic technique for this process and test a specific application to the OpenSim model Gait2392...
November 6, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29122451/in-vivo-tibiofemoral-skeletal-kinematics-and-cartilage-contact-arthrokinematics-during-decline-walking-after-isolated-meniscectomy
#12
Liying Zheng, Robert Carey, Eric Thorhauer, Scott Tashman, Christopher Harner, Xudong Zhang
We investigated the effects of isolated meniscectomy on tibiofemoral skeletal kinematics and cartilage contact arthrokinematics in vivo. We recruited nine patients who had undergone isolated medial or lateral meniscectomy, and used a dynamic stereo-radiography (DSX) system to image the patients' knee motion during decline walking. A volumetric model-based tracking process determined 3D tibiofemoral kinematics from the recorded DSX images. Cartilage contact arthrokinematics was derived from the intersection between tibial and femoral cartilage models co-registered to the bones...
November 6, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29117912/measurement-of-physical-activity-in-the-pre-and-early-post-operative-period-after-total-knee-arthroplasty-for-osteoarthritis-using-a-fitbit-flex-device
#13
Joshua Twiggs, Lucy Salmon, Elizabeth Kolos, Emily Bogue, Brad Miles, Justin Roe
Total knee arthroplasty (TKA) is a standard treatment for patients with end stage knee Osteoarthritis (OA) to reduce pain and restore function. The aim of this study was to assess pre- and early post-operative physical activity (PA) with Fitbit Flex devices for patients with OA undergoing TKA and determine any benchmarks for expected post-operative activity. Significant correlations of pre-operative step count, post-operative step count, Body Mass Index (BMI) and Short Form 12 Physical Component Summaries (SF-12 PCS) were found...
November 6, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29108684/study-of-main-and-cross-over-effects-on-pressure-relief-among-body-mass-index-bmi-body-position-and-supporting-material-properties
#14
Chi-Leung Hui, Qilong Feng, M S Wong, Sau-Fun Ng, Yummy Y M Lin
Pressure ulcers influence people with limited mobility who must spend a long time lying or sitting because these positions create high interfacial pressure between the body and supporting materials. Supporting materials, such as mattresses and cushions, are designed to prevent pressure ulcers by increasing the contact area, reducing the interfacial pressure or reducing the contact time. Foam is the most common supporting material for relieving pressure because it is cheap and easy to change its shape to fit the contour of the body...
November 3, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29108683/arduino-control-of-a-pulsatile-flow-rig
#15
S Drost, B J de Kruif, D Newport
This note describes the design and testing of a programmable pulsatile flow pump using an Arduino micro-controller. The goal of this work is to build a compact and affordable system that can relatively easily be programmed to generate physiological waveforms. The system described here was designed to be used in an in-vitro set-up for vascular access hemodynamics research, and hence incorporates a gear pump that delivers a mean flow of 900 ml/min in a test flow loop, and a peak flow of 1106 ml/min. After a number of simple identification experiments to assess the dynamic behaviour of the system, a feed-forward control routine was implemented...
November 3, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29096986/ct-image-segmentation-methods-for-bone-used-in-medical-additive-manufacturing
#16
REVIEW
Maureen van Eijnatten, Roelof van Dijk, Johannes Dobbe, Geert Streekstra, Juha Koivisto, Jan Wolff
AIM OF THE STUDY: The accuracy of additive manufactured medical constructs is limited by errors introduced during image segmentation. The aim of this study was to review the existing literature on different image segmentation methods used in medical additive manufacturing. METHODS: Thirty-two publications that reported on the accuracy of bone segmentation based on computed tomography images were identified using PubMed, ScienceDirect, Scopus, and Google Scholar...
October 30, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29089237/the-effects-of-cutting-parameters-on-cutting-forces-and-heat-generation-when-drilling-animal-bone-and-biomechanical-test-materials
#17
Akos Cseke, Robert Heinemann
The research presented in this paper investigated the effects of spindle speed and feed rate on the resultant cutting forces (thrust force and torque) and temperatures while drilling SawBones(®) biomechanical test materials and cadaveric cortical bone (bovine and porcine femur) specimens. It also investigated cortical bone anisotropy on the cutting forces, when drilling in axial and radial directions. The cutting forces are only affected by the feed rate, whereas the cutting temperature in contrast is affected by both spindle speed and feed rate...
October 28, 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29107572/trapeziometacarpal-joint-contact-varies-between-men-and-women-during-three-isometric-functional-tasks
#18
Marco T Y Schneider, Ju Zhang, Joseph J Crisco, Arnold-Peter C Weiss, Amy L Ladd, Kumar Mithraratne, Poul Nielsen, Thor Besier
Trapeziometacarpal (TMC) joint osteoarthritis (OA) affects women two to six times more than men, and is influenced by stresses and strains in the cartilage. The purpose of this study was to characterise sex and age differences in contact area and peak stress location of the healthy TMC joint during three isometric tasks including pinch, grasp and jar twist. CT images of the hand from 50 healthy adult men and women were used to create a statistical shape model that was used to create finite element models for each subject and task...
December 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29102275/motorized-adaptive-compression-system-for-enhancing-venous-return-a-feasibility-study-on-healthy-individuals
#19
Mahan Rahimi, Andrew P Blaber, Carlo Menon
Notwithstanding the extensive use of conventional compression devices in managing venous disorders, these modalities have shortages that diminish their treatment efficacy and lessen patient adherence to therapy. The purpose of this study was to develop an improved compression system that eliminates the flaws of the existing devices. A motorized bandage was designed that takes advantage of continuous feedback from force-sensing resistors to apply reproducible, controlled pressure on the lower extremities. The performance of the device in enhancing venous return was explored in a pilot test on 11 healthy participants, wherein graded lower body negative pressure was employed as a surrogate of passive standing...
December 2017: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29102274/prediction-of-ground-reaction-forces-for-parkinson-s-disease-patients-using-a-kinect-driven-musculoskeletal-gait-analysis-model
#20
Moataz Eltoukhy, Christopher Kuenze, Michael S Andersen, Jeonghoon Oh, Joseph Signorile
Kinetic gait abnormalities result in reduced mobility among individuals with Parkinson's disease (PD). Currently, the assessment of gait kinetics can only be achieved using costly force plates, which makes it difficult to implement in most clinical settings. The Microsoft Kinect v2 has been shown to be a feasible clinic-based alternative to more sophisticated three-dimensional motion analysis systems in producing acceptable spatiotemporal and kinematic gait parameters. In this study, we aimed to validate a Kinect-driven musculoskeletal model using the AnyBody modeling system to predict three-dimensional ground reaction forces (GRFs) during gait in patients with PD...
December 2017: Medical Engineering & Physics
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