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Medical Engineering & Physics

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https://www.readbyqxmd.com/read/29903535/improved-osseointegration-with-as-built-electron-beam-melted-textured-implants-and-improved-peri%C3%A2-implant-bone-volume-with-whole-body-vibration
#1
David S Ruppert, Ola L A Harrysson, Denis J Marcellin-Little, Laurence E Dahners, Paul S Weinhold
Transcutaneous osseointegrated prostheses provide stable connections to the skeleton while eliminating skin lesions experienced with socket prosthetics. Additive manufacturing can create custom textured implants capable of interfacing with amputees' residual bones. Our objective was to compare osseointegration of textured surface implants made by electron beam melting (EBM), an additive manufacturing process, to machine threaded implants. Whole body vibration was investigated to accelerate osseointegration...
June 11, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29895449/kinematics-based-prediction-of-trunk-muscle-activity-in-response-to-multi-directional-perturbations-during-sitting
#2
Jacques Bobet, Kei Masani, Milos R Popovic, Albert H Vette
Recent work suggests that functional electrical stimulation can be used to enhance dynamic trunk stability following spinal cord injury. In this context, knowledge of the relation between trunk kinematics and muscle activation in non-disabled individuals may assist in developing kinematics-based neuroprostheses. Our objective was therefore to predict the activation profiles of the major trunk muscles from trunk kinematics following multi-directional perturbations during sitting. Trunk motion and electromyograms (EMG) from ten major trunk muscles were acquired in twelve non-disabled, seated individuals who experienced a force of approximately 200 N applied to the trunk in eight horizontal directions...
June 9, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29802013/positioning-accuracy-of-a-patient-tailored-rimmed-wedge-implant-for-corrective-osteotomy-of-the-distal-radius
#3
Johannes G G Dobbe, Giuliana Caiti, Albert W Schreurs, Simon D Strackee, Maikel Beerens, Geert J Streekstra
Conventional corrective osteotomy surgery is based on 2-D imaging for planning and evaluation of bone positioning. In this feasibility study we propose and evaluate the use of 3-D preoperative planning and design of a custom rimmed wedge to be inserted into the osteotomy gap. The shape of the wedge provides 3-D bone positioning as planned, while the rims keep the bone segments in place. The method is evaluated experimentally using 3-D printed radii specimens of five different malunion patients, as well as in a human cadaver specimen...
May 22, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29773488/identifying-the-myogenic-and-metabolic-components-of-cerebral-autoregulation
#4
S J Payne
Cerebral autoregulation is the term used to describe a number of mechanisms that act together to maintain a near constant cerebral blood flow in response to changes in arterial blood pressure. These mechanisms are complex and known to be affected in a range of cerebrovascular diseases. However, it can be difficult to assign an alteration in cerebral autoregulation to one of the underlying physiological mechanisms without the use of a complex mathematical model. In this paper, we thus set out a new approach that enables these mechanisms to be related to the autoregulation behaviour and hence inferred from experimental measurements...
May 14, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29773487/how-can-a-short-stem-hip-implant-preserve-the-natural-pre-surgery-force-flow-a-finite-element-analysis-on-a-collar-cortex-compression-concept-co-4
#5
B Eidel, A Gote, A Ohrndorf, H-J Christ
The present work proposes a simple, novel fixation concept for short stem hip endoprostheses, which preserves the pre-surgery force flow through femoral bone to an unprecedented extent. It is demonstrated by finite element analyses that a standard implant model endowed with minor geometrical changes can overcome bone loading reduction and can achieve almost physiological conditions. The numerical results underpin that the key aspect of the novel, so-called "collar cortex compression concept CO4 " is the direct, almost full load transmission from the implant collar to the resected femur cortex, which implies that the implant stem must be smooth and therefore interacts mainly by normal contact with the surrounding bone...
May 14, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29764734/can-the-contralateral-limb-be-used-as-a-control-during-the-growing-period-in-a-rodent-model
#6
Tanvir Mustafy, Irène Londono, Isabelle Villemure
The contralateral limb is often used as a control in various clinical, forensic and anthropological studies. However, no studies have been performed to determine if the contra-lateral limb is a suitable control during the bone development period. The aim of this study was to determine the bilateral symmetry of growing rat tibiae in terms of geometric shape, mechanical strength and bone morphological parameters with developmental stages. Left and right tibias of 18 male Sprague-Dawley rats at 4, 8 and 12 weeks of age were scanned with micro-CT for bone-morphometric evaluation and for 3D deviation analysis to quantify the geometric shape variations between left and right tibiae...
May 12, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29759948/measuring-relative-positions-and-orientations-of-the-tibia-with-respect-to-the-femur-using-one-channel-3d-tracked-a-mode-ultrasound-tracking-system-a-cadaveric-study
#7
Kenan Niu, Jasper Homminga, Victor Sluiter, André Sprengers, Nico Verdonschot
The purpose of this study is to investigate the technical feasibility of measuring relative positions and orientations of the tibia with respect to the femur in an in-vitro experiment by using a 3D-tracked A-mode ultrasound system and to determine its accuracy of angular and translational measurements. As A-mode ultrasound is capable of detecting bone surface through soft tissue in a non-invasive manner, the combination of a single A-mode ultrasound transducer with an optical motion tracking system provides the possibility for digitizing the 3D locations of bony points at different anatomical regions on the thigh and the shank...
May 11, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29759947/a-simplified-method-to-account-for-wall-motion-in-patient-specific-blood-flow-simulations-of-aortic-dissection-comparison-with-fluid-structure-interaction
#8
Mirko Bonfanti, Stavroula Balabani, Mona Alimohammadi, Obiekezie Agu, Shervanthi Homer-Vanniasinkam, Vanessa Díaz-Zuccarini
Aortic dissection (AD) is a complex and highly patient-specific vascular condition difficult to treat. Computational fluid dynamics (CFD) can aid the medical management of this pathology, yet its modelling and simulation are challenging. One aspect usually disregarded when modelling AD is the motion of the vessel wall, which has been shown to significantly impact simulation results. Fluid-structure interaction (FSI) methods are difficult to implement and are subject to assumptions regarding the mechanical properties of the vessel wall, which cannot be retrieved non-invasively...
May 11, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29759946/assessment-of-structural-and-hemodynamic-performance-of-vascular-stents-modelled-as-periodic-lattices
#9
Purnendu K M Prithipaul, Michael Kokkolaras, Damiano Pasini
This work considers vascular stents with tubular geometry assumed to follow a periodic arrangement of repeating unit cells. Structural and hemodynamic metrics are presented to assess alternative stent geometries, each defined by the topology of the unit cell. Structural metrics include foreshortening, elastic recoil and radial stiffness, whereas hemodynamic performance is described by a wall shear stress index quantifying the impact of in-stent restenosis. A representative volume element (RVE) modelling approach is used, and results are compared to those obtained from full simulations of entire stents...
May 11, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29753628/numerical-optimization-of-cell-colonization-modelling-inside-scaffold-for-perfusion-bioreactor-a-multiscale-model
#10
T-K Nguyen, O Carpentier, F Monchau, F Chai, J C Hornez, P Hivart
Part of clinically applicable bone graft substitutes are developed by using mechanical stimulation of flow-perfusion into cell-seeded scaffolds. The role of fluid flow is crucial in driving the nutrient to seeded cells and in stimulating cell colonization. A common numerical approach is to use a multiscale model to link some physical quantities (wall shear stress and inlet flow rate) that act at different scales. In this study, a multiscale model is developed in order to determine the optimal inlet flow rate to cultivate osteoblast-like cells seeded in a controlled macroporous biomaterial inside a perfusion bioreactor system...
May 10, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29728330/validated-computational-framework-for-efficient-systematic-evaluation-of-osteoporotic-fracture-fixation-in-the-proximal-humerus
#11
Peter Varga, Jason A Inzana, Boyko Gueorguiev, Norbert P Südkamp, Markus Windolf
The high rate of fixation failure in osteoporotic proximal humerus fractures indicate the need for improved solutions. Computer simulations may help to overcome the limitations of the gold standard biomechanical testing in evaluating the performance of new implants and enhance the effectivity and outcome of the design process. This study presents a framework for automated computational analysis that facilitates efficient and systematic evaluation of proximal humerus fracture plating under a variety of conditions including bone quality, fracture pattern, implant configuration and loading regime...
May 1, 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29706484/air-conditioning-analysis-among-human-nasal-passages-with-anterior-anatomical-variations
#12
Jiawei Ma, Jingliang Dong, Yidan Shang, Kiao Inthavong, Jiyuan Tu, Dennis O Frank-Ito
A major functional role of the nasal cavity is air conditioning of the inspired environmental air to near alveolar conditions. It is well known that the anatomical disparities among nasal passages can change airflow patterns to a great extent. However, its effect on nasal air conditioning performance remains largely unexplored. This research investigated the nasal air conditioning performance among nasal models with distinct vestibule phenotypes, including subjects with and without vestibule notches. For the mass transfer, we used a two-film theory model to determine the species transport...
July 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29703696/evaluation-of-matrix-factorisation-approaches-for-muscle-synergy-extraction
#13
Ahmed Ebied, Eli Kinney-Lang, Loukianos Spyrou, Javier Escudero
The muscle synergy concept provides a widely-accepted paradigm to break down the complexity of motor control. In order to identify the synergies, different matrix factorisation techniques have been used in a repertoire of fields such as prosthesis control and biomechanical and clinical studies. However, the relevance of these matrix factorisation techniques is still open for discussion since there is no ground truth for the underlying synergies. Here, we evaluate factorisation techniques and investigate the factors that affect the quality of estimated synergies...
July 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29699890/separation-of-electrocardiographic-from-electromyographic-signals-using-dynamic-filtration
#14
Ivaylo Christov, Rositsa Raikova, Silvija Angelova
Trunk muscle electromyographic (EMG) signals are often contaminated by the electrical activity of the heart. During low or moderate muscle force, these electrocardiographic (ECG) signals disturb the estimation of muscle activity. Butterworth high-pass filters with cut-off frequency of up to 60 Hz are often used to suppress the ECG signal. Such filters disturb the EMG signal in both frequency and time domain. A new method based on the dynamic application of Savitzky-Golay filter is proposed. EMG signals of three left trunk muscles and pure ECG signal were recorded during different motor tasks...
July 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29691130/detection-of-daily-postures-and-walking-modalities-using-a-single-chest-mounted-tri-axial-accelerometer
#15
Milad Nazarahari, Hossein Rouhani
This study presents a novel method for the detection and classification of a wide range of physical activities, including standing, sitting, lying, level walking, and walking upstairs and downstairs using a single chest-mounted accelerometer. The trunk inclination angle and variation of the gravitational component of the accelerometer recording were used for detection and classification of postural transitions and walking modalities. In addition, biomechanical features of each transition were used to reject false detections...
July 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29685857/three-dimensional-printing-as-a-technology-supporting-the-treatment-of-lower-limb-deformity-and-shortening-with-the-ilizarov-method
#16
Piotr Morasiewicz, Karolina Burzyńska, Wiktor Orzechowski, Szymon Łukasz Dragan, Szymon Feliks Dragan, Jarosław Filipiak
BACKGROUND: Treatment of multiplanar deformities, especially in younger children, requires construction of a complex Ilizarov fixator, frequently with small dimensions. The aim of this study is to verify clinical application of a3D-printed bone model in treatment with the Ilizarov method. METHODS: The study involved a 6-year-old child in whom clinical and radiological examination revealed multiplanar deformity of the right leg. Then, 3D models of individual bones were printed by means of additive manufacturing and were used as a scaffold to install the Ilizarov apparatus...
July 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29699891/electrohysterographic-characterization-of-the-uterine-myoelectrical-response-to-labor-induction-drugs
#17
Carlos Benalcazar-Parra, Yiyao Ye-Lin, Javier Garcia-Casado, Rogelio Monfort-Orti, Jose Alberola-Rubio, Alfredo Perales, Gema Prats-Boluda
Labor induction is a common practice to promote uterine contractions and labor onset. Uterine electrohysterogram (EHG) has proved its suitability for characterizing the uterus electrophysiological condition in women with spontaneous labor. The aim of this study was to characterize and compare uterine myoelectrical activity during the first 4 h in response to labor induction drugs, Misoprostol (G1) and Dinoprostone (G2), by analyzing the differences between women who achieved active phase of labor and those who did not (successful and failed inductions)...
June 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29685858/establishing-the-relationship-between-loading-parameters-and-bone-adaptation
#18
Abhishek Kumar Tiwari, Navin Kumar
Cyclic and low-magnitude loading is considered effective in arresting the bone loss as it promotes osteogenesis (i.e. new bone formation) at the sites of elevated normal strain magnitude. In silico models assumed normal strain as the stimulus to predict the sites of new bone formation. These models, however, may fail to fit the amount of newly formed bone. Loading parameters such as strain, frequency, and loading cycle decide the amount of new bone formation. The models did not incorporate this information...
June 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29685856/importance-of-a-moderate-plate-to-bone-distance-for-the-functioning-of-the-far-cortical-locking-system
#19
Jesse Chieh-Szu Yang, Kang-Ping Lin, Hung-Wen Wei, Wen-Chuan Chen, Chao-Ching Chiang, Ming-Chau Chang, Cheng-Lun Tsai, Kun-Jhih Lin
The far cortical locking (FCL) system, a novel bridge-plating technique, aims to deliver controlled and symmetric interfragmentary motion for a potential uniform callus distribution. However, clinical data for the practical use of this system are limited. The current study investigated the biomechanical effect of a locking plate/far cortical locking construct on a simulated comminuted diaphyseal fracture of the synthetic bones at different distance between the plate and the bone. Biomechanical in vitro experiments were performed using composite sawbones as bone models...
June 2018: Medical Engineering & Physics
https://www.readbyqxmd.com/read/29681441/kinect-v2-implementation-and-testing-of-the-reaching-performance-scale-for-motor-evaluation-of-patients-with-neurological-impairment
#20
Alessandro Scano, Andrea Chiavenna, Matteo Malosio, Lorenzo Molinari Tosatti, Franco Molteni
Automated procedures for neurological patients' motor evaluation may take advantage of the coupling between clinical scales and motion tracking devices to provide affordable, quantified and reliable assessment to be used in clinics, in surgeries and domestic environment. In this study, 20 post-stroke patients performed frontal reaching movements with their more affected limb, and a physician administered the Reaching Performance Scale (RPS) to assess motor functionality. At the same time, patients' kinematics were recorded with the Kinect V2 sensor...
June 2018: Medical Engineering & Physics
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