Medical Engineering and PhysicsThis is an RSS file. You can use it to subscribe to this data in your favourite RSS reader, such as GoogleReader, or to display this data on your own website or blog. Subscribe to this data using MyMedWorm.Subscribe to this data using GoogleReader.Subscribe to this data using Bloglines.Subscribe to this data using MyYahoo.

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(Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - November 20, 2009 Category: Biomedical Engineering Source Type: journals

Cement mantle stress under retroversion torque at heel-strikeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The paper presents a theory of fixation failure and loosening in cemented total hip prostheses and proceeds to investigate this using an experimentally validated finite element model and two prosthesis types, namely the Charnley and the C-Stem. The study investigates the effects of retroversion torque occurring at heel-strike in combination with a loss of proximal cement/bone support and distal implant/cement support with a good distal cement/bone interface. A 3D finite element model was validated by comparison of femoral surface strains with those measured in an in vitro experimental simulation using an implante...
Source: Medical Engineering and Physics - November 2, 2009 Category: Biomedical Engineering Authors: B. Afsharpoya, D.C. Barton, J. Fisher, B. Purbach, M. Wroblewski, T.D. Stewart Tags: Papers Source Type: journals

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(Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - November 1, 2009 Category: Biomedical Engineering Source Type: journals

A method to estimate EMG crosstalk between two muscles based on the silent period following an H-reflexEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The crosstalk phenomenon consists in recording the volume-conducted electromyographic activity of muscles other than that under study. This interference may impair the correct interpretation of the results in a variety of experiments. A new protocol is presented here for crosstalk assessment between two muscles based on changes in their electrical activity following a reflex discharge in one of the muscles in response to nerve stimulation. A reflex compound muscle action potential (H-reflex) was used to induce a silent period in the muscle that causes the crosstalk, called here the remote muscle. The rationale is...
Source: Medical Engineering and Physics - October 30, 2009 Category: Biomedical Engineering Authors: Rinaldo André Mezzarane, André Fabio Kohn Tags: Technical Notes Source Type: journals

Reliability, validity, and precision of an active stereophotogrammetry system for three-dimensional evaluation of the human torsoEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: To determine the reliability, stability, validity and precision of a stereophotogrammetry (SP) system for use in quantifying the complex three-dimensional structure of the human torso, we performed assessments of the system using images of geometric solids and a human-form mannequin. Analysis of geometric solids revealed excellent intra- and interrater reliability of the system for linear, surface area and volume measurements (r>0.99, P0.06). The system exhibited excellent stability in images of the mannequin over time (r>0.99). The limit of precision (error>5%) of the system to detect objects on the surface of t...
Source: Medical Engineering and Physics - October 12, 2009 Category: Biomedical Engineering Authors: Scott M. Paul, Andrew P. Chamberlin, Charles Hatt, Amritha V. Nayak, Jerome V. Danoff Tags: Technical Notes Source Type: journals

On the equivalence of two methods of determining fabric tensorEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: In this paper it is studied how three methods of quantifying structural anisotropy are related. Mean intercept length (MIL) method has been designed for the analysis of binary images. Autocorrelation function and the covariance matrix of the gray-level intensity gradient (GST method) are approaches designed for the analysis of gray-level data. It is shown here that the autocorrelation function and the MIL methods are not related in a general case. In contrast, an analytical proof is provided to show that MIL and GST methods are strictly equivalent. The standard definition of MIL is expressed in terms of a gradien...
Source: Medical Engineering and Physics - October 5, 2009 Category: Biomedical Engineering Authors: Zbisław Tabor Tags: Papers Source Type: journals

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(Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - September 30, 2009 Category: Biomedical Engineering Source Type: journals

A high-resolution three-dimensional far-infrared thermal and true-color imaging system for medical applicationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: As the needs for various kinds of body surface information are wide-ranging, we developed an imaging-sensor integrated system that can synchronously acquire high-resolution three-dimensional (3D) far-infrared (FIR) thermal and true-color images of the body surface. The proposed system integrates one FIR camera and one color camera with a 3D structured light binocular profilometer. To eliminate the emotion disturbance of the inspector caused by the intensive light projection directly into the eye from the LCD projector, we have developed a gray encoding strategy based on the optimum fringe projection layout. A sel...
Source: Medical Engineering and Physics - September 27, 2009 Category: Biomedical Engineering Authors: Victor S. Cheng, Jinfen Bai, Yazhu Chen Tags: Papers Source Type: journals

Advanced modeling strategy for the analysis of heart valve leaflet tissue mechanics using high-order finite element methodEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study is one step towards the modeling of soft tissue mechanics using a meshless finite element approach to be applied in real-time haptic feedback of soft-tissue models in virtual reality simulation. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - September 23, 2009 Category: Biomedical Engineering Authors: Hadi Mohammadi, Fereshteh Bahramian, Wankei Wan Tags: Papers Source Type: journals

Large sizes of vertebral body replacement do not reduce the contact pressure on adjacent vertebral bodies per seEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Large implants for vertebral body replacement (VBR) have a large footprint, and are normally supported by stronger bone at the rim of the vertebral body. But they also necessitate a greater corpectomy defect in the vertebral body concerned. In order to study the effect of implant size on contact pressure on the adjacent vertebral bodies and thus the risk of implant subsidence, an osseoligamentous finite element model of the lumbar spine was employed. The VBR was inserted at the level of L4 and additionally stabilized by posterior spinal instrumentation. Flat and curved vertebral endplates, small and large corpect...
Source: Medical Engineering and Physics - September 22, 2009 Category: Biomedical Engineering Authors: Thomas Zander, Georg Bergmann, Antonius Rohlmann Tags: Papers Source Type: journals

In vitro, in vivo and numerical assessment of the working principle of the truCCOMS™ continuous cardiac output catheter systemEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The truCCOMS™ cardiac output monitor system provides a continuous and instantaneous measurement of cardiac output, derived from the amount of energy required for heating a filament to maintain a fixed 2°C blood temperature difference between two thermistors located distally on a pulmonary artery catheter. Clinical studies, however, reported relatively poor accuracy of the cardiac output estimation, possibly due to linearly assumed power–cardiac output relationship used for calibration of the catheters. We experimentally studied the shape of the truCCOMS™ calibration relationship (i) in a hydraulic bench mo...
Source: Medical Engineering and Physics - September 22, 2009 Category: Biomedical Engineering Authors: T. Claessens, P. Verwilst, C. Missant, P. Claus, P. Verdonck, P. Wouters, P. Segers Tags: Papers Source Type: journals

Partial potentials of selected cardiac muscle regions and heart activity model based on single fibresEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present single fibre heart activity model (SFHAM) based on the current flow through the five bunches of fibres of the cardiac muscle (CM). The five effective fibres are identified and assigned to the appropriate segments of CM. Analytical functions describing ionic flows along the fibres are derived and proposed. The parameters determining the shapes and amplitudes of the functions proposed are obtained on the basis of standard 12-lead ECG measurements after numerical fitting procedures concentrating on the QRS-waves. As a consequence, five independent courses of partial, transient potentials are obtained representing: ...
Source: Medical Engineering and Physics - September 17, 2009 Category: Biomedical Engineering Authors: J.S. Janicki, W. Leoński, J. Jagielski Tags: Papers Source Type: journals

Experimental validation of the nerve conduction velocity selective recording technique using a multi-contact cuff electrodeEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The earthworm (Lumbricus terrestris) is presented as an in vitro model of a peripheral nerve containing only two fibers each with distinctly different conduction velocities, the median and lateral giant fibers (MGF and LGF). The worm model is used with a multi-contact cuff electrode to validate the spatial–temporal filtering effect of different electrode contact configurations and the effect of applying a delay adder and matched filter tuned to either the MGF or LGF action potential (AP) to extract conduction direction and velocity from the recording. The results confirmed the known effect of inter-electrode sp...
Source: Medical Engineering and Physics - September 17, 2009 Category: Biomedical Engineering Authors: K. Yoshida, G.A.M. Kurstjens, K. Hennings Tags: Papers Source Type: journals

Comparative analysis of methods for automatic detection and quantification of microvolt T-wave alternansEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Microvolt T-wave alternans (TWA), consisting of every-other-beat changes in ECG T-wave morphology, is an index of susceptibility to malignant ventricular arrhythmias, requiring automatic techniques to be identified. Five of these, namely, fast-Fourier-transform spectral method (FFTSM), complex-demodulation method (CDM), modified-moving-average method (MMAM), Laplacian-likelihood-ratio method (LLRM) and adaptive-match-filter method (AMFM), were applied here to simulated and sample clinical data. The aim was to compare individual methods ability to properly identify stationary and time-varying TWA, avoiding false-p...
Source: Medical Engineering and Physics - September 16, 2009 Category: Biomedical Engineering Authors: Laura Burattini, Silvia Bini, Roberto Burattini Tags: Papers Source Type: journals

Modeling upper airway collapse by a finite element model with regional tissue propertiesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study presents a new computational system for modeling the upper airway in rats that combines tagged magnetic resonance imaging (MRI) with tissue material properties to predict three-dimensional (3D) airway motion. The model is capable of predicting airway wall and tissue deformation under airway pressure loading up to airway collapse. The model demonstrates that oropharynx collapse pressure depends primarily on ventral wall (tongue muscle) elastic modulus and airway architecture. An iterative approach that involves substituting alternative possible tissue elastic moduli was used to improve model precision. The propos...
Source: Medical Engineering and Physics - September 11, 2009 Category: Biomedical Engineering Authors: Chun Xu, Michael J. Brennick, Lawrence Dougherty, David M. Wootton Tags: Technical Notes Source Type: journals

Wrist pulse signal diagnosis using modified Gaussian models and Fuzzy C-Means classificationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Wrist pulse signal contains important information about the health status of a person and pulse signal diagnosis has been employed in oriental medicine for thousands of years. In this research, a systematic approach is proposed to analyze the computerized wrist pulse signals, with the focus placed on the feature extraction and pattern classification. The wrist pulse signals are first collected and pre-processed. Considering that a typical pulse signal is composed of periodically systolic and diastolic waves, a modified Gaussian model is adopted to fit the pulse signal and the modeling parameters are then taken as...
Source: Medical Engineering and Physics - September 11, 2009 Category: Biomedical Engineering Authors: Yinghui Chen, Lei Zhang, David Zhang, Dongyu Zhang Tags: Papers Source Type: journals

Mesh morphing for finite element analysis of implant positioning in cementless total hip replacementsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Finite element (FE) analysis of the effect of implant positioning on the performance of cementless total hip replacements (THRs) requires the generation of multiple meshes to account for positioning variability. This process can be labour intensive and time consuming as CAD operations are needed each time a specific orientation is to be analysed. In the present work, a mesh morphing technique is developed to automate the model generation process. The volume mesh of a baseline femur with the implant in a nominal position is deformed as the prosthesis location is varied. A virtual deformation field, obtained by sol...
Source: Medical Engineering and Physics - September 10, 2009 Category: Biomedical Engineering Authors: Mamadou T. Bah, Prasanth B. Nair, Martin Browne Tags: Papers Source Type: journals

Modeling the relationship between wrist angle and muscle thickness during wrist flexion–extension based on the bone–muscle lever system: A comparison studyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: A structural model of skeletal muscle based on the bone–muscle lever system is proposed to describe the relationship between wrist angle and thickness of the extensor carpi radialis muscle during the process of wrist flexion–extension. This model applied the cosine theorem to the expression for muscle length, in order to relate wrist angle to muscle thickness by the invariance of muscle volume, which was used to calculate the length of the extensor carpi radialis muscle from the muscle thickness. To validate the proposed model, wrist angles were also computed by other models based on regression, such as linea...
Source: Medical Engineering and Physics - September 9, 2009 Category: Biomedical Engineering Authors: Jun Shi, Yongping Zheng, Xin Chen, Hongbo Xie Tags: Papers Source Type: journals

The effects of bone marrow stromal cell transplants on tendon healing in vitroEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The purpose of this study was to investigate the effect of bone marrow stromal cells (BMSCs) on tendon healing in a canine ex vivo model. Bone marrow was harvested and BMSCs were isolated and cultured according to established protocols. Cells were seeded into 0.5mg/ml collagen gels and cultured for 24h to allow gel contraction, and then implanted between the lacerated ends of repaired flexor digitorum profundus tendons. Tendons repaired with a gel patch alone and without a gel patch served as control groups. After 2 and 4 weeks in culture, the repaired tendons were evaluated for breaking strength and stiffness. C...
Source: Medical Engineering and Physics - September 7, 2009 Category: Biomedical Engineering Authors: Chunfeng Zhao, Hsiao-Feng Chieh, Karim Bakri, Jun Ikeda, Yu-Long Sun, Steven L. Moran, Kai-Nan An, Peter C. Amadio Tags: Papers Source Type: journals

Real-time model based electrical powered wheelchair controlEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The purpose of this study was to evaluate the effects of three different control methods on driving speed variation and wheel slip of an electric-powered wheelchair (EPW). A kinematic model as well as 3D dynamic model was developed to control the velocity and traction of the wheelchair. A smart wheelchair platform was designed and built with a computerized controller and encoders to record wheel speeds and to detect the slip. A model based, a proportional-integral-derivative (PID) and an open-loop controller were applied with the EPW driving on four different surfaces at three specified speeds. The speed errors, ...
Source: Medical Engineering and Physics - September 7, 2009 Category: Biomedical Engineering Authors: Hongwu Wang, Benjamin Salatin, Garrett G. Grindle, Dan Ding, Rory A. Cooper Tags: Papers Source Type: journals

Large eddy simulation of high frequency oscillating flow in an asymmetric branching airway modelEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, transitional and turbulent flow within an asymmetric bifurcating model of the upper airway during HFOV are studied using large eddy simulation (LES) methods. The flow, characterized by a peak Reynolds number of 8132, is analysed using a validated LES model of a three-dimensional branching geometry. The pressures, velocities, and vorticity within the flow are presented and compared with prior models for branching flow systems. The results demonstrate how pendelluft occurs at asymmetric branches within the respiratory system. These results may be useful in optimising treatments using HFOV methods. (Source: Med...
Source: Medical Engineering and Physics - August 28, 2009 Category: Biomedical Engineering Authors: Martin A. Nagels, John E. Cater Tags: Papers Source Type: journals

A study on the mechanical properties of beagle femoral head using the digital speckle correlation methodEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The mechanical properties of the femoral head are known to play an important role in the athletic performance of animals. In this paper, the full-field displacement and strain distributions of beagle femoral head samples in the U and V fields under loading were measured using the digital speckle correlation method (DSCM), and some deformation characteristics were analyzed. Young's modulus and Poisson's ratio were calculated to demonstrate the notable axial anisotropy of the femoral head. The axial compressive Young's modulus varies from 361MPa to 583MPa, and the transverse one is 213MPa. The Poisson's ratio in th...
Source: Medical Engineering and Physics - August 27, 2009 Category: Biomedical Engineering Authors: Qinghua Wang, Huimin Xie, Peifu Tang, Qi Yao, Peng Huang, Pengwan Chen, Fenglei Huang Tags: Papers Source Type: journals

Ballistocardiogaphic studies with acceleration and electromechanical film sensorsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, the configuration of the constructed device provided reliable measurements of the electrocardiogram, BCG, heart sound, and carotid and ankle pulse wave signals. Attached EMFi sensor strips on the neck and limbs yield completely new applications of the EMFi sensors aside from the conventional seat and supine recordings. Higher sensitivity, ease of utilization, and minimum discomfort of the EMFi sensor compared with acceleration sensors strengthen the status of the EMFi sensor for accurate and reliable BCG and PWV measurements, providing novel evaluation of the elastic properties of the cardiovascular system. ...
Source: Medical Engineering and Physics - August 27, 2009 Category: Biomedical Engineering Authors: J. Alametsä, A. Värri, J. Viik, J. Hyttinen, A. Palomäki Tags: Papers Source Type: journals

Modeling the finger joint moments in a hand at the maximal isometric grip: The effects of frictionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The interaction between the handle and operator’s hand affects the comfort and safety of tool and machine operations. In most of the previous studies, the investigators considered only the normal contact forces. The effect of friction on the joint moments in fingers has not been analyzed. Furthermore, the observed contact forces have not been linked to the internal musculoskeletal loading in the previous experimental studies. In the current study, we proposed a universal model of a hand to evaluate the joint moments in the fingers during grasping tasks. The hand model was developed on the platform of the commer...
Source: Medical Engineering and Physics - August 25, 2009 Category: Biomedical Engineering Authors: John Z. Wu, Ren G. Dong, Thomas W. McDowell, Daniel E. Welcome Tags: Papers Source Type: journals

Evaluation of a bioceramic-based nanocomposite material for controlled delivery of a non-steroidal anti-inflammatory drugEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, nanocomposite of 50wt% calcium sulfate and 50wt% nanocrystalline apatite was produced and its biocompatibility, physical and structural properties were compared with pure calcium sulfate (CS) cement. Indomethacin (IM), a non-steroidal anti-inflammatory drug, was also loaded on both CS and nanocomposite cements and its in vitro release was evaluated over a period of time. The effect of the loaded IM on basic properties of the cements was also investigated. Biocompatibility tests showed a partial cytotoxicity in CS cement due to the reduced number of viable mouse fibroblast L929 cells in contact with the sampl...
Source: Medical Engineering and Physics - August 21, 2009 Category: Biomedical Engineering Authors: S. Hesaraki, F. Moztarzadeh, N. Nezafati Tags: Papers Source Type: journals

A computer model of the artificially ventilated human respiratory system in adult intensive careEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: A multi-technique approach to modelling artificially ventilated patients on the adult general intensive care unit (ICU) is proposed. Compartmental modelling techniques were used to describe the mechanical ventilator and the flexible hoses that connect it to the patient. 3D CFD techniques were used to model flow in the major airways and a Windkessel style balloon model was used to model the mechanical properties of the lungs. A multi-compartment model of the lung based on bifurcating tree structures representing the conducting airways and pulmonary circulation allowed lung disease to be modelled in terms of altere...
Source: Medical Engineering and Physics - August 21, 2009 Category: Biomedical Engineering Authors: A.J. Wilson, C.M. Murphy, B.S. Brook, D. Breen, A.W. Miles, D.G. Tilley Tags: Papers Source Type: journals

A robust wavelet-based multi-lead electrocardiogram delineation algorithmEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: A robust multi-lead ECG wave detection-delineation algorithm is developed in this study on the basis of discrete wavelet transform (DWT). By applying a new simple approach to a selected scale obtained from DWT, this method is capable of detecting QRS complex, P-wave and T-wave as well as determining parameters such as start time, end time, and wave sign (upward or downward). First, a window with a specific length is slid sample to sample on the selected scale and the curve length in each window is multiplied by the area under the absolute value of the curve. In the next step, a variable thresholding criterion is ...
Source: Medical Engineering and Physics - August 19, 2009 Category: Biomedical Engineering Authors: A. Ghaffari, M.R. Homaeinezhad, M. Akraminia, M. Atarod, M. Daevaeiha Tags: Papers Source Type: journals

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(Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - August 18, 2009 Category: Biomedical Engineering Source Type: journals

Determination of body segment masses and centers of mass using a force plate method in individuals of different morphologyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study presented a simple force plate method that can be used to determine subject-specific segment masses and COM locations and compared it to other well-known methods. The proposed method was tested in individuals with different body mass index (i.e., lean, normal, and obese) to verify its sensitivity. All the segmental mass and COM values obtained from the force plate method were within the range of those of the other methods for the entire sample. Significant differences were identified between the morphological groups in relative segmental masses at the upper arm and leg and foot, and COM locations at the leg and ...
Source: Medical Engineering and Physics - August 17, 2009 Category: Biomedical Engineering Authors: Mohsen Damavandi, Nader Farahpour, Paul Allard Tags: Technical Notes Source Type: journals

Assessment of cortical bone elasticity and strength: Mechanical testing and ultrasound provide complementary dataEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Cortical bone is a compact tissue with anisotropic macroscopic mechanical properties determined by a microstructure and the quality of a mineralised collagen matrix. Anisotropic elastic properties and strength are usually measured on different groups of sample which can hardly be pooled; as a consequence little is known on the relationships between strength and elasticity in the different anatomical directions. A method is presented to measure on a same cortical bone sample: (1) Young's modulus and strength (σmax) in the longitudinal direction; (2) stiffness (C11) in the transverse direction. Longitudinal and tr...
Source: Medical Engineering and Physics - August 17, 2009 Category: Biomedical Engineering Authors: Quentin Grimal, Sylvain Haupert, David Mitton, Laurent Vastel, Pascal Laugier Tags: Papers Source Type: journals

A fracture risk assessment model of the femur in children with osteogenesis imperfecta (OI) during gaitEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study begins the development of a patient-specific model for femur fracture risk assessment and prediction based on individuals’ gait analysis data, bone geometry from imaging and material properties from nanoindentation (Young's modulus=19GPa, Poisson's ratio=0.3). Finite element models of the femur were developed to assess fracture risk of the femur in a pediatric patient with OI type I. Kinetic data from clinical gait analysis was used to prescribe loading conditions on the femoral head and condyles along with muscle forces on the bone's surface. von Mises stresses were analyzed against a fracture strength of 115...
Source: Medical Engineering and Physics - August 17, 2009 Category: Biomedical Engineering Authors: Jessica M. Fritz, Yabo Guan, Mei Wang, Peter A. Smith, Gerald F. Harris Tags: Papers Source Type: journals

Investigation of spiral blood flow in a model of arterial stenosisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The spiral component of blood flow has both beneficial and detrimental effects in human circulatory system [Stonebridge PA, Brophy CM. Spiral laminar flow in arteries? Lancet 1991; 338: 1360–1]. We investigate the effects of the spiral blood flow in a model of three-dimensional arterial stenosis with a 75% cross-sectional area reduction at the centre by means of computational fluid dynamics (CFD) techniques. The standard k–ω model is employed for simulation of the blood flow for the Reynolds number of 500 and 1000. We find that for Re=500 the spiral component of the blood flow increases both the total pressu...
Source: Medical Engineering and Physics - August 12, 2009 Category: Biomedical Engineering Authors: Manosh C. Paul, Arkaitz Larman Tags: Technical Notes Source Type: journals

Modeling and simulation of flexible needlesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Needle insertion is performed in many clinical and therapeutic procedures. Tissue displacement and needle bending which result from needle–tissue interaction make accurate targeting difficult. For performing physicians to gain essential needle targeting skills, needle insertion simulators can be used for training. An accurate needle bending model is essential for such simulators. These bending models are also needed for needle path planning.In this paper, three different models are presented to simulate the deformations of a needle. The first two models use the finite element method and take the geometric nonli...
Source: Medical Engineering and Physics - August 12, 2009 Category: Biomedical Engineering Authors: Orcun Goksel, Ehsan Dehghan, Septimiu E. Salcudean Tags: Papers Source Type: journals

Muscle motion and EMG activity in vibration treatmentEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The aim of this study is to highlight the relationship between muscle motion, generated by whole body vibration, and the correspondent electromyographic (EMG) activity and to suggest a new method to customize the stimulation frequency. Simultaneous recordings of EMG and tri-axial accelerations of quadriceps rectus femoris from fifteen subjects undergoing vibration treatments were collected. Vibrations were delivered via a sinusoidal oscillating platform at different frequencies (10–45Hz). Muscle motion was estimated by processing the accelerometer data. Large EMG motion artifacts were removed using sharp notch ...
Source: Medical Engineering and Physics - August 11, 2009 Category: Biomedical Engineering Authors: Antonio Fratini, Antonio La Gatta, Paolo Bifulco, Maria Romano, Mario Cesarelli Tags: Papers Source Type: journals

The effect of impact direction on the fracture load of osteoporotic proximal femursEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this study was (1) to confirm whether or not differences in bone strength are reflected in the proximal femur finite element (FE) model constructed from CT images of healthy subjects and osteoporosis patients, and (2) to investigate the effect of loading angle direction on bone fractures. The results from comparison of bone strength between the fracture group, fragile group (osteoporosis patients with no fracture after falling), and healthy group showed that differences in bone strength were definitely reflected in this FE model. Furthermore, the relationship between the loading direction and fracture load...
Source: Medical Engineering and Physics - August 10, 2009 Category: Biomedical Engineering Authors: Norimitsu Wakao, Atsushi Harada, Yasumoto Matsui, Marie Takemura, Hiroshi Shimokata, Masashi Mizuno, Masako Ito, Yukihiro Matsuyama, Naoki Ishiguro Tags: Papers Source Type: journals

Probabilistic constitutive law for damage in ligamentsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: A new constitutive equation is presented to describe the damage evolution process in parallel-fibered collagenous tissues such as ligaments. The model is formulated by accounting for the fibrous structure of the tissues. The tissue’s stress is defined as the average of the collagen fiber’s stresses. The fibers are assumed to be undulated and straightened out at different stretches that are randomly defined according to a Weibull distribution. After becoming straight, each collagen fiber is assumed to be linear elastic. Damage is defined as a reduction in collagen fiber’s stiffness and occurs at different st...
Source: Medical Engineering and Physics - August 10, 2009 Category: Biomedical Engineering Authors: Zheying Guo, Raffaella De Vita Tags: Papers Source Type: journals

Electric field distribution in a finite-volume head model of deep brain stimulationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study presents a whole-head finite element model of deep brain stimulation to examine the effect of electrical grounding, the finite conducting volume of the head, and scalp, skull and cerebrospinal fluid layers. The impedance between the stimulating and reference electrodes in the whole-head model was found to lie within clinically reported values when the reference electrode was incorporated on a localized surface in the model. Incorporation of the finite volume of the head and inclusion of surrounding outer tissue layers reduced the magnitude of the electric field and activating function by approximately 20% in the...
Source: Medical Engineering and Physics - August 5, 2009 Category: Biomedical Engineering Authors: Peadar F. Grant, Madeleine M. Lowery Tags: Papers Source Type: journals

Measurements of body composition in limbs and trunk using a eight contact electrodes impedancemeterEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Regional body composition measurements may be achieved in a single operation with impedancemeters equipped with four plantar and four hand electrodes. By measuring sequentially the resistances of five current lines connecting the hands and feet and solving a system of five linear equations, it is possible to calculate the resistances of each limb and the trunk. The impedancemeter used in this study was a prototype with four plantar electrodes and four additional contact electrodes for the hands. Its electronic hardware was identical to that of a Tefal commercial foot-to-foot impedancemeter (FFI). The Tefal FFI wa...
Source: Medical Engineering and Physics - August 5, 2009 Category: Biomedical Engineering Authors: Michel Y. Jaffrin, Hélène Morel Tags: Papers Source Type: journals

Cardiac signal extraction in patients with Implantable Cardioverter DefibrillatorsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: According to the guidelines the indication for Implantable Cardioverter Defibrillator (ICD) implantation is based on the ejection fraction. However, only a fraction of patients with implanted ICD shows live threatening arrhythmic events followed by adequate shocks. For this reason, further research is needed to find a more sensitive risk stratificator for patients prone to ventricular tachycardia or fibrillation. Unfortunately, standard prospective studies are time consuming.An alternative approach is to perform retrospective studies on patients with already implanted ICDs. So far, an implanted ICD is an exclusio...
Source: Medical Engineering and Physics - August 3, 2009 Category: Biomedical Engineering Authors: D. Di Pietro Paolo, H.-P. Mueller, M. Goernig, J. Haueisen, S.N. Erne Tags: Papers Source Type: journals

Biomechanical behaviour of oesophageal tissues: Material and structural configuration, experimental data and constitutive analysisEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The aim of the present work is to propose an approach to the biomechanical analysis of oesophagus by defining an appropriate constitutive model and the associated constitutive parameters. The configuration of the different tissues and layers that compose the oesophagus shows very complicated internal anatomy, geometry and mechanical properties. The coupling of these tissues adds to the complexity. The constitutive models must be capable of interpreting the highly non-linear mechanical response. This is done adopting a specific hyperelastic anisotropic formulation. Experimental data are essential for the investiga...
Source: Medical Engineering and Physics - August 3, 2009 Category: Biomedical Engineering Authors: Arturo N. Natali, Emanuele L. Carniel, Hans Gregersen Tags: Papers Source Type: journals

Swallow segmentation with artificial neural networks and multi-sensor fusionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Swallow segmentation is a critical precursory step to the analysis of swallowing signal characteristics. In an effort to automatically segment swallows, we investigated artificial neural networks (ANN) with information from cervical dual-axis accelerometry, submental MMG, and nasal airflow. Our objectives were (1) to investigate the relationship between segmentation performance and the number of signal sources and (2) to identify the signals or signal combinations most useful for swallow segmentation. Signals were acquired from 17 healthy adults in both discrete and continuous swallowing tasks using five stimuli....
Source: Medical Engineering and Physics - July 31, 2009 Category: Biomedical Engineering Authors: Joon Lee, Catriona M. Steele, Tom Chau Tags: Papers Source Type: journals

Exploratory study of a non-invasive method based on acoustic emission for assessing the dynamic integrity of knee jointsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The paper presents the development of a new measurement system based on acoustic emission (AE) for assessing the dynamic integrity of knee joints, and the evaluation of its efficacy, through an exploratory study using healthy and osteoarthritic knees. For the former, the paper describes the system implemented to acquire joint angle-based AE and the protocol developed to obtain repeatable results. For the latter, the paper reports significant differences between healthy and osteoarthritic knees using statistical analysis of AE occurrence and distribution of AE features in different movement phases. Osteoarthritic ...
Source: Medical Engineering and Physics - July 29, 2009 Category: Biomedical Engineering Authors: B. Mascaro, J. Prior, L.-K. Shark, J. Selfe, P. Cole, J. Goodacre Tags: Papers Source Type: journals

Finite element analysis of the middle ear transfer functions and related pathologiesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: With developments in software and micro-measurement technology, a three-dimensional middle ear finite element (FE) model can now be more easily constructed to study sound transfer function. Many FE models of the middle ear have been constructed to date, and each has its own particular advantages and disadvantages. In this article, we review the latest developments and technologies in the field of the FE models of the middle ear, and the use of FE in the study of middle ear pathology. Proposals are made for future developments in the field of finite element analysis of middle ear transfer function. (Source: Medica...
Source: Medical Engineering and Physics - July 29, 2009 Category: Biomedical Engineering Authors: Fei Zhao, Takuji Koike, Jie Wang, Hans Sienz, Rhys Meredith Tags: Reviews Source Type: journals

Surgical instrumentation for the in vivo determination of human lumbar spinal segment stiffness and viscoelasticityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The definition of spinal instability is still controversial. For this reason, it is essential to better understand the difference in biomechanical behaviour between healthy and degenerated human spinal segments in vivo. A novel computer-assisted instrument was developed with the objective to characterize the biomechanical parameters of the spinal segment. Investigation of the viscoelastic properties as well as the dynamic spinal stiffness was performed during a minimally invasive procedure (microdiscectomy) on five patients. Measurements were performed intraoperatively and the protocol consisted of a dynamic part...
Source: Medical Engineering and Physics - July 24, 2009 Category: Biomedical Engineering Authors: Sveva Ambrosetti-Giudici, Alois Pfenniger, Michael H. Krenn, Wolfgang P. Piotrowski, Stephen J. Ferguson, Juergen Burger Tags: Papers Source Type: journals

A low-cost thermoelectrically cooled tissue clamp for in vitro cyclic loading and load-to-failure testing of muscles and tendonsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article describes a simple custom-made thermoelectrically cooled freeze clamp. The effectiveness of the clamp to transmit loads without tissue slippage was evaluated on 10 canine quadriceps femoris myo-tendinous junctions in both load-to-failure and cyclic loading settings. Dynamic cyclic loading during an extensive period of time was successfully achieved. Loads up to 4.84kN were applied in quasi-static conditions without evidence of clamp slippage or failure. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 23, 2009 Category: Biomedical Engineering Authors: Marc-Olivier Kiss, Nicola Hagemeister, Annie Levasseur, Julio Fernandes, Bertrand Lussier, Yvan Petit Tags: Technical Notes Source Type: journals

Battery powered neuromuscular stimulator circuit for use during simultaneous recording of myoelectric signalsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Surface Functional Electrical Stimulation (FES) requires high stimulation voltages. A step-up transformer in the output stage of the stimulation circuit is often used. In the present technical paper a voltage controlled current source (VCCS) is presented as an alternative to the transformer coupling. Two (master–slave) coupled transconductance amplifiers (TAs)—in series with pre-charged capacitors—are used to drive the output current. After each stimulation pulse the capacitors are recharged to a high voltage by a switch mode power supply (SMPS). A multiplexer in the output stage is used to provide biphasic...
Source: Medical Engineering and Physics - July 20, 2009 Category: Biomedical Engineering Authors: Rune Thorsen, Maurizio Ferrarin Tags: Technical Note Source Type: journals

On the use of sample entropy to analyze human postural sway dataEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present a practical method to select the input parameters of the SampEn algorithm. We show that the computed SampEn successfully discriminates two sensory conditions (eyes-open and eyes-closed) in a group of healthy young adults. We also perform surrogate data tests to investigate the nature of the underlying dynamics of our experimental data. Finally, the results of the proposed approach are compared to those obtained with the multiscale entropy algorithm. (Source: Medical Engineering and Physics)
Source: Medical Engineering and Physics - July 15, 2009 Category: Biomedical Engineering Authors: Sofiane Ramdani, Benoît Seigle, Julien Lagarde, Frédéric Bouchara, Pierre Louis Bernard Tags: Papers Source Type: journals

Experimental modelling of aortic aneurysms: Novel applications of silicone rubbersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: A range of silicone rubbers were created based on existing commercially available materials. These silicones were designed to be visually different from one another and have distinct material properties, in particular, ultimate tensile strengths and tear strengths. In total, eleven silicone rubbers were manufactured, with the materials designed to have a range of increasing tensile strengths from approximately 2 to 4MPa, and increasing tear strengths from approximately 0.45 to 0.7N/mm. The variations in silicones were detected using a standard colour analysis technique. Calibration curves were then created relati...
Source: Medical Engineering and Physics - July 12, 2009 Category: Biomedical Engineering Authors: Barry J. Doyle, Timothy J. Corbett, Aidan J. Cloonan, Michael R. O’Donnell, Michael T. Walsh, David A. Vorp, Timothy M. McGloughlin Tags: Papers Source Type: journals

Can in vitro systems capture the characteristic differences between the flexion–extension kinematics of the healthy and TKA knee?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: In vitro systems provide a powerful means to evaluate the efficacy of total knee arthroplasty (TKA) in restoring normal knee kinematics. The Oxford knee rig (OKR) and the robotic knee testing system (RKTS) represent two systems that have been extensively used to study TKA biomechanics. Nonetheless, a frequently asked question is whether in vitro simulations can capture the in vivo behavior of the knee. Here, we compared the flexion–extension kinematics of intact knees and knees after TKA tested on the OKR and RKTS, to results of representative in vivo studies. The goal was to determine if the in vitro systems c...
Source: Medical Engineering and Physics - July 12, 2009 Category: Biomedical Engineering Authors: Kartik M. Varadarajan, Rubash E. Harry, Todd Johnson, Guoan Li Tags: Reviews Source Type: journals

Review on aspects of artificial tactile feedback in laparoscopic surgeryEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article provides an overview of the technological aspects of ATF in laparoscopic surgery, gives background information on principles of human perception of related feedback information, and reviews current research attempts in the field of ATF systems in laparoscopic surgery, broken down into three main system components: tactile sensor, display, and data processing.Tactile sensors have been developed to measure tissue compliance, reveal hidden structures or foreign bodies in tissue through measurement of pressure distribution, and to identify and locate arteries by detecting their pulsation. Furthermore, different so...
Source: Medical Engineering and Physics - July 12, 2009 Category: Biomedical Engineering Authors: Sebastian Schostek, Marc O. Schurr, Gerhard F. Buess Tags: Reviews Source Type: journals