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Three-dimensional reconstruction and characterization of human external shapes from two-dimensional images using volumetric methods.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This work presents a volumetric approach to reconstruct and characterise 3D models of external anatomical structures from 2D images. Volumetric methods represent the final volume using a finite set of 3D geometric primitives, usually designed as voxels. Thus, from an image sequence acquired around the object to reconstruct, the images are calibrated and the 3D models of the referred object are built using different approaches of volumetric methods. The final goal is to analyse the accuracy of the obtained models when modifying some of the parameters of the considered volumetric methods, such as the type of voxel projec...
Source: Computer Methods in Biomechanics and Biomedical Engineering - October 19, 2009 Category: Biomedical Engineering Authors: Azevedo TC, Tavares JM, Vaz MA Tags: Comput Methods Biomech Biomed Engin Source Type: journals

CAD/CAM bilateral ear prostheses construction for Treacher Collins syndrome patients using laser scanning and rapid prototyping.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ear defects in patients affected by Treacher Collins syndrome necessitate the replacement of the existing anatomic residuals of the ears with custom-made prostheses. This paper describes a multidisciplinary protocol involving both medicine and computer-aided design/computer-aided manufacturing for manufacturing ear prostheses. Using innovative prototyping technologies together with conventional silicone processing procedures, a step-by-step procedure is presented. The complete workflow includes laser scanning of the defective regions of a patient's face, the use of 3D anatomic models from an ear digital library and rap...
Source: Computer Methods in Biomechanics and Biomedical Engineering - October 19, 2009 Category: Biomedical Engineering Authors: Ciocca L, De Crescenzio F, Fantini M, Scotti R Tags: Comput Methods Biomech Biomed Engin Source Type: journals

The evolution of an ideal stent design and its impact on the aortic endothelium during and after percutaneous replacement.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article describes the merits and demerits of various stent designs and details the specific reasons why a particular novel design is expected to be the most suitable implant during and after percutaneous aortic valve replacement. PMID: 19816835 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering)
Source: Computer Methods in Biomechanics and Biomedical Engineering - October 7, 2009 Category: Biomedical Engineering Authors: Praveen Kumar GV, Mathew L Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Method for the estimation of a double hinge kinematic model for the trapeziometacarpal joint using MR imaging.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper, we propose a method to estimate the parameters of a double hinge model of the trapeziometacarpal joint (TMC) by MRI-based motion analysis. The model includes two non-orthogonal and non-intersecting rotation axes accounting for flexion-extension (F-E) and adduction-abduction (A-A). We evaluated the quality of the estimated model parameters in the prediction of the relative motion of the first metacarpal bone with respect to the trapezium. As a result, we obtained that: (a) the estimated location and orientation of the F-E and A-A axes were in agreement with previous in vitro studies, (b) the motion of the...
Source: Computer Methods in Biomechanics and Biomedical Engineering - October 1, 2009 Category: Biomedical Engineering Authors: Cerveri P, De Momi E, Marchente M, Baud-Bovy G, Scifo P, Barros RM, Ferrigno G Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A new method for motion capture of the scapula using an optoelectronic tracking device: a feasibility study.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Optoelectronic tracking systems are rarely used in 3D studies examining shoulder movements including the scapula. Among the reasons is the important slippage of skin markers with respect to scapula. Methods using electromagnetic tracking devices are validated and frequently applied. Thus, the aim of this study was to develop a new method for in vivo optoelectronic scapular capture dealing with the accepted accuracy issues of validated methods. Eleven arm positions in three anatomical planes were examined using five subjects in static mode. The method was based on local optimisation, and recalculation procedures were ma...
Source: Computer Methods in Biomechanics and Biomedical Engineering - October 1, 2009 Category: Biomedical Engineering Authors: Senk M, Cheze L Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Design considerations for ceramic resurfaced femoral head: effect of interface characteristics on failure mechanisms.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ceramic hip resurfacing may offer improved wear resistance compared to metallic components. The study is aimed at investigating the effects of stiffer ceramic components on the stress/strain-related failure mechanisms in the resurfaced femur, using three-dimensional finite element models of intact and resurfaced femurs with varying stem-bone interface conditions. Tensile stresses in the cement varied between 1 and 5 MPa. Postoperatively, 20-85% strain shielding was observed inside the resurfaced head. The variability in stem-bone interface condition strongly influenced the stresses and strains generated within the resu...
Source: Computer Methods in Biomechanics and Biomedical Engineering - September 23, 2009 Category: Biomedical Engineering Authors: Pal B, Gupta S, New AM Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Inverse engineering of medical devices made of bioresorbable polymers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The degradation of medical devices made of bioresorbable polymers such as fixation devices in orthopaedic surgeries and scaffolds for tissue engineering can take from months to years. The trial and error approach of device development is therefore problematic and mathematical modelling of the biodegradation can help to accelerate the device development. This paper presents an inverse scheme to obtain the material parameters in a biodegradation model developed by Pan and his co-workers from existing experimental data of bioresorbable devices. The parameters can then be used to predict the degradation rate of new devices...
Source: Computer Methods in Biomechanics and Biomedical Engineering - September 20, 2009 Category: Biomedical Engineering Authors: Huang R, Pan J Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Parallel processing of ECG and blood pressure waveforms for detection of acute hypotensive episodes: a simulation study using a risk scoring model.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The aim of this study is to detect acute hypotensive episodes (AHE) and mean arterial pressure dropping regimes (MAPDRs) using electrocardiographic (ECG) signals and arterial blood pressure waveforms. To meet this end, the QRS complexes and end-systolic end-diastolic pulses are first extracted using two innovative modified Hilbert transform-based algorithms, namely ECGMHT and BPMHT. The resulting systolic and diastolic blood pressure pulses are then used to calculate the MAP trend. A new smoothing algorithm is developed, next based on piecewise polynomial fitting (PPF) to smooth the fast fluctuations observed in RR-tac...
Source: Computer Methods in Biomechanics and Biomedical Engineering - August 19, 2009 Category: Biomedical Engineering Authors: Ghaffari A, Homaeinezhad MR, Atarod M, Akraminia M Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Comparative analysis of bone remodelling models with respect to computerised tomography-based finite element models of bone.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Subject-specific finite element models are an extensively used tool for the numerical analysis of the biomechanical behaviour of human bones. However, bone modelling is not an easy task due to the complex behaviour of bone tissue, involving non-homogeneous and anisotropic mechanical properties. Moreover, bone is a living tissue and therefore its microstructure and mechanical properties evolve with time in a known process called bone remodelling. This phenomenon has been widely studied, many being the numerical models that have been formulated to predict density distribution and its evolution in several bones. The aim o...
Source: Computer Methods in Biomechanics and Biomedical Engineering - August 19, 2009 Category: Biomedical Engineering Authors: Perez MA, Fornells P, Doblare M, Garcia-Aznar JM Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A computationally efficient optimisation-based method for parameter identification of kinematically determinate and over-determinate biomechanical systems.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper introduces a general optimisation-based method for identification of biomechanically relevant parameters in kinematically determinate and over-determinate systems from a given motion. The method is designed to find a set of parameters that is constant over the time frame of interest as well as the time-varying system coordinates, and it is particularly relevant for biomechanical motion analysis where the system parameters can be difficult to accurately determine by direct measurements. Although the parameter identification problem results in a large-scale optimisation problem, we show that, due to a special ...
Source: Computer Methods in Biomechanics and Biomedical Engineering - August 18, 2009 Category: Biomedical Engineering Authors: Andersen MS, Damsgaard M, Macwilliams B, Rasmussen J Tags: Comput Methods Biomech Biomed Engin Source Type: journals

LES of additive and non-additive pulsatile flows in a model arterial stenosis.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Transition of additive and non-additive pulsatile flows through a simple 3D model of arterial stenosis is investigated by using a large eddy simulation (LES) technique. We find in both the pulsatile cases that the interaction of the two shear layers, one of which separates from the nose of the stenosis and the another one from its opposite wall, causes recirculation in the flow downstream of the stenosis where the nature of the transient flow becomes turbulent. The strength of this recirculation is found to be quite high from the non-additive pulsations when the flow Reynolds numbers, [image omitted] , for which both t...
Source: Computer Methods in Biomechanics and Biomedical Engineering - August 3, 2009 Category: Biomedical Engineering Authors: Molla MM, Paul MC, Roditi G Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A new method for improved standardisation in three-dimensional computed tomography cephalometry.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, a new approach is presented, in which landmarks are calculated after selection of the landmark region on a triangular model and in which the skull is automatically orientated in a standardised way. Two examiners each performed five analyses on three skull models. Landmark reproducibility was tested by calculating the standard deviation for each observer and the difference between the mean values of both observers. The variation can be limited to 0.1 mm for most landmarks. However, some landmarks perform less well and require further investigation. With the proposed reference system, a symmetrical orientation...
Source: Computer Methods in Biomechanics and Biomedical Engineering - August 3, 2009 Category: Biomedical Engineering Authors: Van Cauter S, Okkerse W, Brijs G, De Beule M, Braem M, Verhegghe B Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A pilot finite element study of an osteoporotic L1-vertebra compared to one with normal T-score.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper, two patient-specific finite element (FE) models of both an L1 vertebra with a normal T-score and a mildly wedging, osteoporotic one were created and analysed under usual action. Utilising commercial software packages for image processing and FE analysis (FEA) along with in house computer codes for a posteriori assignment of material properties, in vivo high-resolution spiral computed tomography of the entire vertebrae and FEA were combined. Using the vertebra with a normal T-score as baseline it was found that the maximum value of the von Mises stress in the osteoporotic vertebra was 60% higher but still...
Source: Computer Methods in Biomechanics and Biomedical Engineering - August 3, 2009 Category: Biomedical Engineering Authors: Provatidis C, Vossou C, Koukoulis I, Balanika A, Baltas C, Lyritis G Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A reliability measure of protein-protein interactions and a reliability measure-based search engine.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Many methods developed for estimating the reliability of protein-protein interactions are based on the topology of protein-protein interaction networks. This paper describes a new reliability measure for protein-protein interactions, which does not rely on the topology of protein interaction networks, but expresses biological information on functional roles, sub-cellular localisations and protein classes as a scoring schema. The new measure is useful for filtering many spurious interactions, as well as for estimating the reliability of protein interaction data. In particular, the reliability measure can be used to sear...
Source: Computer Methods in Biomechanics and Biomedical Engineering - August 3, 2009 Category: Biomedical Engineering Authors: Park B, Han K Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A review of algorithms for medical image segmentation and their applications to the female pelvic cavity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper aims to make a review on the current segmentation algorithms used for medical images. Algorithms are classified according to their principal methodologies, namely the ones based on thresholds, the ones based on clustering techniques and the ones based on deformable models. The last type is focused on due to the intensive investigations into the deformable models that have been done in the last few decades. Typical algorithms of each type are discussed and the main ideas, application fields, advantages and disadvantages of each type are summarised. Experiments that apply these algorithms to segment the organs...
Source: Computer Methods in Biomechanics and Biomedical Engineering - August 3, 2009 Category: Biomedical Engineering Authors: Ma Z, Tavares JM, Jorge RN, Mascarenhas T Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Aortic valve leaflet mechanical properties facilitate diastolic valve function.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This work was concerned with the numerical simulation of the behaviour of aortic valves whose material can be modelled as non-linear elastic anisotropic. Linear elastic models for the valve leaflets with parameters used in previous studies were compared with hyperelastic models, incorporating leaflet anisotropy with pronounced stiffness in the circumferential direction through a transverse isotropic model. The parameters for the hyperelastic models were obtained from fits to results of orthogonal uniaxial tensile tests on porcine aortic valve leaflets. The computational results indicated the significant impact of trans...
Source: Computer Methods in Biomechanics and Biomedical Engineering - August 3, 2009 Category: Biomedical Engineering Authors: Koch TM, Reddy BD, Zilla P, Franz T Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A finite element study of invariant-based orthotropic constitutive equations in the context of myocardial material parameter estimation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A previous study investigated a number of invariant-based orthotropic and transversely isotropic constitutive equations for their suitability to fit three-dimensional simple shear mechanics data of passive myocardial tissue. The study was based on the assumption of a homogeneous deformation. Here, we extend the previous study by performing an inverse finite element material parameter estimation. This ensures a more realistic deformation state and material parameter estimates. The constitutive relations were compared on the basis of (i) 'goodness of fit': how well they fit a set of six shear deformation tests and (ii) '...
Source: Computer Methods in Biomechanics and Biomedical Engineering - July 27, 2009 Category: Biomedical Engineering Authors: Schmid H, Wang W, Hunter PJ, Nash MP Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A finite volume method solution for the bidomain equations and their application to modelling cardiac ischaemia.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper presents an implementation of the finite volume method with the aim of studying subendocardial ischaemia during the ST segment. In this implementation, based on hexahedral finite volumes, each quadrilateral sub-face is split into two triangles to improve the accuracy of the numerical integration in complex geometries and when fibre rotation is included. The numerical method is validated against previously published solutions obtained from slab and cylindrical models of the left ventricle with subendocardial ischaemia and no fibre rotation. Epicardial potential distributions are then obtained for a half-ellip...
Source: Computer Methods in Biomechanics and Biomedical Engineering - July 27, 2009 Category: Biomedical Engineering Authors: Johnston PR Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Human cortical bone: the SiNuPrOs model. Part II - a multi-scale study of permeability.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This article proposes a new vision of the permeability based on a concept of multi-scale medium corresponding to the scales already introduced in the SiNuPrOs model which has been developed for cortical bone. According to this model, several architectural levels are proposed and a mathematical development based on the homogenisation theory, which can be applied to each of these levels, allows a numerical computation of the permeability tensor coefficients. A comparative analysis of our simulations and some experimental results (already published) shows a good accordance with the literature. PMID: 19639487 [PubMed - as ...
Source: Computer Methods in Biomechanics and Biomedical Engineering - July 27, 2009 Category: Biomedical Engineering Authors: Predoi-Racila M, Stroe MC, Crolet JM Tags: Comput Methods Biomech Biomed Engin Source Type: journals

New equations for the dose under pulsative/periodic conditions in the design of coated stents.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The notion of dose that comes from the biologists has been introduced by Delfour et al. (2005 SIAM J. Appl. Math. 65(3):858-881) in the context of coated stents to control restenosis. Assuming a stationary velocity profile of the blood flow in the lumen, it leads to a time-independent equation for the dose that considerably simplifies the analysis and the design problem. Under stable conditions the blood flow is pulsative, that is the velocity field can be assumed to be periodic. So it is necessary to justify the replacement of the periodic field by its time average over the pulsation period. In this paper, firstly we ...
Source: Computer Methods in Biomechanics and Biomedical Engineering - July 27, 2009 Category: Biomedical Engineering Authors: Delfour MC, Garon A Tags: Comput Methods Biomech Biomed Engin Source Type: journals

An object-oriented modelling framework for the arterial wall.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
An object-oriented modelling framework for the arterial wall is presented. The novelty of the framework is the possibility to generate customisable artery models, taking advantage of imaging technology. In our knowledge, this is the first object-oriented modelling framework for the arterial wall. Existing models do not allow close structural mapping with arterial microstructure as in the object-oriented framework. In the implemented model, passive behaviour of the arterial wall was considered and the tunica adventitia was the objective system. As verification, a model of an arterial segment was generated. In order to s...
Source: Computer Methods in Biomechanics and Biomedical Engineering - July 13, 2009 Category: Biomedical Engineering Authors: Balaguera MI, Briceno JC, Glazier JA Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Modal behaviour of bones during fracture.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A common cause of human disability is related to the fracture of bones, complex structural materials whose properties vary with time. An analytical study (using ANSYS, a commercial finite element package) of bones under fracture conditions is presented, focusing on the frequency variation versus depth of crack, as well as on the evolution of strength in the fracture area. PMID: 19603306 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering)
Source: Computer Methods in Biomechanics and Biomedical Engineering - July 13, 2009 Category: Biomedical Engineering Authors: Horta-Rangel J, Rivera AL, Castano VM Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A dynamic model of Nordic diagonal stride skiing, with a literature review of cross country skiing.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The forces during the kicking phase in Nordic diagonal stride skiing are described by differential equations and the results are compared with experiments. The difference between static and dynamic friction, interacting with characteristics of the skier such as weight, velocity and the kicking force's angle with the terrain, are essential for high-velocity diagonal striding. Analytical results for relationships between glide length, friction and kicking force are shown. Aerodynamic drag and gravity are accounted for. A propulsion force based on the Hill (1970) equation for muscle contraction velocity and activation is ...
Source: Computer Methods in Biomechanics and Biomedical Engineering - June 17, 2009 Category: Biomedical Engineering Authors: Moxnes JF, Hausken K Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Difference between palpation and optoelectronics recording of scapular motion.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The aim of this study is to determine the errors of scapular localisation due to skin relative to bone motion with an optoelectronic tracking system. We compared three-dimensional (3D) scapular positions obtained with skin markers to those obtained through palpation of three scapular anatomical landmarks. The scapular kinematics of nine subjects were collected. Static positions of the scapula were recorded with the right arm elevated at 0 degrees , 40 degrees , 80 degrees , 120 degrees and 160 degrees in the sagittal plane. Palpation and subsequent digitisation of anatomical landmarks on scapula and thorax were done at...
Source: Computer Methods in Biomechanics and Biomedical Engineering - June 17, 2009 Category: Biomedical Engineering Authors: Lempereur M, Brochard S, Burdin V, Remy-Neris O Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Quantifying nonlinear anisotropic elastic material properties of biological tissue by use of membrane inflation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Determination of material parameters for soft tissue frequently involves regression of material parameters for nonlinear, anisotropic constitutive models against experimental data from heterogeneous tests. Here, parameter estimation based on membrane inflation is considered. A four parameter nonlinear, anisotropic hyperelastic strain energy function was used to model the material, in which the parameters are cast in terms of key response features. The experiment was simulated using finite element (FE) analysis in order to predict the experimental measurements of pressure versus profile strain. Material parameter regres...
Source: Computer Methods in Biomechanics and Biomedical Engineering - May 31, 2009 Category: Biomedical Engineering Authors: Bischoff JE, Drexler ES, Slifka AJ, McCowan CN Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Characterisation of a pneumatic muscle test station with two dynamic plants in cascade.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Pneumatic muscle actuators (PMAs) offer significant advantages over more traditional actuators, which make them prime candidates in rehabilitation devices. A dynamic test station (DTS) is modified to demonstrate the use of a PMA for this application. The DTS includes two dynamic systems: a PMA and a DC servomotor. An overall transfer function was developed utilising characterisation data for the PMA and DC servomotor. A Tustin (bilinear) transform was performed on the overall transfer function to obtain a discrete time system. Model parameters were optimised and used to generate input voltage profiles that achieve isok...
Source: Computer Methods in Biomechanics and Biomedical Engineering - May 31, 2009 Category: Biomedical Engineering Authors: Serres JL, Reynolds DB, Phillips CA, Rogers DB, Repperger DW Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A computational tool for the probabilistic finite element analysis of an uncemented total hip replacement considering variability in bone-implant version angle.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In the present study, a probabilistic finite element tool was implemented to assess an uncemented total hip replacement including variability in bone-implant version angle. The Monte Carlo method was used with two different performance indicators: the bone maximum nodal von-Mises elastic strain and the bone volume (BV) percentage exceeding specified strain limits. Implant version, bone stiffness and load magnitude were the most sensitive parameters. The results were more consistent using percentage BV under specified limit strains as the performance indicator, even for a low number of simulations. The reliability of th...
Source: Computer Methods in Biomechanics and Biomedical Engineering - May 31, 2009 Category: Biomedical Engineering Authors: Dopico-Gonzalez C, New AM, Browne M Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Could passive knee laxity be related to active gait mechanics? An exploratory computational biomechanical study using probabilistic methods.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study demonstrates conceptually how probabilistic studies might further provide a framework to explore relationships not just within but between multiple different activities, e.g. intra-operative passive laxity drawer loading and post-operative active gait. Two implants were compared using simulated ISO-gait and passive laxity loading, with factors including mal-positioning and soft-tissue constraint varied using Monte-Carlo analysis. The results illustrate that correlations between different activities can be quantified; this demonstration study suggests further research is justified (with detailed clinically repres...
Source: Computer Methods in Biomechanics and Biomedical Engineering - May 5, 2009 Category: Biomedical Engineering Authors: Strickland MA, Browne M, Taylor M Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Application of MRI and biomedical engineering in speech production study.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Speech production has always been a subject of interest both at the morphological and acoustic levels. This knowledge is useful for a better understanding of all the involved mechanisms and for the construction of articulatory models. Magnetic resonance imaging (MRI) is a powerful technique that allows the study of the whole vocal tract, with good soft tissue contrast and resolution, and permits the calculation of area functions towards a better understanding of this mechanism. Thus, our aim is to demonstrate the value and application of MRI in speech production study and its relationship with engineering, namely with ...
Source: Computer Methods in Biomechanics and Biomedical Engineering - May 4, 2009 Category: Biomedical Engineering Authors: Ventura SR, Freitas DR, Tavares JM Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A novel approach to evaluate abdominal coactivities for optimal spinal stability and compression force in lifting.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A novel optimisation algorithm is developed to predict coactivity of abdominal muscles while accounting for both trunk stability via the lowest buckling load (P(cr)) and tissue loading via the axial compression (F(c)). A nonlinear multi-joint kinematics-driven model of the spine along with the response surface methodology are used to establish empirical expressions for P(cr) and F(c) as functions of abdominal muscle coactivities and external load magnitude during lifting in upright standing posture. A two-component objective function involving F(c) and P(cr) is defined. Due to opposite demands, abdominal coactivities t...
Source: Computer Methods in Biomechanics and Biomedical Engineering - April 30, 2009 Category: Biomedical Engineering Authors: El Ouaaid Z, Arjmand N, Shirazi-Adl A, Parnianpour M Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Ambulatory estimation of mean step length during unconstrained walking by means of COG accelerometry.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It has been reported that spatio-temporal gait parameters can be estimated using an accelerometer to calculate the vertical displacement of the body's centre of gravity. This method has the potential to produce realistic ambulatory estimations of those parameters during unconstrained walking. In this work, we want to evaluate the crude estimations of mean step length so obtained, for their possible application in the construction of an ambulatory walking distance measurement device. Two methods have been tested with a set of volunteers in 20 m excursions. Experimental results show that estimations of walking distance c...
Source: Computer Methods in Biomechanics and Biomedical Engineering - April 29, 2009 Category: Biomedical Engineering Authors: Gonzalez RC, Alvarez D, Lopez AM, Alvarez JC Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Adaptive computer control of anesthesia in humans.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper presents an efficient computer control technique for regulation of anesthesia in humans. The anesthetic used is propofol and the objective is to control the degree of hypnosis of the patient. The paper describes the basic hardware/software setup of the system and the closed-loop methodologies. The bispectral index (BIS) is considered as the feedback signal. The control methods proposed here are based in the use of proportional integral controllers with dead-time compensation to avoid undesirable oscillations in the BIS signal during the process. The compensation is based on the Smith predictor. To guarantee ...
Source: Computer Methods in Biomechanics and Biomedical Engineering - April 29, 2009 Category: Biomedical Engineering Authors: Mendez JA, Torres S, Reboso JA, Reboso H Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Efficient probabilistic representation of tibiofemoral soft tissue constraint.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objectives of this study were to develop an efficient probabilistic representation of knee ligamentous constraint using the advanced mean value (AMV) probabilistic approach, and to compare the AMV representation with the gold standard Monte Carlo (MC) approach. Specifically, the effects of inherent uncertainty in ligament stiffness, reference strain and attachment site locations on joint constraint were assessed. An explicit finite element model of the knee was evaluated under a series of anterior-posterior (AP) and internal-external (IE) loading at full extension and 90 degrees flexion. Distributions of AP and IE laxi...
Source: Computer Methods in Biomechanics and Biomedical Engineering - April 14, 2009 Category: Biomedical Engineering Authors: Baldwin MA, Laz PJ, Stowe JQ, Rullkoetter PJ Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Bone remodelling analysis of a bovine femur for a veterinary implant design.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The response of bovine bone to the presence of an implant is analysed with the aim of simulating bone remodelling in a developing model of a polymeric intramedullary interlocking nail for veterinary use. A 3-D finite element model of the femur diaphysis is built based on computed tomography images and using a CAD-based modelling pipeline. The bone remodelling process after the surgery is analysed and compared with the healthy bone. The remodelling law assumes that bone adapts to the mechanical environment. For the analyses a consistent set of loads is determined for the bovine walk cycle. The remodelling results reprod...
Source: Computer Methods in Biomechanics and Biomedical Engineering - April 8, 2009 Category: Biomedical Engineering Authors: Rodrigues LB, Lopes DS, Folgado J, Fernandes PR, Pires EB, Las Casas EB, Faleiros RR Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Electrocardiogram data mining based on frame classification by dynamic time warping matching.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper presents an electrocardiogram (ECG) data mining scheme based on the ECG frame classification realised by a dynamic time warping (DTW) matching technique, which has been used successfully in speech recognition. We use the DTW to classify ECG frames because ECG and speech signals have similar non-stationary characteristics. The DTW mapping function is obtained by searching the frame from its end to start. A threshold is setup for DTW matching residual either to classify an ECG frame or to add a new class. Classification and establishment of a template set are carried out simultaneously. A frame is classified i...
Source: Computer Methods in Biomechanics and Biomedical Engineering - April 8, 2009 Category: Biomedical Engineering Authors: Zhang G, Kinsner W, Huang B Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A systematic approach to feature tracking of lumbar spine vertebrae from fluoroscopic images using complex-valued wavelets.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This paper presents a systematic approach to lumbar spine vertebrae tracking in fluoroscopic images using complex-valued wavelets. The proposed algorithm is designed specifically based on a set of performance criteria associated with the detection and tracking of feature points in lumbar spine vertebrae from fluoroscopic images. The algorithm handles contrast and illumination non-homogeneities and noise in fluoroscopic images through the use of local phase information obtained using complex-valued wavelets. The algorithm is capable of tracking feature points that undergo various geometric deformations caused during the...
Source: Computer Methods in Biomechanics and Biomedical Engineering - April 7, 2009 Category: Biomedical Engineering Authors: Wong A, Dunk NM, Callaghan JP Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Influence of femoral stem geometry, material and extent of porous coating on bone ingrowth and atrophy in cementless total hip arthroplasty: an iterative finite element model.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This work presents a computational model for the concurrent study of bone remodelling and ingrowth around cementless femoral stems in total hip arthroplasty. It is assumed that biological fixation depends upon the magnitude of relative displacement at the bone-stem interface as well as an ongoing updating of interface conditions during the remodelling process. The remodelling model determines the distribution of bone density by producing the stiffest structure for a given set of biological conditions at the point of equilibrium in bone turnover. Changes in bone density and patterns of ingrowth are compared for differen...
Source: Computer Methods in Biomechanics and Biomedical Engineering - March 1, 2009 Category: Biomedical Engineering Authors: Folgado J, Fernandes PR, Jacobs CR, Pellegrini VD Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Finite element dynamic analysis of soft tissues using state-space model.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A finite element (FE) model is employed to investigate the dynamic response of soft tissues under external excitations, particularly corresponding to the case of harmonic motion imaging. A solid 3D mixed 'u-p' element S8P0 is implemented to capture the near-incompressibility inherent in soft tissues. Two important aspects in structural modelling of these tissues are studied; these are the influence of viscous damping on the dynamic response and, following FE-modelling, a developed state-space formulation that valuates the efficiency of several order reduction methods. It is illustrated that the order of the mathematica...
Source: Computer Methods in Biomechanics and Biomedical Engineering - March 1, 2009 Category: Biomedical Engineering Authors: Iorga LN, Shan B, Pelegri AA Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Pulsed magnetohydrodynamic blood flow in a rigid vessel under physiological pressure gradient.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Blood flow in a steady magnetic field has been of great interest over recent years. Many researchers have examined the effects of magnetic fields on velocity profiles and arterial pressure, and major studies have focused on steady or sinusoidal flows. In this paper, we present a solution for pulsed magnetohydrodynamic blood flow with a somewhat realistic physiological pressure wave obtained using a Windkessel lumped model. A pressure gradient is derived along a rigid vessel placed at the output of a compliant module which receives the ventricle outflow. Then, velocity profile and flow rate expressions are derived in th...
Source: Computer Methods in Biomechanics and Biomedical Engineering - February 25, 2009 Category: Biomedical Engineering Authors: Abi-Abdallah D, Drochon A, Robin V, Fokapu O Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Computer simulation of the effects of shoe cushioning on internal and external loading during running impacts.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we use a subject-specific computer simulation approach to estimate internal and external loading of the distal tibia during the impact phase for two runners when running in shoes with different midsole cushioning parameters. The results suggest that: (1) changes in tibial loading induced by footwear are not reflected by changes in ground reaction force (GRF) magnitudes; (2) the GRF loading rate is a better surrogate measure of tibial loading and stress fracture risk than the GRF magnitude; and (3) averaging results across groups may potentially mask differential responses to training interventions between in...
Source: Computer Methods in Biomechanics and Biomedical Engineering - February 19, 2009 Category: Biomedical Engineering Authors: Miller RH, Hamill J Tags: Comput Methods Biomech Biomed Engin Source Type: journals

The influence of aortic dimensions on calculated wall shear stress in the mouse aortic arch.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this paper, the influence of the aortic dimensions of an investigated mouse on its resulting wall shear stress (WSS) was studied. A numerical model of a mouse aortic arch was created based on a micro-CT scan of a vascular corrosion cast of an 8-week-old wild type mouse. This model was then rescaled to obtain five models with aortic root diameters corresponding to five different stages in the mouse life cycle varying from late fetal (0.7 mm) to old adult (1.5 mm). Consistent with literature, WSS values much higher than those normally encountered in humans were found. WSS was found to decrease rapidly in early life st...
Source: Computer Methods in Biomechanics and Biomedical Engineering - February 17, 2009 Category: Biomedical Engineering Authors: Trachet B, Swillens A, Van Loo D, Casteleyn C, De Paepe A, Loeys B, Segers P Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Stresses in cement mantles of hip replacements: effect of femoral implant sizes, body mass index and bone quality.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The effects of femoral prosthetic heads of diameters 22 and 28 mm were investigated on the stability of reconstructed hemi-pelves with cement mantles of thicknesses 1-4 mm and different bone qualities. Materialise medical imaging package and I-Deas finite element (FE) software were used to create accurate geometry of a hemi-pelvis from CT-scan images. Our FE results show an increase in cement mantle stresses associated with the larger femoral head. When a 22 mm femoral head is used on acetabulae of diameters 56 mm and above, the probability of survivorship can be increased by creating a cement mantle of at least 1 mm t...
Source: Computer Methods in Biomechanics and Biomedical Engineering - February 14, 2009 Category: Biomedical Engineering Authors: Lamvohee JM, Mootanah R, Ingle P, Cheah K, Dowell JK Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Modelling the early phases of bone regeneration around an endosseous oral implant.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of this study was to see whether a mathematical model of fracture healing was able to mimic bone formation around an unloaded screw-shaped titanium implant as it is well-believed that both processes exhibit many biological similarities. This model describes the spatio-temporal evolution of cellular activities, ranging from mesenchymal stem cell migration, proliferation, differentiation to bone formation, which are initiated and regulated by the growth factors present at the peri-implant site. For the simulations, a finite volume code was used and adequate initial and boundary conditions were applied. Two sets...
Source: Computer Methods in Biomechanics and Biomedical Engineering - February 9, 2009 Category: Biomedical Engineering Authors: Amor N, Geris L, Vander Sloten J, Van Oosterwyck H Tags: Comput Methods Biomech Biomed Engin Source Type: journals

On the implementation of a wrinkling, hyperelastic membrane model for skin and other materials.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
A number of researchers have studied the mechanical properties of skin and developed constitutive models to describe its behaviour. Typically, many of these studies have concentrated on the uniaxial tensile behaviour of the skin, on the grounds that it will wrinkle under in-plane compression and have minimal stiffness. However, although there is a substantial body of literature on wrinkling models, the practical implementation of such a model of skin in a finite element setting has not been widely addressed. This paper presents computational details of a wrinkling, hyperelastic membrane model and aspects of its impleme...
Source: Computer Methods in Biomechanics and Biomedical Engineering - February 9, 2009 Category: Biomedical Engineering Authors: Evans SL Tags: Comput Methods Biomech Biomed Engin Source Type: journals

A multi-objective evolutionary algorithm for protein structure prediction with immune operators.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Genetic algorithms (GA) are often well suited for optimisation problems involving several conflicting objectives. It is more suitable to model the protein structure prediction problem as a multi-objective optimisation problem since the potential energy functions used in the literature to evaluate the conformation of a protein are based on the calculations of two different interaction energies: local (bond atoms) and non-local (non-bond atoms) and experiments have shown that those types of interactions are in conflict, by using the potential energy function, Chemistry at Harvard Macromolecular Mechanics. In this paper, ...
Source: Computer Methods in Biomechanics and Biomedical Engineering - January 26, 2009 Category: Biomedical Engineering Authors: Judy MV, Ravichandran KS, Murugesan K Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Improving the damage accumulation in a biomechanical bone remodelling model.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We extend, reformulate and analyse a phenomenological model for bone remodelling. The original macrobiomechanical model (MBM), proposed by Hazelwood et al. [J Biomech 2001; 34:299-308], couples a population equation for the cellular activities of the basic multicellular units (BMUs) in the bone and a rate equation to account for microdamage and repair. We propose to account for bone failure under severe overstressing by incorporating a Paris-like power-law damage accumulation term. The extended model agrees with the Hazelwood et al. predictions when the bone is under-stressed, and allows for suitably loaded bones to fa...
Source: Computer Methods in Biomechanics and Biomedical Engineering - December 17, 2008 Category: Biomedical Engineering Authors: Restrepo JM, Choksi R, Hyman JM, Jiang Y Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Myocardial material parameter estimation: a comparison of invariant based orthotropic constitutive equations.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study investigated a number of invariant based orthotropic and transversely isotropic constitutive equations for their suitability to fit three-dimensional simple shear mechanics data of passive myocardial tissue. A number of orthotropic laws based on Green strain components and one microstructurally based law have previously been investigated to fit experimental measurements of stress-strain behaviour. Here we extend this investigation to include several recently proposed functional forms, i.e. invariant based orthotropic and transversely isotropic constitutive relations. These laws were compared on the basis of (i) ...
Source: Computer Methods in Biomechanics and Biomedical Engineering - December 16, 2008 Category: Biomedical Engineering Authors: Schmid H, Wang YK, Ashton J, Ehret AE, Krittian SB, Nash MP, Hunter PJ Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Biomechanical evaluation of porous biodegradable scaffolds for revision knee arthroplasty.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study suggests that biodegradable bone scaffolds could be used to fill bone defects in revision knee arthroplasty, but scaffold size seems to be the limiting factor. PMID: 19089683 [PubMed - as supplied by publisher] (Source: Computer Methods in Biomechanics and Biomedical Engineering)
Source: Computer Methods in Biomechanics and Biomedical Engineering - December 16, 2008 Category: Biomedical Engineering Authors: Terrier A, Sedighi-Gilani M, Roshan Ghias A, Aschwanden L, Pioletti DP Tags: Comput Methods Biomech Biomed Engin Source Type: journals

XXXIII Congress of the Societe de Biomécanique, Compiègne, France, 1-3 September 2008.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
XXXIII Congress of the Societe de Biomécanique, Compiègne, France, 1-3 September 2008. Comput Methods Biomech Biomed Engin. 2008;11 Suppl 1:1-227 Authors: PMID: 18665475 [PubMed - in process] (Source: Computer Methods in Biomechanics and Biomedical Engineering)
Source: Computer Methods in Biomechanics and Biomedical Engineering - December 3, 2008 Category: Biomedical Engineering Tags: Comput Methods Biomech Biomed Engin Source Type: journals

Computer methods in biomechanics and biomedical engineering acceptance in the Science Citation Index Expanded!Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 18979301 [PubMed - in process] (Source: Computer Methods in Biomechanics and Biomedical Engineering)
Source: Computer Methods in Biomechanics and Biomedical Engineering - November 4, 2008 Category: Biomedical Engineering Authors: Morris L Tags: Comput Methods Biomech Biomed Engin Source Type: journals