論文 - 高野　直樹

Irregular Iocation of Major Pectoral Muscle Can Be A Causativ Factor of Pectus Excavatum

高野 直樹

Medical Hypotheses 82 （ 5 ） 512 - 517 2014年05月

研究論文（学術雑誌）, 共著, 査読有り

Irregular location of major pectoral muscle can be a causative factor of pectus excavatum

Nagasao T., Shimizu Y., Morotomi T., Takano N., Jiang H., Kishi K.

Medical Hypotheses （Medical Hypotheses）  82 （ 5 ） 512 - 517 2014年05月

ISSN  03069877

　概要を見る

Pectus excavatum-commonly known as funnel chest-is one of the most frequently observed congenital deformities, in which the patients' thoraces present concavity. This paper presents our original hypothesis that the abnormal positioning of the major pectoral muscle can be a potential factor in the occurrence of pectus excavatum, and evaluates the validity of the hypothesis by performing an anatomical and a biomechanical study. An anatomical study on clinical cases revealed that the major pectoral muscle tends to be positioned more superiorly in pectus excavatum patients than in normal persons. The biomechanical study, using three-dimensional finite element dynamic simulation, revealed that the major pectoral muscle functions to elevate the sternum and that the elevating effect is reduced when the muscle is located at superior regions on the thoracic wall. These findings support our hypothesis that the abnormal position of the major pectoral muscle is a potential causative factor for pectus excavatum. This hypothesis suggests that, during surgical correction of pectus excavatum with an open approach, surgeons should reposition the major pectoral muscle to its correct anatomical position to avoid recurrence. © 2014 .

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Classification and Visualization of Primary Trabecular Bone in Lumbar Vertebrae

高野 直樹

Advances in Biomechanics and Applications 1 （ 2 ） 111 - 126 2014年04月

研究論文（学術雑誌）, 共著, 査読有り

Estimation of apparent elastic moduli of trabecular bone considering biological apatite (BAp) crystallite orientation in tissue modulus

高野 直樹

Advanced Materials Research （Advanced Materials Research）  894   167-171 - 171 2014年03月

研究論文（学術雑誌）, 共著,  ISSN  9783038350323

　概要を見る

This study presents a prediction of apparent elastic moduli of vertebral trabecular bone using the homogenization method. A micro-finite element (FE) model of trabecular bone was reconstructed from a sequential of cross-section micro-CT image by converting bone voxels to brick elements. Eight regions of interest (ROIs) were extracted from two lumbar vertebra bone specimens of healthy and osteoporotic. The homogenization method and finite element method was employed to analyze the microscopic trabecular bone. Bone tissue property was modeled as orthotropy material considering the biological apatite (BAp) crystallite orientation. This research focuses on the effect of morphological difference between healthy and osteoporotic bones to the apparent elastic moduli. The change of degree of anisotropy was also discussed. Comparison of the calculated Young's moduli in vertical axis with Keyak et al.'s experimental result showed good agreement and proved the reliability of the numerical model. © (2014) Trans Tech Publications, Switzerland.

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Practical Monte Carlo simulation method highlighting on tail probability with application to biomechanics analysis of pressure ulcer

高野 直樹

Transactions of the Japan Society for Computational Engineering and Science （Transactions of the Japan Society for Computational Engineering and Science）  2014 （ 2014 ） Paper No.20140001 2014年02月

研究論文（学術雑誌）, 共著, 査読有り

　概要を見る

The Monte Carlo method is a well-known method for calculating uncertainty, but it has the disadvantage of high computational cost because it usually requires 10,000 sampling points. In this paper, a practical sampling algorithm named Stepwise Limited Sampling (SLS) is proposed to obtain both accurate expected values and very accurate tail probability values in the Monte Carlo simulation. This method was then applied to a biomechanics problem concerning the risk prediction of pressure ulcers. It is known that the initial damage that leads to a fatal stage of pressure ulcer occurs in deep muscle, but its location has not been clarified. By modeling assumed damage at the bone-muscle interface in the human buttock as a cutout, and by judging whether the damage propagates or not, sets of material properties of muscle and fat in the tail probability that result in high interface shear strain were obtained as a function of body positioning during nursing. © 2014 by the Japan Society for Computational Engineering and Science.

Association between the peri-implant bone structure and stress distribution around the mandibular canal: A three-dimensional finite element analysis

高野 直樹

Dental Materials Journal （Dental Materials Journal）  32 （ 4 ） 637-642 - 642 2013年08月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  02874547

　概要を見る

The aim of this study was to elucidate the association between the bone structure at implant insertion sites and stress distribution around the mandibular canal by means of three-dimensional finite element (3D FE) analysis. Four FE models were created with slice data using micro-computed tomography (micro-CT), and 3D FE analysis was performed. Mechanical analysis showed that the load reached the mandibular canal via the trabecular structure in all FE models. High levels of stress were generated around the mandibular canal when the distance between the mandibular canal and the implant decreased. High stress levels were also observed when cortical bone thickness and bone volume/total volume (BV/TV) were low. Our findings suggest that load is transmitted to the mandibular canal regardless of differences in the thickness of cortical bone or cancellous bone structure, but excessive load may be generated in bone with thin cortical and coarse cancellous structures.

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Consideration of Shear Modulus in Biomechanicl Analysis of Peri-implant Jaw Bone: Accuracy Verification using Image- based Multi-scale Simulation

高野 直樹

Dental Materials Journal 32 （ 3 ） 425-432 2013年08月

研究論文（学術雑誌）, 共著, 査読有り

Transformation of Keloids is Determinel by Stress Occurrence Patterns on Peri-keloid Regions in Response to Body Movement

高野 直樹

Medical Hypotheses 81 （ 1 ） 136-141 2013年07月

研究論文（学術雑誌）, 共著, 査読有り

Transformation of keloids is determined by stress occurrence patterns on peri-keloid regions in response to body movement

Nagasao T., Aramaki-Hattori N., Shimizu Y., Yoshitatsu S., Takano N., Kishi K.

Medical Hypotheses （Medical Hypotheses）  81 （ 1 ） 136 - 141 2013年07月

ISSN  03069877

　概要を見る

Keloids gradually change their shapes as they grow. We hypothesize that the change of keloid morphology reflects the incremental change of the stress patterns occurring in peri-keloid regions due to movement of the keloid-carrying body part. To examine the validity of this hypothesis, we used three-dimensional finite element analysis to calculate the stresses occurring in the peri-keloid regions of keloids on the chest in response to respiratory movement. The stresses concentrate at the peri-keloid regions close to the bilateral ends of the keloids. By reviewing this result in reference to our hypothesis, we can explain why keloids on the chest are likely to present crab or butterfly shapes. Although we know that keloids grow in response to mechanical stresses, our hypothesis differs from existing ones in that it focuses on morphological transformation. Our hypothesis is helpful for physicians in performing treatment for keloids, because they can predict what part of a keloid is likely to grow and perform preventive treatment in reference to the hypothesis. © 2013 Elsevier Ltd.

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Consideration of shear modulus in biomechanical analysis of peri-implant jaw bone: Accuracy verification using image-based multi-scale simulation

Matsunaga S., Naito H., Tamatsu Y., Takano N., Abe S., Ide Y.

Dental Materials Journal （Dental Materials Journal）  32 （ 3 ） 425 - 432 2013年05月

ISSN  02874547

　概要を見る

The aim of this study was to clarify the infuence of shear modulus on the analytical accuracy in peri-implant jaw bone simulation. A 3D fnite element (FE) model was prepared based on micro-CT data obtained from images of a jawbone containing implants. A precise model that closely reproduced the trabecular architecture, and equivalent models that gave shear modulus values taking the trabecular architecture into account, were prepared. Displacement norms during loading were calculated, and the displacement error was evaluated. The model that gave shear modulus values taking the trabecular architecture into account showed an analytical error of around 10-20% in the cancellous bone region, while in the model that used incorrect shear modulus, the analytical error exceeded 40% in certain regions. The shear modulus should be evaluated precisely in addition to the Young modulus when considering the mechanics of peri-implant trabecular bone structure.

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Relationship between locations of rib defects and loss of respiratory function-A biomechanical study

高野 直樹

Thoracic and Cardiovascular Surgeon （Thoracic and Cardiovascular Surgeon）  62 （ 4 ） DOI:10.1055/s-0033-1338107 - 362 2013年04月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  01716425

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Objective The present study elucidates the relationship between the locations of rib defects and loss of respiratory function. Methods Ten sets of three-dimensional finite element models were produced from computed tomography data of 10 persons and categorized as normal type models. These models were modified by removing part of the ribs, and the resultant models were categorized as defect type models. Varying the location of the defects, six types of defect model were produced from each of the 10 normal models; the defects were made on the anterior-superior, anterior-inferior, lateral-superior, lateral-inferior, posterior-superior, and posterior-inferior regions of the thorax. To simulate respiration, contracture forces were applied to nonlinear springs modeling respiratory muscles for each of the normal and defect models. Difference in volume of the thoracic cavity between inspiration and expiration phases was viewed as the indicator of respiratory function and was defined as ΔV. The values of ΔV were compared between normal type models and their corresponding defect type models. Results Among the six types of defect, the degree of functional loss was greatest with those defects on the lateral-inferior part of the thorax, where ΔV of the affected side hemithorax drops to 38 to 45% of normal values, whereas ΔV was 62 to 88% with other defect models. Conclusion Thoraces that have defects on their lateral-inferior regions present lower respiratory functioning than thoraces with other defect locations. Hence, in treating clinical cases where defects are expected to occur in this region, effort should be made to minimize the area of the defect. © 2014 Georg Thieme Verlag KG Stuttgart New York.

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Uncertainty modeling in the prediction of effective mechanical properties using stochastic homogenization method with application to porous trabecular bone

高野 直樹

Materials Transactions （Materials Transactions）  54 （ 8 ） 1250-1256 - 1256 2013年04月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  13459678

　概要を見る

A systematic modeling of uncertainty due to image processing, material characteristics and experimental works was developed in order to propose a novel stochastic image-based multi-scale method for heterogeneous media. The effective mechanical properties with application to three porous trabecular bone models were predicted by introducing the correction factor (β) to represent the miscellaneous errors or unknown factors. Finally, the probability density was obtained for the effective mechanical properties, which could evaluate the reliability of scattered experimental results. It has been concluded that variation in effective properties of heterogeneous media can be predicted even when only limited measured values are available by using the present extrapolation technique based on verified simulation results. © 2013 The Japan Institute of Metals and Materials.

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Stochastic multi-scale prediction on the apparent elastic moduli of trabecular bone considering uncertainties of biological apatite (BAp) crystallite orientation and image-based modelling

Khairul Salleh Basaruddin, Naoki Takano and Takayoshi Nakano

Computer Methods in Biomechanics and Biomedical Engineering （Computer Methods in Biomechanics and Biomedical Engineering）  18 （ 2 ） DOI:10.1080/10255842.2013.785537 - 174 2013年04月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  10255842

　概要を見る

© 2013 Taylor & Francis. An assessment of the mechanical properties of trabecular bone is important in determining the fracture risk of human bones. Many uncertainty factors contribute to the dispersion of the estimated mechanical properties of trabecular bone. This study was undertaken in order to propose a computational scheme that will be able to predict the effective apparent elastic moduli of trabecular bone considering the uncertainties that are primarily caused by image-based modelling and trabecular stiffness orientation. The effect of image-based modelling which focused on the connectivity was also investigated. A stochastic multi-scale method using a first-order perturbation-based and asymptotic homogenisation theory was applied to formulate the stochastically apparent elastic properties of trabecular bone. The effective apparent elastic modulus was predicted with the introduction of a coefficient factor to represent the variation of bone characteristics due to inter-individual differences. The mean value of the predicted effective apparent Young's modulus in principal axis was found at approximately 460 MPa for respective 15.24% of bone volume fraction, and this is in good agreement with other experimental results. The proposed method may provide a reference for the reliable evaluation of the prediction of the apparent elastic properties of trabecular bone.

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Stochastic modeling and analysis of porous media using first-order perturbation-based homogenization method

Basaruddin K., Takano N.

ECCOMAS 2012 - European Congress on Computational Methods in Applied Sciences and Engineering, e-Book Full Papers （ECCOMAS 2012 - European Congress on Computational Methods in Applied Sciences and Engineering, e-Book Full Papers）     621 - 630 2012年12月

ISSN  9783950353709

　概要を見る

A stochastic analysis of multi-scale problem in porous media was introduced in this paper to determine the variation of macroscopic homogenized properties considering uncertainties at microscopic level. By assuming the small fluctuation that arises in microscopic properties was distributed in Gaussian normal distribution, the macroscopic homogenized properties has been formulated in stochastic manner using first-order perturbation-based. The merit of this method lies in the ability to consider other uncertainties instead of microscopic properties due to random microstructure variations. Hence, the proposed stochastic homogenization method was established by adding two demonstrative problems that commonly occur in engineering materials. First, the fluctuation of Young's modulus in adhesive of two-phase materials was considered to demonstrate a simple numerical model that can predict the dispersion of macroscopic properties. Next, the variation in microscopic properties was combined with misalignment of stacked plate microstructure to investigate the effects on macroscopic properties of corrugated-core. The results showed that the misaligned position in some distances increased the macroscopic properties but by taking the probability function on misalignment reduced that. It proved that the significance of this study in design and fabrication of porous media considering random variation of microstructure.

Biomechanics Analysis of Pressure Ulcer Using Damaged Interface Model between Bone and Muscle in the Human Buttock

高野 直樹

Journal of Computational Science and Technology 6 （ 2 ） 70-80 2012年06月

研究論文（学術雑誌）, 共著

Morphology analysis of vertebral trabecular bone under dynamic loading based on multi-scale theory

高野 直樹

Medical and Biological Engineering and Computing （Medical and Biological Engineering and Computing）  50 （ 10 ） 1091-1103 - 1103 2012年

研究論文（学術雑誌）, 共著,  ISSN  01400118

　概要を見る

Trabecular bone has a complicated porous microstructure and consists of interconnected plates and rods known as trabeculae. The microarchitecture of the trabeculae contributes to load distribution capacity and, particularly, the optimal bone strength. Many previous studies have shown that morphological parameters are used to characterize the microarchitecture of trabecular bone, but little is known about the mechanical role of trabecular morphology in the context of load-bearing behavior. Therefore, this study proposes a new segmentation method for examining the morphology of trabecular structure foci of load-bearing capability. A micro-finite element model of trabecular bone was obtained from the fourth lumbar vertebra on the basis of a three-dimensionally reconstructed micro-computed tomography (CT) image. We used an asymptotic homogenization method to determine microscopic stress by applying three unidirectional compressive loads in the vertical, anteroposterior, and right-left axes of two trabecular bone volumes. We then classified the complicated trabecular microstructure into three segments: primary and secondary trabeculae and trabeculae of no contribution. Next, a dynamic analysis was conducted by applying a force impulse load. The result indicated that 1/3 of the trabecular volume functions as primary trabecula. The morphology of the trabecular network could be visualized successfully highlighting the percolation of the stress wave in the primary trabecular segment. Further, we found that the role of the plate-like structures was that of a hub in the trabecular network system. © International Federation for Medical and Biological Engineering 2012.

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Monte Carlo Simulation of Dynamic Problem Using Model Order Reduction Technique Highlighting on Tail Probability

高野 直樹

Journal of Computational Science and Technology 6 （ 3 ） 169-181 2012年

研究論文（学術雑誌）, 共著

Calibration of Wet Etching Parameters for Sacrifice Layer of MEMS

高野 直樹

Journal of Computational Science and Technology 5 （ 3 ） 106-119 2011年10月

研究論文（学術雑誌）, 共著

Numerical study on the morphology and mechanical role of healthy and osteoporotic vertebral trabecular bone

高野 直樹

Journal of Biomechanical Science and Engineering （Journal of Biomechanical Science and Engineering）  6 （ 4 ） 270-285 - 285 2011年09月

研究論文（学術雑誌）, 共著,  ISSN  18809863

　概要を見る

This study presents a numerical methodology to clarify the morphology of complex trabecular network architecture in human lumbar vertebra by means of the new post-processing technique for calculated microscopic stress by the homogenization method. Micro-CT image-based modeling technique is used and careful but intuitive and easy-to-use method for microstructure model, in other words region of interest (ROI), is also presented. The macroscopic homogenized properties that include not only the Young's moduli but also shear moduli could explain the difference of morphology between healthy and osteoporotic bones. This paper focuses on the change of degree of anisotropy. Then, the microscopic stress under three basis load cases was analyzed. In this analysis, the homogenization method has a merit in the computational cost. The trabeculae are classified into eight groups from the viewpoint of load bearing function against three loading conditions in the proposed post-processing of numerical results. It contributes to the understanding of the mechanical role of trabecular bone in vertebra. The primary trabecular bone that has been supposed to support the self-weight and secondary bone that connects the primary bone are successfully visualized. The discussion on the mechanical role of plate-like trabecular bone in the load path network system is also highlighted. © 2011 by JSME.

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Formation of polymer microneedle arrays using soft lithography

Yoshimichi Ami, Hiroto Tachikawa, Naoki Takano and Norihisa Miki

Journal of Micro/Nanolithography, MEMS, and MOEMS （Journal of Micro/Nanolithography, MEMS, and MOEMS）  10 （ 1 ） 011503/1-6 2011年03月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  19325150

　概要を見る

We demonstrate the fabrication of polymer microneedle arrays using soft lithography. A photomask was designed to use Fresnel diffraction of UV light to create sharp, tapered hollows in SU-8, a negative photoresist, after development. Polymer microneedles were formed using these SU-8 structures as a mold. These polymer needles may be applicable as flexible electrodes in brain-machine interfaces because they are more likely to survive movement of the skin than conventional brittle silicon needles. Similar needles, made from medicinal substances, could be used for transdermal drug administration. For these applications, the needles must be long, sharp, and stiff enough to penetrate the stratum corneum (∼20 m in thickness) and reach the viable epidermis (200-300 m in thickness), but must not reach the dermis, which contains sensitive nerve endings. We successfully manufactured 2020 microneedle arrays of polydimethylsiloxane with a needle length of 200 m. We experimentally verified that these manufactured electrodes successfully penetrated the stratum corneum of a cultured skin. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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