Faculty Profiles - KOBAYASHI Koichi

DRR画像を用いた二次元画像上の大腿骨・脛骨間の回旋評価法の精度検証

In Vivo Strain Ultrasound Elastographic Assessment of the Stiffness of the Medial Collateral Ligament at Varying Knee Flexion Angles

SAKAMOTO Makoto, WADUGODAPITIYAI Surangika, MORISE Yusuke, TANAKA Masaei, KOBAYASHI Koichi

The Proceedings of Mechanical Engineering Congress, Japan 2019 J02513 2019

森隆裕, 古賀良生, 小林公一, 古賀寛, 望月友晴, 勝見亮太, 大森豪, PRAMUDITA Jonas Aditya, 田邊裕治

臨床バイオメカニクス 39 125‐129 - 129 2018.10

コーンビームCTによる前歯部の三次元自動歯軸および歯列決定法

坂本信, 坂上勇太, 森清友亮, 亀田剛, 小林公一, 坂井幸子, 遠藤英昭

臨床バイオメカニクス 39 207‐216 - 216 2018.10

核磁気共鳴画像法を用いた母指指節間関節および中手指節関節の三次元生体内接触運動解析

杉田魁人, 坂本信, 森清友亮, 風間清子, 小林公一, 田邊裕治

臨床バイオメカニクス 39 237‐246 - 246 2018.10

骨盤姿勢を考慮した三次元下肢アライメント評価の精度検証

五十嵐良樹, 佐藤卓, 小林公一, 田邊裕治, PRAMUDITA Jonas Aditya

臨床バイオメカニクス 39 149‐152 2018.10

大腿脛骨軟骨間の接触動態と相対滑り量の検討

中原大輔, 小林公一, 坂本信, 佐藤卓, 渡邉聡, 大森豪, 古賀良生, PRAMUDITA Jonas Aditya, 田邊裕治

臨床バイオメカニクス 39 299‐303 2018.10

二方向スロットラジオグラフィを用いた自動イメージマッチング法の開発

岡庭大祐, 中原大輔, 小林公一, 坂本信, 田邊裕治, PRAMUDITA Jonas, Aditya, 佐藤卓, 大森豪, 湊泉, 古賀良生

臨床バイオメカニクス 39 143‐148 2018.10

Analytical solution of axisymmetric indentation of an elastic layer-substrate body Reviewed

Kotaro MIURA, Makoto SAKAMOTO, Koichi KOBAYASHI, Jonas A, PRAMUDITA, Yuji TANABE

Theretical and Applied Mechanics 67 81 - 101 2018.10

Language：English Publishing type：Research paper (scientific journal) Publisher：National Committee for IUTAM

We focus on an elastic contact problem for indentation of a layer-substrate body. An elastic layer assumed to be perfectly bonded to an elastic semi-infinite substrate. The elastic layer is smoothly indented with a flat-ended cylindrical indenter and a spherical indenter. The analytical and exact solutions are obtained by solving an infinite system of simultaneous equations using the method to express a normal contact stress at the upper surface of the elastic layer as an appropriate series. This paper presents not only the axial load but also the distribution of the dimensionless normal contact stress under cylindrical and spherical indentation, the distribution of the dimensionless normal displacement at the upper surface of the elastic layer and the stress singularity factor. Numerical results are given for several combinations of the ratio of shear modulus and Poisson’s ratios of the elastic layer and substrate, and the thickness of the elastic layer.

DOI： 10.11345/nctam.64.81

Correlation between posterior tibial slope and sagittal alignment under weight-bearing conditions in osteoarthritic knees Reviewed International journal

Mochizuki Tomoharu, Tanifuji Osamu, Koga Yoshio, Sato Takashi, Kobayashi Koichi, Watanabe Satoshi, Fujii Toshihide, Yamagiwa Hiroshi, Katsumi Ryota, Koga Hiroshi, Omori Go, Endo Naoto

PLOS ONE 13 ( 9 ) e0202488 2018.9

Language：English Publishing type：Research paper (scientific journal)

INTRODUCTION: Posterior tibial slope (PTS) and sagittal alignment are important factors in the etiology of knee osteoarthritis and knee surgery. Clinically, sagittal alignment, which indicates flexion contracture of the knee, contributes to knee function in weight-bearing (WB) conditions. PTS and sagittal alignment under WB conditions in varus osteoarthritic knees are presumed to affect each other, but their association remains unclear. In this study, we aimed to clarify the association. MATERIAL AND METHODS: In total, 140 osteoarthritic varus knees were investigated. Under WB conditions, a three-dimensional (3D) alignment assessment system was applied via biplanar long-leg X-rays, using 3D-to-2D image registration technique. The evaluation parameters were as follows: 1) 3D mechanical flexion angle (3DMFA) in regards to sagittal alignment, 2) passing point in the WB line (PP), and 3) medial and lateral PTS. RESULTS: The medial and lateral PTS showed a positive correlation with 3DMFA and PP, respectively (medial PTS-3DMFA, p = 0.001; medial PTS-PP, p < 0.0001; lateral PTS-3DMFA, p < 0.0001; lateral PTS-PP, p = 0.002). The flexion contracture group with 3DMFA >5° demonstrated greater PTS than non-flexion contracture group (medial PTS, p = 0.006; lateral PTS, p = 0.006). CONCLUSIONS: Both medial and lateral PTS were correlated with sagittal alignment under WB conditions and were larger in the flexion contracture group. This finding can explain the function to take the load articular surface parallel to the ground for holding the balance in WB conditions in the sagittal plane for osteoarthritic knees. Moreover, surgeons may be required to decrease the PTS during knee arthroplasty to restore full extension in knees of patients with fixed flexion contracture.

DOI： 10.1371/journal.pone.0202488

Web of Science

脛骨近位内側関節面傾斜の健常者と進行期変形性膝関節症患者の三次元評価―臥位と立位での変化―

望月友晴, 谷藤理, 古賀良生, 森隆裕, 佐藤卓, 渡辺聡, 大森豪, 小林公一, 西野勝敏, 田邊裕治, 遠藤直人

日本整形外科学会雑誌 92 ( 8 ) S2016 - S2016 2018.8

Analysis of in vivo static contact surface motion of thumb interphalangeal joint Reviewed

Yusuke MORISE, Makoto SAKAMOTO, Kaito SUGITA, Kiyoko KAZAMA, Koichi KOBAYASHI, Yuji TANABE

Advenced Experimental Mechanics 3 209 - 214 2018.8

Contribution of sex and body constitution to three-dimensional lower extremity alignment for healthy, elderly, non-obese humans in a Japanese population. Reviewed International journal

Katsumi R, Mochizuki T, Sato T, Kobayashi K, Watanabe S, Tanifuji O, Endo N

Journal of experimental orthopaedics 5 ( 1 ) 32 - 32 2018.8

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Humans support their bodies exclusively by vertical balance in bipedal locomotion, and the body, especially the lower extremity, generally changes with age. Sex and body constitution are assumed to be associated with lower extremity alignment, but this association remains to be elucidated. This study sought to clarify this association in healthy, elderly, non-obese humans in a Japanese population. METHODS: The present study investigated 55 healthy volunteers (mean age: 70 ± 6 years). A 3D extremity alignment system was applied under weight-bearing conditions on biplane long lower extremities X-rays using a 3D-to-2D image registration technique. The evaluation parameters included 3D hip-knee-ankle angle (3DHKA) alignment in the coronal (coronal alignment) and sagittal planes (sagittal alignment) and rotational alignment between the femur and tibia. The influences of sex and body constitution on all the alignment were analyzed. RESULTS: Multiple linear regression analysis with the dependent variable of each alignment showed that sex was the dominant factor for coronal and rotational alignment (coronal: p < 0.01; rotational: p < 0.01), and body weight was the dominant factor for sagittal alignment (p < 0.01). CONCLUSIONS: The association of sex with coronal and rotational alignment and of body constitution with sagittal alignment were proved in healthy, elderly, non-obese humans in a Japanese population. This finding can lead to further understanding of the etiology of many diseases and age-related changes.

DOI： 10.1186/s40634-018-0147-3

Extrinsic Factors as Component Positions to Bone and Intrinsic Factors Affecting Postoperative Rotational Limb Alignment in Total Knee Arthroplasty Reviewed

Tomoharu Mochizuki, Takashi Sato, Osamu Tanifuji, Satoshi Watanabe, Koichi Kobayashi, Naoto Endo

Journal of Arthroplasty 33 ( 7 ) 2100 - 2110 2018.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Churchill Livingstone Inc.

Background: This study aimed to identify the factors affecting postoperative rotational limb alignment of the tibia relative to the femur. We hypothesized that not only component positions but also several intrinsic factors were associated with postoperative rotational limb alignment. Methods: This study included 99 knees (90 women and 9 men) with a mean age of 77 ± 6 years. A three-dimensional (3D) assessment system was applied under weight-bearing conditions to biplanar long-leg radiographs using 3D-to-2D image registration technique. The evaluation parameters were (1) component position
(2) preoperative and postoperative coronal, sagittal, and rotational limb alignment
(3) preoperative bony deformity, including femoral torsion, condylar twist angle, and tibial torsion
and (4) preoperative and postoperative range of motion (ROM). Results: In multiple linear regression analysis using a stepwise procedure, postoperative rotational limb alignment was associated with the following: (1) rotation of the component position (tibia: β = 0.371, P &lt
.0001
femur: β = −0.327, P &lt
.0001), (2) preoperative rotational limb alignment (β = 0.253, P =.001), (3) postoperative flexion angle (β = 0.195, P =.007), and (4) tibial torsion (β = 0.193, P =.010). Conclusion: In addition to component positions, the intrinsic factors, such as preoperative rotational limb alignment, ROM, and tibial torsion, affected postoperative rotational limb alignment. On a premise of correct component positions, the intrinsic factors that can be controlled by surgeons should be taken care. In particular, ROM is necessary to be improved within the possible range to acquire better postoperative rotational limb alignment.

DOI： 10.1016/j.arth.2018.02.009

Scopus

関節のバイオメカニクス核磁気共鳴画像法による示指中手指節関節の三次元生体内接触運動の解析

坂本信, 小林公一, 春日勇人, 風間清子

非破壊検査 67 ( 4 ) 174‐179 - 179 2018.4

An analytical solution for the axisymmetric problem of a penny-shaped crack in an elastic layer sandwiched between dissimilar materials Reviewed

Miura Kotaro, Sakamoto Makoto, Kobayashi Koichi, Pramudita Jonas A, Tanabe Yuji

MECHANICAL ENGINEERING JOURNAL 5 ( 3 ) 18 - 00125-18-00125 2018

Language：English Publisher：The Japan Society of Mechanical Engineers

<p>Herein, we consider the axisymmetric problem of a penny-shaped crack in an elastic material sandwiched between other materials. It is assumed that the central substance is composed of an elastic layer held between two semi-infinite bodies with different elastic constants, and that the crack is situated in the central plane of the elastic layer and subjected to uniform pressures on its internal surfaces. We consider two contact conditions; perfectly bonded and frictionless contact at the interfaces with the dissimilar materials. Dual integral equations are reduced to an infinite system of simultaneous equations by expressing normal displacements on the crack surfaces as an appropriate series function. Numerical results were obtained to examine the effects of the elastic constants of the layer and semi-infinite bodies and contact conditions on the stress intensity factor at the tip of the penny-shaped crack, the distribution of normal displacement, and stress on the crack plane. Based on the results of these numerical calculations, several conclusions can be made, as follows. 1) The distributions of normal displacement and stress at the crack plane and the stress intensity factor at the tip of the crack become larger than the results for an infinite solid when the ratio of the shear modulus of the layer to that of the semi-infinite bodies is larger than 1. 2) The numerical results for normal displacement and stress, and for stress intensity factors, in the frictionless case are higher than for the perfectly bonded case regardless of the shear modulus ratio and layer thickness ratio. The difference between the perfectly bonded and frictionless cases becomes greater as the layer thickness ratio becomes smaller. 3) There is a slight difference in the stress intensity factor values obtained from the present work and the corresponding results previously reported in the literature.</p>

DOI： 10.1299/mej.18-00125

Web of Science

Three-Dimensional Elastic Problem of a Penny-Shaped Crack in an Elastic Layer Sandwiched Between Dissimilar Materials

MIURA Kotaro, SAKAMOTO Makoto, KOBAYASHI Koichi, PRAMUDITA Jonas A., TANABE Yuji

The Proceedings of Mechanical Engineering Congress, Japan 2018 G0300401 2018

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

DOI： 10.1299/jsmemecj.2018.G0300401

Viscoelastic behavior of bovine femoral articular cartilage in relaxation indentation test

OYAMA Chihiro, MIURA Kotaro, SAKAMOTO Makoto, KOBAYASHI Koichi, A. PRAMUDITA Jonas, TANABE Yuji

The Proceedings of the Materials and Mechanics Conference 2018 OS0604 2018

Language：Japanese Publisher：The Japan Society of Mechanical Engineers

<p>The indentation test has been widely used to evaluate mechanical properties of industrial and biological materials in many studies. In this study, we obtained an analytical solution of axisymmetric contact problem of viscoelastic layer bonded on rigid substrate indented by flat-ended cylindrical punch using elastic-viscoelastic corresponding principle. The relaxation indentation tests were conducted for silicon rubber, Echo PAD which is a soft material used for elastography, and articular cartilage of bovine femoral head. For articular cartilage, fresh articular cartilage was treated by collagenase after a relaxation indentation test and was then used again in same test. The viscoelastic models in this study were selected as three-element model (standard linear solid model) and five-element model (generalized Maxwell model) and viscoelastic parameters of the models were determined by fitting the analytical solution to applied load varying with time collected from the relaxation indentation test. As the results, it was suggested that the five-element model was more appropriate than three-element model to reproduce the behavior of relaxation indentation of silicon rubber, Echo PAD, and articular cartilage. Furthermore, the viscoelastic parameters of treated articular cartilage decreased sufficiently compared with those of fresh articular cartilage. From these results, it was suggested that the method of evaluating the time-dependent mechanical properties of articular cartilage based on the analytical solutions of the relaxation indentation test obtained from this study could be a useful tool for evaluating the state of degenerated cartilage.</p>

DOI： 10.1299/jsmemm.2018.OS0604