バイオエンジニアリング部門 メーリングリスト登録者各位 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 主査　大橋　俊朗 下記の要領にて第41回「計測と力学-生体への応用」研究会（共催）を開催いたします． 多数のご参加をお待ちしております．なお，本研究会は日本機械学会北海道支 部バイオメカニクス 懇話会第12回講演会の共催として開催いたします． ＊2013年4月1日より，本研究会の主査は但野　茂教授（北海道大学）から大橋 （北海道大学） へ交代いたしました．引き続きよろしくお願い申し上げます． ----------------------------------　記　---------------------------------- 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　　　　　　　2013年4月9日 　　　　　　　　　　　日本機械学会北海道支部　バイオメカニクス懇話会 　　　　　　　　　　　　　　　　　　第12回講演会 （共催：日本機械学会北海道支部，日本機械学会バイオエンジニアリング部門 「計測と力学-生体への応用-」 　　　　研究会，日本生体医工学会専門別研究会「バイオメカニクス研究会」） 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 　　　　　　主査　大橋　俊朗 下記の要領にて第12回講演会を開催いたします．本講演会は日本機械学会北海 道支部特別講演会，日本機械学会 バイオエンジニアリング部門第41回「計測と力学-生体への応用-」研究会，日 本生体医工学会専門別研究会 「バイオメカニクス研究会」第148回研究会と共催いたします．多数のご参加 をお待ちしております． 日　時：2013年4月24日（水），14:00ｰ15:00 場　所：北海道大学大学院工学研究院・工学部　大会議室A1-17室 　　　　http://www.eng.hokudai.ac.jp/building/?place=outer 講　師：Senior Lecturer Ashvin Thambyah, Ph.D. (The University of Auckland, New Zealand) 演　題：1. On the mechanobiology of joint degeneration 　　　　2. Design considerations for the deep flexion knee implant: what can we learn from natural knee biomechanics? 要　旨： 1. During early development of the joint, a local environment of shear stress is preferred for bone formation, while hydrostatic stresses are more conducive to maintaining cartilage tissue. We propose that the degenerative breakdown of the joint tissues also involve similar mechanobiological factors. In osteoarthritis for example, our recent finding of primary bone formation in a pre-osteoarthritic joint, found to be related to micro-to-nanoscale tissue structural changes, highlights the role of mechano-structural factors in the pathophysiology of the joint. Importantly therefore, to determine critical levels of stresses and strains that are involved in joint physiology, for both the joint's development or demise, the complexities of tissue structure and its load-bearing mechanics would need to be addressed. In this talk, our multiscalar interpretations of cartilage-bone structural response to load are presented with a view of elucidating previously unaddressed subtleties of tissue mechanics and joint degeneration. 2. There is still much to be done to improve the design of knee implants both in terms of longevity and their ability to serve a wider range of patient needs. The increasing medical needs of aging Asian populations (in which deep knee bending and squatting are common activities of daily living) presents the call for better design in implants that will allow deep flexion to be performed safely and reliably, without affecting the expected longevity of the implant. In order to provide the design rationale for an appropriate knee implant, a more in-depth knowledge of the kinematics and kinetics of deep knee flexion in the natural knee is crucial. The author has conducted several studies to investigate the biomechanics of the natural knee in squatting and the data and analyses from these studies form the basis for this talk. From gait studies it was found that in Asian-style squatting the knee flexes up to 150_ and the tibiofemoral contact forces are as high as 3 to 4 times bodyweight. Translating the contact forces into stresses, in-vitro studies on human cadaver knees showed that the peak pressures can be as high as 20 MPa as a result of the drastic reduction in contact area. Coupled with high stresses, the external rotation of the femur about the tibia ranged from 10_ to 20_. The extent of this rotation was attributed to the unique morphology of the medial versus lateral tibial plateaus. The study also highlights an additional important kinematic feature of knee bending found in the subjects studied that has received little attention in the literature. In descending and ascending from a squat there were significant shear forces in the tibiofemoral joint that underwent rapid reversal from being posteriorly directed to anteriorly directed. This rapid reversal, if incorporated into simulated loadings of implants in in-vitro materials testing systems, may provide further insight into mechanisms of implant failure typically attributed to deep flexion knee activity. 問い合わせ先： 大橋　俊朗　北海道大学大学院工学研究院人間機械システムデザイン部門 Tel&Fax: 011-706-6424, Email: ohashi@eng.hokudai.ac.jp ------------------------------(in English)---------------------------------- April 9, 2013 The Japan Society of Mechanical Engineers Hokkaido Branch “Biomechanics Research Meeting” 12th Seminar (Cosponsored by Hokkaido branch, The Japan Society of Mechanical Engineers; “Instrumentation and Mechanics - Application to Living Bodies -” technical sections, Bioengineering division, The Japan Society of Mechanical Engineers; “Biomechanics" technical sessions, Japanese Society for Medical and Biological Engineering) Chairman: Toshiro Ohashi The Biomechanics Research Meeting will sponsor a presentation by a distinguished scientist, Dr. Ashvin Thambyah from The University of Auckland. Faculty members, graduate students, and undergraduates are encouraged to participate in the seminar. Date&Time: April 24, 2013, 14:00ｰ15:00 Place: Room#A1-17, Faculty of Engineering, Hokkaido University http://www.eng.hokudai.ac.jp/building/?place=outer Speaker: Senior Lecturer Ashvin Thambyah, Ph.D. (The University of Auckland, New Zealand) Title: 1. On the mechanobiology of joint degeneration 　　 2. Design considerations for the deep flexion knee implant: what can we learn from natural knee biomechanics? Abstract: 1. During early development of the joint, a local environment of shear stress is preferred for bone formation, while hydrostatic stresses are more conducive to maintaining cartilage tissue. We propose that the degenerative breakdown of the joint tissues also involve similar mechanobiological factors. In osteoarthritis for example, our recent finding of primary bone formation in a pre-osteoarthritic joint, found to be related to micro-to-nanoscale tissue structural changes, highlights the role of mechano-structural factors in the pathophysiology of the joint. Importantly therefore, to determine critical levels of stresses and strains that are involved in joint physiology, for both the joint's development or demise, the complexities of tissue structure and its load-bearing mechanics would need to be addressed. In this talk, our multiscalar interpretations of cartilage-bone structural response to load are presented with a view of elucidating previously unaddressed subtleties of tissue mechanics and joint degeneration. 2. There is still much to be done to improve the design of knee implants both in terms of longevity and their ability to serve a wider range of patient needs. The increasing medical needs of aging Asian populations (in which deep knee bending and squatting are common activities of daily living) presents the call for better design in implants that will allow deep flexion to be performed safely and reliably, without affecting the expected longevity of the implant. In order to provide the design rationale for an appropriate knee implant, a more in-depth knowledge of the kinematics and kinetics of deep knee flexion in the natural knee is crucial. The author has conducted several studies to investigate the biomechanics of the natural knee in squatting and the data and analyses from these studies form the basis for this talk. From gait studies it was found that in Asian-style squatting the knee flexes up to 150_ and the tibiofemoral contact forces are as high as 3 to 4 times bodyweight. Translating the contact forces into stresses, in-vitro studies on human cadaver knees showed that the peak pressures can be as high as 20 MPa as a result of the drastic reduction in contact area. Coupled with high stresses, the external rotation of the femur about the tibia ranged from 10_ to 20_. The extent of this rotation was attributed to the unique morphology of the medial versus lateral tibial plateaus. The study also highlights an additional important kinematic feature of knee bending found in the subjects studied that has received little attention in the literature. In descending and ascending from a squat there were significant shear forces in the tibiofemoral joint that underwent rapid reversal from being posteriorly directed to anteriorly directed. This rapid reversal, if incorporated into simulated loadings of implants in in-vitro materials testing systems, may provide further insight into mechanisms of implant failure typically attributed to deep flexion knee activity. Contact: Toshiro Ohashi Division of Human Mechanical Systems and Design, Faculty of Engineering, Hokkaido University Tel&Fax: 011-706-6424, Email: ohashi@eng.hokudai.ac.jp