ebook img

Degradation Phenomena on Polymeric Biomaterials PDF

201 Pages·1992·5.408 MB·English
Save to my drive
Quick download
Download
Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.

Preview Degradation Phenomena on Polymeric Biomaterials

H. Planck M. Dauner M. Renardy (Eds.) Degradation Phenomena on Polymeric Biomaterials With 85 Figures and 27 Tables Springer-Verlag Berlin Heidelberg NewY ork London Paris Tokyo HongKong Barcelona Budapest Proceedings of the 4th International Conference on Biomaterials, Denkendorf September 3 -5, 1991 Dr. Ing.Heinrich Planck Dipl.-Ing. Martin Dauner Dipl. BioI. Monika Renardy Institut fUr Textil-und Verfahrenstechnik KorschtalstraBe 26 W -7306 Denkendorf FRG ISBN-13 : 978-3-642-77565-9 e-ISBN-13 : 978-3-642-77563-5 DOl: 10.1007/978-3-642-77563-5 111is work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on rnicrofihn or in other ways, and storage in data banks. Duplication of this publication or parts thereof is pennitted only under the provisions of the Gennan Copyright Law of September 9, 1965, in its current version, and pennission for use must always be obtained from Springer·V erlag. Violations are liable for prosecution act under Gernlan Copyright Law. © Springer·Verlag Berlin Heidelberg 1992 Softcover reprint of the hardcover 1st edition 1992 The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specificstatement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Product Liability: The publisher can give no guarantee for infonnation about drug dosage and application thereof contained in this book. In every individual case the respective user must check its accuracy by consulting other phannaceuticalliterature. Typesetting: Camera ready by authors 02/3020·543 2 1 0 -Printed on acid -free paper PREFACE Tradi tionally, the International lTV - Conferences on Biomate rials are focussing on problems in Biomedical Engineering, problems, which are still unsolved, of main interest, and which are of interdisciplinary character. In 1983, the Division of Biomedical Engineering of the Institute of Textile Technology and Chemical Engineering, Denkendorf, started wi th a conference about the use of polyurethanes in biomedicine. Three years later,. in 1986, progress in development and use of polyurethanes was selected as conference topic. It had to be realized that degradation problems were still dominating the discussions. The main discussion topics were: What are the causes for the degradation? How can one prevent them? What are the degradation products, and do they affect the human body? How can one simu late the degradation? How can one accelerate the in vitro tests and how can the results predict the in vivo behaviour of the material? How do in vitro tests correlate with animal tests and the behaviour in the human body? At the third conference in 1989, the speakers focused on the use of textiles in medicine. Again the problem of degradation was discussed intensively and demonstrated by the failure of textile implants, the degradation of aramide polymers or the degradation of resorbable suture materials. The examples make clear, that degradation may be a desired or undesired property of an implant. For the temporary fixation of tissue or bones, a controlled degradation followed by the resorption of the mate rial is wanted. Implants made of nonresorbable materials should show no changes in properties, which means that degradation is undesired and should be avoided; examples are vascular grafts and heart valves. Or, if this is not possible because of the type of application, degradation has to be minimized. An example for this application are hip endoprostheses. VI Degradation can be caused by hydrolysis, oxidation or enzymes as well as by mechanical stress. Degradation depends on the type of polymer, the processing, the processing addi tiv es needed, and also on the finish of the device. As it is known from the polyurethanes, degradation is strongly related to and sometimes caused by the processing of the material, especially, if it is a thermal processing beyond the melting temperature or if the material is stressed mechanically in the solid state. The in vivo degradation of implants is not fully understood. That is the reason why we decided to organize the 4th Inter national ITV Conference on Biomaterials as a meeting concen trating on the degradation phenomena of polymeric biomaterials. Following the presentation of test methods for simulation, evaluation and acceleration of biodegradation, the behaviour of nondegradable, degradable, or resorbable materials was discussed in separate sessions. The effects of the processing on biodegra dation was the topic of another session. Clinical aspects and experiences completed the presentations. Each paper was discussed intensively. The discussion remarks are added to each paper. As usual, a round table summarized the results of the conference. We would like to thank all participants and speakers for the excellent presentations and discussions during the meeting. Denkendorf, 17. February 1992 The editors CONTENTS I. EVALUATION OF DEGRADATION IN VITRO: PHYSICAL, CHEMICAL AND BIOLOGICAL TEST METHODS 1. Testing of PUR-Biomaterials for Enzymatically 1 Induced Degradation: An in vitro study Glasmacher-Seiler, B., Jonas, J., Schadlich, G., Reul, H., Rau, G. 2. Chemical Alteration of Biomer™ as a Result of 9 Oxidative Degradation Tyler, B.J., Ratner, B. 3. In vitro Degradation Test for Screening of 25 Biomaterials Welling, C., Schwengler, H., Strahl, B. II. DEGRADATION PHENOMENA OF "NON-DEGRADABLE" BIOMATERIALS 4. The Biodegradation of Nondegradable Polymers 37 Stokes, K.B., Urbanski, P.W. 5. A Comparison of in vivo Degradation of Novel 59 Polyurethanes with Performance in in vitro Accelerated Tests Brandwood, A., Noble, K.R., Schindhelm, K., Meijs, G.F., Gunatillake, P.A., Chatelier, R.C., McCarthy, S.J., Rizzardo, E. ~II III. THE RESORBABLE BIOMATERIALS AND THEIR DEGRADA TION MECHANISMS 6. Accelerated Degradation Test on Resorbable 67 Polymers Buchholz, B. 7. Kinetics of Resorption of Different suture 77 Materials Depending on the Implantation site and the Species Scherer, M.A., Fruh, H.-J., Ascherl, R., Mau, H., Siebels, W., BIUmel, G. IV. THE INFLUENCE OF POLYMER MODIFICATION AND PROCESSING PARAMETERS ON DEGRADATION 8. Tissue Response to Resorbable Synthetic Polymers 97 Gibbons, D.F • . 9. In vitro Degradation of Polylactides Depending 107 on Different Solution Processes Dauner, M., Muller, E., Wagner, B., Planck, H. 10. Tissue Response to Pre-Degraded Poly(L-Lactide) 123 Rozema, F.R., Bos, R.R.M., Boering, G., Nijenhuis, A.J., Pennings, A.J., Jansen, H.W.B., de Bruijn, W.C. V. CLINICAL APPLICATION OF RESORBABLE BIOMATE RIALS: SUTURES 11. Modern Absorbable Suture Materials and Biode 133 gradable Anastomotic Rings in Gastrointestinal Surgery Thiede, A., Lunstedt, B. 12. A Novel Bioabsorbable Monofilament surgical 153 suture made from (€-Caprolactone-L-Lactide) Copolymer Nakamura, T., Shimizu, Y., Matsui, T., Okumura, N., Hyon, S.H., Nishiya, K. VI. CLINICAL APPLICATION OF RESORBABLE BIOMATERIALS IN RECONSTRUCTIVE SURGERY 13. Clinical Application of Resorbable Biomaterials 163 in Reconstructive Surgery Rehm, K.E. 14. Biodegradable PLA Versus Stainless Steel 177 Intramedullary Devices for Fracture Fixation. A Comparative Histological Study Van der Elst, M., Dijkema, A.R.A., Klein, C.P.A.T., Patka, P., Haarman, H.J.T.M. x ROUND TABLE DISCUSSION AT THE END OF THE CONFERENCE 185 KEYWORDS 191 AUTHOR INDEX 193 ACKNOWLEDGEMENT 197 TESTING OF PUR -BIOMATERIALS FOR ENZYMAT ICAUY INDUCED DEGRADATION: AN IN VITRO STUDY B. Glasmacher-Seiler, J. Jonas, G. Schiidlich, H. Reul, G. Rau Helmholtz-Institute for Biomedical Engineering PauwelsstraBe 30, D-5100 Aachen Abstract: The enzymatically induced degradation of a group of medical grade polyurethanes (PUR) for cardiovascular applications such as heart valve prostheses and blood pumps has been investigated. Mechanical stability of these polyether-, polyester-and polyurethaneureas has been tested by incubation of microtensile specimens according to ASTM 1708-79 into enzymatic solutions and bovine blood plasma for up to 4 months. The degree of degradation is assessed by measuring tensile properties, water absorption and molecular weight. Changes in surface quality are determined by SEM and contact angle measurements. The results so far reveal degradative changes depending on PUR-type and type of enzyme but to a degree not impairing the implant function within the chosen test period and test conditions. INTRODUCTION When we talk of testing of materials for biomedical applications which means investigating the biocompatiblity of these materials, we should always keep in mind that we have to perform screening tests that means testing of a couple of materials in parallel. In addition we should select test methods and test conditions and parameters in the view of the desired application of the materials. Only in this configuration, testing of biocompatibility is meaningful. Within this study materials are tested which are used to make heart valve prostheses or blood contacting surfaces of blood pumps. For these applications biomedical polyurethanes are investigated. The test parameters and conditions are chosen in an appropriate manner for example with regard to the time period, blood pumps are in contact with the human body. The tests are performed at physiological temperatures and in physiological solutions. Another important parameter adapted to the valve or pump application is the type of specimen fabrica tion: The samples are solution cast in a similar manner that pumps are made. In addition, the size of the test specimens is comparable. The surface to volume ratio is certainly of importance. Therefore, the test specimens are in the same thickness range of 0.2 mm as pump membranes or valve leaflets. Three types of polyurethanes are under investigation: polyether-, and polyesterurethanes, and polyetherurethaneureas depending on the components of the polymer (type of polyol, diiso- H. Planck M. Danner M. Renardy (Eds.) Degradation Phenomena on Polymeric Biomaterials © Springer·V erlag Berlin Heidelberg 1992

See more

The list of books you might like

Most books are stored in the elastic cloud where traffic is expensive. For this reason, we have a limit on daily download.