journal of the mechanical behavior of biomedical materials 31 (2014) 1 –2
Available online at www.sciencedirect.com
www.elsevier.com/locate/jmbbm
Editorial
Advances in artificial joint materials Artificial joints, as the many other endoprostheses nowadays available for implantation into the human body, have come into our lives as one of the most magnificent achievements of medical science, comparable with the development of new drugs and vaccines. Endoprosthetics of joints nowadays represents the most efficient available method of recovering body mobility through partial or total replacement with artificial components. However, the production of joint endoprostheses belongs to a commercial sphere of extreme scientific and technological specialization, especially regarding the employed biomaterials. Joint biomaterials should meet a series of strict requirements, including chemical inertness, purity, biological compatibility, structural reliability, and wear resistance. Moreover, the industrial production of artificial joints is related, as a rule of thumb, to the capability of delivering high-precision products. The bearing surfaces should be machined very thoroughly and include strict tolerances, accuracy of the conjunctions, and interchangeability in accordance to strict international standards. Although the human joints consist of biological tissues that are significantly less strong than the modern structural biomaterials used in artificial joints, biological tissues largely surpass endoprostheses in lubrication capacity with the cartilage being the natural reservoir for the synovia. Unfortunately, it is quite hard to fully reproduce such an efficient lubrication mechanism in artificial prostheses, which thus might unavoidably remain insufficiently adjusted for operation in the human body as compared to human joints. The consequent problem of ameliorating inadequate wear resistance and surface sliding characteristics is archetypal in the biomedical field in the fact that it stems at the junction of multivariate scientific disciplines, including medicine, biophysics, chemistry, tribology, and materials science, and its solution requires the strict collaboration of different professional figures besides medical doctors. The guest editors of this special issue have duly pursued the aim to challenge specialists of different spheres to share their knowledge in the difficult field of artificial joints and to publish it in compact form in the same issue. While our strategic view on joint biomaterials has been explicitly given in the first (review) paper of this issue, we want to briefly comment in this editorial on the way new biomaterials are scientifically conceived, then how such a knowledge can be developed, and finally how such information is delivered to the world market. Regarding the scientific path towards new biomaterials, the process of providing clear answers to fundamental topics
like as, for example, the structural stability of artificial biomaterials in biological environment, should at least deal with clarifying the underlying roles played by stoichiometry, micromechanics and molecular physics in biomaterials science. There could not be any clear and comprehensive understanding of biomaterials without a basic development of such advanced fields. We hope that the papers contained in this special issue have contributed to provide somewhat updated answers to such fundamental issues. In the further context of how the scientific knowledge of newly launched biomaterials is built up, we strongly believe that surgeons should become capable to deeply assert their requirements for scientific proofs on the efficacy of new implants and/or of modifications of the used biomaterials, based on strictly developed scientific programs rather than on merely bureaucratic regulatory procedures. The fundamental truth in this assertion is often shaded by the difficulties that surgeons, as well as independent scientists, might find in obtaining implant materials from the manufacturers for the mere purpose of scientific research. In our viewpoint, it could not be acceptable that surgeons should trust, in making their implant choices, what the implant manufacturers, merely driven by their own profits, give them as the only available scientific data, or even wait for retrievals becoming available for studying post mortem the performance of the selected product. Implementations are needed to the way scientific data from independent parties could reach the biomaterials audience. Finally, as a consequence of the previous point, the possible development of biases in the delivered information might become an issue, given the practical difficulty encountered in having published investigations on commercial products by independent entities. We believe that the field of joint arthroplasty needs nowadays to obtain the precious contributions of chemists and physicists besides the surgical experience of medical doctors, putting forward new scientific perspectives without attempting to oversimplify real situations in search for wider consensus from less specialized audiences. Past experiences have taught us how formulating and promoting an outstanding and innovative idea could be a necessary but not sufficient prerequisite to obtain progress in this field, which is driven not only by scientific but also by economic and social driving forces. It is gradually becoming clear that new social schemes and strategies should be developed that will allow tackling the problem of a continuously increasing demand for biomedical devices in a more reliable way. The
2
Editorial / journal of the mechanical behavior of biomedical materials 31 (2014) 1 –2
papers in this special issue, conceived as pure treatises of biomaterials science, are intended to represent few elementary steps toward these new principles. Giuseppe Pezzotti is a full professor (tenure) at the Ceramic Physics Laboratory of the Kyoto Institute of Technology, Japan, since 2000. He graduated summa cum laude in mechanical engineering from Rome University “La Sapienza”, Italy, in 1984 and holds three doctoral degrees in engineering, in medical, and in physical sciences, all obtained in Japan, the country where he has been steadily living since 26 years. From 2002 to 2012, Prof. Pezzotti served as the director of the Research Institute for Nanoscience at Kyoto Institute of Technology. From 2005, he is an adjunct professor at the Department of Orthopaedic Research of Loma Linda University, Loma Linda, CA. Since 2009, he has held an invited professorship at the Department of Medical Engineering of Osaka University and since 2010 has been visiting professor at the Department of Molecular Cell Physiology of Kyoto Prefectural University of Medicine. Prof. Pezzotti has published about 560 scientific papers and 10 book chapters, and holds 8 patents, including a world patent regarding nanoscale stress microscopy in the scanning electron microscope. In 2013, concurrently with the publication of his new book entitled “Advanced Materials for Joint Implants”, he has become a Fellow of the Academy of Science of Bologna Institute in appreciation of his advanced studies linking quantum mechanics to medical sciences. Kengo Yamamoto is since 2004 a Professor and Chairman in the Department of Orthopaedic Surgery, Tokyo Medical University, Japan. From 2010, he is concurrently serving as the director of the Rehabilitation Center at the Hospital of Tokyo Medical University. He received his M.D. and Ph.D. degrees from Tokyo Medical University in 1983 and 1987, respectively. From 1998 to 1999, he joined Loma Linda University, California, United States, for a research fellowship related to total joint replacement, involving biomaterials
n
Corresponding author.
and biomechanics. Prof. Yamamoto has published more than 300 papers and 30 review chapters, and he is a member of the Japanese Orthopaedic Association (Delegate), the Japanese Hip Society (Director), the Japanese Society for Musculoskeletal Medicine (Director), the Japanese Society for Replacement Arthroplasty (Councilor), the Japanese Society for Biomaterials (Councilor), and the Japanese Orthopaedic Society of Knee, Arthroplasty and Sports Medicine (Councilor), among others. In addition to his practice in joint replacement surgery, his laboratory interests are primarily in the area of biomaterials used in total hip and knee arthroplasty.
Giuseppe Pezzottin Kyoto Institute of Technology, Ceramic Physics Laboratory, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan E-mail address: [email protected] Kengo Yamamoton Tokyo Medical University, Department of Orthopaedic Surgery, Shinjuku-ku, Nishishinjuku, Tokyo 160-0023, Japan E-mail address: [email protected]
1751-6161/$ - see front matter & 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jmbbm.2013.12.012
Available online at www.sciencedirect.com
www.elsevier.com/locate/jmbbm
Editorial
Advances in artificial joint materials Artificial joints, as the many other endoprostheses nowadays available for implantation into the human body, have come into our lives as one of the most magnificent achievements of medical science, comparable with the development of new drugs and vaccines. Endoprosthetics of joints nowadays represents the most efficient available method of recovering body mobility through partial or total replacement with artificial components. However, the production of joint endoprostheses belongs to a commercial sphere of extreme scientific and technological specialization, especially regarding the employed biomaterials. Joint biomaterials should meet a series of strict requirements, including chemical inertness, purity, biological compatibility, structural reliability, and wear resistance. Moreover, the industrial production of artificial joints is related, as a rule of thumb, to the capability of delivering high-precision products. The bearing surfaces should be machined very thoroughly and include strict tolerances, accuracy of the conjunctions, and interchangeability in accordance to strict international standards. Although the human joints consist of biological tissues that are significantly less strong than the modern structural biomaterials used in artificial joints, biological tissues largely surpass endoprostheses in lubrication capacity with the cartilage being the natural reservoir for the synovia. Unfortunately, it is quite hard to fully reproduce such an efficient lubrication mechanism in artificial prostheses, which thus might unavoidably remain insufficiently adjusted for operation in the human body as compared to human joints. The consequent problem of ameliorating inadequate wear resistance and surface sliding characteristics is archetypal in the biomedical field in the fact that it stems at the junction of multivariate scientific disciplines, including medicine, biophysics, chemistry, tribology, and materials science, and its solution requires the strict collaboration of different professional figures besides medical doctors. The guest editors of this special issue have duly pursued the aim to challenge specialists of different spheres to share their knowledge in the difficult field of artificial joints and to publish it in compact form in the same issue. While our strategic view on joint biomaterials has been explicitly given in the first (review) paper of this issue, we want to briefly comment in this editorial on the way new biomaterials are scientifically conceived, then how such a knowledge can be developed, and finally how such information is delivered to the world market. Regarding the scientific path towards new biomaterials, the process of providing clear answers to fundamental topics
like as, for example, the structural stability of artificial biomaterials in biological environment, should at least deal with clarifying the underlying roles played by stoichiometry, micromechanics and molecular physics in biomaterials science. There could not be any clear and comprehensive understanding of biomaterials without a basic development of such advanced fields. We hope that the papers contained in this special issue have contributed to provide somewhat updated answers to such fundamental issues. In the further context of how the scientific knowledge of newly launched biomaterials is built up, we strongly believe that surgeons should become capable to deeply assert their requirements for scientific proofs on the efficacy of new implants and/or of modifications of the used biomaterials, based on strictly developed scientific programs rather than on merely bureaucratic regulatory procedures. The fundamental truth in this assertion is often shaded by the difficulties that surgeons, as well as independent scientists, might find in obtaining implant materials from the manufacturers for the mere purpose of scientific research. In our viewpoint, it could not be acceptable that surgeons should trust, in making their implant choices, what the implant manufacturers, merely driven by their own profits, give them as the only available scientific data, or even wait for retrievals becoming available for studying post mortem the performance of the selected product. Implementations are needed to the way scientific data from independent parties could reach the biomaterials audience. Finally, as a consequence of the previous point, the possible development of biases in the delivered information might become an issue, given the practical difficulty encountered in having published investigations on commercial products by independent entities. We believe that the field of joint arthroplasty needs nowadays to obtain the precious contributions of chemists and physicists besides the surgical experience of medical doctors, putting forward new scientific perspectives without attempting to oversimplify real situations in search for wider consensus from less specialized audiences. Past experiences have taught us how formulating and promoting an outstanding and innovative idea could be a necessary but not sufficient prerequisite to obtain progress in this field, which is driven not only by scientific but also by economic and social driving forces. It is gradually becoming clear that new social schemes and strategies should be developed that will allow tackling the problem of a continuously increasing demand for biomedical devices in a more reliable way. The
2
Editorial / journal of the mechanical behavior of biomedical materials 31 (2014) 1 –2
papers in this special issue, conceived as pure treatises of biomaterials science, are intended to represent few elementary steps toward these new principles. Giuseppe Pezzotti is a full professor (tenure) at the Ceramic Physics Laboratory of the Kyoto Institute of Technology, Japan, since 2000. He graduated summa cum laude in mechanical engineering from Rome University “La Sapienza”, Italy, in 1984 and holds three doctoral degrees in engineering, in medical, and in physical sciences, all obtained in Japan, the country where he has been steadily living since 26 years. From 2002 to 2012, Prof. Pezzotti served as the director of the Research Institute for Nanoscience at Kyoto Institute of Technology. From 2005, he is an adjunct professor at the Department of Orthopaedic Research of Loma Linda University, Loma Linda, CA. Since 2009, he has held an invited professorship at the Department of Medical Engineering of Osaka University and since 2010 has been visiting professor at the Department of Molecular Cell Physiology of Kyoto Prefectural University of Medicine. Prof. Pezzotti has published about 560 scientific papers and 10 book chapters, and holds 8 patents, including a world patent regarding nanoscale stress microscopy in the scanning electron microscope. In 2013, concurrently with the publication of his new book entitled “Advanced Materials for Joint Implants”, he has become a Fellow of the Academy of Science of Bologna Institute in appreciation of his advanced studies linking quantum mechanics to medical sciences. Kengo Yamamoto is since 2004 a Professor and Chairman in the Department of Orthopaedic Surgery, Tokyo Medical University, Japan. From 2010, he is concurrently serving as the director of the Rehabilitation Center at the Hospital of Tokyo Medical University. He received his M.D. and Ph.D. degrees from Tokyo Medical University in 1983 and 1987, respectively. From 1998 to 1999, he joined Loma Linda University, California, United States, for a research fellowship related to total joint replacement, involving biomaterials
n
Corresponding author.
and biomechanics. Prof. Yamamoto has published more than 300 papers and 30 review chapters, and he is a member of the Japanese Orthopaedic Association (Delegate), the Japanese Hip Society (Director), the Japanese Society for Musculoskeletal Medicine (Director), the Japanese Society for Replacement Arthroplasty (Councilor), the Japanese Society for Biomaterials (Councilor), and the Japanese Orthopaedic Society of Knee, Arthroplasty and Sports Medicine (Councilor), among others. In addition to his practice in joint replacement surgery, his laboratory interests are primarily in the area of biomaterials used in total hip and knee arthroplasty.
Giuseppe Pezzottin Kyoto Institute of Technology, Ceramic Physics Laboratory, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan E-mail address: [email protected] Kengo Yamamoton Tokyo Medical University, Department of Orthopaedic Surgery, Shinjuku-ku, Nishishinjuku, Tokyo 160-0023, Japan E-mail address: [email protected]
1751-6161/$ - see front matter & 2014 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jmbbm.2013.12.012
