Bone tissue: Hierarchical simulations for clinical applications

Bone tissue: Hierarchical simulations for clinical applications

Journal of Biomechanics 44 (2011) 211–212 Contents lists available at ScienceDirect Journal of Biomechanics journal homepage: www.elsevier.com/locat...

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Journal of Biomechanics 44 (2011) 211–212

Contents lists available at ScienceDirect

Journal of Biomechanics journal homepage: www.elsevier.com/locate/jbiomech www.JBiomech.com

Editorial

Bone tissue: Hierarchical simulations for clinical applications

This special issue addresses three-dimensional (3D), multi-scale (also known as hierarchical) modeling of bone for clinical applications. Clinicians continue to face difficulties in making the decision of how to treat patients because the prediction of fragility fractures remains clinically problematic, and the effects of emerging therapeutic treatments on bone’s elementary components still require explanation. Interfacing the knowledge of bone’s microand nano-structure with its well-recognized macro-structure can now confront these challenges. Clinicians and researchers increasingly recognize the multiple characteristics that bone displays through a hierarchically organized heterogeneous structure that varies across nano-, micro-, and macro-length scales. Bone’s rigidity, strength, toughness, and porosity affect clinical scenarios that include pathologies such as osteoporosis and osteogenesis imperfecta. Interfacing the knowledge of bone characteristics at the various scales of dimension will help to solve the macro-structural problems whose solution has remained murky in the absence of consideration of the smaller dimension parameters. The papers presented in this issue arise from the workshop ‘‘Bone Tissue: Hierarchical Simulations for Clinical Applications’’ held in April 2010 at UCLA. The workshop sought to map a strategy to achieve biomechanical simulation of bone tissue that incorporates the range of structural levels from cellular to a patient’s macroscopic bone. Clinicians, clinical researchers, system biologists, engineers, physicists, and mathematicians, convened to formulate a plan to develop 3D multi-scale virtual rendering of bone tissue able to address specific clinical issues. UCLA’s Department of Orthopaedic Surgery, its Office of Continuing Medical Education, and its Institute for Pure and Applied Mathematics (IPAM) assisted the Organizing Committee, that in addition to us (respectively, a mathematician seasoned in biological problems and a biomechanical/tissue engineer), included a bone metabolic expert—John Adams, an anatomist—Paul Dechow, a biomechanical engineer—Eve Donnelly, and a mathematician—Elena Cherkaev. We are grateful to Russel Caflisch, direct of IPAM, for his continuous, valuable advice. On the basis of definition by clinicians of the challenges that they face, expert researchers in the disparate fields of orthopaedics, dentistry, bone biology, biomechanical engineering, biomaterials, and applied mathematics shared recent research findings and existing techniques specific to each field that, appropriately marshaled, will make it possible to prepare and validate costeffective multi-scale models for clinical assessment of bone. Indeed, bone multi-scale modeling is highly interdisciplinary, inherently drawing on developments that occur independently

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across multiple scientific disciplines and address phenomena manifested at the different scales. This issue offers clinicians and researchers, including junior colleagues, unique exposure to diverse, but compatible areas of expertise, along the lines of the Interagency Modeling and Analysis Group aim and the National Institutes of Health Roadmap, to design a common plan of action to develop state-of-the-art 3D multi-scale models of bone. We strive to encourage experts from different fields to teach each other the latest developments concerning bone modeling and to design collaborative plans to solve challenging problems. Clinical problems and the technologies relevant to their solution often require that additional experimental data be obtained and that existing mathematical and engineering tools be adapted for preparation of the appropriate multi-scale models. This special issue contains papers of various types that contribute to the hierarchical modeling of bone to solve clinical issues. It includes (i) presentations of medical problems by clinicians involved in research, (ii) experimental results on bone structure at various scales of bone hierarchy that include considerations of variations of parameters at specific scales, (iii) sophisticated finite element modeling linking two or more hierarchical levels of bone, (iv) methods and models by applied mathematicians to further investigate the specifications of bone structure and its changes with pathology, and (v) investigations of tissue engineering. In essence, what we present here is work in progress towards the achievement of a hierarchical representation of bone at young, adult, and old ages, in both good health and in pathological conditions. We hope that this issue inspires you. We are happy to report that various new collaborations have been initiated in conjunction with the preparation of papers for this special issue. Obviously, many existing models of bone tissue within our research groups can be improved by taking into account an additional parameter or a structural-level above or below the one considered depending on the question addressed. We have worked hard to make each paper accessible to a wide audience. We invite you to join in the effort by not hesitating to contact the corresponding author of the papers of your interest, with a view to establishing new collaborations. In our highly specialized clinical and research environment, collaborations across disciplines can bring about tremendous progress. This special issue was made possible by grants and donations from the National Science Foundation, Amgen, Lilly USA,

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Editorial / Journal of Biomechanics 44 (2011) 211–212

Gwendolen C. Reilly 1 Department of Materials Science and Engineering, The Kroto Research Institute, University of Sheffield, Sheffield, UK E-mail address: g.reilly@sheffield.ac.uk

Medtronics, Musculoskeletal Transplant Foundation, Nature, Simulia and Springer-Verlag.

Maria-Grazia Ascenzi n Orthopaedic Hospital/UCLA Department of Orthopaedic Surgery, University of California, Los Angeles, CA, USA E-mail address: [email protected]

n

Corresponding author. Tel.: + 1 310 825 6341; fax: + 1 310 825 5290.

15 October 2010

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Tel.: + 44 0 114 222 5986; fax: + 44 0 114 222 5943.