Download or read book Effect of Aging on the Toughness of Human Cortical Bone written by and published by . This book was released on 2004 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Age-related deterioration of the fracture properties of bone, coupled with increased life expectancy, are responsible for increasing incidence of bone fracture in the elderly, and hence, an understanding of how its fracture properties degrade with age is essential. The present study describes ex vivo fracture experiments to quantitatively assess the effect of aging on the fracture toughness properties of human cortical bone in the longitudinal direction. Because cortical bone exhibits rising crack-growth resistance with crack extension, unlike most previous studies the toughness is evaluated in terms of resistance-curve (R-curve) behavior, measured for bone taken from wide range of age groups (34-99 years). Using this approach, both the ex vivo crack-initiation and crack-growth toughness are determined and are found to deteriorate with age; the initiation toughness decreases some 40% over six decades from 40 to 100 years, while the growth toughness is effectively eliminated over the same age range. The reduction in crack-growth toughness is considered to be associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging in the wake of the crack.

Download or read book Bioinspired Structures and Design written by Wole Soboyejo and published by Cambridge University Press. This book was released on 2020-09-17 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master simple to advanced biomaterials and structures with this essential text. Featuring topics ranging from bionanoengineered materials to bio-inspired structures for spacecraft and bio-inspired robots, and covering issues such as motility, sensing, control and morphology, this highly illustrated text walks the reader through key scientific and practical engineering principles, discussing properties, applications and design. Presenting case studies for the design of materials and structures at the nano, micro, meso and macro-scales, and written by some of the leading experts on the subject, this is the ideal introduction to this emerging field for students in engineering and science as well as researchers.

Download or read book Anisotropic Changes in Fracture Toughness of Aging Human Cortical Bone written by Jennifer Rebecca Zuba and published by . This book was released on 2006 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Age related Changes in the Plasticity and Toughness of Human Cortical Bone at Multiple Length scales written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen and hydroxyapatite at the nanoscale to osteonal structures at nearmillimeter dimensions, which all provide the basis for its mechanical properties. To resist fracture, bone's toughness is derived intrinsically through plasticity (e.g., fibrillar sliding) at structural-scales typically below a micron and extrinsically (i.e., during crack growth) through mechanisms (e.g., crack deflection/bridging) generated at larger structural-scales. Biological factors such as aging lead to a markedly increased fracture risk, which is often associated with an age-related loss in bone mass (bone quantity). However, we find that age-related structural changes can significantly degrade the fracture resistance (bone quality) over multiple lengthscales. Using in situ small-/wide-angle x-ray scattering/diffraction to characterize sub-micron structural changes and synchrotron x-ray computed tomography and in situ fracture-toughness measurements in the scanning electron microscope to characterize effects at micron-scales, we show how these age-related structural changes at differing size-scales degrade both the intrinsic and extrinsic toughness of bone. Specifically, we attribute the loss in toughness to increased non-enzymatic collagen cross-linking which suppresses plasticity at nanoscale dimensions and to an increased osteonal density which limits the potency of crack-bridging mechanisms at micron-scales. The link between these processes is that the increased stiffness of the cross-linked collagen requires energy to be absorbed by?plastic? deformation at higher structural levels, which occurs by the process of microcracking.

Download or read book Aging and Fracture of Human Cortical Bone and Tooth Dentin written by and published by . This book was released on 2008 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mineralized tissues, such as bone and tooth dentin, serve as structural materials in the human body and, as such, have evolved to resist fracture. In assessing their quantitative fracture resistance or toughness, it is important to distinguish between intrinsic toughening mechanisms which function ahead of the crack tip, such as plasticity in metals, and extrinsic mechanisms which function primarily behind the tip, such as crack bridging in ceramics. Bone and dentin derive their resistance to fracture principally from extrinsic toughening mechanisms which have their origins in the hierarchical microstructure of these mineralized tissues. Experimentally, quantification of these toughening mechanisms requires a crack-growth resistance approach, which can be achieved by measuring the crack-driving force, e.g., the stress intensity, as a function of crack extension ("R-curve approach"). Here this methodology is used to study of the effect of aging on the fracture properties of human cortical bone and human dentin in order to discern the microstructural origins of toughness in these materials.

Download or read book Strength of Biological Materials written by Hiroshi Yamada and published by . This book was released on 1970 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Compositional and Physicochemical Heterogeneity on Age related Fragility of Human Cortical Bone written by Janardhan Srinivas Yerramshetty and published by . This book was released on 2006 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt: The progressive loss of bone with age very commonly leads to osteoporosis, a condition characterized by increased skeletal fragility. Osteoporosis and its consequences are significant causes of frailty, morbidity, and even mortality. While reduced bone mass, currently used in estimating fragility, enhances risk of fracture, low bone mass alone is not a sufficient explanation for osteoporotic or elderly fractures. This is exemplified by substantial overlap in bone density between normal individuals and patients who sustain hip and other osteoporotic fractures. A new perspective, in addition to bone mass, is needed that broadens the conceptual basis of skeletal integrity. Bone is studied at various levels starting from ultrastructural and chemical to histological and structural properties with the ultimate goal being prediction of bone strength accurately. Researchers used photon absorptiometry and CT scan techniques to predict fractures in elderly people believing bone mineral density is a major determinant of bone strength. However, later many researchers are convinced that other factors, such as bone quality, also contribute significantly to bone strength. Consequently, the proposed study investigated heterogeneity of compositional, physicochemical and micro-structural properties, and related them to mechanical properties. Raman spectroscopy was used to characterize distribution of mineralization, crystallinity and carbonation from gage regions of tensile specimens, which were bio-mechanically tested afterwards. Using linear polarized light, collagen fiber orientation and microstructures were determined from sections close to the fracture surface. Results indicated that distribution of mineralization became more uniform with age, which benefited stiffness and strength at the expense of deformation of bone. Moreover, fatigue life was improved and modulus degradation rate was decreased. Volume fractions of highly mineralized locations increased and spacing between them were reduced with age, which improved monotonic properties but proved unfavorable with respect to fatigue properties. Bigger osteons, porosity and transversely oriented collagen fibers largely found in elderly individuals considerably reduced strength of bone. Transverse collagen fiber orientation also decreased fatigue life. In conclusion, ultra and micro level changes in bone can be supplementary to BMD measures for better clinical assessment of age-related bone's fragility; however, their predictive power is limited and depends on anatomical location.

Download or read book The Deformation and Fracture of Human Cortical Bone Across Multiple Length scales written by Elizabeth Ann Zimmermann and published by . This book was released on 2011 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: The complex structure of human cortical bone evolves over multiple length-scales from its basic constituents of collagen molecules and hydroxyapatite crystals at the nanoscale to the osteonal structures at near-millimeter dimensions. There is a need to understand how all levels of the structure contribute to the deformation and fracture resistance of cortical bone under physiological loading conditions and how structural changes due to aging and disease lead to diminished mechanical properties. The first part of this thesis addresses the latter by using non-enzymatic crosslinking measurements and in situ small- and wide-angle x-ray scattering/diffraction to characterize changes in the bone structure at sub-micron dimensions, while synchrotron x-ray computed micro-tomography and in situ fracture-toughness measurements in the scanning electron microscope were performed to characterize corresponding changes at micron-scale dimensions. This multi-scale analysis allows us to better understand how load is transferred across multiple length-scales and how biological aging impacts energy absorption throughout the structure. The second part of this thesis addresses the fracture toughness of human cortical bone under multiaxial loading. Most studies to date have only considered the toughness of bone under mode I (tensile) loading conditions; however, due to the complex, anisotropic structure of cortical bone, the mode I fracture toughness is not necessarily the limiting value. Thus, this research investigates the effects of combined tensile and shear loading at the crack tip on the initiation and crack-growth toughnesses to better understand how bone fractures under physiologically relevant loading conditions.

Download or read book Fundamentals of Fracture Mechanics written by John Frederick Knott and published by Gruppo Italiano Frattura. This book was released on 1973 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Skeletal Aging and Osteoporosis written by Matthew J. Silva and published by Springer Science & Business Media. This book was released on 2012-08-30 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this book is on mechanical aspects of skeletal fragility related to aging and osteoporosis. Topics include: Age-related changes in trabecular structure and strength; age-related changes in cortical material properties; age-related changes in whole-bone structure; predicting bone strength and fracture risk using image-based methods and finite element analysis; animal models of osteoporosis and aging; age-related changes in skeletal mechano responsiveness; exercise and physical interventions for osteoporosis.

Download or read book Geriatric Gastroenterology written by C. S. Pitchumoni and published by Springer Science & Business Media. This book was released on 2012-07-26 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt: As aging trends in the United States and Europe in particular are strongly suggestive of increasingly older society, it would be prudent for health care providers to better prepare for such changes. By including physiology, disease, nutrition, pharmacology, pathology, radiology and other relevant associated topics, Geriatric Gastroenterology fills the void in the literature for a volume devoted specifically to gastrointestinal illness in the elderly. This unique volume includes provision of training for current and future generations of physicians to deal with the health problems of older adults. It will also serve as a comprehensive guide to practicing physicians for ease of reference. Relevant to the geriatric age group, the volume covers epidemiology, physiology of aging, gastrointestinal physiology, pharmacology, radiology, pathology, motility disorders, luminal disorders, hepato-biliary disease, systemic manifestations, neoplastic disorders, gastrointestinal bleeding, cancer and medication related interactions and adverse events, all extremely common in older adults; these are often hard to evaluate and judge, especially considering the complex aging physiology. All have become important components of modern medicine. Special emphasis is be given to nutrition and related disorders. Capsule endoscopy and its utility in the geriatric population is also covered. Presented in simple, easy to read style, the volume includes numerous tables, figures and key points enabling ease of understanding. Chapters on imaging and pathology are profusely illustrated. All chapters are written by specialists and include up to date scientific information. Geriatric Gastroenterology is of great utility to residents in internal medicine, fellows in gastroenterology and geriatric medicine as well as gastroenterologists, geriatricians and practicing physicians including primary care physicians caring for older adults.

Download or read book The Effect of Age and Gender on the Kinetics of Fatigue Crack Propagation of Human Cortical Bone written by Allison Marie Stawarz and published by . This book was released on 2002 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bone Health and Osteoporosis written by United States Public Health Service and published by . This book was released on 2004-12 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first-ever Surgeon General's Report on bone health and osteoporosis illustrates the large burden that bone disease places on our Nation and its citizens. Like other chronic diseases that disproportionately affect the elderly, the prevalence of bone disease and fractures is projected to increase markedly as the population ages. If these predictions come true, bone disease and fractures will have a tremendous negative impact on the future well-being of Americans. But as this report makes clear, they need not come true: by working together we can change the picture of aging in America. Osteoporosis, fractures, and other chronic diseases no longer should be thought of as an inevitable part of growing old. By focusing on prevention and lifestyle changes, including physical activity and nutrition, as well as early diagnosis and appropriate treatment, Americans can avoid much of the damaging impact of bone disease and other chronic diseases. This Surgeon General's Report brings together for the first time the scientific evidence related to the prevention, assessment, diagnosis, and treatment of bone disease. More importantly, it provides a framework for moving forward. The report will be another effective tool in educating Americans about how they can promote bone health throughout their lives. This first-ever Surgeon General's Report on bone health and osteoporosis provides much needed information on bone health, an often overlooked aspect of physical health. This report follows in the tradition of previous Surgeon Generals' reports by identifying the relevant scientific data, rigorously evaluating and summarizing the evidence, and determining conclusions.

Download or read book Fragility Fracture Nursing written by Karen Hertz and published by Springer. This book was released on 2018-06-15 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book aims to provide a comprehensive but practical overview of the knowledge required for the assessment and management of the older adult with or at risk of fragility fracture. It considers this from the perspectives of all of the settings in which this group of patients receive nursing care. Globally, a fragility fracture is estimated to occur every 3 seconds. This amounts to 25 000 fractures per day or 9 million per year. The financial costs are reported to be: 32 billion EUR per year in Europe and 20 billon USD in the United States. As the population of China ages, the cost of hip fracture care there is likely to reach 1.25 billion USD by 2020 and 265 billion by 2050 (International Osteoporosis Foundation 2016). Consequently, the need for nursing for patients with fragility fracture across the world is immense. Fragility fracture is one of the foremost challenges for health care providers, and the impact of each one of those expected 9 million hip fractures is significant pain, disability, reduced quality of life, loss of independence and decreased life expectancy. There is a need for coordinated, multi-disciplinary models of care for secondary fracture prevention based on the increasing evidence that such models make a difference. There is also a need to promote and facilitate high quality, evidence-based effective care to those who suffer a fragility fracture with a focus on the best outcomes for recovery, rehabilitation and secondary prevention of further fracture. The care community has to understand better the experience of fragility fracture from the perspective of the patient so that direct improvements in care can be based on the perspectives of the users. This book supports these needs by providing a comprehensive approach to nursing practice in fragility fracture care.

Download or read book Studies on Age related Changes in Human Cortical Bone written by Edward Donald Simmons and published by . This book was released on 1986 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Juvenile Skeleton written by Louise Scheuer and published by Elsevier. This book was released on 2004-04-02 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: The identification of even the smallest human fetal bone can be vital to the success of a criminal investigation or to the identification of the deceased. This book examines every bone in the human body from its earliest embryological stage through to maturity and is profusely illustrated with superb bone drawings at every stage of development. The ability to identify every component of the developing skeleton is of core relevance not only to the forensic profession but also to clinicians, skeletal biologists and physical anthropologists. Identifies every component of the developing skeleton Provides detailed analysis of juvenile skeletal remains and the development of bone as a tissue Summarizes key morphological stages in the development of every bone

Download or read book Effects of Age and Estrogen on Fatigue induced Repair of Cortical Bone written by John R. Marble and published by . This book was released on 2007 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: