Cancellous Bone
The metabolism of the cancellous bone is more active than cortical bone due to the dependence of bone turnover on the surface area. This led to bone loss, as usually found in the vertebrae of patients with post-menopausal osteoporosis. Bone remodeling pro
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Cancellous Bone
The metabolism of the cancellous bone is more active than cortical bone due to the dependence of bone turnover on the surface area. This led to bone loss, as usually found in the vertebrae of patients with post-menopausal osteoporosis. Bone remodeling process as described by Frost [20] more than a half of century ago had helped many specialists and researchers to better understand the progress of osteoporosis (see Chap. 1). Cancellous bone architecture is highly heterogeneous [11, 28–30], anisotropic and skeletally site-dependent due to the difference in external mechanical stimuli [6–9]. Therefore, the mechanical properties of cancellous bone vary according to the level of physical activities [31] of individuals as well as of the bone itself [6–8]. Due to the complexity of cancellous bone structure, modes of failures are very difficult to predict and the correlation in between the morphology and failure mode is staggeringly complicated. The permeability of cancellous bone guarantees efficient transport of nutrients through the porous structure. Furthermore, permeability is also important in the studies of bone fusion, cementing techniques, and tissue engineering scaffold. Several factors that influence permeability of the cancellous structures are porosity, architecture, mechanical properties, and viscosity [80, 82–84]. Nauman et al. [80] describes that the intertrabecular permeability depends primarily on the flow direction relative to the principal trabecular orientation as well as anatomic site, and was less dependent on volume fraction.
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Physiology
Bone is a complex organ which plays a major role in movement, protection, support, mineral storage, and formation of blood cells in a human body [32]. Bone tissue can be divided into two types of different apparent density; cortical or compact bone (high density), and trabecular or porous bone (low density) as shown © Springer Nature Singapore Pte Ltd. 2018 A. Syahrom et al., Cancellous Bone, Advanced Structured Materials 82, DOI 10.1007/978-981-10-5472-3_2
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Cancellous Bone
Fig. 2.1 Bone structure at different length scale in hierarchical order
in Fig. 2.1. Both cortical and trabecular bone have different loading adaptation upon physiological activities and across skeletal sites, thus contributing in different mechanical properties. Compact bone tissue is developed by Harversian systems in which is known to resist the mechanical shock. In human body, cortical bone makes up for about 80% of total bone mass. On the other hand, trabecular tissue imparts strength which holds marrow, a substance involved in producing blood cells. Stresses in bone signal the osteoblasts to deposit minerals more than osteoclasts withdrawals resulting in denser and stronger bone. However, mineral withdrawals prevail in injured bones. Furthermore, as people aged, physical activities are less, the formation of bone cells declines, calcium is lost, protein is over-consumed, and sex hormone is deficient. All these are the contributing factors of osteoporosis [32]
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