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Viscoelasticity of bone can arise from multiple factors related to structures on multiple length scales. [1] Bone is a composite of the bio-polymer collagen and the bio-ceramic hydroxyapatite. Additionally the collagen is plied in various directions around the bone. Bone has two structural forms; cortical and cancellous. [2]
The cortical bone gives bone its smooth, white, and solid appearance, and accounts for 80% of the total bone mass of an adult human skeleton. [10] It facilitates bone's main functions—to support the whole body, to protect organs, to provide levers for movement, and to store and release chemical elements, mainly calcium.
Therefore, their mechanical properties are very important. Mechanical properties of some biomaterials and bone are summarized in Table 1. [2] Among them, hydroxyapatite is most widely studied bioactive and biocompatible material. However, it has lower Young's modulus and fracture toughness with a brittle nature. Hence, it is required to produce ...
Since bone often remodels both its trabecular and cortical structure to optimize strength in the longitudinal direction, the formation of microcracks in human bone are also formed longitudinally. This directionally in human bone contrasts with the more random orientation in bovine bone and lends to longitudinal bone toughness in humans. [10]
Mechanotransduction leading to bone remodeling involves the steps of mechanocoupling, biochemical coupling, signal transmission, and cell response. [7] The specific effects on bone structure depend on the duration, magnitude, and rate of loading, and it has been found that only cyclic loading can induce bone formation. [7]
Diagram of a typical long bone showing both compact (cortical) and cancellous (spongy) bone. Osteons on cross-section of a bone. In osteology, the osteon or haversian system (/ h ə ˈ v ɜːr. ʒ ən /; named for Clopton Havers) is the fundamental functional unit of much compact bone.
The material needed for each application is different, and dependent on the desired mechanical properties of the material. Tissue engineering of long bone defects for example, will require a rigid scaffold with a compressive strength similar to that of cortical bone (100-150 MPa), which is much higher compared to a scaffold for skin regeneration.
Bone tissue is removed by osteoclasts, and then new bone tissue is formed by osteoblasts. Both processes utilize cytokine (TGF-β, IGF) signalling.In osteology, bone remodeling or bone metabolism is a lifelong process where mature bone tissue is removed from the skeleton (a process called bone resorption) and new bone tissue is formed (a process called ossification or new bone formation).