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Radiobiological studies focused mainly on tracking the effects of photons (X and gamma rays) and high-energy charged particles over low energy ions, which raises interest in studying their biological effects. Therefore, the aim of this study is to investigate the interaction of low-energy hydrogen ions beam with xcortical bovine bone as a biological model. A hydrogen ions beam was used to bombard cortical bone with different fluences; 45, 70 and $90\times 10^{17}$ions/cm² at low energy of 5keV. The interaction of hydrogen ions with cortical bone was estimated theoretically by the SRIM/TRIM code. The obtained results showed that the average distribution range and the maximum depth for 5keV hydrogen ions are 91 and 150nm respectively. The energy losses from incident ions are 4.45keV for ionization, 170eV for phonons and 18eV for vacancies. Also, the energy losses from the recoil atoms are 119eV for ionization, 234eV for phonons and 8eV for vacancies. At the same time, the effect of low-energy hydrogen ions bombardment on the structure of bone was studied by X-ray diffraction (XRD) and FTIR.

Bone behaves as a complex composite material, and is highly heterogenous and anisotropic in nature due to its hierarchical structure. The effect of the location and orientation of bone specimens on the viscoelastic properties of bovine femoral cortical bone was examined in this study. The bone samples were extracted from different locations i.e., proximal, central and distal along the direction of longitudinal and transverse and underwent sinusoidal loading. The longitudinal orientation shows more values of loss tangent and loss modulus in comparison to transverse orientation bone samples. Across locations reveal no significant difference in the storage modulus, loss tangent, loss modulus and complex modulus. The trends in the complex and storage moduli remain consistent within both types of orientations. Significant differences were observed across the locations for both storage and recovered energy, with no variance in the hysteresis loss. The findings from the study shall help in a deep understanding of the bone biomechanics, offering insights for material design and orthopedic interventions in biomechanical engineering.

In spite of its importance, the fracture toughness of human bone has been the subject of only a few studies. The objective of the first part of the present work was, thus, to expand this database. For this purpose, linear elastic fracture mechanics (LEFM) principles and single-edge-notched three-point bend specimens were used to determine the fracture toughness of compact bone cut from the tibiae of embalmed cadavers (donor ages between 36 and 94 years). The overall mean and standard deviations of the fracture toughness were 3.12 and 1.21 MP/m, respectively. The case for using LEFM principles, various aspects of four key variables, and the present results are all fully discussed. In the second part of the study, the computed tomography (CT) number of all the specimens were measured. Correlational analysis of all the results demonstrated that CT number exerts a moderately positive influence on fracture toughness for this bone. The clinical significance of this finding is discussed.

Cigarette smoking is commonly recognized for its carcinogenic effects. Clinical studies have found that smoking also increases the risk of stress fracture and decreases the fusion rate during bone healing. Nicotine is the most well-known chemical found in cigarettes, and has been implicated in the debilitating effects of smoking. This study investigated the effect of nicotine and secondhand smoke on the fracture resistance of cortical bone taken from rabbit tibias. Nicotine was delivered via a transdermal nicotine patch and a smoking chamber. There were three groups in this study: the control group, a 5-week nicotine patch group, and a 5-week smoking group. The results of this study showed that rabbits exposed to secondhand smoke for 5 weeks had a significant reduction in cortical bone fracture toughness compared to control rabbits, while the fracture toughness of rabbits exposed to nicotine alone was not significantly different than the fracture toughness of the control group.

Composition-structure-property relations of bone provide fundamental understanding of bone quality. The objective of this paper was to investigate age dependent changes in the composition, structure and mechanical properties of porcine femoral cortical bone at mid-diaphysis region from six age groups (1, 3.5, 6, 12, 30, 48 months). This study was motivated by the fact that limited data is available in the literature on young porcine cortical bone. Nanoindentation technique with Berkovich fluid cell tip was employed to measure the elastic modulus and hardness. Individual lamellae were indented in the longitudinal direction of bone in different microstructural components (osteonal, interstitial and plexiform bone). A grid of indentations was also made on one bone sample to obtain spatial variations in the elastic modulus and hardness. Ash and water content tests were performed to measure water, organic and mineral contents of bone as a function of age. Finally, high resolution micro-computed tomography was used to measure porosity and visualize three-dimensional void structures. We found that the elastic modulus and hardness of bone increased with age but at different rates in each microstructural component. The mineral content increased correspondingly with age while the porosity decreased. The obtained structure, composition, and mechanical properties data give new insights on the age related changes in young cortical bone and can serve as inputs for and validation of multiscale models of bone.

The tensile properties of cortical bone are usually determined with the help of uniaxial tensile test which requires enough amount of bone material. Further, it is very complicated to examine the heterogeneity and anisotropy associated with the deformational properties of cortical bone with the help of uniaxial tensile test. Through this study, small punch testing has been proposed as an alternate technique to evaluate the deformational behavior of cortical bone utilizing optimum amount of bone material. The comparison between elastic modulus values obtained from tensile test and stiffness values obtained through small punch testing was done for validation. The values of these properties were found to be having a significant positive correlation with each other. The effects of bone density and compositional parameters on these properties were also found to be having a similar trend. It is observed through this study that stiffness values from small punch technique are having a similarity with elastic modulus values from uniaxial tensile testing. It is proposed that small punch testing technique can be used as an alternate to examine the deformational behavior of cortical bone.

Bone mechanical behavior varies according to the mechanical loading to which it is subjected, and its response effectiveness mainly depends on its quality. Thus, measuring the indicators controlling the bone quality is required to assess its strength. Indeed, the Finite Element Method (FEM) provides a non-invasive tool to interpret bone quality. Therefore, this work coupled the FEM with a micromechanical law, aiming to provide an exhaustive description of the human bone mechanical behavior. Anisotropy, viscoplasticity and damage were introduced in the material behavior law and the damage evolution was plotted based on the applied loading. Then a sensitivity study was conducted to evaluate the effects of viscoplasticity and damage parameters on bone behavior. The obtained numerical results were in a good agreement with the previously reported experimental data and allowed to distinguish key parameters from non-significant ones. This new computational model provided a better understanding of the main parameters affecting bone behavior.

Cortical bone consists of osteons embedded in interstitial bone tissue and there is a thin amorphous interface, named cement line, between osteon and interstitial bone. Due to fatigue and cyclic loading, the pullout or debonding phenomenon often occurs in osteonal and interstitial tissue bone. The study aims to construct a fiber-reinforced composite material debonding model for cortical bone, in which the bonding condition along the osteon, cement line and interstitial tissue bone are assumed to be imperfect. In the study, we used the complex variable method to obtain series representations for stress fields in the osteon, cement line and the interstitial tissue bone with a radial crack. The effects of material properties of osteon and cement line, crack position, and varying degrees of debonding on the fracture behavior were investigated by computing the stress intensity factor (SIF) in the vicinity of the microcrack tips. The investigation results indicated that the cement line was important for controlling the fracture toughening mechanisms and that the level of imperfect bonding among osteon, cement line and interstitial tissue bone had a pronounced effect on the crack behavior and should not be ignored.

The increase of patients with osteoporosis is becoming a social problem, thus it is an urgent issue to find its prevention and treatment methods. Since cancellous bone is metabolically more active than cortical bone, cancellous bone is often used for diagnosis of osteoporosis and has received much attention within the study of bone. Bone is a hierarchically structured material and its mechanical properties vary at different structural levels, therefore it is important to break down the mechanical testing of bone according to the various levels within bone material. Mechanical properties of cancellous bone is said to be depended on quantities and orientation of trabecular bone. It is supposed that mechanical properties of trabecular bone are constant without depending on any structural arrangement and parts. However, such assumption has not been established in studies of trabecular bone. Furthermore test results have a large margin of error caused by insufficient shape assessment. In this study, three point bending tests of single cancellous bone trabeculae extracted from bovine femur were conducted to evaluate the effects of directions to the femur major axis direction on the mechanical properties. X-ray μCT was used to obtain shape of trabecular bone specimens. Furthermore compression tests of cancellous bone specimens, which were extracted in 10mm cubic geometry, were conducted for evaluation of directional properties.There were small difference in the elastic modulus of the trabecular bones which were extracted in parallel and in perpendicular to the major axis of femur. Considering from the results that the cancellous bone specimens, which were extracted in 10mm cubic geometry, have different elastic properties depending on the tested directions; the bone structure has larger influence than bone material property on the mechanical properties of cancellous bone.

It would be useful to be able to determine the mechanical properties of bone using a noninvasive technique such as computed tomography (CT). However, in contrast to cancellous bone tissue, quantifying the elastic modulus of cortical bone from bone density and CT number has not been investigated extensively. This study measured the elastic moduli of cortical bone from eight bovine femora in the longitudinal, circumferential, and radial directions using mechanical compressive testing. Before testing, the CT number and wet apparent bone density were obtained. The experimentally determined coefficient of determination between CT number and bone density was around 0.6. Bone density was a good predictor of the elastic modulus of cortical bone in the longitudinal direction (r² > 0.79), but it could not be used to predict the elastic moduli in the circumferential (r² < 0.4) and radial (r² < 0.22) directions. The coefficient of determination between CT number and the elastic modulus in the longitudinal direction was higher than 0.41. However, the correlations between CT number and elastic moduli were weak in the circumferential (r² < 0.21) and radial (r² < 0.19) directions. Moreover, the elastic modulus was much higher in the longitudinal direction than the circumferential and radial directions, and hence cortical bone can be considered a transversely isotropic property.