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lCT cross-sectional images of a the intact and b regenerating bone for which nanoindentation analysis was performed. Only the mineralized regions are shown. Indents were placed on the ulna near the neighboring radius in the intact site and the newly formed bone in the regenerating site, as indicated by white circles. The scale bar corresponds to 1 mm
Source publication
It is crucial to measure the mechanical function of regenerating bone in order to assess the mechanical performance of the regenerating portion as well as the efficiency of the regeneration methods. In this study, nanoindentation was applied to regenerating and intact rabbit ulnae to determine the material properties of hardness and elasticity; vis...
Contexts in source publication
Context 1
... of the unloading curve from 50 to 95% of the maximum load was used for determining S [34] by fitting with a power function [21]. For each load hold condition, indentation was carried out 5 times along the long bone axis, and the mechanical parameters were averaged. All indentation points were located on the mineralized region of the intact ulna (Fig. 1a) and regenerating bone (Fig. 1b) near the radius, as determined from the lCT image. Osteocyte lacunae were avoided by observation using a CCD microscope attached to the nanoindentation ...
Context 2
... to 95% of the maximum load was used for determining S [34] by fitting with a power function [21]. For each load hold condition, indentation was carried out 5 times along the long bone axis, and the mechanical parameters were averaged. All indentation points were located on the mineralized region of the intact ulna (Fig. 1a) and regenerating bone (Fig. 1b) near the radius, as determined from the lCT image. Osteocyte lacunae were avoided by observation using a CCD microscope attached to the nanoindentation ...
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... Statistical Package for Social Study (SPSS) version 14.0J software (SPSS Japan Inc., Tokyo, Japan) for Microsoft Windows was used for all statistical analyses. Figure 1 shows the lCT images of the intact and regenerating bone taken at the cross-section at which the nanoindentation measurements were performed. In the defect, there were very small amounts of mineralized bone tissue only along the radius at 2 weeks postoperatively. ...
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... were performed. In the defect, there were very small amounts of mineralized bone tissue only along the radius at 2 weeks postoperatively. The BMD of the regenerating bone (430 mg/cm 3 ) was much lower than that of the intact bone (1,040 mg/cm 3 ). Conventional mechanical tests could not be conducted for the newly formed portion. The circles in Fig. 1 indicate the location at which the nanoindentation measurements were performed. Figure 2 shows the typical nanoindentation load-depth curves obtained along the longitudinal axis for the intact bone with and without a load hold at the maximum load. Without the load hold, an overhanging portion, indicated by the arrow in Fig. 2, appeared ...
Context 5
... of the unloading curve from 50 to 95% of the maximum load was used for determining S [34] by fitting with a power function [21]. For each load hold condition, indentation was carried out 5 times along the long bone axis, and the mechanical parameters were averaged. All indentation points were located on the mineralized region of the intact ulna (Fig. 1a) and regenerating bone (Fig. 1b) near the radius, as determined from the lCT image. Osteocyte lacunae were avoided by observation using a CCD microscope attached to the nanoindentation ...
Context 6
... to 95% of the maximum load was used for determining S [34] by fitting with a power function [21]. For each load hold condition, indentation was carried out 5 times along the long bone axis, and the mechanical parameters were averaged. All indentation points were located on the mineralized region of the intact ulna (Fig. 1a) and regenerating bone (Fig. 1b) near the radius, as determined from the lCT image. Osteocyte lacunae were avoided by observation using a CCD microscope attached to the nanoindentation ...
Context 7
... Statistical Package for Social Study (SPSS) version 14.0J software (SPSS Japan Inc., Tokyo, Japan) for Microsoft Windows was used for all statistical analyses. Figure 1 shows the lCT images of the intact and regenerating bone taken at the cross-section at which the nanoindentation measurements were performed. In the defect, there were very small amounts of mineralized bone tissue only along the radius at 2 weeks postoperatively. ...
Context 8
... were performed. In the defect, there were very small amounts of mineralized bone tissue only along the radius at 2 weeks postoperatively. The BMD of the regenerating bone (430 mg/cm 3 ) was much lower than that of the intact bone (1,040 mg/cm 3 ). Conventional mechanical tests could not be conducted for the newly formed portion. The circles in Fig. 1 indicate the location at which the nanoindentation measurements were performed. Figure 2 shows the typical nanoindentation load-depth curves obtained along the longitudinal axis for the intact bone with and without a load hold at the maximum load. Without the load hold, an overhanging portion, indicated by the arrow in Fig. 2, appeared ...
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Citations
... Larger grain sizes have flatter surfaces and low surface roughness [23]. Regenerating bone has been found to possess a lower E value than mature bone [24]. These results suggest that the degree of bone mineralization increases with age and that bone strength increases as an individual matures from infancy to adulthood [23]. ...
Background and Aim
Captivity alters the locomotor behavior of wild artiodactyls and affects the mechanical loading of the calcaneus; however, the resulting adaptive changes in calcaneus morphology have not been sufficiently studied to date. This study aimed to investigate the morphological and mechanical adaptive variations in the calcaneus of Saiga tatarica to understand further the functional adaptation of the calcaneus in wild artiodactyl to captivity.
Materials and Methods
Paired calcanei from autopsy samples of six captive wild artiodactyls (S. tatarica) and six domesticated artiodactyls (Ovis aries) were divided into skeletally immature and mature groups using X-ray evaluation of growth plate closure. High-resolution microcomputed tomography revealed a calcaneal diaphyseal cross-section. The mechanical and nanomorphological characteristics of the trabecular bone were determined by atomic force microscopy.
Results
The percent cortical bone area (%CA), cortical thickness ratio (CTR), and Young’s modulus (E) differed between species in the immature groups but not in the mature groups. S. tatarica had significantly higher growth rates for %CA, CTR, and E in the mid-shaft than O. aries (p < 0.05).
Conclusion
The calcaneus morphology of S. tatarica converges with that of domesticated O. aries during ontogeny. These results indicate that the calcaneus of wild artiodactyls can undergo potentially transitional changes during the short-term adaptation to captivity. The above parameters can be preliminarily identified as morphological signs of functional bone adaptation in artiodactyls.
... After the samples were dried, Young's modulus was measured along the ulnar longitudinal direction using a nanoindentation system (ENT-1100a; Elionix, Tokyo, Japan) with a Berkovich diamond indenter at 25 • C, as described in a previous study [26]. Five indentations were created on the medial region within 50 μm from the periosteal surface, in which the μXRD analysis was performed, and the results were averaged. ...
... The loading/unloading rate and maximum load were 400 μN/ s and 6000 μN, respectively. A constant maximum load was held for 180 s before unloading to minimize the effects of the viscoelastic behavior of bone [26]. All measurements included a second constant load held for 30 s at 10 % of the maximum load to establish the thermal drift rate and obtain the correct data. ...
... Bone biomechanics can assess the mechanical properties of bone tissues using external forces and facilitate the analysis of bone fracture possibilities in load states (Ishimoto et al., 2011). To assess the effect of different calcium supplements on improving bone strength, the mechanical properties of the femurs were evaluated using a three-point bending method, measuring the maximum load and maximum stress. ...
The low-calcium-specific pathogen-free C57BL/6 (SPF–C57BL/6) mice were used to explore the effectiveness of phosvitin phosphopeptides (PPPs) and eggshell membrane peptides (EMPs) in improving the intestinal calcium absorption and promoting bone deposition of eggshell calcium (ESCa). Intake of ESCa + PPPs + EMPs significantly down regulated the abnormal elevation of serum alkaline phosphatase (ALP) induced by calcium deficiency. The CaCO3 group had lower calcium absorption rate (34.34%) and femur bone mineral density (BMD) (0.13 g/cm³), while the ESCa + PPPs + EMPs treatment significantly improved calcium absorption rate (55.01%) and femur BMD (0.15 g/cm³). The three-dimensional reconstruction images of mice femur showed that the ESCa + PPPs + EMPs group had a more complete, compact, and thicker trabecular structure than the low-calcium, CaCO3, and ESCa groups. These results indicated that the ESCa is a low-cost alternative calcium supplement to achieve adequate calcium intake, and the presence of polypeptides, such as PPPs and EMPs, is more beneficial to calcium absorption and deposition than the ESCa.
... Embedded humeral bone specimens were cut transversely at the longitudinal center, and their surfaces were ground and mirror-polished. Load-depth measurements were carried out according to the established conditions [36]. Young's modulus and hardness were determined using the method described by Oliver and Pharr [37]. ...
Introduction:
Osteoblasts require substantial amounts of energy to synthesize the bone matrix and coordinate skeleton mineralization. This study analyzed the effects of mitochondrial dysfunction on bone formation, nano-organization of collagen and apatite, and the resultant mechanical function in mouse limbs.
Materials and methods:
Limb mesenchyme-specific Tfam knockout (Tfamf/f;Prx1-Cre: Tfam-cKO) mice were analyzed morphologically and histologically, and gene expressions in the limb bones were assessed by in situ hybridization, qPCR, and RNA sequencing (RNA-seq). Moreover, we analyzed the mitochondrial function of osteoblasts in Tfam-cKO mice using mitochondrial membrane potential assay and transmission electron microscopy (TEM). We investigated the pathogenesis of spontaneous bone fractures using immunohistochemical analysis, TEM, birefringence analyzer, microbeam X-ray diffractometer and nanoindentation.
Results:
Forelimbs in Tfam-cKO mice were significantly shortened from birth, and spontaneous fractures occurred after birth, resulting in severe limb deformities. Histological and RNA-seq analyses showed that bone hypoplasia with a decrease in matrix mineralization was apparent, and the expression of type I collagen and osteocalcin was decreased in osteoblasts of Tfam-cKO mice, although Runx2 expression was unchanged. Decreased type I collagen deposition and mineralization in the matrix of limb bones in Tfam-cKO mice were associated with marked mitochondrial dysfunction. Tfam-cKO mice bone showed a significantly lower Young's modulus and hardness due to poor apatite orientation which is resulted from decreased osteocalcin expression.
Conclusion:
Mice with limb mesenchyme-specific Tfam deletions exhibited spontaneous limb bone fractures, resulting in severe limb deformities. Bone fragility was caused by poor apatite orientation owing to impaired osteoblast differentiation and maturation.
... Moreover, ultrasound cannot penetrate the cortex of mature bone, and the limb line of force is not intuitive enough to be presented either (Eyres et al., 1993). Biomechanical testing is usually considered for laboratory fundamental research (Floerkemeier et al., 2005;Ishimoto et al., 2011). Nevertheless, X-ray is the most common choice for being inexpensive and convenient. ...
Background: Distraction osteogenesis (DO) is an approach for bone lengthening and reconstruction. The pixel value ratio (PVR), an indicator calculated from X-ray images, is reported to assess the final timing for the external fixator removal. However, the early PVR and its potential influencing factors and the relationship between the early PVR and clinical outcomes are rarely discussed. Therefore, this study was employed to address these issues.
Methods: A total of 125 patients with bone lengthening were investigated retrospectively. The early PVR of regenerated bone was monitored in the first 3 months after osteotomy. The potential effect of sex, chronological age, BMI, lengthening site, and involvement of internal fixation during the consolidation period was analyzed. Moreover, the associations of the healing index (HI) and lengthening index (LI) with early PVR were also investigated.
Results: The early PVRs were 0.78 ± 0.10, 0.87 ± 0.06, and 0.93 ± 0.06 in the first 3 months after osteotomy, respectively. Moreover, the PVR in juvenile was significantly higher than that in adults in the first 3 months after osteotomy (0.80 ± 0.09 vs. 0.74 ± 0.10; p = 0.008), (0.89 ± 0.06 vs. 0.83 ± 0.06; p = 0.018), and (0.94 ± 0.05 vs. 0.87 ± 0.05; p = 0.003). In addition, the PVR in males was significantly higher than that in females in the first month after osteotomy (0.80 ± 0.09 vs. 0.76 ± 0.10; p = 0.015), and the PVR in femur site was significantly higher than that in the tibia site in the second and third months after osteotomy (0.88 ± 0.07 vs. 0.87 ± 0.06; p = 0.015) and (0.93 ± 0.06 vs. 0.92 ± 0.06, p = 0.037). However, the BMI and involvement of the internal fixator during the consolidation period seem to not influence the early PVR of regenerated callus during DO. Interestingly, the early PVR seems to be moderately inversely associated with HI (mean = 44.98 ± 49.44, r = -0.211, and p = 0.029) and LI (mean = 0.78 ± 0.77, r = -0.210, and p = 0.029), respectively.
Conclusion: The early PVR is gradually increasing in the first 3 months after osteotomy, which may be significantly influenced by chronological age, sex, and the lengthening site. Moreover, the early PVR of callus may reflect the potential clinical outcome for DO. Our results may be beneficial to the clinical management of the subjects with bone lengthening.
... Bones with a strongly oriented collagen/apatite structure exhibit high anisotropy in Young's modulus [9], yield stress [10], and ultimate stress [9,11]. On the contrary, bones with poorly oriented collagen/apatite structures, including regenerating bones [12,13], are found to be isotropic and exhibit a low Young's modulus [14]. Recent studies have shown that collagen/apatite preferential orientation is an indicator of bone health [15]; it is thus important to elucidate the factors controlling collagen/apatite orientation to establish innovative diagnostic and therapeutic strategies for strengthening bones. ...
... Mechanical adaptation of the bone has attracted considerable attention in the past few decades. In recent years, it has become clear that not only bone volume and shape but also bone quality, such as collagen/apatite orientation, undergo a functional adaptation to external mechanical stimuli [3][4][5][6]13,14]. In this study, we established an ex vivo bone culture model that enabled the artificial regulation of static uniaxial loading and successfully induced the mechanical adaptation of the bone microstructure via the mechano-sensitivity of osteocytes. ...
The anisotropic microstructure of bone, composed of collagen fibers and biological apatite crystallites, is an important determinant of its mechanical properties. Recent studies have revealed that the preferential orientation of collagen/apatite composites is closely related to the direction and magnitude of in vivo principal stress. However, the mechanism of alteration in the collagen/apatite microstructure to adapt to the mechanical environment remains unclear. In this study, we established a novel ex vivo bone culture system using embryonic mouse femurs, which enabled artificial control of the mechanical environment. The mineralized femur length significantly increased following cultivation; uniaxial mechanical loading promoted chondrocyte hypertrophy in the growth plates of embryonic mouse femurs. Compressive mechanical loading using the ex vivo bone culture system induced a higher anisotropic microstructure than that observed in the unloaded femur. Osteocytes in the anisotropic bone microstructure were elongated and aligned along the long axis of the femur, which corresponded to the principal loading direction. The ex vivo uniaxial mechanical loading successfully induced the formation of an oriented collagen/apatite microstructure via osteocyte mechano-sensation in a manner quite similar to the in vivo environment.
... Five indentations were created, and the results were averaged. Load-depth measurements were performed on the specimen surface in accordance with the established conditions [29]. Briefly, the loading/unloading rate and maximum ...
... load were 400 μN/s and 6000 μN, respectively. To minimize the effects of the viscoelastic deformation behavior of the bone, which could help to prevent overestimation of the mechanical properties, a constant maximum load was held for 180 s before unloading [29]. All measurements also included a second constant load held for 30 s at 600 μN to establish the thermal drift rate and correct the data. ...
Bone material quality is important for evaluating the mechanical integrity of diseased and/or medically treated bones. However, compared to the knowledge accumulated regarding changes in bone mass, our understanding of the quality of bone material is lacking. In this study, we clarified the changes in bone material quality mainly characterized by the preferential orientation of the apatite c-axis associated with estrogen deficiency-induced osteoporosis, and their prevention using ibandronate (IBN), a nitrogen-containing bisphosphonate. IBN effectively prevented bone loss and degradation of whole bone strength in a dose-dependent manner. The estrogen-deficient condition abnormally increased the degree of apatite orientation along the craniocaudal axis in which principal stress is applied; IBN at higher doses played a role in maintaining the normal orientation of apatite but not at lower doses. The bone size-independent Young's modulus along the craniocaudal axis of the anterior cortical shell of the vertebra showed a significant and positive correlation with apatite orientation; therefore, the craniocaudal Young’s modulus abnormally increased under estrogen-deficient conditions, despite a significant decrease in volumetric bone mineral density. However, the abnormal increase in craniocaudal Young's modulus did not compensate for the degradation of whole bone mechanical properties due to the bone loss. In conclusion, it was clarified that changes in the material quality, which are hidden in bone mass evaluation, occur with estrogen deficiency-induced osteoporosis and IBN treatment. Here, IBN was shown to be a beneficial drug that suppresses abnormal changes in bone mechanical integrity caused by estrogen deficiency at both the whole bone and material levels.
... Recently, some novel techniques have been reported to evaluate the biomechanical properties of bone, such as micron indentation and nanoindentation technology. These technologies can be utilized to evaluate the hardness of regenerated bone [75]. By placing a tapered diamond probe hardness tester on a smooth bone surface with a preset time and load, the hardness value changes with the dynamics of the indentation depth. ...
The manual monitoring of callus with digital radiography (X-ray) is the primary bone healing evaluation, assessing the number of bridged callus formations. However, this method is subjective and nonquantitative. Recently, several quantitative monitoring methods, which could assess the recovery of the structure and biomechanical properties of the callus at different stages and the process of bone healing, have been extensively investigated. These methods could reflect the bone mineral content (BMC), bone mineral density (BMD), stiffness, callus and bone metabolism at the site of bone lengthening. In this review, we comprehensively summarized the latest techniques for evaluating bone healing during distraction osteogenesis (DO): 1) digital radiography; 2) dual-energy X-ray scanning; 3) ultrasound; 4) quantitative computed tomography; 5) biomechanical evaluation; and 6) biochemical markers. This evidence will provide novel and significant information for evaluating bone healing during DO in the future.
... linear elastic material model for all tissues in the dual-zone model. The use of linear elastic models for bone is widespread common practice in finite-element modeling of bone, but cortical bone exhibits anisotropy particularly with respect to its strength and post-yield behavior 34,35 and the soft tissues present in early fracture healing can have viscoelastic or poroelastic behavior [36][37][38][39] . The mechanical testing data for this study used a constant loading rate (5°/min) and produced linear torque-angle response curves 12 . ...
Bone fractures commonly repair by forming a bridging structure called callus, which begins as soft tissue and gradually ossifies to restore rigidity to the bone. Virtual mechanical testing is a promising technique for image-based assessment of structural bone healing in both preclinical and clinical settings, but its accuracy depends on the validity of the material model used to assign tissue mechanical properties. The goal of this study was to develop a constitutive model for callus that captures the heterogeneity and biomechanical duality of the callus, which contains both soft tissue and woven bone. To achieve this, a large-scale optimization analysis was performed on 2363 variations of 3D finite element models derived from computed tomography (CT) scans of 33 osteotomized sheep under normal and delayed healing conditions. A piecewise material model was identified that produced high absolute agreement between virtual and physical tests by differentiating between soft and hard callus based on radiodensity. The results showed that the structural integrity of a healing long bone is conferred by an internal architecture of mineralized hard callus that is supported by interstitial soft tissue. These findings suggest that with appropriate material modeling, virtual mechanical testing is a reliable surrogate for physical biomechanical testing.
... The Young's modulus of the specimen was measured along the craniocaudal axis for the L4 vertebra and the longitudinal axis for the tibia using a nanoindentation system (ENT-1100a; Elionix, Tokyo, Japan) with a Berkovich diamond indenter. Load-depth measurements were performed according to the established condition [42], and Young's modulus was calculated using the method of Oliver and Pharr [43]. Poisson's ratio of bone was assumed to be 0.3, and the region between 95% and 50% of the maximum load was used to calculate the slope of the unloading curve. ...
... In particular, ELD is a vitamin D 3 analog; therefore, different 7. Effect of drug administration on osteocyte condition. The ratio of normal osteocytes (other than atypical osteocytes) to total osteocytes were counted according to osteocyte morphology observed by bright-field images [42]. Arrowheads in the images indicate atypical osteocytes (S: lacuna with shrunken osteocyte, E: empty lacunae, P: osteocyte with pyknotic nuclei). ...
Combination therapy with bisphosphonates and vitamin D3 analogs has been frequently used for the treatment of osteoporosis. However, its effects on bone anisotropies, such as orientations of collagen and apatite at the nanometer-scale, which is a promising bone quality index, and its trabecular architecture at the micrometer scale, are not well understood despite its important mechanical properties and its role in fracture risk. In the present study, we analyzed the effects of ibandronate (IBN), eldecalcitol (ELD), and their combination on the collagen/apatite orientation and trabecular architectural anisotropy using an estrogen-deficiency-induced osteoporotic rat model. Estrogen deficiency caused by ovariectomy (OVX) excessively increased the degree of collagen/apatite orientation or trabecular architectural anisotropy along the craniocaudal axis in the lumbar vertebra compared to that of the sham-operated group. The craniocaudal axis corresponds to the direction of principal stress in the spine. The excessive material anisotropy in the craniocaudal axis contributed to the enhanced Young’s modulus, which may compensate for the reduced mechanical resistance by bone loss to some extent. The solo administration of IBN and ELD prevented the reduction of bone fraction (BV/TV) determined by μ-CT, and combination therapy showed the highest efficacy in BV/TV gain. Furthermore, the solo administration and combination treatment significantly decreased the degree of collagen/apatite orientation to the sham level. Based on the results of bone mass and collagen/apatite orientation, combination treatment is an effective strategy. This is the first report to demonstrate the efficacy of IBN, ELD, and combination treatment with IBN and ELD relative to the bone micro-architectural anisotropy characterized by collagen/apatite orientation.
