Cross-sectional Bone Research Articles

Effects of bone-specific physical activity, gender and maturity on tibial cross-sectional bone material distribution: a cross-sectional pQCT comparison of children and young adults aged 5–29 years

Growth is the opportune time to modify bone accrual. While bone adaptation is known to be dependent on local loading and consequent deformations (strain) of bone, little is known about the effects of sex, and bone-specific physical activity on location-specific cross-sectional bone geometry during growth. To provide more insight we examined bone traits at different locations around tibial cross sections, and along the tibia between individuals who vary in terms of physical activity exposure, sex, and pubertal status. Data from 304 individuals aged 5–29years (172 males, 132 females) were examined. Peripheral quantitative computed tomography (pQCT) was applied at 4%, 14%, 38%, and 66% of tibial length. Maturity was established by estimating age at peak height velocity (APHV). Loading history was quantified with the bone-specific physical activity questionnaire (BPAQ). Comparisons, adjusted for height, weight and age were made between sex, maturity, and BPAQ tertile groups. Few to no differences were observed between sexes or BPAQ tertiles prior to APHV, whereas marked sexual dimorphism and differences between BPAQ tertiles were observed after APHV. Cross-sectional location-specific differences between BPAQ tertiles were not evident prior to APHV, whereas clear location-specificity was observed after APHV. In conclusion, the skeletal benefits of physical activity are location-specific in the tibia. The present results indicate that the peri- or post-pubertal period is likely a more favourable window of opportunity for enhancing cross-sectional bone geometry than pre-puberty. Increased loading during the peri-pubertal period may enhance the bone of both sexes.

Stochastic diffusion equation with singular diffusivity and gradient-dependent noise in binary tomography

In this work, we use stochastic diffusion equation with a singular diffusivity and a gradient-dependent noise to improve the reconstruction of binary tomography cross-sections obtained from a small number of projections. A first reconstruction image is obtained with the Total Variation regularization method. The reconstruction is then refined with this stochastic approach. The method is applied to a noisy bone cross-section with 10 projection angles.

Improving the estimate of the effective elastic modulus derived from three-point bending tests of long bones.

Three-point bending tests are often used to determine the apparent or effective elastic modulus of long bones. The use of beam theory equations to interpret such tests can result in a substantial underestimation of the true effective modulus. In this study three-dimensional, nonlinear finite element analysis is used to quantify the errors inherent in beam theory and to create plots that can be used to correct the elastic modulus calculated from beam theory. Correction plots are generated for long bones representative of a variety of species commonly used in research studies. For a long bone with dimensions comparable to the mouse femur, the majority of the error in the effective elastic modulus results from deformations to the bone cross section that are not accounted for in the equations from beam theory. In some cases, the effective modulus calculated from beam theory can be less than one-third of the true effective modulus. Errors are larger: (1) for bones having short spans relative to bone length; (2) for bones with thin vs. thick cortices relative to periosteal diameter; and (3) when using a small radius or "knife-edge" geometry for the center loading ram and the outer supports in the three-point testing system. The use of these correction plots will enable researchers to compare results for long bones from different animal strains and to compare results obtained using testing systems that differ with regard to length between the outer supports and the radius used for the loading ram and outer supports.

Stress development at human femur by muscle forces

An analytical model based on the mechanics of solids was developed to estimate the stress distribution at the external surface of human femur medial cross sections, as an alternative to more expensive finite element approach. It recognizes cortical and trabecular bone tissues and proposes circular and elliptical geometries to represent real bone cross sections. Its implementation was accomplished through the utilization of a representative load case, with muscles forces and one joint reaction force. The analytical model results comprise normal and shear stresses at external cortical bone cross sections, as well as principal stresses and angles. These results were compared with a commercial F.E. program with good matches.

Histomorphological species identification of tiny bone fragments from a Paleolithic site in the Northern Japanese Archipelago

Bone histomorphology is an effective method for species identification of fragmentary osseous remains. The 1997–1998 excavations of the Kashiwadai 1 Upper Paleolithic site (ca. 22–20.5 kyBP) in Hokkaido (the northern island of the Japanese Archipelago) yielded tiny bone fragments, which had been burned to white and broken into pieces less than 1 cm in size, making their species identification by gross morphology alone impossible. For the purpose of species identification, histomorphological analyses were performed on thin sections of the Kashiwadai 1 bone fragments. Compact bone cross sections taken from medium- to large-sized land mammals in the Pleistocene and Holocene Hokkaido were prepared for comparison. The structures of the Kashiwadai 1 samples consisted of secondary osteons and plexiform bone. Consideration of the presence versus absence of plexiform bone and quantitative assessments of osteon sizes and bone cortical thickness allows for distinction between medium-sized deer, large-sized artiodactyls, small- to medium-sized carnivores, large-sized carnivores, elephants, and humans. The histomorphological characteristics of the Kashiwadai 1 samples were quite similar to those of both sika deer and ancient sika deer. A probable conclusion is that medium-sized deer was the primary game hunted by Paleolithic people at the Kashiwadai 1 site. Interestingly, the samples did not include elephant or large-sized artiodactyls, which were the predominant species in other Paleolithic sites of the Japanese Archipelago. This is the first evidence of human hunting medium-sized animals in the Upper Paleolithic period of the Japanese Archipelago based on faunal remains.

Effects of strength and endurance training intervention on thigh intermuscular and subcutaneous adipose tissue in sarkopenic women

Effects of strength and endurance training intervention on thigh intermuscular and subcutaneous adipose tissue in sarkopenic women

Virtual plate pre-bending for the long bone fracture based on axis pre-alignment

In this paper, a modeling and visualizing system for assisting surgeons in correctly registering for the closed fracture reduction surgery is presented. By using this system, the geometric parameters of the target fixation plate before the long bone fracture operation can be obtained. The main processing scheme consists of following steps: firstly (image data process), utilize the Curvelet transform to denoise the CT images of fracture part and then reconstruct the 3D models of the broken bones. Secondly (pre-alignment), extract the axial lines of the broken bones and spatially align them. Then drive the broken bone models to be pre-aligned. Thirdly (mesh segmentation), a method based on vertex normal feature is utilized to obtain the broken bone cross-sections mesh models. Fourthly (fine registration), the ICP (Iterative Closest Point) algorithm is used to register the cross-sections and the broken bone models are driven to achieve the fine registration posture. Lastly (plate fitting), an accurate NURBS surface fitting method is used to construct the virtual plate. The experiment proved that the obtained models of the pre-bended plates were closely bonded to the surface of the registered long bone models. Finally, the lengths, angles and other interested geometric parameters can be measured on the plate models.

A CT-image-based framework for the holistic analysis of cortical and trabecular bone morphology

This study introduces a standardized framework for the holistic analysis of cortical and trabecular bone structure. This method, although applicable to all bones of the skeleton, is particularly useful for irregular-shaped or small bones for which the application of traditional methods has been especially challenging. Traditional analyses have quantified cortical or trabecular structure in only selected regions of a bone, such as single cross-sections of cortical bone or volumes of interest of trabecular structure in epiphyses. The proposed method improves on these traditional methods by visualizing and quantifying the internal bony structure throughout the entire bone and in user-defined anatomical subregions. Here, we describe and demonstrate the method using high-resolution microtomographic scans of a first metacarpal of an orangutan, gorilla, chimpanzee and human. Using automated morphological filters, the cortical bone is defined and extracted from the underlying trabecular structure to create two 3D models, one of the cortex and one of the trabecular bone that can be analysed separately. We test the sensitivity of the morphological parameters used to create these 3D models, demonstrating that the parameters defined here are robust and can provide accurate measures of cortical thickness, relative bone density, trabecular orientation, trabecular thickness and degree of anisotropy. This new, holistic method is able to reveal morphological and functional information about bone loading that is obscured or ignored using traditional methods, thus providing more informed interpretations of behaviour in extant and fossil taxa.

The negative impact of traumatic brain injury (TBI) on bone in a mouse model

Introduction: While it is well established that the brain produces hypothalamic hormones and neuropeptides that influence skeletal metabolism, the impact of traumatic brain injury (TBI) on bone is unknown. Based on the recognition from clinical studies that there is an association between TBI and long-term hypothalamic pituitary dysfunction, it was hypothesized that TBI exerts a negative impact on skeletal growth and maintenance.Methods: To test the hypothesis, this study employed a repetitive weight drop model for TBI. Four impacts were applied for four consecutive days on 5-week old female C57BL/6 J mice. Bone measurements were taken 2 weeks after the first impact.Results: Bone mineral content (BMC), bone area (B area) and bone mineral density (BMD) in the total body were reduced by 14.5%, 9.8% and 5.2%, respectively, in the impacted vs. control mice. There was a 17.1% reduction in total volumetric BMD (vBMD) and a 4.0% reduction in material vBMD in cortical bone. In trabecular bone, there was a 44.0% reduction in BV/TV. Although there was no change in the cross-sectional bone size, the tibial growth plate and the tibia itself were shortened.Conclusion: The repetitive animal TBI model produced an immediate, strong negative impact on bone mass acquisition in young mice.

Quantification of calcium content in bone by using ToF-SIMS–a first approach

The determination of the spatially resolved calcium distribution and concentration in bone is essential for the assessment of bone quality. It enables the diagnosis and elucidation of bone diseases, the course of bone remodelling and the assessment of bone quality at interfaces to implants. With time-of-flight secondary ion mass spectrometry (ToF-SIMS) the calcium distribution in bone cross sections is mapped semi-quantitatively with a lateral resolution of up to 1 μm. As standards for the calibration of the ToF-SIMS data calcium hydroxyapatite collagen scaffolds with different compositions were synthesized. The standards were characterised by loss of ignition, x-ray diffractometry (XRD) and x-ray photoelectron spectroscopy (XPS). The secondary ion count rate for calcium and the calcium content of the standards show a linear dependence. The obtained calibration curve is used for the quantification of the calcium content in the bone of rats. The calcium concentration within an animal model for osteoporosis induction is monitored. Exemplarily the calcium content of the bones was quantified by XPS for validation of the results. Furthermore a calcium mass image is compared with an XPS image to demonstrate the better lateral resolution of ToF-SIMS which advances the locally resolved quantification of the calcium content.

Study of fossil bones by synchrotron radiation micro-spectroscopic techniques and scanning electron microscopy

Earlymost Villafranchian fossil bones of an artiodactyl and a perissodactyl from the Milia excavation site in Grevena, Greece, were studied in order to evaluate diagenetic effects. Optical microscopy revealed the different bone types (fibro-lamellar and Haversian, respectively) of the two fragments and their good preservation state. The spatial distribution of bone apatite and soil-originating elements was studied using micro-X-ray fluorescence (µ-XRF) mapping and scanning electron microscopy. The approximate value of the Ca/P ratio was 2.2, as determined from scanning electron microscopy measurements. Bacterial boring was detected close to the periosteal region and Fe bearing oxides were found to fill bone cavities, e.g. Haversian canals and osteocyte lacunae. In the perissodactyl bone considerable amounts of Mn were detected close to cracks (the Mn/Fe weight ratio takes values up to 3.5). Goethite and pyrite were detected in both samples by means of metallographic microscopy. The local Ca/P ratio determined with µ-XRF varied significantly in metal-poor spots indicating spatial inhomogeneities in the ionic substitutions. XRF line scans that span the bone cross sections revealed that Fe and Mn contaminate the bones from both the periosteum and medullar cavity and aggregate around local maxima. The formation of goethite, irrespective of the local Fe concentration, was verified by the Fe K-edge X-ray absorption fine structure (XAFS) spectra. Finally, Sr K-edge extended XAFS (EXAFS) revealed that Sr substitutes for Ca in bone apatite without obvious preference to the Ca1 or Ca2 unit-cell site occupation.

Bone histology as an approach to providing data on certain key life history traits in mammals: Implications for conservation biology

The knowledge of the life histories of wild mammals is of crucial importance in the field of conservation management. The endangered status of many species calls for faster data collection that can be used in risk assessment and, ultimately, for designing conservation policies. This study is pioneering the potential of bone histology to provide data on life history traits crucial for conservation biology in long-lived mammals. Long bone cross-sections show pronounced annual cycles of growth arrest allowing application of skeletochronology (counts of lines of arrested growth ‘LAGs’). Consequently, the number of LAGs within the primary fast-growing bone tissue up to the outer cortical slow-growing bone tissue corresponds to the age at first reproduction; whereas the age at death can be estimated by the total number of rest lines throughout the whole of bone cross-section. Furthermore, the diameters of successive growth rings as well as the osteocyte lacuna density may shed light on growth rates. We use the endangered desert dwelling antelope Addax nasomaculatus as a case study. By analyzing different ontogenetic stages in five Addax individuals (three captive and two wild specimens) from a museum collection, we show that bone histology may be a reliable tool for determining certain key life history traits. In our sample, the wild Addax female attained reproductive maturity at three years, whereas the male specimens, both the captive and the wild ones, reached maturity at four years. This is congruent with data from other large antelopes with male-biased size dimorphism, but differs slightly from data on sexual maturity previously published for wild Addax. Moreover, quantification of osteocyte lacunae in both adult males provides a higher cell density in the captive one than in the wild one suggesting the strong effect of constant resources supply in individuals from zoos on growth rates. While age at first reproduction and longevity are essentials parameters to carry out demographic models, growth rates may allow evaluation of the health status of wild populations. This approach may provide useful data on life history traits when applied to bones collected in the wild.

Power‐law hereditariness of hierarchical fractal bones

In this paper, the authors introduce a hierarchic fractal model to describe bone hereditariness. Indeed, experimental data of stress relaxation or creep functions obtained by compressive/tensile tests have been proved to be fit by power law with real exponent 0 ⩽ β ⩽1. The rheological behavior of the material has therefore been obtained, using the Boltzmann-Volterra superposition principle, in terms of real order integrals and derivatives (fractional-order calculus). It is shown that the power laws describing creep/relaxation of bone tissue may be obtained by introducing a fractal description of bone cross-section, and the Hausdorff dimension of the fractal geometry is then related to the exponent of the power law.

Histology and postural change during the growth of the ceratopsian dinosaur Psittacosaurus lujiatunensis

A few dinosaurs are inferred to have undergone an ontogenetic shift from quadrupedal-to-bipedal posture, or vice versa, based on skeletal allometry. The basal ceratopsian Psittacosaurus lujiatunensis is considered to have been mainly bipedal as an adult. Here we infer a postural shift in this species based on a novel combination of limb measurements and histological data. The forelimb is strongly negatively allometric relative to the hindlimb, and patterns of vascular canal orientation provide evidence that growth of the hindlimb was particularly rapid during the middle part of ontogeny. Histology also makes it possible to determine the ontogenetic ages of individual specimens, showing that the forelimb-to-hindlimb ratio changed rapidly during the first or second year of life and thereafter decreased gradually. Occurrence of an ontogenetic shift from quadrupedality to bipedality was evidently widespread in dinosaurs, and may even represent the ancestral condition for the entire group.

Active-resisted stance modulates regional bone mineral density in humans with spinal cord injury

ObjectiveIn people with spinal cord injury (SCI), active-resisted stance using electrical stimulation of the quadriceps delivered a therapeutic stress to the femur (∼150% of body weight) and attenuated bone mineral density (BMD) decline. In standard densitometry protocols, BMD is averaged over the entire bone cross-section. An asymmetric adaptation to mechanical load may be masked by non-responding regions. The purpose of this study was to test a novel method to assess regional BMD of the femur in individuals with SCI. We hypothesize that there will be regional bone-sparing changes as a result of active-resisted stance.DesignMixed cross-sectional and longitudinal.SettingResearch laboratory.ParticipantsTwelve individuals with SCI and twelve non-SCI controls.InterventionIndividuals with SCI experienced active-resisted stance or passive stance for up to 3 years.Outcome measuresPeripheral quantitative computed tomography images from were partitioned so that femur anatomic quadrants could be separately analyzed.ResultsOver 1.5 years, the slope of BMD decline over time was slower at all quadrants for the active-resisted stance limbs. At >2 years of training, BMD was significantly higher for the active-resisted stance group than for the passive stance group (P = 0.007). BMD was preferentially spared in the posterior quadrants of the femur with active-resisted stance.ConclusionsA regional measurement technique revealed asymmetric femur BMD changes between passive stance and active-resisted stance. Future studies are now underway to better understand other regional changes in BMD after SCI.

Biomechanical insights into activity and long distance trade in the south-central Andes (AD 500–1450)

Long distance trade has been attributed important social and economic roles in the pre-colonial south-central Andes, but how these trade networks were operated and organised, and the roles played by different populations and social groups (e.g. elites), remain uncertain. This study aims to offer new perspective on these questions through biomechanical analyses of human skeletal remains from a probable key site in these networks, San Pedro de Atacama (SPdA). Groups that were more intensively involved in long distance trade are expected to have been more habitually mobile, and thus to show greater robusticity and less circular lower limb bone cross-sections. Lower limb biomechanical properties of elite and non-elite Middle Horizon groups (MH, AD 500–1000) were compared with subsequent transitional MH-Late Intermediate Period (LIP, AD 1000–1450) and LIP groups from SPdA, and with LIP groups from Pica-8 and the Azapa Valley. The results indicate that MH populations from SPdA had less robust lower limbs and were by inference less mobile than their successors, with no differences between elite and non-elite, while robusticity was elevated in the MH-LIP transition group. Alternative explanations for the results, such as changes in herding activities, cannot be entirely discounted based on current evidence, but the results are consistent with hypotheses that SPdA may have served as a hub on long distance trade networks during the MH, before residents became more actively involved in long distance trade following the collapse of key links with the Tiwanaku polity. The results also indicate similar levels of robusticity among LIP populations at SPdA, Pica-8 and in the Azapa Valley, implying they may have been involved in trading activities to a similar extent, and perhaps to a greater extent than SPdA MH groups, as regional intergroup relationships changed.

Bone mechanical competence in hypercholesterolemic rats fed MUFAn9 rich diets.

Reduced bone mass in growing rats fed MUFAn9‐rich diets was observed. But bone stiffness has not been defined yet. To study the mechanical bone competence in hypercholesterolemic (HC) rats fed MUFA diets, weanling male Wistar rats (n=48) were assigned to one of 7 diet groups for 8 weeks (T8). Three control groups fed a commercial diet (C), C+olive oil (COO) or C+high‐oleic sunflower oil (CHOSO) and 4 groups, an atherogenic diet for 3 weeks; then either one of OO, HOSO, HOSO+sterols or HOSO+fish oil diet. At T8, serum lipid‐lipoprotein profile and femur mechanical properties were assessed: Load‐bearing capacity, yielding load and deformation, stiffness, Cross‐sectional bone area, Cortical Area, moment of inertia, yield stress, elastic modulus. Body weight was lower in HOSO (p<0.0001). HOSO had the highest T‐chol & nHDL & the lowest HDL. HOSO+fish oil, the lowest T‐chol & nHDL. HOSO+sterols oil improved HDL, nHDL & T‐chol vs. HOSO (p<0.01). Structural & geometric properties were negatively affected but material bone quality properties remained unchanged in HC. The impaired mechanical bone competence in HC could be due to an altered bone mass and architectural distribution rather than to intrinsic bone quality with detrimental effects on femoral stiffness and strength. UBACyT 0613 and 0070 and Ped Sunshine Acad USA grants. Champin G technical support.

Variability and anisotropy of mechanical behavior of cortical bone in tension and compression

The mechanical properties of cortical bone vary not only from bone to bone; they demonstrate a spatial viability even within the same bone due to its changing microstructure. They also depend considerably on different loading modes and orientations. To understand the variability and anisotropic mechanical behavior of a cortical bone tissue, specimens cut from four anatomical quadrants of bovine femurs were investigated both in tension and compression tests. The obtained experimental results revealed a highly anisotropic mechanical behavior, depending also on the loading mode (tension and compression). A compressive longitudinal loading regime resulted in the best load-bearing capacity for cortical bone, while tensile transverse loading provided significantly poorer results. The distinctive stress–strain curves obtained for tension and compression demonstrated various damage mechanisms associated with different loading modes. The variability of mechanical properties for different cortices was evaluated with two-way ANOVA analyses. Statistical significances were found among different quadrants for the Young's modulus. The results of microstructure analysis of the entire transverse cross section of a cortical bone also confirmed variations of volume fractions of constituents at microscopic level between anatomic quadrants: microstructure of the anterior quadrant was dominated by plexiform bone, whereas secondary osteons were prominent in the posterior quadrant. The effective Young's modulus predicted using the modified Voigt-Reuss-Hill averaging scheme accurately reproduced our experimental results, corroborating additionally a strong effect of random and heterogeneous microstructure on variation of mechanical properties in cortical bone.

Trabecular Bone Mineral Density and Bone Geometry of the Distal Radius at Completion of Pubertal Growth in Childhood Type 1 Diabetes

Aim: To identify disease-related risk factors for an altered bone mineral density (BMD) and geometry at young adulthood in patients with diabetes mellitus type 1 (DM1). Methods: Fifty-six DM1 patients (23 females, 33 males) with prepubertal onset of diabetes were studied after completion of skeletal growth. Bone parameters at the distal radius were investigated by peripheral quantitative computed tomography. Disease-related parameters, in particular average HbA1c during the 2 years around peak height velocity, were analyzed. Forty-seven healthy controls (32 females, 15 males) were studied. Results: Trabecular BMD was similar between DM1 patients and controls. The mean (±SD) cross-sectional bone area (CSA) was smaller in DM1 patients compared to controls (282.5 ± 45.4 vs. 326.7 ± 52.2 mm², p = 0.002 and males 391.0 ± 61.3 vs. 423.4 ± 81.9 mm², p = 0.1). In female DM1 patients, the CSA z-score correlated negatively with the body mass index z-score (r = -0.52, p = 0.01) and positively with the height z-score (r = 0.49, p = 0.02). Conclusions: DM1 patients are at risk for smaller bone sizes at the distal radius at the end of pubertal growth, especially females with increased adiposity. Diabetes-specific parameters seem to have a low impact on forearm volumetric apparent mineral density.

Longitudinal elastic properties and porosity of cortical bone tissue vary with age in human proximal femur

Tissue level structural and mechanical properties are important determinants of bone strength. As an individual ages, microstructural changes occur in bone, e.g., trabeculae and cortex become thinner and porosity increases. However, it is not known how the elastic properties of bone change during aging. Bone tissue may lose its elasticity and become more brittle and prone to fractures as it ages. In the present study the age-dependent variation in the spatial distributions of microstructural and microelastic properties of the human femoral neck and shaft were evaluated by using acoustic microscopy. Although these properties may not be directly measured in vivo, there is a major interest to investigate their relationships with the linear elastic measurements obtained by diagnostic ultrasound at the most severe fracture sites, e.g., the femoral neck. However, before the validity of novel in vivo techniques can be established, it is essential to understand the age-dependent variation in tissue elastic properties and porosity at different skeletal sites. A total of 42 transverse cross-sectional bone samples were obtained from the femoral neck (Fn) and proximal femoral shaft (Ps) of 21 men (mean±SD age 47.1±17.8, range 17–82years). Samples were quantitatively imaged using a scanning acoustic microscope (SAM) equipped with a 50MHz ultrasound transducer. Distributions of the elastic coefficient (c33) of cortical (Ct) and trabecular (Tr) tissues and microstructure of cortex (cortical thickness Ct.Th and porosity Ct.Po) were determined. Variations in c33 were observed with respect to tissue type (c33Tr<c33Ct), location (c33(Ct.Ps)=37.7GPa>c33(Ct.Fn)=35.3GPa>c33(Tr.Ps)=33.8GPa>c33(Tr.Fn)=31.9GPa), and cadaver age (R2=0.28–0.46, p<0.05). Regional variations in porosity were found in the neck (superior 13.1%; inferior 6.1%; anterior 10.1%; posterior 8.6%) and in the shaft (medial 9.5%; lateral 7.7%; anterior 8.6%; posterior 12.0%). In conclusion, significant variations in elastic coefficients were detected between femoral neck and shaft as well as between the quadrants of the cross-sections of neck and shaft. Moreover, an age-related increase in cortical porosity and a stiffening of the bone tissue were observed. These findings may explain in part the increase in susceptibility to suffer low energy fractures during aging and highlight the potential of ultrasound in clinical osteoporosis diagnostics.