Bone Geometry Research Articles

Advancing HR-pQCT-based homogenised FE models with smooth structured hexahedral meshes.

Nonlinear homogenised finite element (hFE) models can accurately predict stiffness and strength of ultra-distal sections of the radius and tibia using in vivo HR-pQCT images. Recent findings showed good stiffness prediction at these distal sections but a limited ability to reproduce experimental strain localisation. The coarseness of voxel-based meshes reduces the computational effort at the cost of heavily simplifying the underlying geometry of the cortex, the gradient of material properties, and the resulting strain distribution. To overcome these limitations, we present a comprehensive approach to generating fully automated, smooth, and structured hexahedral meshes for HR-pQCT scans at the distal radius and tibia. This study used three datasets to validate the proposed hFE pipeline and its short-term repeatability: ex vivo 2nd generation HR-pQCT images of 21 human radii and 25 human tibiae, and 208 in vivo images from same-day repeated scans on 39 individuals. Results show high accuracy in predicting stiffness (tibia: R2=0.94, radius: R2=0.88) and yield force (tibia: R2=0.93, radius: R2=0.95). Mesh sensitivity analysis reveals stabilisation within a ± 3 % error margin. Dice similarity coefficients between mesh and scanned image were >0.99, and good element quality was achieved across the validation datasets (tibia: S-ICNavg=0.809, radius: S-ICNavg=0.764). Along with the improved volumetric representation of distal cortical and trabecular bone geometry and the good element quality, the new pipeline shows gains in computational performance: 11.70±1.49 min for triple-stack tibia images and 11.00±0.97 min for double-stack radius images, respectively. Generating structured meshes with consistent element-to-element correspondence facilitates seamless comparison between patient models or in longitudinal settings, providing an additional clinical information.

Relationship of skeletal muscle mass, length of sports experience, and sexual maturity with bone density and geometry in adolescent athletes.

To identify the relationship between length of sports experience, muscle mass, and sexual maturity with bone mineral density (BMD) and geometry in adolescent basketball and track and field athletes. The study included adolescent (11-18 years) athletes, of both sexes, who practiced basketball (n = 26) or track and field (n = 24). Skeletal muscle mass was measured by bioelectrical impedance analysis. Data on sports training and sexual maturity were collected through a questionnaire. Total body, lumbar, femoral, and forearm BMD were determined by dual-energy X-ray absorptiometry. Femoral scans were used to generate bone geometry measurements (femur strength index, cross-sectional area, cross-sectional moment of inertia, section modulus, and buckling ratio). Bone outcomes were compared between modalities by the Mann-Whitney U-test or Student's t-test and by analysis of covariance with adjustment for sports experience, sexual maturity, and skeletal muscle mass. In the crude analysis, the basketball group had higher mean values for height, body weight, muscle mass, femoral neck BMD, cross-sectional area, and cross-sectional moment of inertia. In the covariate-adjusted analysis, the track and field group had higher total-body-less-head (0.995 vs. 1.035, p = 0.043), lumbar (1.012 vs. 1.107, p = 0.005), and radial (0.734 vs. 0.800, p = 0.005) BMD. Muscle mass was the main covariate influencing bone parameters, followed by sexual maturity. Skeletal muscle mass was the main determinant of bone outcomes in adolescent athletes, followed by sexual maturity, underscoring the importance of considering these variables when assessing bone health in this population.

Development of a Finite Element Model of the Human Wrist Joint with Radial and Ulnar Axial Force Distribution and Radiocarpal Contact Validation.

This study presents a comprehensive finite element model for the human wrist, constructed from a CT scan of a 68-year-old male (type I wrist). This model intricately captures the bone and soft tissue geometries to study the biomechanics of wrist axial loading through tendon-driven simulations and grasping biomechanics using metacarpal loads. Validation is carried out by assessing the radial and ulnar axial loading distribution, radiocarpal articulation contact patterns, and other standard finite element metrics. The results show radial transmission of the load, consistent with results from wrist finite element models conducted in the last decade and other experimental studies. Our results confirm the model's efficacy in reproducing key known biomechanical aspects, laying the groundwork for future investigations into ongoing wrist biomechanics challenges and pathology mechanism studies.

Effect of Eight Months of Swimming on Bone Quality of Different Anatomical Regions: A Study on Wistar Rat Models

Swimming is a popular sport with several health benefits, but its effects on bone quality are controversial possibly due to distinct effects on different anatomical regions. Our aim was to investigate the effect of 8-month swimming on bone growth, mass, geometry, trabecular microarchitecture and osteocyte density of the lumbar vertebrae, femur and tibia of male rats. Wistar rat models were assigned to either a swimming (n = 10; 2h/d, 5 d/week) or a physically active control group (n = 10) for 8 months, after which they were sacrificed and their lumbar vertebrae, femur and tibia assessed for bone mass, cortical geometry, trabecular microarchitecture and osteocyte density through µ-CT and histology. Variables were compared between groups through independent samples t tests. Swimming animals displayed higher vertebral trabecular connectivity and lower trabecular separation compared to controls. However, femur length, trabecular and cortical bone mass and cortical thickness were lower compared to controls. At the tibia, animals from the swimming group also presented lower trabecular number and connectivity and higher trabecular separation. Osteocyte density at the femur and vertebra was similar between groups. Eight months of swimming negatively affected bone mass, cortical geometry and trabecular microarchitecture at the femur and tibia whilst having a favourable effect on vertebral trabecular microarchitecture. These results suggest that swimming has divergent effects on different anatomical regions.

Effects of 12-week power training on bone in mobility-limited older adults: randomised controlled trial.

This study aimed to compare the effects of 12-week of power training (PWT), an explosive form of strength training, on bone microarchitecture, estimated bone strength, and markers in mobility-limited (gait speed < 0.9m/s) older adults. Fifty-seven older adults (83 ± 5years) were randomly assigned to either a training group (TRAIN, n = 28, 15 females, 13 males) performing high-intensity PWT or a control group (CTRL, n = 29, 22 females, 7 males) maintaining their usual lifestyle. High-resolution peripheral quantitative computed tomography (HR-pQCT) assessed bone geometry, densities, microarchitecture (e.g. trabecular number (Tb.N) and thickness (Tb.Th)), and estimated bone strength (stiffness and failure load) at the tibia and radius. Blood markers for bone metabolism (PINP and CTX-1) and muscle strength (handgrip and leg press) were also measured. Baseline sex differences showed females having lower stiffness (- 37.5%) and failure load (- 38%) at the radius compared with males. After PWT, females in the TRAIN group exhibited declines in Tb.N (- 4.4%) and improvements in Tb.Th (+ 6.0%), stiffness (+ 2.7%), and failure load (+ 2.4%) at the radius (p < 0.05). A time x group interaction indicated increases in leg press strength for the whole TRAIN group (+ 23%), and within females (+ 29%) and males (+ 19%) (p < 0.001). Baseline handgrip strength correlated with stiffness (r = 0.577) and failure load (r = 0.612) at the radius (p < 0.001). Females in the TRAIN group showed a reduction in PINP (- 25%), while males showed an increase in CTX-1 (+ 18%). A 12-week PWT may enhance estimated bone strength in mobility-limited older adults, especially at sites less accustomed to daily loading (i.e. radius). NCT02051725.

Anatomic variability of the human femur and its implications for the use of artificial bones in biomechanical testing.

Aside from human bones, epoxy-based synthetic bones are regarded as the gold standard for biomechanical testing os osteosyntheses. There is a significant discrepancy in biomechanical testing between the determination of fracture stability due to implant treatment in experimental methods and their ability to predict the outcome of stability and fracture healing in a patient. One possible explanation for this disparity is the absence of population-specific variables such as age, gender, and ethnicity in artificial bone, which may influence the geometry and mechanical properties of bone. The goal of this review was to determine whether commercially available artificial bones adequately represent human anatomical variability for mechanical testing of femoral osteosyntheses. To summarize, the availability of suitable bone surrogates currently limits the validity of mechanical evaluations of implant-bone constructs. The currently available synthetic bones neither accurately reflect the local mechanical properties of human bone, nor adequately represent the necessary variability between various populations, limiting their generalized clinical relevance.

Integrating deep learning and machine learning for improved CKD-related cortical bone assessment in HRpQCT images: A pilot study.

High resolution peripheral quantitative computed tomography (HRpQCT) offers detailed bone geometry and microarchitecture assessment, including cortical porosity, but assessing chronic kidney disease (CKD) bone images remains challenging. This proof-of-concept study merges deep learning and machine learning to 1) improve automatic segmentation, particularly in cases with severe cortical porosity and trabeculated endosteal surfaces, and 2) maximize image information using machine learning feature extraction to classify CKD-related skeletal abnormalities, surpassing conventional DXA and CT measures. We included 30 individuals (20 non-CKD, 10 stage 3 to 5D CKD) who underwent HRpQCT of the distal and diaphyseal radius and tibia and contributed data to develop and validate four different AI models for each anatomical site. Manually annotated cortical bone was used to train each segmentation deep-learning model. Textural features were extracted via Gray-Level Co-occurrence Matrix (GLCM) and classified as CKD or non-CKD using XGBoost with each segmentation model. For comparison, manufacturer-supplied segmentation was used to extract cortical geometry, microarchitecture, and finite element analysis (FEA) outcomes. Model performance was confirmed using the test dataset and a separate independent validation cohort which included HRpQCT imaging from 42 additional individuals (18 non-CKD, 24 CKD stage 5D). For segmentation, the diaphyseal location showed strong performance on test datasets, with Mean IoUs of 0.96 and 0.95, and accuracies of 0.97 for both radius and tibia sites in CKD. Model 4 developed from the diaphyseal tibia region excelled in classifying test and independent validation datasets, achieving F1 scores of 0.99 and 0.96, AUCs of 0.99 and 0.94, sensitivities of 0.99, and specificities of 0.99 and 0.92. No single parameter, including BMD and cortical porosity, among conventional CT outcomes consistently differentiated CKD from non-CKD across all anatomical sites. Integrating HRpQCT with deep and machine learning, this innovative approach enables precise automatic segmentation of severely deteriorated endocortical surfaces and enhances sensitivity to CKD-related cortical bone changes compared to standard DXA and HRpQCT outcomes.

Restructuring of Femoral Cortical Bone During Growth and Locomotor Development of Wild Chimpanzees (Pan troglodytes verus).

Chimpanzees are altricial in terms of their locomotor development and transition from being carried to engaging in suspensory and arboreal locomotor behaviors to eventually relying on terrestrial quadrupedalism as their main form of locomotion. Here, we consider the mechanical implications of femoral cortical bone restructuring during growth and locomotor development in wild chimpanzees. Cortical bone structure was examined in an ontogenetic sample of wild chimpanzees from a single subspecies (P. t. verus) spanning in age from 2 weeks to 12.6 years. Diaphyseal cross-sections were extracted from micro-CT scans of the femur at 35%, 50%, and 65% of total intermetaphyseal length and variation in cortical bone structure was assessed based on bending rigidity (Imax/Imin, Ix/Iy), relative medullary area, and cortical bone porosity. Diaphyseal shape is relatively circular with a high amount of cortical bone porosity and a large relative medullary area during early infancy. Distinct shifts in cortical bone structure occurred for each studied parameter with the biggest changes occurring within the first 5 years. Values appear to stabilize as quadrupedal walking increases in frequency and is established as the main form of locomotion. Collectively, the results suggest a degree of integration in which cortical bone restructures in response to rapid changes in locomotion in addition to nonmechanical influences such as hormonal, and growth factors, without compromising function and structural integrity. The extent of influence of each factor varies throughout growth and highlights the need for caution in functional interpretations of cortical bone geometry.

Infant skull fractures align with the direction of bone mineralization.

The geometry and mechanical properties of infant skull bones differ significantly from those of adults. Over the past decades, debates surrounding whether fractures in infants come from deliberate abuse or accidents have generated significant impacts in both legal and societal contexts. However, the etiology of infant skull fractures remains unclear, which motivates this study with two main components of work. Firstly, we present and implement a progressive unidirectional fabric composite damage model for infant cranial vaults to represent ductile and anisotropic properties-two typical mechanical characteristics of infant skulls. Secondly, we hypothesize that these intrinsic material properties cause injuries perpendicular to the fiber direction to dominate infant skull fractures, resulting in fracture lines that align with the direction of mineralization in the infant skull. The material model and the finite element (FE) model were verified hierarchically, and this hypothesis was verified by reconstructing two legal cases with known fall heights and implementing the above damage model into CT-based subject-specific infant FE head models. We discovered that the infant skull is more susceptible to injuries within planes perpendicular to the mineralization direction because of the anisotropic mechanical property caused by the direction of mineralization, leading to infant skull fractures aligning with the mineralization direction. Our findings corroborated the several previously reported observations of fractures on cranial vaults, demonstrating that these fractures were closely associated with sutures and oriented along the mineralization direction, and revealed the underlying mechanisms of infant skull fracture pattern. The modeling methods and results of this study will serve as an anchor point for more rigorous investigations of infant skull fractures, ultimately aiming to provide convincing biomechanical evidence to aid forensic diagnoses of abusive head trauma.

Bone microarchitecture evaluated by HR-pQCT in Chinese adolescent and pediatric patients with X-linked hypophosphatemia.

X-linked hypophosphatemia (XLH) is the most common form of heritable hypophosphatemic rickets. Previous studies have found deteriorated bone microarchitecture in the XLH adults. Detailed studies on the skeletal microarchitecture of XLH adolescent and pediatric patients are still lacking. This study aimed to evaluate bone geometry, density, microarchitecture, stiffness in XLH adolescent and pediatric patients by using high-resolution peripheral quantitative computed tomography (HR-pQCT).Method: This study utilized HR-pQCT to assess bone geometry, density, microarchitecture, and stiffness in 106 Chinese adolescent and pediatric patients with XLH. Compared with the sex- and age-matched controls, XLH patients had significantly higher trabecular area (Tb.Ar), lower total volumetric bone mineral density (Tot.vBMD), lower cortical volumetric BMD (Ct.vBMD), and lower stiffness at both the distal radius and the tibia after adjusting for height and weight. Alkaline phosphatase Z score (ALP-Z), a marker to reflect the disease activity of rickets, was negatively correlated with Ct.vBMD and cortical thickness (Ct.Th) at the distal radius, and Ct.vBMD at the distal tibia, and positively correlated with cortical porosity (Ct.Po) at the distal tibia. We developed an online calculator to estimate Tb.Ar, Ct.vBMD, and stiffness of the distal tibia of XLH adolescent and pediatric patients based on clinical general characteristic and biochemical indicators. The bone microarchitecture of XLH adolescent and pediatric patients was deteriorated, and ALP-Z was negatively correlated with the skeletal quality of XLH adolescent and pediatric patients, especially in the cortical bone. HR-pQCT parameters can be estimated using clinical characteristics and biochemical indicators, which may assist physicians to monitor the disease progression in areas without HR-pQCT access.

Prognostic bone fracture healing simulations in an ovine tibia model validated with in vivo sensors.

Bone fracture healing is a complex physiological process influenced by biomechanical and biomolecular factors. Mechanical stability is crucial for successful healing, and disruptions can lead to delayed healing or nonunion. Bone commonly heals itself through secondary fracture healing, which is governed by the mechanical strain at the fracture site. To investigate these phenomena, a validated methodology for capturing the mechanoregulatory process in specimen-specific models of fracture healing could provide insight into the healing process. This study implemented a prognostic healing simulation framework to predict healing trajectories based on mechanical stimuli. Sixteen sheep were subjected to a 3 mm transverse tibial mid-shaft osteotomy, stabilized with a custom plate, and equipped with displacement transducer sensors to measure interfragmentary motion over 8 weeks. Computed tomography scans were used to create specimen-specific bone geometries for finite element analysis. Virtual mechanical testing was performed iteratively to calculate strains in the callus region, which guided tissue differentiation and consequently, healing. The predicted healing outcomes were compared to continuous in vivo sensor data, providing a unique validation data set. Healing times derived from the in vivo sensor and in silico sensor showed no significant differences, suggesting the potential for these predictive models to inform clinical assessments and improve nonunion risk evaluations. This study represents a crucial step towards establishing trustworthy computational models of bone healing and translating these to the preclinical and clinical setting, enhancing our understanding of fracture healing mechanisms. Clinical significance: Prognostic bone fracture healing simulation could assist in non-union diagnosis and prediction.

Design and validation of finite element models for the assessment of post-fixation distal femur fracture motion.

Fracture site motion is thought to play an important role in the healing of complex fractures of the distal femur via mechanotransduction. Measuring this motion in vivo is challenging, and this has led researchers to turn to finite element modeling approaches to gain insights into the mechanical environment at the fracture site. Developing a systematic understanding of the effect of different model choices for distal femur fractures may allow more accurate prediction of fracture site motion from these types of simulations. In this study, we aim to assess the effect of four different modeling choices and parameters. We looked at the effect of using bone specific density distributions vs generic values, employing landmark-based geometry generation, varying fracture alignment within clinically relevant ranges, and determining whether direct apposition of the fracture to the plate was achieved. For validation, five cadaveric femurs had fractures created and repaired with plated constructs, and these were then loaded and fracture site motion was directly measured. We found that using landmark based bone geometry and patient-specific bone density distributions had a minimal effect on the overall model predictions. Changing the alignment, particularly into varus and procurvatum could have a large (>50%) effect on predicted shear motion, as could direct apposition of the bone to the plate. These findings demonstrate that modeling choices can play an important role in simulating distal femur fracture mechanics, and it is particularly critical that patient customized models attempt to accurately represent alignment of the bone fragments and lateral plate apposition.

Bone turnover, areal BMD, and bone microarchitecture by second-generation high-resolution peripheral quantitative computed tomography in transfusion-dependent thalassemia.

Thalassemic osteopathy includes low bone mass and impaired bone microarchitecture. We aimed to evaluate the prevalence and determinants of bone quantity (osteoporosis) and quality (microarchitecture) in a cohort of adult patients with transfusion-dependent thalassemia (TDT). Patients with TDT (n = 63) and age- and BMI-matched controls (n = 63) were recruited in the study. Areal bone mineral density (BMD) was measured using DXA Hologic scanner. P1NP and β-CTX were estimated by electrochemiluminescence assay. Bone geometry and volumetric BMD (vBMD) were estimated by second-generation high-resolution peripheral quantitative computed tomography. Bone turnover marker β-CTX was significantly lower in the TDT group, but there was no difference in P1NP levels. Low bone mass (Z ≤ -2) was present in greater proportion of patients both at lumbar spine (LS) (54 vs 0%; p = .001) and femoral neck (FN) (33 vs 8%; p = .001). Hypogonadism was associated with low BMD at FN (OR 10.0; 95% CI, 1.2-86; p = .01) and low hemoglobin with low BMD at LS (OR 1.58; 95% CI, 0.96-2.60; p = .07). The mean trabecular bone score was also significantly lower in patients compared with controls (1.261 ± 0.072 vs 1.389 ± 0.058). Total, cortical and trabecular vBMD were significantly lower in cases than controls. The trabecular number and cortical thickness were significantly lower and trabecular separation higher in cases than controls. Adults with TDT have significantly lower areal, cortical and trabecular vBMD. The bone microarchitecture is also significantly impaired in terms of lower number and wider spacing of trabeculae as well as lower cortical thickness and area at both radius and tibia.

An open-source framework for the generation of OpenSim models with personalised knee joint geometries for the estimation of articular contact mechanics

Musculoskeletal modelling pipelines typically use generic models scaled to individual’s anthropometry. The ability to represent variations in bone or joint geometry and alignment is highly limited. This may have a large effect, particularly when modelling contact between articular surfaces such as for the knee where articular contact mechanics are used to determine joint kinematics and the resulting cartilage contact pressures and locations. Here we describe a developed open-source framework for the personalisation of such models and compare dynamic simulation outputs. The framework involves three main steps: (1) positions personalised geometries from magnetic resonance imaging and replaces generic bone and contact geometries. (2) Repositions muscle and ligament attachments and via points and optimisation of wrapping surfaces to ensure physiological lengthening behaviour. Finally, (3) muscle and ligament properties are calibrated to ensure physiological behaviour. Following model creation, dynamic simulations from a single participant and gait trial were compared. Small changes in knee adduction/abduction and rotation angles were observed between models. Joint moment differences however were present in not only the knee but also hip and ankle joints. These differences resulted in changes in both the magnitude and location of knee joint contact pressure. The framework developed is automated and requires only minimal user interaction and is built using open-source software packages which can be freely downloaded and installed. The adoption of such personalised modelling approaches facilitates patient specific modelling and may provide more detailed information regarding disease progression, patient stratification and facilitate personalised rehabilitation and treatment planning.

A novel framework for elucidating the effect of mechanical loading on the geometry of ovariectomized mouse tibiae using principal component analysis.

Murine models are used to test the effect of anti-osteoporosis treatments as they replicate some of the bone phenotypes observed in osteoporotic (OP) patients. The effect of disease and treatment is typically described as changes in bone geometry and microstructure over time. Conventional assessment of geometric changes relies on morphometric scalar parameters. However, being correlated with each other, these parameters do not describe separate fractions of variations and offer only a moderate insight into temporal changes. The current study proposes a novel image-based framework that employs deformable image registration on in vivo longitudinal images of bones and Principal Component Analysis (PCA) for improved quantification of geometric effects of OP treatments. This PCA-based model and a novel post-processing of score changes provide orthogonal modes of shape variations temporally induced by a course of treatment (specifically in vivo mechanical loading). Errors associated with the proposed framework are rigorously quantified and it is shown that the accuracy of deformable image registration in capturing the bone shapes (∼1 voxel = 10.4μm) is of the same order of magnitude as the relevant state-of-the-art evaluation studies. Applying the framework to longitudinal image data from the midshaft section of ovariectomized mouse tibia, two mutually orthogonal mode shapes are reliably identified to be an effect of treatment. The mode shapes captured changes of the tibia geometry due to the treatment at the anterior crest (maximum of 0.103mm) and across the tibia midshaft section and the posterior (0.030mm) and medial (0.024mm) aspects. These changes agree with those reported previously but are now described in a compact fashion, as a vector field of displacements on the bone surface. The proposed framework enables a more detailed investigation of the effect of disease and treatment on bones in preclinical studies and boosts the precision of such assessments.

Finite element analysis confirms the optimal apex position in medial opening wedge high tibial osteotomy to avoid lateral hinge fracture.

Lateral hinge fracture is a significant complication of medial opening wedge high tibial osteotomy. While fracture risk is closely associated with the osteotomy apex position, the optimum position remains variable within the literature. Our hypothesis is that stresses at the osteotomy apex predicted by finite element analysis can be used to identify an apex position which minimises intra and postoperative fracture risks. A finite element model was studied to investigate the effect of varying the hinge position on fracture risk and severity for a given bone geometry; variables analysed included stress, strain and micromotion levels. Nine further knee models were studied to assess the variability between patients' bone properties and examine the effect of apex location on strains. Lateral hinge width and height significantly influence intra-operative stress, strain, and fracture risk, while hinge width predominately determines postoperative stability. Wider hinges improve postoperative stability, but increase the likelihood of intra-articular fractures. Aiming the apex at the fibular head height minimises strain. The osteotomy apex should be located such that the hinge width is equal to 13% of the medial-lateral width to minimise apex stress and fracture risk while preserving sufficient bone at the hinge for stability. The height of the apex from the tibial plateau should maintain a minimum value of 16% of the medial-lateral width to avoid intra-articular fracture, with the apex below the fibula head if necessary. The size of the tibia does not alter the optimal location, making our findings applicable across all tibia sizes. Our study has investigated and verified a proposed optimal apex position, based upon fracture risk prediction and micromotion at the osteotomy apex. This is clinically useful due to the potential use of the apex point on preoperative 2D radiographs when planning surgery. Not applicable.

Finite element analysis of macro-crack behavior in the cortical bone of a human tibia

The bone is a biological tissue that possesses a highly complicated hierarchical structure; hence, the tissue components of the bone exhibit variable mechanical proper-ties and a complex bone geometry. This is why the creation of a three-dimensional mod-el through CAD software facilitates the study of the mechanical behavior of bones. Com-bining the concepts of linear elastic fracture mechanics and finite element analysis pro-vides a practical solution to study the fracture behavior of the tibial bone. The objective of this study is to analyze the behavior of cracks in the cortical bone of the human tibia us-ing stress intensity factors in mode I, II, and III as rupture criteria to assess the bone damage response. The tibial bone is one of the most common sites for lower limb stress fractures, which pose problematic injuries. The results investigating the effect of the crack position in the bone demonstrate that the risk of crack propagation is mainly due to mode I opening and is highly favored in the distal zone compared to the middle and proximal regions, regardless of bone density. For the second case study, it is observed that regardless of the crack size, the maximum values of stress intensity factors KI are obtained in the distal zone. Regarding the effect of crack orientation, the results indicate the dominance of mode II for angles α = – 45°, 30°, 45°, leading to high values of stress intensity factors KII.

Comparisons of longitudinal radiographic measures of keel bones, tibiotarsal bones, and pelvic bones versus post-mortem measures of keel bone damage in Bovans Brown laying hens housed in an aviary system.

Keel bone damage, include deviations and fractures, is common in both white and brown laying hens, regardless of the housing system. Radiography for assessing birds' keel bones is was proposed by previous studies. However, radiographs show only 2 out of 3 dimensions of the dissected keel bones. The current study aimed to (1) investigate the association of radiographic optical density (keel and tibiotarsal) and geometry (keel) with dissected keel bone pathology. Previous studies suggested that keel bone fractures may result from internal pressure exerted by pelvic cavity contents. The current study also aimed to (2) investigate the potential associations between pelvic dimensions and measures of keel bone damage. A sample of 200 laying hens on a commercial farm were radiographed at 16, 29, 42, 55, and 68 weeks, and culled at the end of the laying period (week 74). The birds were examined post-mortem for pelvic dimensions and underwent whole-body radiography, followed by keel and tibiotarsal bone dissection and radiography, and keel bone scoring. The radiographs were used to estimate radiographic optical density (keel and tibiotarsal bone) and keel bone geometry (ratio of keel bone length to mid-depth). The method for on-farm radiography of laying hens, including live bird restraint, positioning for live keel imaging, and post-imaging measurements, was developed, tested, and found to be reproducible. The radiographs (1,116 images of 168 birds) and the respective measurements and post-mortem scores of keel bones are also provided for further development of radiographic metrics relevant to keel bone damage. Some longitudinal radiographic measurements of keel geometry (ratio of length to mid-depth) and optical density (keel and tibiotarsal) showed associations with the damage (deviations/fractures) observed on the dissected keel bones. The associations of keel damage were clearer with the radiographic keel geometry than with keel and tibiotarsal optical density, also clearer for the keel deviations than for keel fractures. The higher radiography ratio of keel length to mid-depth at weeks 42, 55 and 68 of age, the larger deviations size observed on the dissected keels at age of 74 weeks. The higher the tibiotarsal radiographic optical density at week 55 of age, the lower deviations size and fractures count observed on the dissected keels at age of 74 weeks. Pelvic dimensions showed a positive correlation with body weight, but a larger pelvic cavity was associated with increased keel bone damage. These findings lay the foundations for future use of on-farm radiography in identifying appropriate phenotypes for genetic selection for keel bone health.

Maternal high-fat high-sugar diet impairs bone quality and strength but not cartilage in aging mice.

Osteoarthritis (OA) is a prevalent aging disorder of synovial joints and recent work suggests that a parental high-fat diet increases OA severity following joint injury in offspring. We hypothesized that a maternal high-fat high-sugar (HFHS) diet would promote spontaneous osteoarthritis-related cartilage and bone changes in 1-year-old offspring. Female C57BL/6 J mice were placed on either a chow control or HFHS diet for 6 weeks before mating to a chow-fed C57BL/6 J male and maintained on their assigned diets throughout pregnancy and lactation. Male and female offspring were weaned onto a chow diet, raised to 1 year of age, and evaluated for cartilage and bone changes indicative of OA. However, offspring did not show early signs of OA as measured by histological Mankin scoring, mechanical testing of the pericellular matrix, histological synovitis scoring, or subchondral bone thickening as measured by microcomputed Tomography. On the other hand, male offspring from HFHS-fed dams had reduced trabecular bone quality in the tibial metaphysis and decreased cortical thickness. Although maternal HFHS diet did not impact trabecular or cortical bone quality in tibias of female offspring, the radii of these animals had decreased cortical thickness, increased medullary area, and impaired breaking strength compared to those of control-fed dams. Finally, we evaluated bone quality and strength in male and female F2 offspring and found that the grandmaternal diet modestly impacted radial bone geometry but not strength. Together these results suggest that maternal HFHS diet impairs F1 offspring skeletal integrity in a sex and bone site-specific manner.

Longitudinal Analysis of Bone Metabolic Markers and Bone Mechanical Properties in STZ-Induced Diabetic Rats.

Background: This longitudinal study examined the early effects of type 1 diabetes on bone mechanical properties and metabolic markers in mature rats, focusing on the natural progression of diabetes-induced changes without external treatments. Methods: Forty-eight 8-month-old male Wistar rats were divided into two groups, with one group receiving a single dose of streptozotocin (STZ, 60 mg/kg). Assessments were performed 2, 4, and 8 weeks post-administration, including serum biochemical analyses, bone marker assessments, and mechanical bone tests. The data were analyzed using two-way ANOVA to evaluate the impact of time and treatment. Results: At 2 weeks, diabetic rats showed increased fasting blood glucose (p < 0.001), decreased insulin levels (p = 0.03), and changes in HOMA markers (p < 0.001), liver enzymes (p < 0.001), inflammatory markers (p < 0.001), and bone metabolism markers (osteocalcin (p < 0.001), OPG (p = 0.006), RANKL (p < 0.001), and OPG/RANKL ratio (p < 0.001)), with initial alterations in bone geometry. By week 4, decreased body weight in the diabetic group (p < 0.001) led to further changes in bone geometry and initial differences in mechanical properties. At 8 weeks, significant declines in body (p < 0.001) and bone (p < 0.001) weights were observed, along with further deterioration in bone geometry and mechanical properties. Conclusions: The study highlights the significant impact of STZ-induced diabetes on bone health as early as two weeks post-STZ administration, with marked temporal changes in biochemical markers and mechanical properties.