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High-resolution magnetic resonance imaging (HR-MRI) has been increasingly used to assess the trabecular bone structure. High susceptibility at the marrow/bone interface may significantly reduce the marrow's apparent transverse relaxation time (T2*), overestimating trabecular bone thickness. Ultrashort echo time MRI (UTE-MRI) can minimize the signal loss caused by susceptibility-induced T2* shortening. However, UTE-MRI is sensitive to chemical shift artifacts, which manifest as spatial blurring and ringing artifacts partially due to non-Cartesian sampling. In this study, we proposed UTE-MRI at the resonance frequency of fat to minimize marrow-related chemical shift artifacts and the overestimation of trabecular thickness. Cubes of trabecular bone from six donors (75 ± 4 years old) were scanned using a 3 T clinical scanner at the resonance frequencies of fat and water, respectively, using 3D UTE sequences with five TEs (0.032, 1.1, 2.2, 3.3, and 4.4 ms) and a clinical 3D gradient echo (GRE) sequence at 0.2 × 0.2 × 0.4 mm3 voxel size. Trabecular bone thickness was measured in 30 regions of interest (ROIs) per sample. MRI results were compared with thicknesses obtained from micro-computed tomography (μCT) at 50 μm3 voxel size. Linear regression models were used to calculate the coefficient of determination between MRI- and μCT-based trabecular thickness. All MRI-based trabecular thicknesses showed significant correlations with μCT measurements. The correlations were higher (examined with paired Student's t-test, P

The cellular component and an extracellular matrix make up the bone. Osteoblasts, bone- lining cells, osteocytes, and osteomacs that are dormant osteoblasts trapped in the extracellular matrix, make up the cellular component. An organic and a mineral phase combine to produce the matrix, which is responsible for the mechanical strength of the bone tissue. There is also a liquid component. As a result, bone has been identified as a natural composite material. "Bone is composed of roughly 60% mineral, 10% water, and 30% collagenous matrix by weight". An increasing number of skeletal fractures are a major problem for aging populations. Given that cortical bone bears a significant portion of the physiological loading in the lower limbs, it would be ideal to comprehend the scale effects and structure–mechanical property correlations in this tissue. The quality of all these elements and their interactions play a crucial role in shaping bone's mechanical behavior. This work presents a review on 55 research works collected from the year 2008 to 2021. The basic mechanical features and behaviour of bone are discussed in this study. The "cortical bone, trabecular bone, and whole bones" are also discussed in this work along with numerous elements of material behaviour, such as flexibility, yields, fractures, tiredness, and damage. In addition, the roles of bone quantity (e.g., density, porosity) in each of the works have been analyzed. The analysis of best performance of the porosity value of the model is 44.22%, 30.34%, and 3.23% higher as compared to the other existing methods. Moreover, the research gaps and challenges of this work are addressed to enlighten future researchers. [ABSTRACT FROM AUTHOR]

Introduction: Bone spinal metastases disrupt the bone homeostasis, inducing a local imbalance in the bone formation and/or resorption, with consequent loss of the structural optimisation of the vertebrae and increase of the risk of fracture. Little is known about the microstructure of the metastatic tissue, the microstructure of the tissue surrounding the lesion, and how it does compare with vertebrae with no lesions observed on the biomedical images. A comprehensive assessment of the microstructural properties of the entire vertebral body can be obtained with micro computed tomography. In this study, we evaluated to what extent the vertebral body is affected by the presence of a metastatic lesion, the properties of the metastatic lesions, and whether the tissue surrounding the lesion has microstructural features similar to those of healthy tissue. Methods: A total of 30 metastatic vertebrae, including lytic (N = 12), blastic (N = 10), and mixed (N = 8) metastases, and 20 control vertebrae with no visible lesions on computed tomography were scanned using micro computed tomography (voxel size = 39 mm). The images were segmented and analysed to evaluate the microstructural properties in the entire vertebral body, in the lesion, and in the bone surrounding the lesion. Results: The microstructural properties evaluated on the entire vertebral bodies showed remarkable differences between metastatic and control vertebral bodies (p < 0.034) in terms of bone volume fraction, trabecular thickness, degree of anisotropy, connectivity density, and trabecular pattern factor. On the other hand, when the tissue surrounding the lesion was considered, no differences were found between metastatic and control vertebral bodies, except for differences in the degree of anisotropy (p = 0.008). All microstructural parameters measured in the regions including the lytic or the blastic metastases significantly differed (p < 0.001) from those in the tissues surrounding the lesions. The lytic lesions minimally affected the regions closest to the metastases, with significant differences only in the connectivity density. On the other hand, blastic metastases also affected the trabecular separation, the bone surface density, and the connectivity density in the closest tissue surrounding the lesion. Discussion: Most of the microstructural features of the trabecular bone in metastatic vertebrae were locally affected by lytic and blastic metastases, whereas the surrounding tissue showed a microstructure similar to that of adjacent vertebrae without visible lesions [ABSTRACT FROM AUTHOR]

This paper presents an experimental method for estimating the fatigue limit of trabecular bone using a single trabecular bone sample, the microstructural parameters of which were determined by microCT. Fatigue tests were carried out using the Locati method, with stepwise increasing load amplitude. The fatigue limits of the trabecular structures were determined experimentally in accordance with Miner's law of fatigue damage accumulation, based on the parameters of the reference S-N curve taken from the literature. On the basis of the fatigue limits, the S-N curves were determined for the tested samples, and from them the compressive strength USS-N corresponding to the fatigue limit for the N = 1 cycle. Ultimate compressive strength US was determined as a result of compression to failure tests. Computational dependencies combining the BV/TV index with US and the BMD index with US were formulated. To verify the proposed method, two groups of human trabecular bone samples were analysed: n = 42 were tested under monotonic loading, and n = 61 were tested under cyclic loading with stepwise increasing amplitude. The statistical test of the distribution conformity of the calculated USS-N compressive strength to the experimental US ultimate strength was performed. The results of the Kolmogorov–Smirnov statistical test were D = 0.19 (p = 0.314). The agreement of the distributions of BV/TV, as determined experimentally and calculated from the computational dependencies, was also tested statistically, with the result of the Kolmogorov–Smirnov test being D = 0.286 (p = 0.065). A similar analysis performed for BMD yielded D = 0.238 (p = 0.185). [ABSTRACT FROM AUTHOR]

The prevention and treatment of osteoporosis is currently a research hotspot, and the existing treatments pay more attention to the function of osteoblasts and osteoclasts, while the damage of bone microstructure will lead to the reduction of bone strength, which also plays an important role in the pathogenesis of osteoporosis. In the microstructure of bone, trabecula is the main structure to withstand complex mechanics, while cortical bone mainly maintains the ability to adapt to mechanical changes. The two have different performance in the process of osteoporosis and have different drug responses to conventional anti-osteoporosis therapy. In this paper, we will explore the progress of diagnosis and treatment of osteoporosis from the perspective of bone microstructure. [ABSTRACT FROM AUTHOR]

Background: The high-sugar and high-fat diet exerts distinct effects on bone volume and structure, depending on the type of carbohydrates and the amount of lipids. However, the effects of this diet on human bone health remain unexplored. Objective: This study examined the effects of a high-sucrose/high-fat diet on the bone health of Sprague–Dawley (SD) rats. Methods: Five-week-old SD rats were divided into two groups based on whether they received a normal (CE-2) or high-sucrose/high-fat (HSF) diet: SD＋CE-2 (control) and SD + HSF (treatment) groups (n = 5 rats/group). After 35 weeks of treatment, bone mineral density, structural parameters, and bone metabolism markers were measured. Student's t-test, Welch's t-test, and Mann-Whitney's U-test were used to determine differences between the two groups. Results: Femur weight did not differ significantly between the control and treatment groups. The femur area was considerably wider in the treatment group than in the control group. However, trabecular bone density was lower in the treatment group than in the control group. Trabecular volume and node structure number were significantly reduced in the treatment group when compared with those in the control group. Conclusions: Although high-sucrose/high-fat diet loading decreased trabecular bone volume and node strut number in SD rats, the diet did not contribute to bone density or structural changes. [ABSTRACT FROM AUTHOR]

Objectives: Primary hyperparathyroidism (PHPT) is a disorder marked by chronic parathyroid hormone hypersecretion, which affects bone turnover and remodelling processes. With a loss of bone density and an increase in bone porosity, the cortical compartment is most severely impacted. The study's goal is to assess PHPT's effects on the volumetric bone mineral density (vBMD) of the femur's trabecular compartment as well as the vBMD and thickness of the cortical bone. Methods: This is a retrospective case–control study, valuating age, biochemical doses, anthropometric measurements, and bone measurements. Between 2011 and 2016, 74 Caucasian Italian women and men with PHPT were sought out. Biochemical analyses were added to bone mineral density (BMD) values found in the lumbar spine and femoral neck. Proximal femur parameters such as cortical and trabecular volumetric (v) BMD, cortical thickness (CTh) and surface (s) BMD were analyzed by 3D-DXA software (3D-SHAPER Medical, Spain). Results: The findings showed a negative correlation between PHPT patients and controls, which was equally affecting the cortical and trabecular compartments. This correlation was especially evident in the areal BMD (aBMD) and vBMD measurements. Nonetheless, no appreciable correlation was found between the cortical level and the thickness of the cortical bone. Conclusions: Parathormone (PHT) levels had an adverse effect on the cortical, trabecular volumetric density in this investigation, as was expected. Cortical thickness, however, is unaffected significantly. The literature and these findings are consistent. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mandibular bone defect reconstruction remains a significant challenge for surgeons worldwide. Among multiple biodegradable biopolymers, allogeneic bone scaffolds derived from human sources have been used as an alternative to autologous bone grafts, providing optimal conditions for cell recruitment, adhesion, and proliferation and demonstrating significant osteogenic properties. This study aims to investigate the bone microstructure of the human scapula as a source for allogeneic bone scaffold fabrication for mandibular tissue engineering purposes. We created color-coded anatomical maps of the scapula and the mandible, reflecting the best anatomical and geometrical match. In this pilot study, we hypothesized a microstructural similarity of these bone structures and evaluated the human scapula's bone tissue engineering potential for mandibular bone tissue engineering by focusing on the microstructural characteristics. Lyophilized human scapular and mandibular bioimplants were manufactured and sterilized. Experimental bone samples from the scapula's acromion, coracoid, and lateral border from the mandibular condyle, mandibular angle, and mental protuberance were harvested and analyzed using micro-CT and quantitative morphometric analysis. This pilot study demonstrates significant microstructural qualitative and quantitative intra-group differences in the scapular and mandibular experimental bone samples harvested from the various anatomical regions. The revealed microstructural similarity of the human scapular and mandibular bone samples, to a certain extent, supports the stated hypothesis and, thus, allows us to suggest the human scapula as an alternative off-the-shelf allogeneic scaffold for mandibular reconstruction and bone tissue engineering applications. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to evaluate the effectiveness of a novel technique for securing the tibial component in cementless total knee arthroplasty (TKA) by utilizing resected cancellous bone to fill the peg holes. It was hypothesized that this method would reduce the incidence of radiolucent lines (RLLs) on plain radiographs. To test this hypothesis, a retrospective comparison of plain radiographs from patients who underwent the bone-filling technique (bone filling group) versus those who did not receive this treatment (conventional group) was conducted. Methods: Participants were 151 patients (213 joints) who underwent TKA with the NexGen trabecular metal (TM) modular tibia (Zimmer Biomet) from 2011 to 2016 [bone filling group, 54 patients (69 joints); conventional group, 100 patients (144 joints); 3 patients had 1 joint in each group]. Clinical evaluations, plain radiographs, and operative time were compared between groups. Results: The mean follow-up period was 5 years and 5 months. Knee Society Scores and Knee Society Functional Scores did not differ significantly between groups; however, the bone filling group had a significantly lower incidence of RLLs (p ​

Magnetic resonance imaging (MRI) is increasingly used to evaluate the microstructural and compositional properties of bone. MRI-based biomarkers can characterize all major compartments of bone: organic, water, fat, and mineral components. However, with a short apparent spin-spin relaxation time (T2*), bone is invisible to conventional MRI sequences that use long echo times. To address this shortcoming, ultrashort echo time MRI sequences have been developed to provide direct imaging of bone and establish a set of MRI-based biomarkers sensitive to the structural and compositional changes of bone. This review article describes the MRI-based bone biomarkers representing total water, pore water, bound water, fat fraction, macromolecular fraction in the organic matrix, and surrogates for mineral density. MRI-based morphological bone imaging techniques are also briefly described.

Abstract Background The aim of this study is to evaluate the changes in the trabecular structure of the mandibular bone and temporomandibular joint following Rapid Maxillary Expansion. Methods Thirty-nine patients who received Rapid Maxillary Expansion treatment in the Department of Orthodontics of the Faculty of Dentistry were selected from the archieve for the study. Trabecular structure changes of the angulus mandible, corpus mandible, and condyle regions were examined using fractal analysis on the dental panoramic radiographs. Radiographs taken before the treatment (T0) and at the end of the 3-month retention period (T1) of the patients. Results There was no statistically significant difference between T0 and T1 in the condyle, ramus mandible, and corpus mandible regions depending on time and sex. (p

Trabecular bone is highly dynamic in response to external and internal stimuli, and changes in its structure can be quantified through fractal analysis. However, fractal analysis is still an incipient technique in equine research. This study aimed to evaluate the complexity, heterogeneity, and density of the trabecular bone of the proximal phalanx (P1) of healthy adult horses of different breeds and sexes by measuring the values of fractal dimension (FD), lacunarity, and bone area fraction (BA/TA) in 65 radiographic examinations of the metacarpophalangeal joint and evaluate the agreement between the BoneJ and FracLac plugins for measuring FD. Regions of interest of 50 × 50 pixels were manually selected on the trabecular bone in the proximal epiphysis of the P1. No differences were observed for FD, lacunarity, and BA/TA between horses of different breeds and sexes (p > 0.1). The BoneJ and FracLac plugins showed no agreement when measuring FD (p < 0.01). Therefore, the radiographic texture of the trabecular bone of the P1 in horses had no influence depending on the analyzed breed or sex. The FracLac plugin measured higher FD values, and hence standardization using the BoneJ plugin is recommended. Further studies are required to evaluate other breeds, age groups, and training levels.

Background: The aim of this study is to evaluate the changes in the trabecular structure of the mandibular bone and temporomandibular joint following Rapid Maxillary Expansion. Methods: Thirty-nine patients who received Rapid Maxillary Expansion treatment in the Department of Orthodontics of the Faculty of Dentistry were selected from the archieve for the study. Trabecular structure changes of the angulus mandible, corpus mandible, and condyle regions were examined using fractal analysis on the dental panoramic radiographs. Radiographs taken before the treatment (T0) and at the end of the 3-month retention period (T1) of the patients. Results: There was no statistically significant difference between T0 and T1 in the condyle, ramus mandible, and corpus mandible regions depending on time and sex. (p < 0.05) Conclusion: The results of this study showed that Rapid Maxillary Expansion treatment does not have a significant impact on the trabecular structure of the mandible and temporomandibular joint depending on time and gender. [ABSTRACT FROM AUTHOR]

The "gold standard" for the assessment of trabecular bone structure is high‐resolution micro‐CT. In this technical note, we test the influence of initial scan resolution and post hoc downsampling on the quantitative and qualitative analysis of trabecular bone in a Gorilla tibia. We analyzed trabecular morphology in the right distal tibia of one Gorilla gorilla individual to investigate the impact of variation in voxel size on measured trabecular variables. For each version of the micro‐CT volume, trabecular bone was segmented using the medical image analysis method. Holistic morphometric analysis was then used to analyze bone volume (BV/TV), anisotropy (DA), trabecular thickness (Tb.Th), spacing (Tb.Sp), and number (Tb.N). Increasing voxel size during initial scanning was found to have a strong impact on DA and Tb.Th measures, while BV/TV, Tb.Sp, and Tb.N were found to be less sensitive to variations in initial scan resolution. All tested parameters were not substantially influenced by downsampling up to 90 μm resolution. Color maps of BV/TV and DA also retained their distribution up to 90 μm. This study is the first to examine the effect of variation in micro‐CT voxel size on the analysis of trabecular bone structure using whole epiphysis approaches. Our results indicate that microstructural variables may be measured for most trabecular parameters up to a voxel size of 90 μm for both scan and downsampled resolutions. Moreover, if only BV/TV, Tb.Sp or Tb.N is measured, even larger voxel sizes might be used without substantially affecting the results. [ABSTRACT FROM AUTHOR]

Osseodensification enhances the stability of endosteal implants. However, pre-clinical studies utilizing osseodensification instrumentation do not account for the limited presence of trabeculae seen clinically. This study aimed to evaluate the effect of osseodensification instrumentation on osteotomy healing in scenarios with and without the presence of trabecular bone. A ~10 cm incision was made over the hip of twelve sheep. Trabecular bone was surgically removed from twelve sites (one site/animal; negative control (Neg. Ctrl)) and left intact at twelve sites (one site/animal; experimental group (Exp.)). All osteotomies were created using the osseodensification drilling protocol. Each osteotomy received an endosteal implant and was evaluated after 3 or 12 weeks of healing (n = 6 animals/time). Histology revealed increased woven and lamellar bone surrounding the implants in the Exp. group relative to the Neg. Ctrl group. The Exp. group demonstrated the presence of bone fragments, which acted as nucleating sites, thereby enhancing the bone formation and remodeling processes. Bone-to-implant contact (%BIC) and bone area fractional occupancy (%BAFO) were significantly higher in the Exp. group relative to the Neg. Ctrl group both at 3 weeks (p = 0.009 and p = 0.043) and 12 weeks (p = 0.010 and p = 0.008). Osseodensification instrumentation in the presence of trabecular bone significantly improved osseointegration. However, no negative influences such as necrosis, inflammation, microfractures, or dehiscence were observed in the absence/limited presence of trabeculae. [ABSTRACT FROM AUTHOR]

Drinking alcohol while pregnant can cause several diseases, belonging to an umbrella of disorders known as Fetal Alcohol spectrum disorders. Alcohol exposure during pregnancy is linked to reduced birth weights, shorter bones, delayed bone growth, decreased bone resilience, and delayed ossification of the bones. However, the specific effects on the craniofacial bones, particularly the mandible, remain less explored. This study aims to fill this gap by examining the impact of gestational alcohol consumption on mandibular structure. Time-mated pregnant Sprague Dawley dams were divided into an ethanol group (n=6) and a saline control group (n=6). The ethanol group was given 0.015ml/g of 25.2% ethanol, while the control group received 0.9% saline for the first 19 days of gestation. The presence of a vaginal plug indicated the first day of gestation. After birth, the pups were euthanized at three weeks of age, and their mandibles were harvested and analyzed using a 3D-mCT scanner to assess bone ratio, trabecular thickness, number, and spacing. Osteometric measurements for mandibular length and height were also taken. The study found no significant differences in trabecular morphometric parameters between the groups. However, one parameter for mandibular length (Cd-Bi) and two parameters for mandibular height (Cd-Ag and Cr-Ag) were significantly smaller in the ethanol group than in the controls. The study reveals that gestational alcohol consumption can significantly affect the development of the mandible, with potential implications for understanding the mechanisms behind alcohol-induced teratogenicity. The findings highlight the need for further research to explore the intricate interactions between embryological, biological, genetic, and epigenetic factors that contribute to the varied effects of alcohol exposure during pregnancy on different skeletal systems. [ABSTRACT FROM AUTHOR]

The femoral head is one of the most commonly used bones for allografts and biomechanical studies. However, there are few reports on the trabecular bone microarchitectural parameters of freshly harvested trabecular bones. To our knowledge, this is the first study to characterize the microstructure of femoral heads tested immediately after surgery and compare it with the microstructure obtained with conventional freezing. This study aims to investigate whether freezing at −80 °C for 6 weeks affects the trabecular microstructure of freshly harvested bone tissue. This study was divided into two groups: one with freshly harvested human femoral heads and the other with the same human femoral heads frozen at −80 °C for 6 weeks. Each femoral head was scanned using an X-ray microcomputed tomography scanner (µCT) to obtain the microarchitectural parameters, including the bone volume fraction (BV/TV), the mean trabecular thickness (Tb.th), the trabecular separation (Tb.sp), the degree of anisotropy (DA), and the connectivity density (Conn.D). There was no statistically significant difference between the fresh and the frozen groups for any of the parameters measured. This study shows that freezing at −80 °C for 6 weeks does not alter bone microstructure compared with freshly harvested femoral heads tested immediately after surgery. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

IntroductionBone spinal metastases disrupt the bone homeostasis, inducing a local imbalance in the bone formation and/or resorption, with consequent loss of the structural optimisation of the vertebrae and increase of the risk of fracture. Little is known about the microstructure of the metastatic tissue, the microstructure of the tissue surrounding the lesion, and how it does compare with vertebrae with no lesions observed on the biomedical images. A comprehensive assessment of the microstructural properties of the entire vertebral body can be obtained with micro computed tomography. In this study, we evaluated to what extent the vertebral body is affected by the presence of a metastatic lesion, the properties of the metastatic lesions, and whether the tissue surrounding the lesion has microstructural features similar to those of healthy tissue.MethodsA total of 30 metastatic vertebrae, including lytic (N = 12), blastic (N = 10), and mixed (N = 8) metastases, and 20 control vertebrae with no visible lesions on computed tomography were scanned using micro computed tomography (voxel size = 39 mm). The images were segmented and analysed to evaluate the microstructural properties in the entire vertebral body, in the lesion, and in the bone surrounding the lesion.ResultsThe microstructural properties evaluated on the entire vertebral bodies showed remarkable differences between metastatic and control vertebral bodies (p < 0.034) in terms of bone volume fraction, trabecular thickness, degree of anisotropy, connectivity density, and trabecular pattern factor. On the other hand, when the tissue surrounding the lesion was considered, no differences were found between metastatic and control vertebral bodies, except for differences in the degree of anisotropy (p = 0.008). All microstructural parameters measured in the regions including the lytic or the blastic metastases significantly differed (p < 0.001) from those in the tissues surrounding the lesions. The lytic lesions minimally affected the regions closest to the metastases, with significant differences only in the connectivity density. On the other hand, blastic metastases also affected the trabecular separation, the bone surface density, and the connectivity density in the closest tissue surrounding the lesion.DiscussionMost of the microstructural features of the trabecular bone in metastatic vertebrae were locally affected by lytic and blastic metastases, whereas the surrounding tissue showed a microstructure similar to that of adjacent vertebrae without visible lesions

Background: Primary implant stability is a crucial factor for the successful osseointegration and long-term success of dental implants. The contribution of trabecular and cortical bone to primary implant stability is not well understood. Materials and Methods: An in vitro model using synthetic bone blocks mimicking trabecular and cortical bone was used to simulate implant placement. The study involved 40 implants, divided into four groups based on bone type and density: Group A (low-density trabecular bone), Group B (high-density trabecular bone), Group C (low-density cortical bone), and Group D (high-density cortical bone). Primary stability was assessed using insertion torque values and resonance frequency analysis (RFA). Insertion torque was measured using a digital torque meter, and RFA was measured using an Osstell ISQ device. Results: Group D (high-density cortical bone) exhibited the highest insertion torque values (mean: 45 Ncm) and Implant Stability Quotient (ISQ) values (mean: 75), indicating superior primary stability. Group C (low-density cortical bone) showed moderate stability, with mean insertion torque values of 30 Ncm and ISQ values of 60. Group B (high-density trabecular bone) had lower stability, with mean insertion torque values of 25 Ncm and ISQ values of 55. Group A (low-density trabecular bone) demonstrated the least stability, with mean insertion torque values of 15 Ncm and ISQ values of 45. Conclusion: The study concludes that cortical bone, especially high-density cortical bone, significantly contributes to primary implant stability compared to trabecular bone. The findings suggest that bone quality should be a major consideration during implant placement to ensure optimal primary stability and long-term success.

ABSTRACT: Background: Primary implant stability is a crucial factor for the successful osseointegration and long-term success of dental implants. The contribution of trabecular and cortical bone to primary implant stability is not well understood. Materials and Methods: An in vitro model using synthetic bone blocks mimicking trabecular and cortical bone was used to simulate implant placement. The study involved 40 implants, divided into four groups based on bone type and density: Group A (low-density trabecular bone), Group B (high-density trabecular bone), Group C (low-density cortical bone), and Group D (high-density cortical bone). Primary stability was assessed using insertion torque values and resonance frequency analysis (RFA). Insertion torque was measured using a digital torque meter, and RFA was measured using an Osstell ISQ device. Results: Group D (high-density cortical bone) exhibited the highest insertion torque values (mean: 45 Ncm) and Implant Stability Quotient (ISQ) values (mean: 75), indicating superior primary stability. Group C (low-density cortical bone) showed moderate stability, with mean insertion torque values of 30 Ncm and ISQ values of 60. Group B (high-density trabecular bone) had lower stability, with mean insertion torque values of 25 Ncm and ISQ values of 55. Group A (low-density trabecular bone) demonstrated the least stability, with mean insertion torque values of 15 Ncm and ISQ values of 45. Conclusion: The study concludes that cortical bone, especially high-density cortical bone, significantly contributes to primary implant stability compared to trabecular bone. The findings suggest that bone quality should be a major consideration during implant placement to ensure optimal primary stability and long-term success. [ABSTRACT FROM AUTHOR]

Abstract Background Telomere attrition may share common biological mechanisms with bone and muscle loss with aging. Here, we investigated the association between these hallmarks of aging using data from UK Biobank, a large observational study. Methods Leukocyte telomere length (LTL as T/S ratio) was measured using a multiplex qPCR assay at baseline (2006–2010). Bone mineral density (whole body and regional; via dual‐energy X‐ray absorptiometry), trabecular bone score (via lumbar‐spine dual‐energy X‐ray absorptiometry images), fat‐free muscle volume (thighs; via magnetic resonance imaging), and muscle fat infiltration (thighs; via magnetic resonance imaging) were measured during the imaging visit (2014–2018). Regression models were used to model LTL against a muscle or bone outcome, unadjusted and adjusted for covariates. Results A total of 16 356 adults (mean age: 62.8 ± 7.5 years, 50.5% women) were included. In the fully adjusted model, thigh fat‐free muscle volume was associated with LTL in the overall sample (adjusted standardized β (aβ) = 0.017, 95% CI 0.009 to 0.026, P 0.05). Conclusions LTL was consistently associated with thigh fat‐free muscle volume in men and women. Future research should investigate moderating effects of lifestyle factors (e.g., physical activity, nutrition, or chronic diseases) in the association between LTL and muscle volume.

(1) Background and aim: The effects of functional therapies on dentoalveolar and skeletal structures have been investigated in orthodontics for many years. The aim of this retrospective study was to evaluate the changes caused by fixed and removable functional therapy in the mandibular anterior trabecular structures using fractal dimension (FD) analysis. (2) Methods: A total of 60 patients with skeletal and dental class II malocclusion were included in the study and three groups were formed: the untreated control group (CG), the Forsus fatigue-resistant device group (FFRDG), and the Monoblock group (MBG). Bone areas of interest determined in the buccoapical of the mandibular incisors and the symphysis in the lateral cephalometric radiographs taken before (T0) and after (T1) functional therapy were evaluated using FD analysis. The relationship between the FD and IMPA (Incisor Mandibular Plane Angle) angles was evaluated. Parametric and nonparametric tests were used in statistical analysis according to normality distribution. The statistical significance level was determined as p < 0.05. (3) Results: There was no statistically significant difference between the FD values of all groups at T0 (p > 0.05). At T1, buccoapical FD values were significantly lower in FFRDG and MBG compared to the control group (p < 0.05), while symphyseal FD values were not found to be significant (p > 0.05). The IMPA angle was significantly lower in the FFRDG and MBG than in the control group at T0, while it was higher at T1 (p < 0.05). While a significant negative correlation was observed between the IMPA angle and buccoapical FD values in both FFRDG and MBG (p < 0.05), it was not observed with the symphysis FD values (p > 0.05). (4) Conclusions: Trabecular changes caused by functional therapy in the mandibular anterior bone can be evaluated on lateral cephalometric radiographs with FD analysis. It was concluded that orthodontists should ensure controlled changes in the IMPA angle during functional therapy, especially for the decreases in FDs seen in the buccoapical alveolar region due to the forward movement of the mandibular incisors. [ABSTRACT FROM AUTHOR]

Background The longitudinal changes in hip-bone microstructures and estimated bone strength in dialysis patients, and the impact of chronic kidney disease–mineral and bone disorder (CKD-MBD) biomarkers on these changes, remain insufficiently explored. Methods This retrospective study examined changes in cortical and trabecular bone compartments and estimated bone-strength indices, obtained by using 3D-SHAPER software, in the hip regions of 276 dialysis patients over up to 2.5 years. We used multivariate mixed models to investigate the associations between time-dependent CKD-MBD biomarkers and bone health metrics. Results There was a significant decrease in areal bone mineral density (aBMD), integral volumetric BMD (vBMD), trabecular vBMD, cortical thickness and cortical surface BMD (sBMD). Similar deteriorations were found in estimated bone-strength indices [cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), section modulus (SM) and buckling ratio]. Neither serum calcium nor phosphate levels were significantly associated with changes in three-dimensional parameters or estimated bone-strength indices. In contrast, serum alkaline phosphatase levels showed a significant inverse correlation with aBMD and CSA. The intact-parathyroid hormone (i-PTH) was significantly inversely correlated with aBMD, integral vBMD, trabecular vBMD, cortical thickness, cortical vBMD, CSA, CSMI and SM. When applying the KDIGO criteria as a sensitivity analysis, the higher PTH group had significant negative associations with aBMD, integral vBMD, cortical vBMD, cortical thickness and cortical sBMD. Notably, the lower PTH group showed a positive significant correlation with integral vBMD and trabecular vBMD. Conclusions Elevated PTH, not low PTH, was associated with deterioration of hip-bone microstructures. Better management of PTH levels may play a crucial role in the hip-bone microstructure in dialysis patients. [ABSTRACT FROM AUTHOR]

Understanding bone surface curvatures is crucial for the advancement of bone material design, as these curvatures play a significant role in the mechanical behavior and functionality of bone structures. Previous studies have demonstrated that bone surface curvature distributions could be used to characterize bone geometry and have been proposed as key parameters for biomimetic microstructure design and optimization. However, understanding of how bone surface curvature distributions correlate with bone microstructure and mechanical properties remains limited. This study hypothesized that bone surface curvature distributions could be used to predict the microstructure as well as mechanical properties of trabecular bone. To test the hypothesis, a convolutional neural network (CNN) model was trained and validated to predict the histomorphometric parameters (e.g., BV/TV, BS, Tb.Th, DA, Conn.D, and SMI), geometric parameters (e.g., plate area PA, plate thickness PT, rod length RL, rod diameter RD, plate-to-plate nearest neighbor distance NNDPP, rod-to-rod nearest neighbor distance NNDRR, plate number PN, and rod number RN), as well as the apparent stiffness tensor of trabecular bone using various bone surface curvature distributions, including maximum principal curvature distribution, minimum principal curvature distribution, Gaussian curvature distribution, and mean curvature distribution. The results showed that the surface curvature distribution-based deep learning model achieved high fidelity in predicting the major histomorphometric parameters and geometric parameters as well as the stiffness tenor of trabecular bone, thus supporting the hypothesis of this study. The findings of this study underscore the importance of incorporating bone surface curvature analysis in the design of synthetic bone materials and implants. [ABSTRACT FROM AUTHOR]

Trabecular bone is highly dynamic in response to external and internal stimuli, and changes in its structure can be quantified through fractal analysis. However, fractal analysis is still an incipient technique in equine research. This study aimed to evaluate the complexity, heterogeneity, and density of the trabecular bone of the proximal phalanx (P1) of healthy adult horses of different breeds and sexes by measuring the values of fractal dimension (FD), lacunarity, and bone area fraction (BA/TA) in 65 radiographic examinations of the metacarpophalangeal joint and evaluate the agreement between the BoneJ and FracLac plugins for measuring FD. Regions of interest of 50 × 50 pixels were manually selected on the trabecular bone in the proximal epiphysis of the P1. No differences were observed for FD, lacunarity, and BA/TA between horses of different breeds and sexes (p > 0.1). The BoneJ and FracLac plugins showed no agreement when measuring FD (p < 0.01). Therefore, the radiographic texture of the trabecular bone of the P1 in horses had no influence depending on the analyzed breed or sex. The FracLac plugin measured higher FD values, and hence standardization using the BoneJ plugin is recommended. Further studies are required to evaluate other breeds, age groups, and training levels. [ABSTRACT FROM AUTHOR]

Background: Osteoporosis is a bone disease related to increased bone loss and fracture‐risk. The variability in bone strength is partially explained by bone mineral density (BMD), and the remainder is contributed by bone microstructure. Recently, clinical CT has emerged as a viable option for in vivo bone microstructural imaging. Wide variations in spatial‐resolution and other imaging features among different CT scanners add inconsistency to derived bone microstructural metrics, urging the need for harmonization of image data from different scanners. Purpose: This paper presents a new deep learning (DL) method for the harmonization of bone microstructural images derived from low‐ and high‐resolution CT scanners and evaluates the method's performance at the levels of image data as well as derived microstructural metrics. Methods: We generalized a three‐dimensional (3D) version of GAN‐CIRCLE that applies two generative adversarial networks (GANs) constrained by the identical, residual, and cycle learning ensemble (CIRCLE). Two GAN modules simultaneously learn to map low‐resolution CT (LRCT) to high‐resolution CT (HRCT) and vice versa. Twenty volunteers were recruited. LRCT and HRCT scans of the distal tibia of their left legs were acquired. Five‐hundred pairs of LRCT and HRCT image blocks of 64×64×64$64 \times 64 \times 64 $ voxels were sampled for each of the twelve volunteers and used for training in supervised as well as unsupervised setups. LRCT and HRCT images of the remaining eight volunteers were used for evaluation. LRCT blocks were sampled at 32 voxel intervals in each coordinate direction and predicted HRCT blocks were stitched to generate a predicted HRCT image. Results: Mean ± standard deviation of structural similarity (SSIM) values between predicted and true HRCT using both 3DGAN‐CIRCLE‐based supervised (0.84 ± 0.03) and unsupervised (0.83 ± 0.04) methods were significantly (p < 0.001) higher than the mean SSIM value between LRCT and true HRCT (0.75 ± 0.03). All Tb measures derived from predicted HRCT by the supervised 3DGAN‐CIRCLE showed higher agreement (CCC ∈$ \in $ [0.956 0.991]) with the reference values from true HRCT as compared to LRCT‐derived values (CCC ∈$ \in $ [0.732 0.989]). For all Tb measures, except Tb plate‐width (CCC = 0.866), the unsupervised 3DGAN‐CIRCLE showed high agreement (CCC ∈$ \in $ [0.920 0.964]) with the true HRCT‐derived reference measures. Moreover, Bland‐Altman plots showed that supervised 3DGAN‐CIRCLE predicted HRCT reduces bias and variability in residual values of different Tb measures as compared to LRCT and unsupervised 3DGAN‐CIRCLE predicted HRCT. The supervised 3DGAN‐CIRCLE method produced significantly improved performance (p < 0.001) for all Tb measures as compared to the two DL‐based supervised methods available in the literature. Conclusions: 3DGAN‐CIRCLE, trained in either unsupervised or supervised fashion, generates HRCT images with high structural similarity to the reference true HRCT images. The supervised 3DGAN‐CIRCLE improves agreements of computed Tb microstructural measures with their reference values and outperforms the unsupervised 3DGAN‐CIRCLE. 3DGAN‐CIRCLE offers a viable DL solution to retrospectively improve image resolution, which may aid in data harmonization in multi‐site longitudinal studies where scanner mismatch is unavoidable. [ABSTRACT FROM AUTHOR]

The mechanical quality of trabecular bone is influenced by its mineral content and spatial distribution, which is controlled by bone remodelling and mineralisation. Mineralisation kinetics occur in two phases: a fast primary mineralisation and a secondary mineralisation that can last from several months to years. Variations in bone turnover and mineralisation kinetics can be observed in the bone mineral density distribution (BMDD). Here, we propose a statistical spatio-temporal bone remodelling model to study the effects of bone turnover (associated with the activation frequency Ac. f ) and mineralisation kinetics (associated with secondary mineralisation T sec ) on BMDD. In this model, individual basic multicellular units (BMUs) are activated discretely on trabecular surfaces that undergo typical bone remodelling periods. Our results highlight that trabecular BMDD is strongly regulated by Ac. f and T sec in a coupled way. Ca wt% increases with lower Ac. f and short T sec . For example, a Ac. f = 4 BMU/year/mm 3 and T sec = 8 years result in a mean Ca wt% of 25, which is in accordance with Ca wt% values reported in quantitative backscattered electron imaging (qBEI) experiments. However, for lower Ac. f and shorter T sec (from 0.5 to 4 years) one obtains a high Ca wt% and a very narrow skew BMDD to the right. This close link between Ac. f and T sec highlights the importance of considering both characteristics to draw meaningful conclusion about bone quality. Overall, this model represents a new approach to modelling healthy and diseased bone and can aid in developing deeper insights into disease states like osteoporosis. [ABSTRACT FROM AUTHOR]

Both cell migration and osteogenic differentiation are critical for successful bone regeneration. Therefore, understanding the mechanobiological aspects that govern these two processes is essential in designing effective scaffolds that promote faster bone regeneration. Studying these two factors at different locations is necessary to manage bone regeneration in various sections of a scaffold. Hence, a multiscale computational model was used to observe the mechanical responses of osteoblasts placed in different positions of the trabecular bone and gyroid scaffold. Fluid shear stresses in scaffolds at cell seeded locations (representing osteogenic differentiation) and strain energy densities in cells at cell substrate interface (representing cell migration) were observed as mechanical response parameters in this study. Comparison of these responses, as two critical factors for bone regeneration, between the trabecular bone and gyroid scaffold at different locations, is the overall goal of the study. This study reveals that the gyroid scaffold exhibits higher osteogenic differentiation and cell migration potential compared to the trabecular bone. However, the responses in the gyroid only mimic the trabecular bone in two out of nine positions. These findings can guide us in predicting the ideal cell seeded sites within a scaffold for better bone regeneration and in replicating a replaced bone condition by altering the physical parameters of a scaffold. [ABSTRACT FROM AUTHOR]

This numerical analysis, by employing Tresca and Von Mises failure criteria, assessed the biomechanical behavior of a trabecular bone component subjected to 0.6, 1.2, and 2.4 N orthodontic forces under five movements (intrusion, extrusion, tipping, rotation, and translation) and during a gradual horizontal periodontal breakdown (0–8 mm). Additionally, they assessed the changes produced by bone loss, and the ischemic and resorptive risks. The analysis employed eighty-one models of nine patients in 405 simulations. Both failure criteria showed similar qualitative results, with Tresca being quantitatively higher by 1.09–1.21. No qualitative differences were seen between the three orthodontic loads. Quantitatively, a doubling (1.2 N) and quadrupling (2.4 N) were visible when compared to 0.6 N. Rotation and translation followed by tipping are the most stressful, especially for a reduced periodontium, prone to higher ischemic and resorptive risks. In an intact periodontium, 1.2 N can be safely applied but only in a reduced periodontium for extrusion and intrusion. More than 0.6 N is prone to increasing ischemic and resorptive risks for the other three movements. In an intact periodontium, stress spreads in the entire trabecular structure. In a reduced periodontium, stress concentrates (after a 4 mm loss—marker for the stress change distribution) and increases around the cervical third of the remaining alveolar socket. [ABSTRACT FROM AUTHOR]

Abstract Bone strength depends on both mineral content and bone structure. Measurements of bone microstructure on specimens can be performed by micro-CT. In vivo measurements are reliably performed by high-resolution peripheral computed tomography (HR-pQCT) using dedicated software. In previous studies from our research group, trabecular bone properties on CT data of defatted specimens from many different CT devices have been analyzed using an Automated Region Growing (ARG) algorithm-based code, showing strong correlations to micro-CT. The aim of the study was to validate the possibility of segmenting and measuring trabecular bone structure from clinical CT data of fresh-frozen human wrist specimens. Data from micro-CT was used as reference. The hypothesis was that the ARG-based in-house built software could be used for such measurements. HR-pQCT image data at two resolutions (61 and 82 µm isotropic voxels) from 23 fresh-frozen human forearms were analyzed. Correlations to micro-CT were strong, varying from 0.72 to 0.99 for all parameters except trabecular termini and nodes. The bone volume fraction had correlations varying from 0.95 to 0.98 but was overestimated compared to micro-CT, especially at the lower resolution. Trabecular separation and spacing were the most stable parameters with correlations at 0.80-0.97 and mean values in the same range as micro-CT. Results from this in vitro study show that an ARG-based software could be used for segmenting and measuring 3D trabecular bone structure from clinical CT data of fresh-frozen human wrist specimens using micro-CT data as reference. Over-and underestimation of several of the bone structure parameters must however be taken into account.

Abstract Blade cut-out is a common complication when using proximal femoral nail anti-rotation (PFNA) for the treatment of intertrochanteric fractures. Although cement augmentation has been introduced to overcome the cut-out effect, the micromechanics of this approach remain to be clarified. While previous studies have developed finite element (FE) models based on lab-prepared or cadaveric samples to study the cement-trabeculae interface, their demanding nature and inherent disadvantages limit their application. The aim of this study was to develop a novel 'one-step forming' method for creating a cement-trabeculae interface FE model to investigate its micromechanics in relation to PFNA with cement augmentation. A human femoral head was scanned using micro-computed tomography, and four volume of interest (VOI) trabeculae were segmented. The VOI trabeculae were enclosed within a box to represent the encapsulated region of bone cement using ANSYS software. Tetrahedral meshing was performed with Hypermesh software based on Boolean operation. Finally, four cement-trabeculae interface FE models comprising four interdigitated depths and five FE models comprising different volume fraction were established after element removal. The effects of friction contact, frictionless contact, and bond contact properties between the bone and cement were identified. The maximum micromotion and stress in the interdigitated and loading bones were quantified and compared between the pre- and post-augmentation situations. The differences in micromotion and stress with the three contact methods were minimal. Micromotion and stress decreased as the interdigitation depth increased. Stress in the proximal interdigitated bone showed a correlation with the bone volume fraction (R2 = 0.70); both micromotion (R2 = 0.61) and stress (R2 = 0.93) at the most proximal loading region exhibited a similar correlation tendency. When comparing the post- and pre-augmentation situations, micromotion reduction in the interdigitated bone was more effective than stress reduction, particularly near the cement border. The cementation resulted in a significant reduction in micromotion within the loading bone, while the decrease in stress was minimal. Noticeable gradients of displacement and stress reduction can be observed in models with lower bone volume fraction (BV/TV). In summary, cement augmentation is more effective at reducing micromotion rather than stress. Furthermore, the reinforcing impact of bone cement is particularly prominent in cases with a low BV/TV. The utilization of bone cement may contribute to the stabilization of trabecular bone and PFNA primarily by constraining micromotion and partially shielding stress.

Objectives: People living with HIV (PLWH) have been shown to have lower bone density at the spine, hip, and radius. However, whether a similar bone phenotype is seen in craniofacial bones is not known. The goal of this study was to evaluate the bone microarchitecture of the mandibular condyle in PLWH. Methods: We recruited 212 participants, which included 88 HIV‐negative participants and 124 PLWH on combination antiretroviral therapy with virological suppression from a single academic center. Each participant filled out a validated temporomandibular disorder (TMD) pain screening questionnaire and had cone beam computed tomography (CBCT) of their mandibular condyles. Qualitative radiographic evidence of temporomandibular joint disorders‐osteoarthritis (TMJD‐OA) assessment and quantitative microarchitecture analysis of their mandibular condylar bones were conducted. Results: There was no statistically significant difference in either self‐reported TMD or in radiographic evidence of TMJD‐OA in PLWH compared with HIV‐negative controls. Linear regression analysis revealed that positive HIV status remained significantly associated with increased trabecular thickness, decreased cortical porosity, and increased cortical bone volume fraction after adjusting for race, diabetes, sex, and age. Conclusion: PLWH have increased mandibular condylar trabecular bone thickness and cortical bone volume fraction compared with HIV‐negative controls. [ABSTRACT FROM AUTHOR]