Trabecular Thickness Research Articles

8136 Using High-Resolution Peripheral Quantitative Computed Tomography to Assess Bone Microarchitecture and Guide Osteoporosis Treatment

Abstract Disclosure: S.V. Rupani: None. J. Sfeir: None. L. Graeff-Armas: None. Bone microarchitecture is an important factor that impacts bone strength. Unlike other factors that affect bone strength, such as bone mineral density and bone turnover, assessment of bone microarchitecture is not yet widely accessible in clinical practice. Computed tomography is the primary method of non-invasively assessing bone microarchitecture. High-resolution peripheral quantitative CT (HR-pQCT) is an emerging imaging modality that provides a three-dimensional assessment of bone densitometry, morphometry, and microarchitecture with a low effective radiation dose. It provides a quantitative and qualitative assessment of cortical and trabecular structural and mechanical properties. We present two similar cases of osteoporosis in males, where knowledge of bone microarchitecture through HR-pQCT helped formulate two distinct and targeted therapeutic approaches. The first case is of a 46-year-old male with a history of idiopathic osteoporosis with multiple nontraumatic vertebral fractures. Given his presentation and age, anabolic therapy such as teriparatide was being considered. He underwent HR-pQCT scanning, which showed average radial trabecular parameters, but his cortical porosity was significantly above average, with similar findings in his tibial parameters. Since teriparatide has been shown to increase cortical porosity, this would not be the best option for our patient, given the risk of further weakening of the microarchitecture of his cortical bone. Therefore, denosumab, which has been shown to decrease cortical porosity, was chosen. Our second patient is a 52-year-old male with idiopathic osteoporosis with multiple nontraumatic vertebral fractures, whose HR-pQCT showed average cortical parameters at both the radius and tibia but low trabecular number and increased trabecular separation at both sites. Since teriparatide increases trabecular thickness and mass, we could confidently choose teriparatide for this patient, with less concern for significant deleterious effects on his cortical bone parameters. These case reports highlight the impact that the assessment of qualitative properties of bone, such as microarchitecture, can have in the management of osteoporosis. Currently, the lack of sufficient validated normative data for HR-pQCT limits its widespread use in the diagnosis of osteoporosis and fracture prediction. However, given that HR-pQCT can characterize the properties of trabecular and cortical bone, it may have a role in helping guide osteoporosis treatment, especially in challenging and atypical cases. Presentation: 6/3/2024

7943 In Obese C57Bl6 Male Mice, Weight Loss due to Caloric Restriction Reduced Bone Morphology but Improved Components of Systemic Metabolism

Abstract Disclosure: C. Chlebek: None. C. McAndrews: None. S.N. Costa: None. C.J. Rosen: None. Obesity and calorie restriction individually alter systemic cellular metabolism and affect musculoskeletal tissue health. Obesity reduces trabecular and cortical bone quality. Clinically, obese patients are advised to lose weight, despite the negative effects of calorie restriction on bone in nonobese preclinical models. Little is known about bone quality following weight loss in obese preclinical models. We hypothesized that in obese models, caloric restriction would further worsen bone quality. To induce obesity, male C57Bl6 mice (8 weeks old) received 60% high fat diet for 12 weeks (high fat feeding phase). Following obesity induction, the HFD-CR group was acclimated to control low fat diet for 2 wks and then underwent 30% caloric restriction for 8 wks (caloric restriction feeding phase). The HFD group received 60% kcal high fat diet from ages 8 to 30 wks. LFD mice received control low fat 10% kcal diet for the study duration. Mice were euthanized at 30 wks of age. Body weight, body composition, and bone mineral density were recorded at baseline and at the end of each diet. Glucose and insulin tolerance were recorded at the end of the high fat and caloric restriction feeding phases. At euthanasia, cortical and trabecular bone morphology (µCT) were assessed.Adverse metabolic parameters worsened with high fat feeding but improved by caloric restriction. Compared to LFD animals, HFD and HFD-CR mice gained body weight, fat mass, and lean mass during the high fat feeding phase. After the caloric restriction feeding phase, body weight, fat mass, and lean mass were reduced in HFD-CR compared to both HFD and LFD controls (p < 0.0001). After 12 weeks of high fat feeding, glucose and insulin tolerance were reduced in HFD and HFD-CR mice compared to LFD (p < 0.0001). Caloric restriction improved both glucose and insulin tolerance in HFD-CR mice compared to both HFD and LFD animals (p < 0.0001). Caloric restriction improved areal bone mineral density, but at euthanasia, HFD-CR mice had worse bone morphology compared to LFD or HFD animals. Although areal bone mineral density (aBMD) was reduced by the high fat feeding phase, HFD-CR and LFD aBMD was not different at the end of the study (p < 0.0001). At euthanasia, HFD-CR mice had reduced cortical area and cortical thickness (p < 0.05). Marrow area and moment of inertia were not different between diets. Compared to LFD, both HFD and HFD-CR mice had reduced tibial bone volume fraction (p < 0.05). HFD-CR animals had smaller trabecular thickness (p < 0.05) and greater trabecular number (p < 0.01) compared to HFD mice. Despite improvements in components of systemic metabolism, caloric restriction in obese preclinical models reduced bone morphology in both trabecular and cortical compartments. This work will improve our understanding of the musculoskeletal system following caloric restriction in obese models and will aid in nutritional counseling for obese patients. Presentation: 6/1/2024

7793 Bone Mineral Density, Turnover And Bone Microarchitecture Alterations With Dapagliflozin In Post-menopausal Women With Type 2 Diabetes Mellitus: An Open-Label, Parallel-Arm, Randomized, Controlled Study

Abstract Disclosure: S.K. Bhadada: None. L. Das: None. M. Baruah: None. V. Singla: None. V. Dhiman: None. S. Ram: None. S. Sharma: None. N. Sachdeva: None. P. Dutta: None. Introduction: Evidence is limited and there is no consensus about the effects of SGLT2i on bone metabolism. The objective of the current study was to assess changes in bone mineral density (BMD), turnover markers (BTMs), and microarchitecture with the use of dapagliflozin in type 2 diabetes mellitus (T2DM). Methods: Post-menopausal women (<65 years) with T2DM (both menopause and T2DM duration > 5 years and HbA1c 7-11%) were randomly allocated (1:1) to receive either add-on dapagliflozin with standard-of-care or standard-of-care alone for T2DM management. Those with osteoporosis, on anti—osteoporotic medication, chronic glucocorticoids (>3 months), thiazolidinediones, phenytoin, tamoxifen, estrogen, eGFR<30ml/min/1.73m2, contraindication/past usage of SGLT2i, or with known endocrinopathy were excluded. Patients were made Vitamin D sufficient [25(OH)D > 30ng/ml] with oral cholecalciferol (60K daily for 1 week), if deficient. BMD (DXA, Hologic), BTMs (P1NP, CTX) and microarchitecture were assessed at baseline, 6 and 12 months. Results: A total of 131 patients were screened, of which 101 were randomized (50 dapagliflozin, 51 non-dapagliflozin). The mean age (± SD) in the dapagliflozin group was 58.1 ± 5.8 years, diabetes duration was 9.4 ± 5.2 years and HbA1c was 8.5 ± 1.7%. Baseline clinico-biochemical, areal BMD, volumetric BMD, trabecular structural (number, thickness, separation) and cortical structural (thickness and porosity) parameters were comparable between both groups. Only cortical pore diameter (Ct.Po.Dm) (±SD) at radius (0.199 ± 0.04 vs 0.180 ± 0.03, p =0.01) and tibia (0.256 ± 0.04 vs 0.226 ± 0.03, p =0.001) were higher in the dapagliflozin than the non-dapagliflozin group. At 6 months, BMD at lumbar spine (LS), hip, femoral neck (FN), and distal radius and BTMs were comparable between the dapagliflozin (n=38) and the non-dapagliflozin (n=39) groups. However, there was significantly higher trabecular thickness (Tb.Th) (0.230 ± 0.02 vs 0.218 ± 0.01, p=0.003), cortical thickness (Co.Th) (1.104 ± 0.2 vs 0.998 ± 0.2, p=0.04), intra-cortical porosity (Ct.Po) (0.008 ± 0.005 vs 0.005 ± 0.003, p= 0.020) and Ct.Po.Dm (0.192 ± 0.03 vs 0.169 ± 0.02, p=0.003), all at radius in the dapagliflozin group. At 12 months follow-up, BMD (g/cm2) at all 4 sites were again comparable between the dapagliflozin (n=36) and non-dapagliflozin (n=36) groups. Serum CTX (pg/ml) (388.8 ± 191.5 vs 327.4 ± 140.8, p = 0.06), and P1NP (ng/ml) (38.8 ± 16.3 vs 32.5 ± 16.3, p = 0.12) were non-significantly higher with dapagliflozin use. Among microarchitecture parameters, only Ct.Po.Dm at the radius (0.189 ± 0.03 vs 0.169 ± 0.03, p= 0.025) and tibia (0.251 ± 0.05 vs 0.228 ± 0.03, p= 0.030) remained significantly higher in the dapagliflozin group. Conclusion: Dapagliflozin has no long-term detrimental effects on BMD, BTMs or bone microarchitecture after 1 year of treatment in postmenopausal women with T2DM. Presentation: 6/1/2024

8711 The Effect of Testosterone Therapy Upon Bone Remodelling in Testosterone Deficient APOE-/- Mice Fed a High Fat Diet

Abstract Disclosure: A. Williamson: None. L. Bateman: None. C. LeMaitre: None. T.H. Jones: None. N. Aberdein: None. D.M. Kelly: None. Introduction: Low testosterone can lead to bone loss in males, but the mechanisms are not fully characterised. This study investigates the effects of testosterone depletion, and subsequent testosterone treatment on parameters of bone remodeling in a murine model of cardiometabolic disease. Methods: At 8 weeks of age, high-fat diet-fed ApoE-/- mice were randomised into three groups: sham surgery + placebo treatment (control, n=9), orchidectomy + placebo treatment (n =8), and orchidectomy + testosterone treatment (n=10). 25 week old mice were sacrificed and tissues collected for analysis. Left tibiae were decalcified, paraffin embedded and sectioned prior to immunostaining of bone turnover markers including receptor activator of nuclear factor κB ligand (RANKL), Osteoprotegerin (OPG), runx2, Alkaline Phosphatase (ALP), adiponectin and marrow lipid content. Right tibiae underwent mechanical 3-point bend testing at 0.05mm/s using a CellScale Univert. Results: µCT demonstrated a significant decrease in trabecular bone volume, number, and bone mineral density (BMD) and increased trabecular thickness in orchidectomised mice compared to controls. These parameters returned to control levels in testosterone treated orchiectomised mice. No significant differences were observed in cortical bone. Lipid deposition within the bone marrow was significantly increased in testosterone deficient mice compared to testosterone replete mice. No significant differences in ALP immunopositivity were detected between groups, and runx2 was significantly decreased in orchiectomised mice treated with testosterone compared to controls. The ratio of RANKL/OPG immunopositivity was significantly increased in testosterone deficient mice compared to testosterone replete mice. 3-point bending demonstrated no significant differences in maximal force between groups despite a downward trend in orchiectomised groups compared to controls. Osteoclast number quantified from TRAP-stained sections was not different between groups. Discussion: Testosterone depletion accelerates trabecular bone loss, mediated by increased osteoclastogenesis via the RANKL/OPG pathway and increased bone marrow adiposity, an effect reversed by testosterone treatment. While this study highlights the benefits of testosterone upon trabecular bone health in male mice these changes may not alter fracture risk as 3-point-bend maximal force was not affected. Presentation: 6/2/2024

The possible protective role of glucosamine versus zoledronic acid on osteopenic effect of pantoprazole in adult male albino rats

Background Osteopenia is an asymptomatic condition till fragility fractures occur and may be linked to prolonged use of pantoprazole. Aim To determine osteopenic effect of long-term use of pantoprazole and study the possible protective role of glucosamine versus zoledronic acid on this effect in adult male albino rats. Patient and methods A total of 60 rats were divided equally into six groups; group I subdivided equally into IA received no treatment and IB received normal saline. Group II received glucosamine. Group III received zoledronic acid. Group IV received pantoprazole. Group V received pantoprazole and glucosamine. Group VI received pantoprazole and zoledronic acid. After 12 weeks, the left femurs were subjected to radiography and measured bone mineral density from the proximal end (neck). The right proximal ends of femurs were processed for histological, immunohistochemical, and scanning electron microscopic studies. Results Groups V and VI showed restoration of normal trabecular histology with a highly significant increase in trabecular thickness and a highly significant decrease in inter-trabecular spaces and mean area% of osteopontin compared with group IV. However, it seemed that group V had a more anabolic effect revealed by significant increase in bone mineral density, Z-score, and mean area% of osteocalcin compared with group VI. Conclusion Long-term use of pantoprazole led to osteopenia. Concomitant use of either glucosamine or zoledronic acid with pantoprazole reduced the severity of trabecular damage induced by pantoprazole. However, it seemed that glucosamine exerted a more anabolic effect than zoledronic acid.

Mineralization of equine proximal sesamoid bones precedes articular cartilage and fibrocartilaginous enthesis maturation in early postgestational development.

To describe the development and maturation of equine proximal sesamoid bones (PSBs) in fetuses and young horses using radiography, microcomputed (micro)-CT, and histology. A descriptive study. Forelimb PSBs from 12 equids ranging in age from 105 days of gestation to 540 days postgestation were evaluated. Radiography was used for preliminary assessment of metacarpophalangeal joint and PSB mineralization, and micro-CT imaging was performed to assess mineralized PSBs. Tissue volume, bone volume fraction, height, width, depth, trabecular thickness, and anisotropy were quantified from midplanar micro-CT sections in 3 dimensions. Midsagittal PSB histologic sections stained with H&E and Safranin O/Fast Green were used to determine the ratio of ossification center to cartilage template size and to describe the formation and development of the cartilage template, ossification center, spherical growth plate, articular cartilage, and entheses. Mineralization of equine PSBs is associated with cartilage canals and a spherical growth plate that undergoes endochondral ossification during the late gestation to early postgestational period. The apical, flexor, basilar, and articular ossification fronts demonstrate morphologic variability. Structural organization of the articular cartilage and entheses occurs concurrently with the development of an underlying plate of compact bone. At 540 days postgestation, the fibrocartilaginous entheses of the flexor cortex of the PSB had yet to mature. Equine PSBs mineralize predominantly by endochondral ossification during the late gestation to early postgestational period. Mineralization precedes maturation of the articular cartilage and fibrocartilaginous entheses. The postgestational maturation of the PSB and its surrounding tissues may predispose young horses to developing lesions at these sites, such as apical avulsion fractures, warranting further investigation.

MicroRNA-324 mediates bone homeostasis and the regulation of osteoblast and osteoclast differentiation and activity

MicroRNAs (miRNAs) modulate the expression of other RNA molecules. One miRNA can target many transcripts, allowing each miRNA to play key roles in many biological pathways. Defects in bone homeostasis result in common age-related diseases including osteoporosis. Serum levels of miR-324-3p positively correlate with several features of bone maintenance. In contrast here, using in vivo micro-computed tomography and histology, global miR-324-null mice demonstrated increased bone mineral density and both trabecular and cortical thickness, with effect magnitudes increasing with age. The bone marrow of miR-324-null mice had reduced lipid content while TRAP staining revealed a decrease in osteoclasts, with histomorphometry demonstrating an increased rate of bone formation. Ex vivo assays showed that the high bone mass phenotype of miR-324-null mice resulted from both increased osteoblast activity and decreased osteoclastogenesis. RNA-seq analysis of osteoblasts, osteoclasts and bone marrow macrophages and target validation assays identified that the osteoclast fusion regulator Pin1 and the master osteogenic regulator Runx2 were targets of miR-324-5p in osteoclast lineage cells and osteoblasts, respectively. Indeed, in vitro Runx2 overexpression recapitulated the increased osteogenesis and decreased adipogenesis phenotype observed in vivo by the loss of miR-324. Overall, these data demonstrate the importance of miR-324 in bone homeostasis by regulating aspects of both bone formation and remodelling. Elucidation of pathways regulated by miR-324 offer promise for the treatment of bone diseases such as osteoporosis.

MORPHOLOGICAL CHANGES IN OSTEOPOROTIC BONES: A COMPARATIVE ANALYSIS USING BIOCHEMICAL AND IMAGING METHODS

Osteoporosis leads to significant bone mass loss and structural deterioration, increasing fracture risk. Objective: This study explores the morphological changes in osteoporotic bones through a comparative analysis using biochemical markers and imaging techniques. Methods: A cohort of 55 osteoporotic patients underwent evaluation. Biochemical markers were measured, including serum calcium, phosphorus, alkaline phosphatase, and vitamin D. Imaging assessments involved dual-energy X-ray absorptiometry (DEXA) for bone mineral density (BMD) and high-resolution computed tomography (HRCT) for bone microarchitecture analysis. Correlations between biochemical data and imaging results were examined. Results: Biochemical analysis showed elevated alkaline phosphatase levels (mean: 210 IU/L) and widespread vitamin D deficiency (mean: 16 ng/mL). DEXA revealed significant reductions in BMD (mean T-score: -3.2), while HRCT detected substantial trabecular thinning (mean trabecular thickness: 0.12 mm) and increased cortical porosity. A strong inverse correlation (r = -0.75, p < 0.01) between BMD and alkaline phosphatase was observed, indicating a link between high bone turnover and reduced density. Vitamin D deficiency correlated with greater cortical porosity (r = 0.60, p < 0.05). Conclusion: The study highlights that integrating biochemical markers and imaging methods provides a comprehensive understanding of osteoporotic bone morphology. These findings emphasize the need for multi-modal diagnostic approaches to enhance osteoporosis management and fracture risk assessment.

Effects of GBT1118, a voxelotor analog, on bone disease in sickle cell disease mice

We assessed the effect of GBT1118, a sickle hemoglobin polymerization inhibitor on bone loss in humanized sickle cell disease (SCD) mice. Healthy control (Ctrl) 4-months-old female and male mice were fed Vehicle-chow for 2-months, while SCD mice were fed Vehicle-chow or GBT1118-chow. By micro-CT, GBT1118 significantly increased femur metaphyseal trabecular thickness (Tb.Th) and tissue mineral density (TMD), and significantly decreased trabecular spacing in female SCD mice. In SCD male mice, there was significant reduction in epiphyseal trabecular bone volume fraction (BV/TV), Tb.Th and TMD and GBT1118 significantly increased BV/TV and TMD but not Tb.Th. A significant decrease in cortical area fraction in SCD female mice was rescued by GBT1118 but not SCD males. Markedly decreased mineralized femur trabeculae in SCD females and males was partially rescued by GBT1118. Bone histomorphometry of femurs demonstrated significantly decreased bone formation parameters and increased bone resorption parameters in SCD mice of both sex that were rescued by GBT1118. Significant alteration in bone and hypoxia related genes of SCD mice of both sexes were differentially modulated by GBT1118. We conclude that "a sickle hemoglobin polymerization inhibitor" might be efficacious in improving some parameters of SCD bone loss.

Evaluation of the effect of tartrazine on the offspring rats in an in vivo experimental model

AbstractTartrazine, an azo dye prevalent in pharmaceuticals and food items, was investigated for its impact on fetal development, specifically examining visceral and skeletal abnormalities in rat offspring exposed to daily oral doses throughout pregnancy. Fourteen pregnant rats were randomly assigned to control and tartrazine groups (seven animals each), with tartrazine administered via oral gavage at 7.5 mg/kg throughout gestation. Offspring were categorized by gender for histopathological and genetic analysis of visceral structures. Bone quality and fracture resistance assessments involved micro‐CT, Raman spectroscopy, and biomechanical testing. Results highlighted distinct internal organ tissue differences in the tartrazine group, notably increased hemorrhagic and inflammatory cell infiltration, degeneration, and vacuolization compared to controls. Gender‐specific alterations in mRNA levels of IL‐6, IL‐1β, TNF‐α, and TRPM2 genes (p < .001) were also noted. Moreover, tartrazine‐exposed groups exhibited reduced trabecular thickness, bone volume, and significant alterations in bone matrix composition and quality alongside significant decreases in fracture resistance (p < 0.05). This study concludes that intrauterine exposure to tartrazine can result in adverse impacts on organ and bone development in rat offspring.

Minimal Impact of Age on Adaptive Bone Formation in the Distal Tibia of US Army Basic Combat Trainees: The ARMI Study

ABSTRACT Introduction Although bone formation has been observed in the distal tibia of trainees during Basic Combat Training (BCT), some animal studies have demonstrated greater mechanosensitivity in the juvenile compared to the mature skeleton. How age affects skeletal adaptations to military training is unknown. The purpose of this study was to determine if skeletal adaptations to US Army BCT differ by age. Methods We enrolled 2085 trainees (1303 males, 782 females). High-resolution peripheral quantitative computed tomography was used to assess total, cortical, and trabecular bone mineral density (BMD) and the microarchitecture of the distal tibia before and after 8 wk of BCT. Generalized linear models were used to compare mean percent change (95% confidence interval (CI)) in each bone parameter by age group (<20, 20–25, 26–29, and ≥30 yr) and to evaluate differences in bone parameter changes between age groups (effect estimates (95% CI)). Models were stratified by sex with multivariable adjustment. Results Male and female trainees in all age groups had increases in total BMD, trabecular BMD, and trabecular bone volume fraction from baseline (P < 0.01 for all). Male and female trainees also had increases in trabecular thickness from baseline in all groups (P < 0.05) except females ≥30 yr old. Female trainees 20–25 yr old had a significantly larger increase in trabecular thickness than those <20 yr old (effect estimate (95% CI), 0.33% (0.02%–0.64%); P < 0.05). Trabecular microarchitecture was largely not otherwise different between age groups for either sex. Male and female trainees <20 yr old had greater changes in cortical BMD compared to older age groups (males, P < 0.01; females, P < 0.05 for all). Conclusion Trainees <20 yr old experience the greatest improvements in cortical BMD at the distal tibia during US Army BCT, suggesting that adaptive bone formation in cortical bone may be attenuated with skeletal maturity. However, the mechanosensitivity of trabecular bone to exercise training remains intact regardless of age.

Unleashing innovation: 3D-printed biomaterials in bone tissue engineering for repairing femur and tibial defects in animal models - a systematic review and meta-analysis.

3D-printed scaffolds have emerged as an alternative for addressing the current limitations encountered in bone reconstruction. This study aimed to systematically review the feasibility of using 3D bio-printed scaffolds as a material for bone grafting in animal models, focusing on femoral and tibial defects. The primary objective of this study was to evaluate the efficacy, safety, and overall impact of these scaffolds on bone regeneration. Electronic databases were searched using specific search terms from January 2013 to October 2023, and 37 relevant studies were finally included and reviewed. We documented the type of scaffold generated using the 3D printed techniques, detailing its characterization and rheological properties including porosity, compressive strength, shrinkage, elastic modulus, and other relevant factors. Before incorporating them into the meta-analysis, an additional inclusion criterion was applied where the regenerated bone area (BA), bone volume (BV), bone volume per total volume (BV/TV), trabecular thickness (Tb. Th.), trabecular number (Tb. N.), and trabecular separation (Tb. S.) were collected and analyzed statistically. 3D bio-printed ceramic-based composite scaffolds exhibited the highest capacity for bone tissue regeneration (BTR) regarding BV/TV of femoral and tibial defects of animal models. The ideal structure of the printed scaffolds displayed optimal results with a total porosity >50% with a pore size ranging between 300- and 400µM. Moreover, integrating additional features and engineered macro-channels within these scaffolds notably enhanced BTR capacity, especially observed at extended time points. In conclusion, 3D-printed composite scaffolds have shown promise as an alternative for addressing bone defects.

Increased cancellous bone mass accompanies decreased cortical bone mineral density and higher axial deformation in femurs of leptin-deficient obese mice

IntroductionLeptin is a pleiotropic hormone that regulates food intake and energy homeostasis with enigmatic effects on bone development. It is unclear if leptin promotes or inhibits bone growth. The aim of this study was to characterize the micro-architecture and mechanical competence of femur bones of leptin-deficient mice. Materials and methodsRight femur bones of 15-week old C57BL/6 (n = 9) and leptin-deficient (ob/ob, n = 9) mice were analyzed. Whole bones were scanned using micro-CT and morphometric parameters of the cortex and trabeculae were assessed. Elastic moduli were determined from microindentations in midshaft cross-sections. Mineral densities were determined using quantitative backscatter scanning electron microscopy. 3D models of the distal femur metaphysis, cleared from trabecular bone, were meshed and used for finite element simulations of axial loading to identify straining differences between ob/ob and C57BL/6 controls. ResultsCompared with C57BL/6 controls, ob/ob mice had significantly shorter bones. ob/ob mice showed significantly increased cancellous bone volume and trabecular thickness. qBEI quantified a ∼7% lower mineral density in ob/ob mice in the distal femur metaphysis. Indentation demonstrated a significantly reduced Young's modulus of 12.14 [9.67, 16.56 IQR] GPa for ob/ob mice compared to 23.12 [20.70, 26.57 IQR] GPa in C57BL/6 mice. FEA revealed greater deformation of cortical bone in ob/ob as compared to C57BL/6 mice. ConclusionLeptin deficient ob/ob mice have a softer cortical bone in the distal femur metaphysis but an excessive amount of cancellous bone, possibly as a response to increased deformation of the bones during axial loading. Both FEA and direct X-ray and electron microscopy imaging suggest that the morphology and micro-architecture of ob/ob mice have inferior biomechanical properties suggestive of a reduced mechanical competence.

Beneficial effects of IVIG treatment on experimental-induced osteoporosis.

Estrogen (E2) plays a significant role in postmenopausal osteoporosis, and its deficiency is related to chronic low-grade inflammation. Intravenous immunoglobulin (IVIG) is composed of immunoglobulins derived from the plasma of healthy donors. Numerous anti-inflammatory pathways are responsible for IVIG's anti-inflammatory action The aim of this study is to investigate the effects of IVIG on experimental-induced osteoporosis. Forty adult female Wistar rats were included in the study. Thirty rats underwent bilateral dorsal ovariectomy. Rats were grouped as Group 1 (n = 10, ovariectomy and saline); Group 2 (n = 10, ovariectomy and E2); Group 3 (n = 10, ovariectomy and IVIG), and Control group (n = 10, no oophorectomy). Histopathological examination of bone tissue, and biochemical analysis for beta-catenin, plasma Tumor Necrosis Factor-α, IL-6, receptor activator of nuclear-κB ligand (RANKL), and osteoprotegerin (OPG) levels were made. The IVIG group had increased trabecular number, area, and thickness with increased bone mineral density as well as decreased trabecular separation compared with the saline group. IVIG group had lower serum RANKL and higher serum OPG levels when compared with the saline group. The bone marrow beta-catenin level was significantly higher in the control and ovariectomy + IVIG groups. IVIG has beneficial effects on experimentally induced osteoporosis with a possible action on inflammation and RANKL-β-catenin pathway.

Changes in bone density and microarchitecture following treatment of Graves' disease and the effects of vitamin D supplementation. A randomized clinical trial.

Vitamin D is important to skeletal health and ensuring a replete vitamin D status is recommended. In thyrotoxicosis, bone turnover is increased and bone mass density (BMD) reduced. We examined whether vitamin D supplementation improves bone recovery in thyrotoxicosis caused by Graves' disease (GD). Using a double-blinded design, hyperthyroid patients with GD were randomized to vitamin D3 70µg/day (2800IU) or similar placebo as add-on to antithyroid drugs (ATD). At baseline and 9months, we measured BMD and bone architecture using DXA and high resolution peripheral quantitative computerized tomography. Bone turnover markers (BTM) were measured at 3months also. Effect of vitamin D versus placebo and the response to ATD treatment were analyzed using linear mixed modelling. Eighty-six GD patients were included (age 41 ± 14years, 86% females). Compared to placebo, vitamin D3 did not improve BMD or microarchitecture. In response to ATD, BMD increased in the hip by 2% (95%CI: 1-4%). Cortical porosity decreased in tibia (- 7% [95%CI: - 12 to - 2%]) and radius [- 14% [95%CI: - 24 to - 3%]), and trabecular thickness increased (tibia (5% [95%CI: 2 - 9%]) and radius (4% [95%CI: 1-7%]). Changes in BTM, but not thyroid hormones, were associated with changes in BMD by DXA and with changes in the cortical compartment. In newly diagnosed GD, 9months of high dose vitamin D3 supplementation does not offer benefit by improving skeletal health. Treatment of thyrotoxicosis is associated with the recovery of BMD and microarchitecture. NCT02384668.

Quantification of bone microarchitecture using photon-counting CT at different radiation doses: A comparison with µCT

PurposeAccurate measurements of trabecular bone microarchitecture are required for a proper assessment of bone fragility. Photon-counting detector CT (PCD-CT) has different technical properties than conventional CT, resulting in higher resolution and thereby potentially enabling in-vivo measurement of trabecular microarchitecture. The purpose of this study was to quantify trabecular bone microarchitectural parameters with PCD-CT at varying radiation doses and compare this to µCT as gold standard. MethodBoth distal radii, distal tibiae, femoral heads, and two vertebrae were dissected from one human. All specimens were scanned ex-vivo on a PCD-CT system (slice increment 0.1 mm; pixel size 0.1042–0.127 mm) and a µCT system (isotropic voxel size 49–68.4 µm). The radiation doses of the PCD-CT scans were varied from 2.5 to 120 mGy based on the volume CT dose index (CTDIvol32). For the PCD-CT scans, contrast-to-noise ratio and trabecular sharpness were calculated and compared between radiation doses. µCT and PCD-CT scans were registered. The trabecular bone was then segmented from all PCD-CT and µCT scans and split into cubes with 6-mm edge length. For each cube, bone volume over total volume, trabecular thickness, trabecular number, and trabecular heterogeneity were calculated and compared between corresponding PCD-CT and µCT cubes. ResultsWith increasing dose, contrast-to-noise ratio and trabecular sharpness values increased for the PCD-CT images. Already at the lowest dose, high correlations between the trabecular microarchitectural parameters between µCT and PCD-CT were found (R2 = 0.55–0.95), which improved with increasing radiation dose (R2 = 0.76–0.96 at 20 mGy). ConclusionsPCD-CT can be used to quantify trabecular bone microarchitecture, with accuracy comparable to µCT and at clinically relevant radiation doses.

Continuous‐Gradient Mineralized Hydrogel Synthesized via Gravitational Osmosis for Osteochondral Defect Repair

AbstractThe repair of hierarchical osteochondral defects requires complex gradient reconstruction at different levels, with continuous‐gradient mineralization being crucial. Strategies for achieving continuous‐gradient mineralization have rarely been reported. Here, a continuous‐gradient mineralized hydrogel is prepared using simple gravitational osmosis of a ≈2 nm amorphous calcium phosphate nanocluster (ACPC) suspension into composite organic frameworks for osteochondral regeneration. During gravitational infiltration, ACPC underwent gradual mineralization, resulting in the spontaneous formation of hydroxyapatite (HAP). The continuous‐gradient mineralized hydrogel aligned closely with the normal osteochondral structure, thereby effectively promoting repair of the cartilage and subchondral bone. In the cartilage layer, organic compounds improved the oxidative stress environment induced by injury and complemented the extracellular matrix of the cartilage. In the subchondral bone layer, HAP from the continuously mineralized hydrogel induced intracellular calcium accumulation in mesenchymal stem cells (MSCs), activating calcium/calmodulin‐dependent protein kinase 2 (CaMK2) and promoting osteogenic differentiation of MSCs through the calcium signaling pathway. Ultimately, compared with the nongradient hydrogel, this innovative gradient mineralization method exhibited significantly enhanced regeneration capabilities for osteochondral defects, as evidenced by metrics, such as bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th), and trabecular number (Tb.N). This holistic strategy provides hope in the field of osteochondral repair.

2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside–stimulated dental pulp stem cells-derived exosomes for wound healing and bone regeneration

Background/purpose-2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) is a bioactive component in the Chinese herb Polygonum multiflorum, recognized for its anti-inflammatory and lipid-lowering properties. Human dental pulp stem cells (hDPSCs) have excellent capabilities in tooth regeneration, wound healing, and neural repair. The exosomes (Exo) released by hDPSCs contain bioactive molecules that influence cell proliferation, differentiation, and immune responses. Therefore, we aimed to unveil the potential of THSG-Exo and evaluate its regenerative capabilities through the in vitro experiment and rat bone defect model. Materials and methodsThe effects of hDPSC-derived exosomes, with or without THSG treatment, on repair and bone regeneration were evaluated through in vitro and in vivo studies. Finally, we conducted a proteomic analysis to meticulously compare the compositional contents of the two types of exosomes. ResultsIn vitro data showed that 10 and 100 μM THSG-Exo enhanced cell proliferation and osteogenic differentiation, reducing wound size to 40 % of its original size. In our maxillary bone defect rat model, THSG-Exo significantly increased bone volume, trabecular thickness, and bone density in the bone defect area. In addition, proteomic analysis of THSG-Exo revealed diverse proteins linked to bone differentiation and tissue repair, including bone morphogenetic protein-1 (BMP-1) and tumor necrosis factor (TNF)-α-stimulated gene 6 (TNFAIP6). Our searches in functional databases revealed that THSG-Exo is involved in numerous biological pathways. ConclusionTHSG-Exo enhanced cell proliferation, wound healing, and osteogenesis in vitro, while also expediting tissue repair and bone regeneration in vivo. The protein diversity of THSG-Exo contributes significant value in both basic and regenerative medicine.

The Importance of Bone Quality Diagnostics in Preventing Displacement of Dental Implants within the Mandibular Body: A Case Report

Abstract Among the immediate complications that can occur after dental implant placement, accidental displacement within the medullary spaces of the mandibular body is a rare clinical situation. This case report describes implant displacements in the posterior mandibular region and emphasizes the importance of assessing bone density and mandibular medullary patterns prior to implant placement according to a new classification by Lekholm and Zarb modified by Rosas et al. The case reports reported three implant displacements in type II bone of the mandibular body, as classified by Lekholm and Zarb. Following the complication, the bone was reclassified as II-B according to the modification by Rosas et al. The implants were extracted from three female patients aged from 37 to 75 years, with only one having a medical history. All complications were treated and resolved without any alteration after implant removal. To reduce the risk of intraoperative complications that affect the primary stability of dental implants, such as implant migration in the mandibular body, it is important to consider factors that may affect the mechanical locking of the implant at the time of placement, such as the pattern and thickness of the bony trabeculae and the size of the medullary spaces in areas of anatomical risk. For this purpose, we recommend using the modified Lekholm and Zarb classification by Rosas et al. This classification considers the trabecular bone biotype, which helps in planning the surgical approach procedure and establishing a regenerative protocol to minimize the risk of complications with the inferior dental nerve.

The ontogeny of human fetal trabecular bone architecture occurs in a limb-specific manner

Gestational growth and development of bone is an understudied process compared to soft tissues and has implications for lifelong health. This study investigated growth and development of human fetal limb bone trabecular architecture using 3D digital histomorphometry of microcomputed tomography data from the femora and humeri of 35 skeletons (17 female and 18 male) with gestational ages between 4 and 9 months. Ontogenetic data revealed: (i) fetal trabecular architecture is similar between sexes; (ii) the proximal femoral metaphysis is physically larger, with thicker trabeculae and greater bone volume fraction relative to the humerus, but other aspects of trabecular architecture are similar between the bones; (iii) between 4 and 9 months gestation there is no apparent sexual or limb dimorphism in patterns of growth, but the size of the humerus and femur diverges early in development. Additionally, both bones exhibit significant increases in mean trabecular thickness (and for the femur alone, bone volume fraction) but minimal trabecular reorganisation (i.e., no significant changes in degree of anisotropy, connectivity density, or fractal dimension). Overall, these data suggest that in contrast to data from the axial skeleton, prenatal growth of long bones in the limbs is characterised by size increase, without major reorganizational changes in trabecular architecture.