Trabecular Bone Density Research Articles

Relationships between QUS and HR-pQCT, DXA, and bone turnover markers.

Relationship of quantitative ultrasound (QUS) with high-resolution peripheral quantitative computed tomography (HR-pQCT), dual-energy X-ray absorptiometry (DXA), and bone-related biochemical markers was analyzed. The subjects were 480 individuals. Speed of sound (SOS) was measured by calcaneal QUS. Volumetric bone mineral density (vBMD) and microarchitecture of trabecular and cortical bone in the distal radius and tibia were assessed by HR-pQCT. Areal bone mineral density (aBMD) in the lumbar spine and proximal femur were measured by DXA. TRACP-5b, P1NP, 25 (OH) vitamin D, and pentosidine were evaluated by biochemical tests. The correlation of each parameter was analyzed for all subjects and by sex and age group. QUS was moderately correlated with Tb.vBMD and Tb.BV/TV in the radius and tibia. No correlation was seen with Ct.vBMD or cortical porosity (Ct.Po). Although a correlation was seen with cortical thickness (Ct.Th) in the tibia in all subjects, no correlation was seen in women aged ≥ 60years. QUS showed moderate correlations with aBMD in the proximal femur. Although moderate correlation was seen with aBMD in the lumbar spine in all subjects, no correlation was seen in subjects aged ≥ 60years. No significant correlations were seen between QUS and biochemical markers. Moderate correlations were seen between QUS and Tb.vBMD and microarchitecture in the radius and tibia and aBMD of the proximal femur. On the other hand, practically no correlations were seen with Ct.vBMD or Ct.Po and the bone-related biochemical markers. Only in middle age, moderate correlations were seen with Ct.Th in the tibia and with aBMD of the lumbar spine.

Low-dose CT hounsfield units: a reliable methodology for assessing vertebral bone density in radiographic axial spondyloarthritis

ObjectiveStudying vertebral bone loss in radiographic axial spondyloarthritis (r-axSpA) has been challenging due to ectopic bone formation. We cross-sectionally analysed low-dose CT (ldCT) trabecular bone density Hounsfield units (HU) measurements...

Biomechanical Analysis of Different Framework Design, Framework Material and Bone Density in the Edentulous Mandible With Fixed Implant-Supported Prostheses: A Three-Dimensional Finite Element Study.

The objective of this finite element study was to investigate the effect of different framework designs, framework materials, and bone densities on the stress distribution of fixed implant-supported prostheses for edentulous mandibles. Under the condition of 2-mm cortical bone, 16 models were created in the edentulous mandible to simulate different framework designs (1-piece or 3-piece frameworks) with different framework material (pure titanium, zirconia, polyetheretherketone, or carbon fiber-reinforced polyetheretherketone) in-high or low-density trabecular bone. Then, vertical loading and oblique loading at 75° were applied to the anterior and posterior regions. The stress distribution and stress concentration region of implant and peri-implant bone with different combinations were compared by finite element analysis. The use of the 1-piece zirconia framework in high-density trabecular bone improved stress distribution on implants and peri-implant bone. The region of stress concentration is located in thebuccal cervix of the distal implants and the distobuccal portion of the cortical bone in all models. To improve the stress distribution on fixed implant-supported dentures for edentulous mandibles, the 1-piece framework and zirconia represent the better combination. Under the condition of 2-mm cortical bone thickness, the full-arch zirconia framework had minimum von Mises stress on implants and peri-implant bone in all models, and high trabecular bone density greatly decreased the stress on cortical bone.

Systematic Review: Anti-Osteoporosis Potential Activities Of Phytoestrogen Compounds In Chrysophyllum cainito L., Elaeis guineensis Jacq., Lannea acida Rich., Marsilea crenata Presl., and Medicago sativa L.

Phytoestrogens are compounds from plants that have a structure and function similar to estrogen (17β-estradiol). Phytoestrogens can be found in Chrysophyllum cainito L., Elaeis guineensis Jacq., Lannea acida Rich., Marsilea crenata Presl., and Medicago sativa L. This systematic review aimed to prove that all of these five plants have phytoestrogens which were observed with several instruments, and to assess activities and bone forming mechanisms from these five plants in the female mice (Mus musculus) and female rats (Rattus norvegicus). This systematic review was done by identifying articles in several databases (Google Scholar, PubMed, and Science Direct). The process of selecting the articles used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to create a flowchart with inclusion and exclusion study criteria. Meta-synthesis was done to analyze, identify, and interpret all of the data in the articles systematically. 31 articles in total were obtained from the selection process, with 27 articles containing a discussion about chemical compound content and 4 articles describing research results for in vivo testing of the plants that were reviewed. The results showed that these five plants have phytoestrogens and by in vivo testing have the activity in increasing trabecular bone density in the experimental animals.

Evaluation of mandibular trabecular bone by fractal analysis on panoramic radiograph in paediatric patients with sleep bruxism.

To evaluate the trabecular bone density in the mandible of paediatric patients diagnosed with sleep bruxism (SB) using the fractal analysis method on panoramic radiographs. A total of 37 patients whose anamnesis and clinical signs were compatible with SB were diagnosed with SB using BiteStrip® . Three areas were identified on the panoramic radiographs of the patients: the geometric center of the condyle, the angulus region under the mandibular canal, and the distal region of the mental foramen. Regions of interest (ROIs) of 60×60pixels were selected in these three locations, and fractal dimensions (FDs) were calculated. Results were compared with the control group. There was no statistically significant difference between the right and left FD values, and male and female FD values in all regions and both groups (p>.05). In the angulus (p=.03) and condyle (p=.03) regions, the SB group had a significantly higher FD value than the control group. There was no statistically significant difference between the SB and control groups in the corpus region (p=.98). A moderate negative correlation arose between age and condyle FD values among controls (r=-0.38, p=.02). Fractal dimension values evaluating trabeculation of the mandibular bone are affected by SB in the angulus and condyle regions.

MO542: Bone Mineral Density, Bone Micro-Architecture Evolution After Kidney Transplantation: A Prospective Cohort Study

Abstract BACKGROUND AND AIMS Bone loss and mineral abnormalities are frequent in kidney transplant recipients (KTRs) and associated with a high risk of fracture, cardiovascular mortality and an increase in health care costs. In daily clinics, the detection of bone abnormalities after transplantation includes bone biomarkers and imaging technique [Dual Energy X-ray (DEXA)] to assess respectively the bone turnover and the bone mineral density (BMD), but with limitations. The high-resolution peripheral quantitative computed tomography (HR-pQCT) provides additional noninvasive information on bone microarchitecture and BMD with a better distinction between cortical and trabecular areas. The goal of our study is to evaluate the evolution of bone structure using HR-pQCT compared to standard technique (DXA) in a prospective cohort of KTRs. METHOD All patients referred for a single kidney transplant at the university hospital of Liège with no history of exposure to antiresorptive agents were eligible for inclusion (NCT04713774). Participants underwent baseline and 3-month biomarkers analysis, BMD measurements by DEXA. HR-pQCT images were obtained of the distal radius and distal tibia (non-dominant, non-fractured limb) using the XtremeCT device with standard protocols. HR-pQCT assessed quantitative measurement of the volumetric density of trabecular and cortical bone as well as bone structure (trabecular number or thickness or cortical porosity for instance). RESULTS A total of 26 patients were prospectively included. The mean age was 57.3 ± 12.1 years. The mean dialysis vintage was 27.5 ± 16.4 months before transplantation. Bone biomarkers showed a significant decrease at 3 months after transplantation. PTH decreased from 221.72 ng/L to 59.6 ng/L (P < 0.0001), P1NP from 211 ug/L to 72 ug/L (P < 0.013) and BLAP from 23 ug/L to 13 ug/L (P = 0.042). BMD was measured by DXA and HR-pQCT at 7 days [6; 8] and 102 days (90; 113) after transplantation. We observed a significant reduction of BMD by DXA at the hip site from 0.868 g/cm2 to 0.856 g/cm2 (P = 0.02), but not at the lumbar site. The HR-pQCT analysis demonstrated a significant reduction of the trabecular BMD from 152.62 mg HA/ccm to 150.80 mg HA/ccm (P < 0.0001) at the tibia site and from 159.09 mg HA/ccm to 156.25 mg HA/ccm (P < 0.0001) at the radius site. No change in bone structure have been observed at 3 months post-transplantation with the HR-pQCT analysis. CONCLUSION HR-pQCT is sensitive enough to show a significant decrease of BMD at the trabecular site, as soon as 3 months after transplantation compared to DEXA at the lumbar spine. However, no change in bone structure nor cortical bone volume has been observed. The sensibility of this technique might be higher than DEXA. The rapid assessment of bone structure (3 months post-transplantation) might be too soon to evaluate such abnormalities. Detecting properly rapid changes in bone density, as soon as 3 months after renal transplantation seems feasible. The impact on bone health management needs to be further studied.

Paraffin Fixed Human Trabecular Bone Specimens for Study of Osteoporosis

Examining and quantifying specific measures of trabecular bone to investigate the progression of osteoporosis presents a challenge. Specifically, the development of analytical and computational strategies to interpret computed tomography (CT) generated data sets requires gross anatomical specimens that closely approximate the intraosseous matrix of the marrow while maintaining the structural integrity of the trabecular network. Moreover, these specimens must be durable, easily transported, and stored at room temperature (e.g., do not require freeze/thaw cycles). Here we investigated if paraffin impregnated bone specimens maintained the trabecular network and bone density of prepared fresh‐frozen specimens used in imaging studies for osteoporosis. Standardized fresh‐frozen human distal tibia specimens (n = 12), from the institution’s Deeded Body Program, were scanned using multi‐row detector computed tomography (MDCT) and micro computed tomography (micro‐CT) imaging at different times in the preparation process to evaluate and quantify the preservation of microstructure and continuity of cortical and trabecular bone constituents. Once scanned, the specimens were placed in a series of acetone baths to remove water and marrow. With the de‐marrowing procedure complete, four specimens were rescanned using MDCT and micro‐CT. De‐marrowed specimens were then impregnated, under vacuum controlled conditions, with either a silicone polymer, gelatin matrix solution, or paraffin wax. After impregnation and curing, the specimens were re‐scanned. Analysis demonstrated a high correlation in the region of interest (ROI) for trabecular bone network area density from micro‐CT data sets of the preprocessed and de‐marrowed states (r = 0.99). Quantitatively, wax impregnated specimens demonstrated congruence in MDCT bone volume fraction (r = 0.92) and trabecular network area (r = 0.94) measures when the preprocessed and impregnated states were correlated. Results were more robust in the micro‐CT data in the bone volume fraction (r = 0.97) and the trabecular network area (r = 0.99). MDCT analysis at the (ROI) corresponding to 14‐16% length measured from the distal aspect of specimens demonstrated an increased estimate of bone mineral density (BMD) relative to scans acquired with the unmodified tissue (polymer +160 mg/cc; gelatin +58 mg/cc), whereas the paraffin wax condition slightly underestimated BMD (‐21 mg/cc). Of the impregnating procedures, paraffin wax provided the best qualitative specimens for handling, storage, and processing time. Together these data suggest that the trabecular structure is preserved through the de‐marrowing procedure and demonstrates that specimens can be transferred away from cold storage. Impregnating bone specimens with paraffin wax effectively provides a space occupying matrix that protects the delicate trabecular network without altering the ability to quantify important biomechanical measures in clinical CT as well as micro‐CT imaging for assessing bone integrity for the study of osteoporosis. This procedure creates specimens that are easily stored and transported, can be scanned across various imaging modalities, and effectively retain the trabecular micro‐structure.

Role of the Phosphate Transport Facilitator XPR1 in Bone Homeostasis and Phosphate‐Dependent FGF23 Secretion

BackgroundEvidence point at Xenotropic and Polytropic retrovirus Receptor 1 (XPR1) as a protein involved in the cellular phosphate export pathway and phosphate homeostasis: systemic constitutive deletion of Xpr1 in mice is lethal and kidney‐specific deletion of Xpr1 induces hypophosphatemic rickets with hypercalciuria. XPR1 is expressed in the bone, but its function remains elusive. We hypothesized that XPR1 is crucial for bone homeostasis and that is involved in the sensing mechanism of phosphate in the bone.MethodsWe established an inducible whole body Xpr1 KO mouse model. The mice were placed in metabolic cages for urine and blood analysis, followed by femur uCT and histomorphometry. The Fgf23 mRNA and protein (c‐terminal and intact FGF23) levels were assessed from tibia and femur incubated ex vivo for 24h with increasing phosphate concentrations. Primary osteoblast cells were isolated from control and Xpr1 KO mouse calvaria.ResultsConditional total body Xpr1KO mice are constantly decreasing their body weight upon Xpr1 deletion, and develop profound hypophosphatemia, compared to their control littermates. Histomorphometry analysis and uCT on femurs of Xpr1 KO mice show high trabecular bone density, despite low bone formation rate and low number of osteoclasts. Increased intact FGF23 secretion by tibia and femur was observed in control mice in response to increased phosphate concentration in the media. However, the bone samples from Xpr1KO mice are resistant to phosphate induced FGF23 secretion. No changes were observed for the c‐terminal FGF23 in response to increased phosphate concentration, for both the control and Xpr1 KO mice.Osteoblasts were successfully prepared from control and Xpr1 KO mouse calvarie and Xpr1 expression was inactivated by tamoxifen treatment.ConclusionXPR1 is essential for phosphate homeostasis and FGF23 secretion upon phosphate exposure. Osteoblasts will now be used to further study phosphate dependent FGF23 secretion.

Factors Associated with Low Bone Density in a Juvenile Mortality Sample

Here we examine relationships between chronic illness and low bone density (BD) in a juvenile mortality sample from New Mexico. Chronic illnesses are often found to be linked to low BD and growth stunting or arrest. Inflammation, either from disease or traumatic injury, has also been linked to bone loss. The purpose of this study is to test two hypotheses: 1) children who experience chronic illness will have lower bone density than those without; 2) children who experience growth stunting or growth arrest will have lower BD than those without. We include 433 individuals 6 months to 17 years old who underwent postmortem computed tomography (PMCT) between 2011 and 2019 at the University of New Mexico OMI.Hounsfield units (HU), a proxy for trabecular BD, were obtained at three sites – lumbar spine, proximal femur, and proximal humerus – from PMCT scans using the freeware DICOM viewer Horos. HU in each region were age and sex standardized using this sample’s data (femur, humerus) or PRAMPTM data (lumbar). The resulting z‐scores were then used as the dependent variable in all analyses. We included age, sex, manner of death (MOD), growth arrest (Harris) lines, stunting, fatty liver, cardiomegaly, asthma, diabetes mellitus, cerebral palsy/seizure disorder, and osteopenia as independent variables in each model. We set the base level for MOD in each analysis as natural. Osteopenia was included as a control variable (as HU should be lower in individuals with osteopenia), along with age and sex. Results provided are coefficients for variables with p≤ 0.05. We used linear and logistic regression (odds ratios) to examine associations between being overweight or obese and fatty liver and cardiomegaly. All analyses were done using Stata 15.We find that lumbar HU are significantly lower in individuals with fatty liver (‐0.58), diabetes (‐0.74), and cerebral palsy or epilepsy (‐0.72). Femoral HU are significantly lower in individuals with Harris lines on the tibia (‐0.28), diabetes mellitus (‐1.61), and cerebral palsy or epilepsy (‐0.59). Humeral HU are significantly lower in individuals with Harris lines on the tibia (‐0.32) and diabetes mellitus (‐0.72), and cerebral palsy or epilepsy (‐0.55). In each analysis, individuals with osteopenia have significantly lower HU than those without. In a subsequent series of regressions, we included overweight or obesity as independent variables and we do not find a link between those and decreased HU, but individuals who are overweight or obese have higher odds of having fatty liver, and those who are obese or morbidly obese have higher odds of having cardiomegaly.Low BD in this sample is likely due to multiple, sometimes interrelated factors, including chronic illness and inflammation, inactivity, and perhaps social determinants of health (e.g., lack of access to healthy foods, healthcare). Obesity and nonalcoholic fatty liver disease are linked in children. While the natural history of pediatric nonalcoholic fatty liver disease is not known, there is some evidence that it may begin in utero. Individuals who are obese or overweight have increased odds of having fatty liver and cardiomegaly. While being obese or overweight is not directly related to decreased BD, the behaviors and social determinants of health that lead to obesity are likely related to low bone density as well.

People living with HIV have low trabecular bone mineral density, high bone marrow adiposity, and poor trabecular bone microarchitecture at the proximal femur.

People living with HIV (PLWH) have increased risk of osteoporosis and fractures. However, studies assessing the main determinants of bone strength in the proximal femur exclude this vulnerable population. We assessed the proximal femur of 40 PLWH and 26 age-matched seronegative controls using quantitative computed tomography and magnetic resonance imaging. We examined cortical volumetric bone mineral density (Ct.vBMD), trabecular vBMD (Tb.vBMD), cortical thickness (Ct.Th), bone marrow adiposity (BMA), and trabecular number, separation, and bone volume fraction. Parametric comparisons between the two groups were made for the femoral head, femoral neck, trochanter, and total hip using linear regression adjusting for several covariates, including metrics of body composition. In addition, we investigated the associations of BMA with Tb.vBMD and trabecular microarchitecture with Spearman's rank partial correlations. PLWH had lower Tb.vBMD and deteriorated trabecular microarchitecture in the femoral neck, trochanter and total hip, and elevated BMA in the femoral head, femoral neck, and total hip. Ct.vBMD and Ct.Th were not significantly different between the two groups. BMA was significantly associated with lower Tb.vBMD and deteriorated trabecular microarchitecture in both groups albeit at different femoral regions. Our findings suggest that the trabecular, and not the cortical, compartment is compromised in the proximal femur of PLWH. The observed impairments in fracture-prone regions in PLWH indicate lower femoral strength and suggest higher fracture risk. The inverse associations of BMA with trabecular bone density and microarchitecture quality agree with findings at other anatomic sites and in other populations, suggesting that excess BMA possibly due to a switch from the osteoblast to the adipocyte lineage may be implicated in the pathogenesis of bone fragility at the femur in PLWH.

Influence of zoledronic acid in physicochemical and morphostructural parameters of bone and dental tissue of mice submitted to a jaw osteonecrosis model

Zoledronic acid (ZA) leads to structural and physicochemical changes in mineralized tissues. The aim was to an- alyze physicochemical and morphostructural properties of bone and dental tissue of mice submitted to a model of ZA-related osteonecrosis of the jaws (OJ). This is a 2 × 2 factorial design experimental study, considering sex (male/female) and treatment (ZA/Saline). Lower left 2nd molar (day 42) extraction was performed after three ad- ministrations (days 0, 7, 14) of ZA 1.0 mg / kg or saline (n=8/group), with another administration on 49^th and eu- thanasia on 70^th day. Histological analysis, computerized microtomography, three-point bending test and Raman spectroscopy were performed. ANOVA 2-way/Bonferroni test was applied (p<0.05). Treatment with ZA promoted histological alterations in femoral epiphysis and increased bone necrosis signs (p <0.05) at sites of exodontia. Be- sides, ZA groups presented a lower number and greater separation of bone trabeculae, and smaller ratio bone/tissue volume in alveolar trabecular bone. Females presented a lower value of these parameters. In femoral bone, sex and treatment factors exerted an independent influence in mechanical parameters, on the cross-sectional area, maximum load, moment of inertia and work to fracture (p <0.05), being lower in females and increased in treated animals, which also presented higher flexural stiffness. Yield stress and flexural modulus were higher in females and lower with ZA treatment (p <0.05). Spectroscopic analysis showed increased crystallinity with ZA in cortical and medullar of right and left hemimandible, respectively, as well as femoral cortical. There was an increase of crys- tallinity in dental enamel and dentin with treatment. It is concluded that treatment with ZA, although associated with occurrence of OJ, modifies bone and dental mineral matrix, contributing to tissue biomechanics' improvement. Females present differences in femoral biomechanical properties and have a lower density of trabecular bone in the post-dental extraction socket, when compared to males.

Plasma Growth and Differentiation Factor 15 Predict Longitudinal Changes in Bone Parameters in Women, but Not in Men.

Bone fragility can progress with aging, but biomarkers to detect emerging osteopenia have not been fully elucidated. Growth/differentiation factor 15 (GDF-15) has pleiotropic roles in a broad range of age-related conditions, but its association with osteopenia is unknown. We examined the relationship between plasma GDF-15 levels and rate of change in bone parameters over 9 years of follow-up in 596 adults in the InCHIANTI study (baseline age, 65-94 years; women, 52.4%; mean follow-up, 7.0 ± 3.0 years). Plasma GDF-15 concentrations were measured using the 1.3k HTS SOMAscan assay. Eight bone parameters were measured in the right tibia by peripheral quantitative computed tomography; total bone density, trabecular bone density, medullary plus trabecular bone density, cortical bone density, total bone area, cortical bone area, medullary bone area, and minimum moment of inertia (mMOI). We ran sex-specific linear mixed-effect models with random intercepts and slopes adjusted for age, age-squared, education, body mass index, the rate of change in weight, smoking, sedentary behavior, cross-sectional areas of calf muscles and fat, 25-hydroxyvitamin D, parathyroid hormone, calcium, diabetes mellitus, and follow-up time. We found a significant association of "baseline GDF-15 × time" in models predicting cortical bone density and the mMOI in women, suggesting that the rates of decline in these bone parameters increased with higher GDF-15 (false discovery rate <0.05). Higher plasma levels GDF-15 predicted an accelerated decline in bone parameters in women, but was less associated in men. Furthermore studies are needed to understand the mechanisms underlying these sex differences.

Study on osteoinductive activity of biotin film by low-energy electron beam deposition.

Biotin film was prepared by low-energy electron beam deposition (LEBD). The molecular structure, chemical composition and micromorphology of the biotin film were investigated by 1HNMR, FTIR, XPS, AFM and SEM. The results showed the molecular structure of a monolayer of biotin film is fully consistent with the molecular structure of the initial biotin powders. The contact angle test showed that the biotin film exhibit good hydrophilicity. The release kinetics of biotin film was tested by UV-Vis method. It was found that the film was almost completely released in about two weeks. The cell viability of MC3T3-E1 cells on the surface of the biotin film was attaining 100.54±1.7% (P<0.05), showing excellent biocompatibility and biosafety. Titanium implant with surface of biotin film was implanted into the femoral head of rabbits as experimental group. The animals were euthanized after four weeks. Compared with the control group, mature lamellar bone formation was observed with dense trabecular bone, and the expression of Coll-I, Runx2 and BMP-2 was better. The results showed that the repair effect of bone defect in the experimental group was excellent.

Assessment of regional sacral bone quality: A step towards patient-specific fracture fixation.

Characterizing changes in sacral bone density could help us to inform instrumentation choices for procedures involving the sacrum. The aim of this study is to provide detailed maps of changes in sacral bone density across a series of patients using opportunistic quantitative computed tomography (QCT). We hypothesized that there would be significant differences in local cortical and trabecular bone density associated with age and sex. Fifty-four three-dimensional sacral models were segmented from routine clinical computed tomographyscans, and detailed bone density estimates were derived for each bone using a calibrated opportunistic QCT approach. The effects of age and sex on cortical and trabecular bone density were determined across the sample. Overall cortical bone loss averaged 2.1and 0.9 mg/cc per year, and trabecular bone loss was 1.6and 0.7 mg/cc for female and males, respectively. Several regions had loss rates several times greater. Areas that were significantly affected by age included the vertebral bodies, bilateral ala, apex, and areas adjacent to both the anterior and posterior sacral foramina. Areas that were significantly affected by sex were the anterior sacral promontory, aspects of the ala. Bone density distribution across the sacrum changes nonuniformly due to factors including sex and age. Despite these overall trends, there remains significant variability between individuals.Clinical significance: This study provides detailed bone density information for both cortical and trabecular bone that could assist orthopaedic surgeons in planning surgical approaches to sacral fracture fixation.

Bone accrual and structural changes over one year in youth with cystic fibrosis

BackgroundPediatric bone accrual governs peak bone mass and strength. Longitudinal studies of bone health in youth with cystic fibrosis (CF) may provide insight into CF-related bone disease (CFBD), a prevalent co-morbidity in adults with CF. MethodsThis one-year longitudinal study of youth with pancreatic insufficient CF, enrolled in a nutrition intervention study [n = 62 (36 M/26F)] 1) examined dual-energy x-ray absorptiometry (DXA)-defined lumbar spine (LS) and total body less head (TBLH) bone accrual and 2) compared their changes in peripheral quantitative computed tomography (pQCT) cortical and trabecular tibial bone density and geometry to those of a healthy reference group [n = 143 (68 M/75F)].Main outcome measures were 1) DXA: lumbar spine areal bone mineral density (LSaBMD) and total body less head bone mineral content (TBLH-BMC), sex- and pubertal status-specific, height velocity (HV)-adjusted or HV and lean body mass velocity (HV-LBMV)-adjusted annualized velocity-Z scores and 2) pQCT: age, sex, pubertal status and, when appropriate, tibial length adjusted Z-scores for bone architecture measures.DXA velocity-Z were compared to expected mean of 0 and correlations with clinical parameters (age, BMI-Z and FEV1%-predicted) tested. Within-subject comparisons of HV-adjusted and LBMV-HV-adjusted DXA velocity-Z were conducted in CF.pQCT Z-scores were compared between the two groups over one year using longitudinal models. Longitudinal relationships between measures of bone health and clinical parameters (age, BMI-Z and FEV1%-predicted) were examined in individuals with CF. ResultsDXA velocity-Z were higher than normal in females (p < 0.05) but not males with CF. HV-adjusted and LBMV-HV-adjusted velocity-Z did not differ for LSaBMD or TBLH-BMC.In males with CF, both HV-adjusted and LBMV-HV-adjusted LSaBMD velocity-Z scores correlated negatively with age (HV rho: −0.35; p = 0.045 and LBMV-HV rho: −0.47; p = 0.0046). In males with CF BMI-Z correlated positively with HV-adjusted LSaBMD velocity-Z (rho: 0.37; p = 0.034), but this relationship did not persist for LBMV-HV (rho: 0.14; p = 0.42). In females with CF, no correlations between LSaBMD velocity-Z scores and age or BMI-Z were found (all p > 0.05). No correlations between LSaBMD velocity-Z scores and FEV1%-predicted were seen in either sex (all p > 0.12). TBLH-BMC velocity Z-scores were not correlated with clinical parameters in either sex (all p > 0.1).At baseline, multiple pQCT parameters were lower in CF (p < 0.05). pQCT Z-scores did not differ between baseline and one-year in either CF or reference group. In a longitudinal model comparing pQCT-Z changes in CF and reference, multiple pQCT-Z outcomes remained lower in CF, but the changes in parameters did not differ in CF vs reference (all p > 0.26). Lower pQCT outcomes in CF were largely restricted to males (CF group*female sex interaction beta coefficients > 0). In this combined longitudinal model, of both CF and reference, BMI-Z was positively associated with pQCT-Z parameters(p < 0.001).Multiple pQCT-Z outcomes positively correlated with both BMI-Z and FEV1%-predicted in males with CF, and with FEV1%-predicted in females with CF (p < 0.05). Age was negatively associated with section modulus (p = 0.001) in males and with cortical density-Z in females (p < 0.001). ConclusionsWith improved longevity, bone health in CF is of increasing importance. On average, bone accrual was preserved in youth with CF, and while deficits in bone geometry and strength were found, these deficits did not worsen over the one-year study. Lower LS bone accrual with increasing age suggests emerging adulthood is a period of vulnerability in CF while the role of LBM in bone health is underscored by the lack of relationship between LBMV-adjusted accrual and BMI. These findings may be useful in targeting screening practices and interventions.

Dual-Energy CT, Virtual Non-Calcium Bone Marrow Imaging of the Spine: An AI-Assisted, Volumetric Evaluation of a Reference Cohort with 500 CT Scans.

Virtual non-calcium (VNCa) images from dual-energy computed tomography (DECT) have shown high potential to diagnose bone marrow disease of the spine, which is frequently disguised by dense trabecular bone on conventional CT. In this study, we aimed to define reference values for VNCa bone marrow images of the spine in a large-scale cohort of healthy individuals. DECT was performed after resection of a malignant skin tumor without evidence of metastatic disease. Image analysis was fully automated and did not require specific user interaction. The thoracolumbar spine was segmented by a pretrained convolutional neuronal network. Volumetric VNCa data of the spine’s bone marrow space were processed using the maximum, medium, and low calcium suppression indices. Histograms of VNCa attenuation were created for each exam and suppression setting. We included 500 exams of 168 individuals (88 female, patient age 61.0 ± 15.9). A total of 8298 vertebrae were segmented. The attenuation histograms’ overlap of two consecutive exams, as a measure for intraindividual consistency, yielded a median of 0.93 (IQR: 0.88–0.96). As our main result, we provide the age- and sex-specific bone marrow attenuation profiles of a large-scale cohort of individuals with healthy trabecular bone structure as a reference for future studies. We conclude that artificial-intelligence-supported, fully automated volumetric assessment is an intraindividually robust method to image the spine’s bone marrow using VNCa data from DECT.

Fixture Length and Primary Stability: An In Vitro Study on Polyurethane Foam

(1) Background: Recently, novel dental implants that are characterized by different levels of surface roughness in the distinct parts of the fixture’s body have been introduced in the market. These surface characteristics could affect the primary stability of the implants. The aim of this in vitro study was to compare the primary stability of short and long implants, characterized by multiscale surface roughness, inserted on polyurethane blocks. The secondary aim was to understand if the implant length could be a crucial factor in the decision-making in immediate or rather than delayed loading protocol in the different bone densities. (2) Methods: A total of 20 cylindrical dental implants with a diameter of 5.0 mm were tested for the lengths 6.0 mm (short implants) versus 13.0 mm (long implants) on two different solid rigid polyurethane blocks (20 and 30 PCF). The primary stability was evaluated by measuring the insertion torque value (ITV), the removal torque (RTV), and the resonance frequency analysis RFA. (3) Results: The values of ITV, RTV, and RFA showed the same trend in all measurements. Long implants showed a significantly higher primary stability on 30 PCF blocks that present mechanical properties similar to high-density bone. On the contrary, no relevant differences were found on 20 PCF blocks, which mimic trabecular bone density. (4) Conclusions: The impact of fixture length on the primary stability of implants with multiscale surface roughness is significant in 30 PCF polyurethane corresponding to higher bone density, but not in lower ones.

Effects of reduced mobility on trabecular bone density in captive big cats.

Bone responds to elevated mechanical loading by increasing in mass and density. Therefore, wild animals should exhibit greater skeletal mass and density than captive conspecifics. This expectation is pertinent to testing bone functional adaptation theories and to comparative studies, which commonly use skeletal remains that combine zoo and wild-caught specimens. Conservationists are also interested in the effects of captivity on bone morphology as it may influence rewilding success. We compared trabecular bone volume fraction (BVF) between wild and captive mountain lions, cheetahs, leopards and jaguars. We found significantly greater BVF in wild than in captive felids. Effects of captivity were more marked in the humerus than in the femur. A ratio of humeral/femoral BVF was also lower in captive animals and showed a positive relationship to home range size in wild animals. Results are consistent with greater forelimb than hindlimb loading during terrestrial travel, and possibly reduced loading of the forelimb associated with lack of predatory behaviour in captive animals. Thus, captivity among felids has general effects on BVF in the postcranial skeleton and location-specific effects related to limb use. Caution should be exercised when identifying skeletal specimens for use in comparative studies and when rearing animals for conservation purposes.

Sfrp4 and the Biology of Cortical Bone.

Periosteal apposition and endosteal remodeling regulate cortical bone expansion and thickness, both critical determinants of bone strength. Yet, the cellular characteristics and local or paracrine factors that regulate the periosteum and endosteum remain largely elusive. Here we discuss novel insights in cortical bone growth, expansion, and homeostasis, provided by the study of Secreted Frizzled Receptor Protein 4 (Sfrp4), a decoy receptor for Wnt ligands. SFRP4 loss-of function mutations cause Pyle disease, a rare skeletal disorder characterized by cortical bone thinning and increased fragility fractures despite increased trabecular bone density. On the endosteal surface, Sfrp4-mediated repression of non-canonical Wnt signaling regulates endosteal resorption. On the periosteum, Sfrp4 identifies as a critical functional mediator of periosteal stem cell/progenitor expansion and differentiation. Analysis of signaling pathways regulating skeletal stem cells/progenitors provides an opportunity to advance our understanding of the mechanisms involved in cortical bone biology.

Subchondral bone changes after joint distraction treatment for end stage knee osteoarthritis

Increased subchondral cortical bone plate thickness and trabecular bone density are characteristic of knee osteoarthritis (OA). Knee joint distraction (KJD) is a joint-preserving knee OA treatment where the joint is temporarily unloaded. It has previously shown clinical improvement and cartilage regeneration, indicating reversal of OA-related changes. The purpose of this research was to explore 3D subchondral bone changes after KJD treatment using CT imaging. Twenty patients were treated with KJD and included to undergo knee CT imaging before, one, and two years after treatment. Tibia and femur segmentation and registration to canonical surfaces were performed semi-automatically. Cortical bone thickness and trabecular bone density were determined using an automated algorithm. Statistical parametric mapping (SPM) with two-tailed F-tests was used to analyze whole-joint changes. Data was available of 16 patients. Subchondral cortical bone plate thickness and trabecular bone density were higher in the weight-bearing region of the most affected compartment (MAC; mostly medial). Especially the MAC showed a decrease in thickness and density in the first year after treatment, which was sustained towards the second year. KJD treatment results in bone changes that include thinning of the subchondral cortical bone plate and decrease of subchondral trabecular bone density in the first two years after treatment, potentially indicating a partial normalization of subchondral bone.