ORCID Profile
0000-0002-2930-5997
Current Organisations
University of Calgary
,
Los Alamos National Laboratory
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Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.JBIOMECH.2014.06.040
Abstract: Understanding proximal femur fracture may yield new targets for fracture prevention screening and treatment. The goal of this study was to characterize force-displacement and failure behaviours in the proximal femur between displacement control and impact loading fall simulations. Twenty-one human proximal femurs were tested in two ways, first to a sub-failure load at a constant displacement rate, then to fracture in an impact fall simulator. Comparisons of sub-failure energy and stiffness were made between the tests at the same compressive force. Additionally, the impact failure tests were compared with previous, constant displacement rate failure tests (at 2 and 100mm/s) in terms of energy, yield force, and stiffness. Loading and displacement rates were characterized and related to specimen stiffness in the impact tests. No differences were observed between the sub-failure constant displacement and impact tests in the aforementioned metrics. Comparisons between failure tests showed that the impact group had the lowest absorbed energy, 24% lower maximum force and 160% higher stiffness than the 100mm/s group (p<0.01 for all), but suffered from low statistical power to differentiate the donor age and specimen BMD. Loading and displacement rates for the specimens tested using impact varied during each test and between specimens and did not show appreciable viscoelasticity. These results indicate that constant displacement rate testing may help understand sub-failure mechanical behaviour, but may not elucidate failure behaviours. The differences between the impact and constant displacement rate fall simulations have important ramifications for interpreting the results of previous experiments.
Publisher: Springer International Publishing
Date: 2019
Publisher: Elsevier BV
Date: 11-2016
DOI: 10.1016/J.MEDENGPHY.2016.08.010
Abstract: Finite element analysis (FEA) of bones scanned with Quantitative Computed Tomography (QCT) can improve early detection of osteoporosis. The accuracy of these models partially depends on the assigned material properties, but anisotropy of the trabecular bone cannot be fully captured due to insufficient resolution of QCT. The inclusion of anisotropy measured from high resolution peripheral QCT (HR-pQCT) could potentially improve QCT-based FEA of the femur, although no improvements have yet been demonstrated in previous experimental studies. This study analyzed the effects of adding anisotropy to clinical resolution femur models by constructing six sets of FE models (two isotropic and four anisotropic) for each specimen from a set of sixteen femurs that were experimentally tested in sideways fall loading with a strain gauge on the superior femoral neck. Two different modulus-density relationships were tested, both with and without anisotropy derived from mean intercept length analysis of HR-pQCT scans. Comparing iso- and anisotropic models to the experimental data resulted in nearly identical correlation and highly similar linear regressions for both whole bone stiffness and strain gauge measurements. Anisotropic models contained consistently greater principal compressive strains, approximately 14% in magnitude, in certain internal elements located in the femoral neck, greater trochanter, and femoral head. In summary, anisotropy had minimal impact on macroscopic measurements, but did alter internal strain behavior. This suggests that organ level QCT-based FE models measuring femoral stiffness have little to gain from the addition of anisotropy, but studies considering failure of internal structures should consider including anisotropy to their models.
Publisher: American Medical Association (AMA)
Date: 07-01-2020
Publisher: Springer Science and Business Media LLC
Date: 08-04-2015
DOI: 10.1007/S00198-015-3110-5
Abstract: The relation between serum 25-hydroxy vitamin D [25(OH)D] and bone quality is not well understood, particularly for high levels. We measured bone microarchitecture in three groups of people stratified by their serum 25(OH)D. There was a weak association of serum 25(OH)D and microarchitecture for this cross-sectional population, suggesting possible benefits to bone quality. Vitamin D plays an important role in bone and mineral metabolism, but the relation between serum 25(OH)D and bone quality is not well understood. Here, we present a cross-sectional study that investigated a convenience group of participants from an ongoing health initiative in Alberta, Canada, who have been receiving daily vitamin D supplementation. A total of 105 participants were organized into three groups based on their serum 25(OH)D levels: low ( 175 nmol/L). They were also assessed with 25(OH)D as a continuous variable. Average daily supplementation was 7670 ± 438 IU, and the change in 25(OH)D ranged from 22 to 33 % during the period of receiving supplements. We used high-resolution peripheral quantitative computed tomography measurements at the radius and tibia to assess bone microarchitecture. Microarchitectural parameters were not strongly associated with serum 25(OH)D. In the tibia, there were fewer trabeculae (TbN p = 0.015) and a non-significant trend toward thicker trabeculae (p = 0.067) of the high group. Body mass index (BMI) was negatively associated with serum 25(OH)D levels (p < 0.001) and PTH levels (p < 0.001). There was no clinically significant relationship detected between high serum 25(OH)D and high serum calcium. These data suggest a weak relationship between serum 25(OH)D and bone microarchitecture in this population of mostly vitamin-D-sufficient participants, and there were no indications of negative effects related to the high supplementation levels. These data provided a basis to design and implement our 3-year dose-dependent randomized controlled trial investigating the effects of vitamin D supplementation on bone health outcomes.
Publisher: Springer Science and Business Media LLC
Date: 19-05-2020
Publisher: Elsevier BV
Date: 12-2016
Publisher: Springer Science and Business Media LLC
Date: 06-10-2015
DOI: 10.1007/S00223-015-0064-8
Abstract: Women with Turner syndrome (TS) are known to be at risk of osteoporosis. While childhood growth hormone (GH) treatment is common in TS, the impact of this therapy on bone health has been poorly understood. The objective of this study was to determine the influence of childhood GH treatment on adult bone quality in women with TS. 28 women aged 17-45 with confirmed TS (12 GH-treated) agreed to participate in this cross-sectional study. Dual X-ray absorptiometry (DXA) of lumbar spine, hip, and radius and high-resolution peripheral quantitative computed tomography (HR-pQCT) scans of the radius and tibia were used to determine standard morphological and micro-architectural parameters of bone health. Finite element (FE) analysis and polar moment of inertia (pMOI) were used to estimate bone strength. GH-treated subjects were +7.4 cm taller (95% CI 2.5-12.3 cm, p = 0.005). DXA-determined areal BMD of hip, spine, and radius was similar between treatment groups. Both tibial and radial total bone areas were greater among GH-treated subjects (+20.4 and +21.2% respectively, p < 0.05), while other micro-architectural results were not different between groups. pMOI was significantly greater among GH-treated subjects (radius +35.0%, tibia +34.0%, p < 0.05). Childhood GH treatment compared to no treatment in TS was associated with an increased height, larger bones, and greater pMOI, while no significant difference in DXA-derived BMD, HR-pQCT micro-architectural parameters, or FE-estimated bone strength was detected. The higher pMOI and greater bone size may confer benefit for fracture reduction in these GH-treated patients.
Publisher: Elsevier BV
Date: 10-2014
Publisher: Wiley
Date: 03-05-2023
DOI: 10.1002/JBMR.4808
Abstract: Most fracture risk assessment tools use clinical risk factors combined with bone mineral density (BMD) to improve assessment of osteoporosis however, stratifying fracture risk remains challenging. This study developed a fracture risk assessment tool that uses information about volumetric bone density and three‐dimensional structure, obtained using high‐resolution peripheral quantitative compute tomography (HR‐pQCT), to provide an alternative approach for patient‐specific assessment of fracture risk. Using an international prospective cohort of older adults ( n = 6802) we developed a tool to predict osteoporotic fracture risk, called μFRAC. The model was constructed using random survival forests, and input predictors included HR‐pQCT parameters summarizing BMD and microarchitecture alongside clinical risk factors (sex, age, height, weight, and prior adulthood fracture) and femoral neck areal BMD (FN aBMD). The performance of μFRAC was compared to the Fracture Risk Assessment Tool (FRAX) and a reference model built using FN aBMD and clinical covariates. μFRAC was predictive of osteoporotic fracture (c‐index = 0.673, p 0.001), modestly outperforming FRAX and FN aBMD models (c‐index = 0.617 and 0.636, respectively). Removal of FN aBMD and all clinical risk factors, except age, from μFRAC did not significantly impact its performance when estimating 5‐year and 10‐year fracture risk. The performance of μFRAC improved when only major osteoporotic fractures were considered (c‐index = 0.733, p 0.001). We developed a personalized fracture risk assessment tool based on HR‐pQCT that may provide an alternative approach to current clinical methods by leveraging direct measures of bone density and structure. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
Publisher: Wiley
Date: 14-02-2023
DOI: 10.1111/NPH.18770
Abstract: Wildfires are a global crisis, but current fire models fail to capture vegetation response to changing climate. With drought and elevated temperature increasing the importance of vegetation dynamics to fire behavior, and the advent of next generation models capable of capturing increasingly complex physical processes, we provide a renewed focus on representation of woody vegetation in fire models. Currently, the most advanced representations of fire behavior and biophysical fire effects are found in distinct classes of fine‐scale models and do not capture variation in live fuel (i.e. living plant) properties. We demonstrate that plant water and carbon dynamics, which influence combustion and heat transfer into the plant and often dictate plant survival, provide the mechanistic linkage between fire behavior and effects. Our conceptual framework linking remotely sensed estimates of plant water and carbon to fine‐scale models of fire behavior and effects could be a critical first step toward improving the fidelity of the coarse scale models that are now relied upon for global fire forecasting. This process‐based approach will be essential to capturing the influence of physiological responses to drought and warming on live fuel conditions, strengthening the science needed to guide fire managers in an uncertain future.
Publisher: Wiley
Date: 22-08-2022
DOI: 10.1002/JBMR.4663
Abstract: Femoral neck areal bone mineral density (FN aBMD) is a key determinant of fracture risk in older adults however, the majority of in iduals who have a hip fracture are not considered osteoporotic according to their FN aBMD. This study uses novel tools to investigate the characteristics of bone microarchitecture that underpin bone fragility. Recent hip fracture patients ( n = 108, 77% female) were compared with sex‐ and age‐matched controls ( n = 216) using high‐resolution peripheral quantitative computed tomography (HR‐pQCT) imaging of the distal radius and tibia. Standard morphological analysis of bone microarchitecture, micro‐finite element analysis, and recently developed techniques to identify void spaces in bone microarchitecture were performed to evaluate differences between hip fracture patients and controls. In addition, a new approach for phenotyping bone microarchitecture was implemented to evaluate whether hip fractures in males and females occur more often in certain bone phenotypes. Overall, hip fracture patients had notable deterioration of bone microarchitecture and reduced bone mineral density compared with controls, especially at weight‐bearing sites (tibia and femoral neck). Hip fracture patients were more likely to have void spaces present at either site and had void spaces that were two to four times larger on average when compared with non‐fractured controls ( p 0.01). Finally, bone phenotyping revealed that hip fractures were significantly associated with the low density phenotype ( p 0.01), with the majority of patients classified in this phenotype (69%). However, female and male hip fracture populations were distributed differently across the bone phenotype continuum. These findings highlight how HR‐pQCT can provide insight into the underlying mechanisms of bone fragility by using information about bone phenotypes and identification of microarchitectural defects (void spaces). The added information suggests that HR‐pQCT can have a beneficial role in assessing the severity of structural deterioration in bone that is associated with osteoporotic hip fractures. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
Publisher: Wiley
Date: 03-02-2021
DOI: 10.1002/JBMR.4247
Publisher: The Journal of Rheumatology
Date: 15-01-2019
Abstract: We assessed construct validity of high-resolution peripheral quantitative computed tomography (HR-pQCT) joint space outcomes by comparison with radiographs in patients with rheumatoid arthritis. In 43 patients, quantitative, volumetric, HR-pQCT measurements were compared with ordinal Sharp/van der Heijde scoring (SvdH) in the 2nd and 3rd metacarpophalangeal joints. Generalized estimating equations showed that joint space minimum, SD, and asymmetry by HR-pQCT were associated with SvdH scores (p 0.05). There was a considerable range in HR-pQCT measurements at SvdH equal to 0. HR-pQCT demonstrated construct validity outcomes and provides improved 3-D visualization of joint space.
Publisher: Springer Science and Business Media LLC
Date: 29-11-2019
DOI: 10.1007/S00198-019-05214-0
Abstract: Manual correction of automatically generated contours for high-resolution peripheral quantitative computed tomography can be time consuming and introduces precision error. However, bias related to the automated protocol is unknown. This study provides insight into error bias that is present when using uncorrected contours and inter-operator precision error based on operator training. High-resolution peripheral quantitative computed tomography workflow includes manually correcting contours generated by the manufacturer's automated protocol. There is interest in minimizing corrections to save time and reduce precision error however, bias related to the automated protocol is unknown. This study quantifies error bias when contours are uncorrected and identifies the impact of operator training on bias and precision error. Forty-five radii and tibiae scans across a representative range of bone density were analyzed using the automated and manually corrected contours of three operators, with training ranging from beginner to expert, and compared with a "ground truth" to estimate bias. Inter-operator precision was measured across operators. The tibia had greater error bias than the radius when contours were uncorrected, with compartmental bone mineral densities and cortical microarchitecture having greatest biases, which could have significant implications for interpretation of studies using this skeletal site. Bias and precision error were greatest when contours were corrected by the beginner operator however, when this operator was removed, bias was no longer present and inter-operator precision was between 0.01 and 3.74% for all parameters except cortical porosity. These findings establish the need for manual correction and provide guidance on operator training needed to maximize workflow efficiency.
Publisher: Springer Science and Business Media LLC
Date: 30-11-2020
DOI: 10.1007/S00223-019-00638-6
Abstract: This study aimed to evaluate associations of parity and breastfeeding history with postmenopausal bone loss. Early postmenopausal women from the Canadian Multicentre Osteoporosis Study were ided into three groups based on their reproductive histories: nulliparous (NP, n = 10), parous with 6 months breastfeeding (P-BF, n = 21). Women underwent dual X-ray absorptiometry and high-resolution peripheral quantitative computed tomography imaging at baseline and after 6 years to evaluate bone mineral density (BMD), bone microstructure, and finite element-estimated failure load. Average age at baseline was 57 years. Baseline density, microstructure, and failure load were not different among groups. In all women, total and cortical BMD decreased significantly at the tibia and radius. P-BF women only experienced a significant decline in tibial trabecular BMD, with a greater magnitude of change for P-BF than NP women (p = 0.002). Overall, results suggest that early postmenopausal bone health did not differ based on parity or breastfeeding history. Over the 6-year follow-up period, postmenopausal bone loss was evident in all women, with subtle differences in the rate of postmenopausal change among women with varying breastfeeding histories. Parous women who had breastfed for at least 6 months showed an elevated rate of trabecular BMD loss at the tibia. Meanwhile, correlation analyses suggest that longer durations of breastfeeding may be associated with reduced cortical bone loss at the radius. The lack of differences among groups in FE-derived failure load suggests that parity and breastfeeding history is unlikely to significantly affect postmenopausal risk of fracture.
Publisher: American Medical Association (AMA)
Date: 27-08-2019
Publisher: The Journal of Rheumatology
Date: 08-2017
Abstract: High-resolution peripheral quantitative computed tomography (HR-pQCT) has the potential to improve radiographic progression determination in clinical trials and longitudinal observational studies. The goal of this work was to describe the current state of research presented at Outcome Measures in Rheumatology (OMERACT) 2016 and ensuing future directions outlined during discussion among attendees. At OMERACT 2016, SPECTRA (Study grouP for xtrEme-Computed Tomography in Rheumatoid Arthritis) introduced efforts to (1) validate the HR-pQCT according to OMERACT guidelines, focusing on rheumatoid arthritis (RA), and (2) find alternatives for automated joint space width (JSW) analysis. The Special Interest Group (SIG) was presented to patient research partners, physicians/researchers, and SIG leaders followed by a 40-min discussion on future directions. A consensus definition for RA erosion using HR-pQCT was demonstrated through a systematic literature review and a Delphi exercise. Histopathology and perfusion studies were presented that analyzed the true characteristics of cortical breaks in HR-pQCT images, and to provide criterion validity. Results indicate that readers were able to discriminate between erosion and small vascular channels. Moderate reliability (ICC 0.206–0.871) of direct erosion size measures was shown, which improved ( 0.9) only when experienced readers were considered. Quantification of erosion size was presented for scoring, direct measurement, and volumetric approaches, as well as a reliability exercise for direct measurement. Three methods for JSW measurement were compared, all indicating excellent reproducibility with differences at the extremes (i.e., near-zero and joint edge thickness). Initial reports on HR-pQCT are promising however, to consider its use in clinical trials and longitudinal observational studies, it is imperative to assess the responsiveness of erosion measurement quantification.
Publisher: Elsevier BV
Date: 2019
Publisher: The Endocrine Society
Date: 20-11-2019
Abstract: More than 3% of adults report vitamin D intakes of 4000 IU/day or more, but the safety of this practice is unknown. The objective of this work is to establish whether vitamin D doses up to 10 000 IU/day are safe and well tolerated. The Calgary Vitamin D Study was a 3-year, double-blind, randomized controlled trial. A single-center study was conducted at the University of Calgary, Canada. Participants included healthy adults (n = 373) ages 55 to 70 years with serum 25-hydroxyvitamin D 30 to 125 nmol/L. Participants were randomly assigned 1:1:1 to vitamin D3 400, 4000, or 10 000 IU/day. Calcium supplementation was initiated if dietary calcium intake was less than 1200 mg/day. In these prespecified secondary analyses, changes in serum 25-hydroxyvitamin D, calcium, creatinine, 24-hour urine calcium excretion, and incidence of adverse events were assessed. Between-group differences in adverse events were examined using incident rate differences and logistic regression. Of 373 participants (400: 124, 4000: 125, 10 000: 124), 49% were male, mean (SD) age was 64 (4) years, and 25-hydroxyvitamin D 78.0 (19.5) nmol/L. Serum calcium, creatinine, and 24-hour urine calcium excretion did not differ between treatments. Mild hypercalcemia (2.56-2.64 mmol/L) occurred in 15 (4%) participants (400: 0%, 4000: 3%, 10 000: 9%, P = .002) all cases resolved on repeat testing. Hypercalciuria occurred in 87 (23%) participants (400: 17%, 4000: 22%, 10 000: 31%, P = .01). Clinical adverse events were experienced by 365 (97.9%) participants and were balanced across treatment arms. The safety profile of vitamin D supplementation is similar for doses of 400, 4000, and 10 000 IU/day. Hypercalciuria was common and occurred more frequently with higher doses. Hypercalcemia occurred more frequently with higher doses but was rare, mild, and transient.
Publisher: Springer Science and Business Media LLC
Date: 15-06-2020
Publisher: Wiley
Date: 16-09-2020
DOI: 10.1002/JBMR.4152
Publisher: Wiley
Date: 03-02-2021
DOI: 10.1002/JBMR.4251
Publisher: Wiley
Date: 14-01-2022
DOI: 10.1002/JBMR.4494
Abstract: Prevalence of osteoporosis is more than 50% in older adults, yet current clinical methods for diagnosis that rely on areal bone mineral density (aBMD) fail to detect most in iduals who have a fragility fracture. Bone fragility can manifest in different forms, and a “one‐size‐fits‐all” approach to diagnosis and management of osteoporosis may not be suitable. High‐resolution peripheral quantitative computed tomography (HR‐pQCT) provides additive information by capturing information about volumetric density and microarchitecture, but interpretation is challenging because of the complex interactions between the numerous properties measured. In this study, we propose that there are common combinations of bone properties, referred to as phenotypes, that are predisposed to different levels of fracture risk. Using HR‐pQCT data from a multinational cohort ( n = 5873, 71% female) between 40 and 96 years of age, we employed fuzzy c‐means clustering, an unsupervised machine‐learning method, to identify phenotypes of bone microarchitecture. Three clusters were identified, and using partial correlation analysis of HR‐pQCT parameters, we characterized the clusters as low density, low volume, and healthy bone phenotypes. Most males were associated with the healthy bone phenotype, whereas females were more often associated with the low volume or low density bone phenotypes. Each phenotype had a significantly different cumulative hazard of major osteoporotic fracture (MOF) and of any incident osteoporotic fracture ( p 0.05). After adjustment for covariates (cohort, sex, and age), the low density followed by the low volume phenotype had the highest association with MOF (hazard ratio = 2.96 and 2.35, respectively), and significant associations were maintained when additionally adjusted for femoral neck aBMD (hazard ratio = 1.69 and 1.90, respectively). Further, within each phenotype, different imaging biomarkers of fracture were identified. These findings suggest that osteoporotic fracture risk is associated with bone phenotypes that capture key features of bone deterioration that are not distinguishable by aBMD. © 2021 American Society for Bone and Mineral Research (ASBMR).
Publisher: Wiley
Date: 30-07-2010
DOI: 10.1002/JBMR.81
Publisher: Springer Science and Business Media LLC
Date: 27-05-2014
DOI: 10.1007/S11657-014-0183-2
Abstract: Within a normative youth cohort (16-29 years) bone parameters for males and females remained stable at the radius. At the tibia, a peak was observed for females at 16-19 years, with bone density and strength decreasing by 29 years. To determine if bone microstructural and strength parameters identified by high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite element analysis (FEA) at the distal radius and tibia, peak within the age range of this youth cohort, and whether the timing of the peaks differ based on sex or skeletal site. We recruited 251 participants (158 female 16 to 29 years), grouping them into 5-year age brackets (16-19 20-24 25-29 years) assessing microstructural and strength parameters with HR-pQCT and FEA. HR-pQCT assessment of males and females (age-matched groups) showed males had higher total area and BMD, trabecular BMD and trabecular number (radius only) cortical thickness and porosity, and failure load, but lower cortical BMD (p < 0.05). Within sex, microstructural and strength parameters remained stable for males, but in females they appeared to peak at 16-19 years at the tibia. Tibia bone strength and trabecular BMD were highest in females 16-19 years (p < 0.05), and tibia cortical porosity was lowest in females 16-19 years (p < 0.001). With the exception of an age-related increase in cortical BMD, all other parameters were stable between 16 and 29 years at the radius for both males and females. We found no peak values for males or females at the radius. At the tibia, a peak was observed for females 16-19 years. These data provide a population-based assessment of bone microstructural and strength parameters from HR-pQCT and FEA in a youth cohort, showing clear differences in bone quality dependent on sex and skeletal site.
Publisher: Wiley
Date: 23-10-2020
DOI: 10.1002/JBMR.4190
Publisher: Wiley
Date: 03-04-2017
DOI: 10.1002/JBMR.3129
Abstract: Longitudinal studies assessing age-related changes using high-resolution peripheral quantitative computed tomography (HR-pQCT) provide novel insight compared with cross-sectional analyses. The purpose of this cohort study was 1) to determine in iduals' change in HR-pQCT parameters over 5 years relative to least significant change (LSC), and 2) to evaluate if predicted rate of change from cross-sectional data is comparable to actual change from longitudinal investigation. A cohort of 466 (162 male, 304 female) participants completed two HR-pQCT scans with 5 years between assessments. After image registration, standard and cortical morphological analyses were conducted. Rate of bone microarchitectural change was compared between cross-sectional models and actual change calculated from longitudinal analyses. At the young end of the life span, we observed gains in total bone density of +0.2% to +2.9% per year, whereas the older participants (aged >50 years) lost total bone density at a rate of -0.3% to -1.3% per year. Declines in total bone density begin at age 40 years in females and 60 years in males, and significant adaptation was found at both ends of the age spectrum with respect to the LSC. Models predicting rate of change from cross-sectional data were similar to the actual change reported in this longitudinal study for total density and cortical thickness at the radius and cortical density at the tibia, but we found that changes in comparison to our 5-year longitudinal results were often overestimated from cross-sectional data. Studies aimed at observing age-related changes in a normative cohort, especially in a follow-up period of less than 5 years, are better to focus on the tibia rather than the radius because of the increased sensitivity to change at the tibia. © 2017 American Society for Bone and Mineral Research.
Publisher: Wiley
Date: 05-04-2017
DOI: 10.1002/JBMR.3128
Abstract: Second-generation high-resolution peripheral quantitative computed tomography (HR-pQCT) provides the highest resolution in vivo to assess bone density and microarchitecture in 3D. Although strong agreement of most outcomes measured with first- (XCTI) and second- (XCTII) generation HR-pQCT has been demonstrated, the ability to use the two systems interchangeably is unknown. From in vivo measurements, we determined the limits of estimating XCTII data from XCTI scans conducted in vivo and whether that estimation can be improved by linear cross-calibration equations. These data are crucial as the research field transitions to the new technology. Our study design established cross-calibration equations by scanning 62 in iduals on both systems on the same day and then tested those cross-calibrations on the same cohort 6 months later so that estimated (denoted as XCTII*) and "true" XCTII parameters could be compared. We calculated the generalized least-significant change (GLSC) for those predictions. There was strong agreement between both systems for density (R
Publisher: Wiley
Date: 24-01-2018
DOI: 10.1002/JBMR.3347
Abstract: The aim of this prospective study was to use high-resolution peripheral quantitative computed tomography (HR-pQCT) to determine if baseline skeletal parameters can predict incident fragility fracture in women and, secondly, to establish if women that fracture lose bone at a faster rate than those who do not fracture. Women older than 60 years who experienced a fragility fracture during the 5-year follow-up period (incident fracture group, n = 22) were compared with those who did not experience a fragility fracture during the study (n = 127). After image registration between baseline and follow-up measures, standard and cortical morphological analyses were conducted. Odds ratios were calculated for baseline values and annualized percent change of HR-pQCT and finite element variables. At the radius, baseline HR-pQCT results show women who fractured had lower total bone mineral density (Tt.BMD 19%), trabecular bone mineral density (Tb.BMD 25%), and trabecular number (Tb.N 14%), with higher trabecular separation (Tb.Sp 19%) than women who did not fracture. At the tibia, women with incident fracture had lower Tt.BMD (15%), Tb.BMD (12%), cortical thickness (Ct.Th 14%), cortical area (Ct.Ar 12%), and failure load (10%) with higher total area (Tt.Ar 7%) and trabecular area (Tb.Ar 10%) than women who did not fracture. Odds ratios (ORs) at the radius revealed every SD decrease of Tt.BMD (OR = 2.1), Tb.BMD (OR = 2.0), and Tb.N (OR = 1.7) was associated with a significantly increased likelihood of fragility fracture. At the tibia, every SD decrease in Tt.BMD (OR = 2.1), Tb.BMD (OR = 1.7), Ct.Th (OR = 2.2), Ct.Ar (OR = 1.9), and failure load (OR = 1.7) were associated with a significantly increased likelihood of fragility fracture. Irrespective of scanning modality, the annualized percent rate of bone loss was not different between fracture groups. The results suggest baseline bone density, microarchitecture, and strength rather than change in these variables are associated with incident fragility fractures in women older than 60 years. Furthermore, irrespective of fragility fracture status, women experienced changes in skeletal health at a similar rate. © 2017 American Society for Bone and Mineral Research.
Publisher: Wiley
Date: 09-06-2016
DOI: 10.1002/JBMR.2873
Abstract: The purpose of this study was to develop age-, site-, and sex-specific centile curves for common high-resolution peripheral quantitative computed tomography (HR-pQCT) and finite-element (FE) parameters for males and females older than 16 years. Participants (n = 866) from the Calgary cohort of the Canadian Multicentre Osteoporosis Study (CaMos) between the ages of 16 and 98 years were included in this study. Participants' nondominant radius and left tibia were scanned using HR-pQCT. Standard and automated segmentation methods were performed and FE analysis estimated apparent bone strength. Centile curves were generated for males and females at the tibia and radius using the generalized additive models for location, scale, and shape (GAMLSS) package in R. After GAMLSS analysis, age-, sex-, and site-specific centiles (10th, 25th, 50th, 75th, 90th) for total bone mineral density and trabecular number as well as failure load have been calculated. Clinicians and researchers can use these reference curves as a tool to assess bone health and changes in bone quality. © 2016 American Society for Bone and Mineral Research.
Publisher: Elsevier BV
Date: 04-2018
DOI: 10.1016/J.CCT.2018.02.009
Abstract: The optimum dose of vitamin D and corresponding serum 25-hydroxyvitamin D (25OHD) concentration for bone health is still debated and some health practitioners are recommending doses well above the Canada/USA recommended Dietary Reference Intake (DRI). We designed a three-year randomized double-blind clinical trial investigating whether there are dose-dependent effects of vitamin D supplementation above the Dietary Reference Intake (DRI) on bone health. The primary aims of this study are to assess, whether supplementation of vitamin D
Publisher: Springer Science and Business Media LLC
Date: 10-01-2017
DOI: 10.1007/S00198-016-3900-4
Abstract: The rate of change in bone density was not different between peri- and post-menopausal women. Differences in rate of change were observed in bone microarchitecture, specifically cortical porosity (Ct.Po), where peri-menopausal women increased +9% per year compared with the +6% per year for post-menopausal women. The purpose of this study was to compare changes in bone density and microarchitecture in peri- and post-menopausal women over 6 years. Peri- (n = 26) and post- (n = 65) menopausal women were selected from the Canadian Multicenter Osteoporosis Study. Caucasian women were scanned on dual x-ray absorptiometry (DXA) and high-resolution peripheral quantitative computed tomography (HR-pQCT) at baseline and follow-up, an average 6 years later. To compare repeat scans, automated 3D image registration was conducted. At the radius and tibia, total volumetric BMD (Tt.BMD), total bone area (Tt.Ar) and cortical porosity (Ct.Po) were assessed, and finite element analysis estimated apparent bone strength. At the tibia, the rate of change for Ct.Po and Tt.Ar was different between groups. Peri-menopausal women had a + 9% per year increase in Ct.Po, but this increase was slower for post-menopausal women at +6% per year (p = 0.049). In addition, post-menopausal women had an increase in Tt.Ar of +0.13% per year compared with a slower increase of +0.06% per year for peri-menopausal women (p = 0.017). The rate of change of density between groups was not significantly different and was approximately -1% per year at the hip by DXA, and -1% per year at the radius and -0.5% per year tibia by HR-pQCT. This is a 6-year prospective HR-pQCT study exploring rate of change in Caucasian peri- and post-menopausal women. The microarchitectural features represented by Ct.Po and Tt.Ar changed at a significantly different rate between groups, but group differences were not detected by density measures.
Publisher: Wiley
Date: 20-07-2020
DOI: 10.1002/JBMR.4114
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.JBIOMECH.2013.02.025
Abstract: Finite element (FE) analysis based on quantitative computed tomography (QCT) images is an emerging tool to estimate bone strength in a specific patient or specimen however, it is limited by the computational power required and the associated time required to generate and solve the models. Thus, our objective was to develop a fast, validated method to estimate whole bone structural stiffness and failure load in addition to a sensitivity analysis of varying boundary conditions. We performed QCT scans on twenty fresh-frozen proximal femurs (age: 77±13 years) and mechanically tested the femurs in a configuration that simulated a sideways fall on the hip. We used custom software to generate the FE models with boundary conditions corresponding to the mechanical tests and solved the linear models to estimate bone structural stiffness and estimated failure load. For the sensitivity analysis, we varied the internal rotation angle of the femoral neck from -30° to 45° at 15° intervals and estimated structural stiffness at each angle. We found both the FE estimates of structural stiffness (R(2)=0.89, p<0.01) and failure load (R(2)=0.81, p<0.01) to be in high agreement with the values found by mechanical testing. An important advantage of these methods was that the models of approximately 500,000 elements took less than 11 min to solve using a standard desktop workstation. In this study we developed and validated a method to quickly and accurately estimate proximal femur structural stiffness and failure load using QCT-driven FE methods.
Publisher: Springer Science and Business Media LLC
Date: 14-08-2023
Publisher: Wiley
Date: 08-03-2022
DOI: 10.1002/JBM4.10615
Abstract: High‐dose vitamin D supplementation (4000 or 10,000 IU/d) in vitamin D‐sufficient in iduals results in a dose‐dependent decrease in radius and tibia total bone mineral density (Tt.BMD) compared with 400 IU/d. This exploratory analysis examined whether the response to high‐dose vitamin D supplementation depends on imaging modality and skeletal site. Participants were aged 55 to 70 years, not osteoporotic, with serum 25(OH)D 30 to 125 nM. Participants’ radius and tibia were scanned on high‐resolution peripheral quantitative computed tomography (HR‐pQCT) to measure Tt.BMD, trabecular bone volume fraction (Tb.BV/TV), trabecular separation (Tb.Sp), cortical thickness (Ct.Th), and finite element analysis (FEA) estimated failure load. Three‐dimensional image registration was used. Dual‐energy X‐ray absorptiometry (DXA) scans of the hip, spine, and radius measured areal BMD (aBMD) and trabecular bone score (TBS). Constrained linear mixed‐effects models determined treatment group‐by‐time and treatment group‐by‐time‐by‐sex interactions. The treatment group‐by‐time interaction previously observed for radial Tt.BMD was observed at both ultradistal (UD, p 0.001) and 33% ( p 0.001) aBMD sites. However, the treatment group‐by‐time‐by‐sex interaction observed for radial Tt.BMD was not observed with aBMD at either the UD or 33% site, and the 4000 and 400 groups did not differ. Registered radial FEA results mirrored Tt.BMD. An increase in Tb.Sp and decrease in Ct.Th underpinned dose‐dependent changes in radial BMD and strength. We observed no effects in DXA‐based aBMD at the hip or spine or TBS. At the tibia, we observed a time‐by‐treatment group effect for Tb.BV/TV. Given that DXA measures at the radius did not detect sex differences or differences between the 4000 and 400 groups, HR‐pQCT at the radius may be more sensitive for examining bone changes after vitamin D supplementation. Although DXA did not reveal treatment effects at the hip or spine, whether that is a true skeletal site difference or a lack of modality sensitivity remains unclear. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
Publisher: Wiley
Date: 17-07-2023
DOI: 10.1002/JBMR.4876
Abstract: In a 36‐month randomized controlled trial examining the effect of high‐dose vitamin D 3 on radial and tibial total bone mineral density (TtBMD), measured by high‐resolution peripheral quantitative tomography (HR‐pQCT), participants (311 healthy males and females aged 55–70 years with dual‐energy X‐ray absorptiometry T‐scores −2.5 without vitamin D deficiency) were randomized to receive 400 IU ( N = 109), 4000 IU ( N = 100), or 10,000 IU ( N = 102) daily. Participants had HR‐pQCT radius and tibia scans and blood s ling at baseline, 6, 12, 24, and 36 months. This secondary analysis examined the effect of vitamin D dose on plasma measurements of the vitamin D metabolome by liquid chromatography–tandem mass spectrometry (LC‐MS/MS), exploring whether the observed decline in TtBMD was associated with changes in four key metabolites [25‐(OH)D 3 24,25‐(OH) 2 D 3 1,25‐(OH) 2 D 3 and 1,24,25‐(OH) 3 D 3 ]. The relationship between peak values in vitamin D metabolites and changes in TtBMD over 36 months was assessed using linear regression, controlling for sex. Increasing vitamin D dose was associated with a marked increase in 25‐(OH)D 3 , 24,25‐(OH) 2 D 3 and 1,24,25‐(OH) 3 D 3 , but no dose‐related change in plasma 1,25‐(OH) 2 D 3 was observed. There was a significant negative slope for radius TtBMD and 1,24,25‐(OH) 3 D 3 (−0.05, 95% confidence interval [CI] −0.08, −0.03, p 0.001) after controlling for sex. A significant interaction between TtBMD and sex was seen for 25‐(OH)D 3 (female: −0.01, 95% CI −0.12, −0.07 male: −0.04, 95% CI −0.06, −0.01, p = 0.001) and 24,25‐(OH) 2 D 3 (female: −0.75, 95% CI −0.98, −0.52 male: −0.35, 95% CI −0.59, −0.11, p 0.001). For the tibia there was a significant negative slope for 25‐(OH)D 3 (−0.03, 95% CI −0.05, −0.01, p 0.001), 24,25‐(OH) 2 D 3 (−0.30, 95% CI −0.44, −0.16, p 0.001), and 1,24,25‐(OH) 3 D 3 (−0.03, 95% CI −0.05, −0.01, p = 0.01) after controlling for sex. These results suggest vitamin D metabolites other than 1,25‐(OH) 2 D 3 may be responsible for the bone loss seen in the Calgary Vitamin D Study. Although plasma 1,25‐(OH) 2 D 3 did not change with vitamin D dose, it is possible rapid catabolism to 1,24,25‐(OH) 3 D 3 prevented the detection of a dose‐related rise in plasma 1,25‐(OH) 2 D 3 . © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
Publisher: MDPI AG
Date: 19-02-2020
DOI: 10.3390/NU12020527
Abstract: Vitamin D supplementation is proposed as a fall prevention strategy, as it may improve neuromuscular function. We examined whether three years of vitamin D supplementation (400, 4000 or 10,000 IU daily) affects postural sway in older adults. Three hundred and seventy-three non-osteoporotic, vitamin D-sufficient, community-dwelling healthy adults, aged 55–70 years, were randomized to 400 (n = 124), 4000 (n = 125) or 10,000 (n = 124) IU daily vitamin D3 for three years. Sway index was assessed at baseline, 12-, 24- and 36-months using the Biosway machine. We tested participants under four conditions: eyes open or eyes closed with firm (EOFI, ECFI) or foam (EOFO, ECFO) surfaces. Secondary assessments examined sway in the anterior-posterior (AP) and medio-lateral (ML) directions. Linear mixed effects models compared sway between supplementation groups across time. Postural sway under EOFO and ECFO conditions significantly improved in all supplementation groups over time. Postural sway did not differ between supplementation groups at any time under any testing conditions in normal, AP or ML directions (p 0.05 for all). Our findings suggest that high dose (4000 or 10,000 IU) vitamin D supplementation neither benefit nor impair balance compared with 400 IU daily in non-osteoporotic, vitamin D-sufficient, healthy older adults.
Publisher: Springer Science and Business Media LLC
Date: 14-10-2020
No related grants have been discovered for Steven Boyd.