Bone Microarchitecture Assessed by HR-pQCT as Predictor of Fracture Risk in Postmenopausal Women: The OFELY Study

Site-specific volumetric skeletal changes in women with and without a distal forearm fracture: a case-control study with a mean 7-year follow-up

Brief rationale: To assess bone dimensions in the radius over 7 years.

MAIN RESULT

Cross-sectional area did not change significantly, but endosteal circumference increased, leading to decreased cortical thickness. Significance of the paper: Bone mineral density loss is associated with a decrease in cortical thickness in the forearm.

PURPOSE

To assess site-specific volumetric bone and muscle differences in women with and without forearm fracture in a longitudinal study.

METHODS

One hundred four postmenopausal women with a forearm fracture and 99 age-matched controls were included and underwent peripheral quantitative computed tomography (pQCT) in the forearm at a mean age of 65 (range 44-88) years and were invited for a reassessment after mean 7 (6-11) years, at which 80 and 79 women took part, respectively. Three cases had movement artifacts on pQCT; 77 cases and 79 controls were finally analysed.

RESULTS

Twenty-two of the cases and 20 of the controls sustained a fracture during the follow-up. From baseline to follow-up, bone mineral content and bone mineral density decreased irrespective of group belonging at baseline, both at the 4% and the 66% level in the forearm. Cross-sectional area did not change significantly at the 4% and the 66% level. At the 66% level, periosteal circumference was unchanged and endosteal circumference increased, leading to decreased cortical thickness. Muscle area decreased, while muscle density was unchanged. A high cross-sectional area and low bone volumetric bone mineral density were predictive of fracture during the follow-up.

CONCLUSION

Over a mean follow-up of 7 years, postmenopausal women lose bone mineral density, associated with a decrease in cortical thickness in the forearm.

Automated micro-CT morphometry of femoral biopsies from hip arthroplasties: adaptive local thresholding, volume of interest wrapping and removal of debris

Bone biopsies are an important biological tool for investigating bone microarchitecture, which can be non-destructively imaged in 3D via micro-computed tomography (micro-CT). Image thresholding and delineation of a region of interest (ROI) are prerequisites for quantifying bone parameters. Validated automatic protocols enable quantification of biopsies that contain trabecular and cortical bone. However, irregularly shaped trabecular bone biopsies with peripheral and internal debris have required manual ROI delineation, which is time-intensive and subject to inter and intra-observer variance. We hypothesise that an automated workflow will be a suitable alternative to overcome these issues and objectively determine bone microarchitecture in surgical biopsies, at higher throughput suitable for clinical studies. Hence, the aim of this study was to develop an objective, reproducible and automated workflow to analyse microarchitecture of trabecular bone biopsies. To accomplish this aim, we tested six different methods of ROI delineation: a whole biopsy ROI, and both manual (slow) and automatically delineated (fast) reduced ROIs to remove peripheral debris, each with (adaptive thresholding and a set of morphological operations to remove debris) and without (global thresholding) processing in a subset (n = 8) of intertrochanteric femoral biopsies obtained from patients undergoing hip arthroplasty. Number of objects, bone volume to tissue volume (BV/TV), trabecular separation (Tb.Sp), structure model index (SMI) and Euler number and trabecular pattern factor (Tb.Pf) were compared between the six workflows using Friedman's test and post-hoc pairwise comparisons with Bonferroni correction was performed. The two most reproducible techniques were tested for validation in a larger cohort of arthroplasty patients (n = 60) and results were compared with appropriate t-test. Subset analysis indicated that the manual and automated ROI with processing increased the ability to resolve real differences between these groups in parameters BV/TV, Tb.Sp and Euler number compared to with no processing and whole biopsy ROI approach. A validation cohort consisted of thirty osteoarthritis patients with a mean age 68.25 ± 8.64 and thirty neck of femur fracture with a mean age 82.4 ± 8.9. The manual technique failed to detect differences in BV/TV, SMI and Tb.Pf between the two patient groups (p > 0.05, for all) while the automated workflow demonstrated significant differences in these parameters between the OA and the NOF patients (p < 0.05). This is probably due to irregularity in the reference VOI volume introduced by manual ROI delineation reducing morphometric precision, compared to the automated method. In conclusion, our automated workflow performed better than customary practice; it represents a user-independent, high throughput technique to measure bone microarchitecture accurately in surgical biopsies.

Analysis of the current status and characteristics of osteoporosis in adult hemophilia patients based on high-resolution peripheral quantitative computed tomography: a case control study

BACKGROUND

Current research on osteoporosis (OP) in hemophilia is insufficient. The suitability of high-resolution peripheral quantitative computed tomography (HR-pQCT) for evaluating osteoporosis in hemophilia remains unclear.

AIM

To investigate the current status of osteoporosis and the applicability of HR-pQCT in adult hemophilia patients.

METHODS

Thirty three hemophilia patients aged 23-49 years were recruited. X-ray examinations were performed on the bleeding joints. Dual energy X-ray absorptiometry (DXA) and HR-pQCT were used to assess bone mineral density (BMD). The HR-pQCT values of the distal tibia and radius were compared between hemophilia patients and healthy controls(HCs).

RESULTS

All bleeding joints showed local osteoporosis on X-ray. Only 33.3% of patients had a hip BMD lower than the expected value according to DXA. The Tb.vBMD(98.5 ± 44.2 mg/cm3), Tt.Ar(612.5 ± 163.5mm2),Tb.Ar(487.0 ± 175.6mm2), Ct.Ar(117.0 ± 25.7mm2), Tb.BV/TV(0.2 ± 0.1), Tb.N(0.9 ± 0.3 1/mm), Ct.Pm(96.3 ± 13.8 mm) of the distal tibia and Tt.Ar(248.4 ± 53.1mm2),Tb.Ar(186.0 ± 55.1mm2), Ct.Ar(66.1 ± 14.4 mm2), Ct.Pm(68.1 ± 7.1 mm) of the distal radius in the hemophilia group was significantly lower than the HCs(tibia Tb.vBMD:186.4 ± 44.3mg/cm3, Tt.Ar:906.8 ± 135.0mm2,Tb.Ar:743.7 ± 137.6mm2, Ct.Ar:169.3 ± 21.9mm2,Tb.

BV/TV

0.3 ± 0.1, Tb.N:1.5 ± 0.2 1/mm,Ct.Pm:117.8 ± 8.2 mm; radius Tt.Ar:285.7 ± 35.6 mm2, Tb.Ar:83.8 ± 7.9mm2, Ct.Ar:0.3 ± 0.1mm2, Ct.Pm:80.2 ± 4.3 mm) with statistically significant differences (p < 0.05). Correlation analysis showed a positive correlation (r = 0.768, p = 0.016) between femoral neck BMD with DXA and total volumetric BMD(Tt.vBMD) at the distal tibia.

CONCLUSION

The bone health status of adult hemophilia patients in China is worrying. The occurrence of OP may be accompanied by varying degrees of bone loss, bone destruction, and structural abnormalities observed in both trabecular and cortical bones of the upper and lower limbs. The condition of the trabecular bones in the lower limbs is particularly severe. The correlation between BMD measurements obtained from HR-pQCT and DXA is strong.

Bone imaging modality precision and agreement between DXA, pQCT, and HR-pQCT

Quantifying precision error for DXA, peripheral QCT (pQCT), and HR-pQCT is crucial for monitoring longitudinal changes in body composition and musculoskeletal outcomes. Agreement and associations between bone variables assessed using pQCT and second-generation HR-pQCT are unclear. This study aimed to determine the precision of, and agreement and associations between, bone variables assessed via DXA, pQCT, and second-generation HR-pQCT. Thirty older adults (mean age: 64.2 ± 8.0 yr; women: 67%) were recruited. DXA scans were performed at the total hip, lumbar spine, and whole body. Distal (4%) and proximal (30%/33%/66%) skeletal sites at the radius and tibia were scanned with pQCT and/or HR-pQCT. Root-mean-squared coefficients of variation (%CVRMS) were calculated to define precision errors, and Bland-Altman plots assessed agreement between densitometric estimates. Pearson correlations and linear regression explored relationships between bone variables at different skeletal sites and proportional bias, respectively. Precision errors ranged between 0.55% and 1.6% for DXA, 0.40% and 4.8% for pQCT, and 0.13% and 30.7% for HR-pQCT. Systematic bias was identified between pQCT- and HR-pQCT-determined radius and tibia volumetric BMD (vBMD) estimates (all p<.001). Proportional bias was not observed between vBMD measures at any skeletal site (all p>.05). pQCT- and HR-pQCT-determined total, trabecular, and cortical vBMD and estimates of bone strength at the radius and tibia were strongly correlated (all p<.05). Precision error was low for most bone variables and within the expected range for all imaging modalities. We observed significant systematic bias, but no proportional bias, between pQCT- and second-generation HR-pQCT-determined vBMD estimates at the radius and tibia. Nevertheless, measures of bone density and strength were strongly correlated at all skeletal sites. These findings suggest that although bone density and strength estimates from both imaging modalities are not interchangeable, they are strongly related and likely have similar fracture prediction capabilities.

Quantitative ultrasound imaging reveals distinct fracture-associated differences in tibial intracortical pore morphology and viscoelastic properties in aged individuals with and without diabetes mellitus - an exploratory study

Introduction

Diabetes mellitus (DM) is a chronic metabolic disorder that increases fragility fracture risk. Conventional DXA-based areal bone mineral density (aBMD) assessments often underestimate this risk. Cortical Backscatter (CortBS) ultrasound, a radiation-free technique, non-invasively analyzes cortical bone's viscoelastic and microstructural properties. This study aimed to evaluate CortBS's discriminative performance in DM patients compared to DXA and characterize changes in cortical bone microstructure in Type 1 and Type 2 DM (T1DM, T2DM) patients.

Methods

This in-vivo study included 89 DM patients (T1DM = 39, T2DM = 48) and 76 age- and sex-matched controls. DXA measured aBMD, while CortBS measurements were taken at the anteromedial tibia using a medical ultrasound scanner with custom software. Multivariate analysis of variance assessed the impact of DM type on CortBS and DXA measurement results. Partial least squares discriminant analyses with cross-validation were used to compare the discrimination performance for vertebral, non-vertebral, and any fragility fractures, adjusting for gender, age, and anthropometric parameters (weight, height, BMI).

Results

Fractures occurred in 8/23 T1DM, 17/18 T2DM, and 16/55 controls. DXA parameters were reduced in fracture patients, with significant diabetes impact. T2DM was associated with altered CortBS parameters, reduced scatterer density, and larger pores. CortBS outperformed DXA in discriminating fracture risk (0.61 ≤ AUC(DXA) ≤ 0.63, 0.68 ≤ AUC(CortBS) ≤ 0.69).

Conclusions

Both T1DM and T2DM showed altered bone metabolism, with T2DM linked to impaired tissue formation. CortBS provides insights into pathophysiological changes in diabetic bone and provided superior fracture risk assessment in DM patients compared to DXA.

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

Thyrotoxicosis leads to loss of bone mass. Vitamin D is important to bone health. In this randomized, placebo-controlled trial, we showed that bone restoration did not improve when adding vitamin D supplementation to standard care of Graves' disease thyrotoxicosis. Bone density and microarchitecture improved markedly with treatment of thyrotoxicosis.

PURPOSE

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).

METHODS

Using a double-blinded design, hyperthyroid patients with GD were randomized to vitamin D3 70 µg/day (2800 IU) or similar placebo as add-on to antithyroid drugs (ATD). At baseline and 9 months, we measured BMD and bone architecture using DXA and high resolution peripheral quantitative computerized tomography. Bone turnover markers (BTM) were measured at 3 months also. Effect of vitamin D versus placebo and the response to ATD treatment were analyzed using linear mixed modelling.

RESULTS

Eighty-six GD patients were included (age 41 ± 14 years, 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.

CONCLUSION

In newly diagnosed GD, 9 months 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.

CLINICALTRIAL

GOV IDENTIFIER

NCT02384668.

Short-term risk of fracture is increased by deficits in cortical and trabecular bone microarchitecture independent of DXA BMD and FRAX: Bone Microarchitecture International Consortium (BoMIC) prospective cohorts

Identifying individuals at risk for short-term fracture is essential to offer prompt beneficial treatment, especially since many fractures occur in those without osteoporosis by DXA-aBMD. We evaluated whether deficits in bone microarchitecture and density predict short-term fracture risk independent of the clinical predictors, DXA-BMD and FRAX. We combined data from eight cohorts to conduct a prospective study of bone microarchitecture at the distal radius and tibia (by HR-pQCT) and 2-year incidence of fracture (non-traumatic and traumatic) in 7327 individuals (4824 women, 2503 men, mean 69 ± 9 years). We estimated sex-specific hazard ratios (HR) for associations between bone measures and 2-year fracture incidence, adjusted for age, cohort, height, and weight, and then additionally adjusted for FN aBMD or FRAX for major osteoporotic fracture. Only 7% of study participants had FN T-score ≤ -2.5, whereas 53% had T-scores between -1.0 and -2.5 and 37% had T-scores ≥-1.0. Two-year cumulative fracture incidence was 4% (296/7327). Each SD decrease in radius cortical bone measures increased fracture risk by 38%-76% for women and men. After additional adjustment for FN-aBMD, risks remained increased by 28%-61%. Radius trabecular measures were also associated with 2-year fracture risk independently of FN-aBMD in women (HRs range: 1.21 per SD for trabecular separation to 1.55 for total vBMD). Decreased failure load (FL) was associated with increased fracture risk in both women and men (FN-aBMD ranges of adjusted HR = 1.47-2.42). Tibia measurement results were similar to radius results. Findings were also similar when models were adjusted for FRAX. In older adults, FL and HR-pQCT measures of cortical and trabecular bone microarchitecture and density with strong associations to short-term fractures improved fracture prediction beyond aBMD and FRAX. Thus, HR-pQCT may be a useful adjunct to traditional assessment of short-term fracture risk in older adults, including those with T-scores above the osteoporosis range.

Bone properties in persons with type 1 diabetes and healthy controls - A cross-sectional study

BACKGROUND

The risk of fractures is increased in persons with type 1 diabetes (T1D) and assessment of bone health has been included in the 2024 updated Standards of Care by The American Diabetes Association (ADA). Previous studies have found that in T1D bone metabolism, mineral content, microstructure, and strength diverge from that of persons without diabetes. However, a clear description of a T1D bone phenotype has not yet been established. We investigated bone mechanical properties and microstructure in T1D compared with healthy controls. For the potential future introduction of additional bone measures in the clinical fracture risk assessment, we aimed to assess any potential associations between various measures related to bone indices in subjects with T1D.

METHODS

We studied human bone indices in a clinical cross-sectional setup including 111 persons with early-onset T1D and 37 sex- and age-matched control persons. Participants underwent hip and spine DXA scans for bone mineral density (BMD) of the femoral neck (FN), total hip (TH), and lumbar spine (LS), and TBS evaluation, microindentation of the tibial shaft for Bone Material Strength index (BMSi), and high-resolution periphery quantitative computed tomography (HRpQCT) of the distal radius and tibia for volumetric BMD (vBMD) and structural measures of trabecular and cortical bone. Results are reported as means with (standard deviation) or (95 % confidence intervals (CI)), medians with [interquartile range], and differences are reported with (95 % CI).

RESULTS

The study included 148 persons aged 20 to 75 years with a median age of 43.2 years. The T1D group who had all been diagnosed with T1D before the age of 18 years demonstrated values of HbA1c ranging from 39 to 107 mmol/mol and a median HbA1c of 57 mmol/mol. The BMD did not differ between groups (the mean difference in FN-BMD was 0.026 g/cm2 (-0.026; 0.079), p = 0.319) and the median BMSi was comparable in the two groups (79.2 [73.6; 83.8] in the T1D group compared with 77.9 [70.5, 86.1] in the control group). Total and trabecular vBMD (Tb.vBMD), cortical thickness (Ct.Th), and trabecular thickness (Tb.Th) of both radius and tibia were lower in participants with T1D. The mean Tb.vBMD at the radius was 143.6 (38.5) mg/cm3 in the T1D group and 171.5 (37.7) mg/cm3 in the control group, p < 0.001. The mean Ct. Thd of the radius was 0.739 mm (0.172) in the T1D group and 0.813 (0.188) in the control group, p = 0.044. Crude linear regressions revealed limited agreement between BMSi and Tb.vBMD (p = 0.010, r2 = 0.040 at the radius and p = 0.008, r2 = 0.040 at the tibia and between BMSi and the estimated failure load (FL) at the tibia (p < 0.001, r2 = 0.090). There were no significant correlations between BMSi and Ct.Th. TBS correlated with Tb.vBMD at the radius (p = 0.008, r2 = 0.044) and the tibia (p = 0.001, r2 = 0.069), and with the estimated FL at the distal tibia (p = 0.038, r2 = 0.026).

CONCLUSION

In this study, we examined the bones of persons with well-controlled, early-onset T1D. Compared with sex- and age-matched healthy control persons, we found reduced total and trabecular vBMD, as well as decreased trabecular and cortical thickness. These results suggest that a debut of T1D before reaching peak bone mass negatively impacts bone microarchitecture. No differences in areal BMD or BMSi were observed. Although the variations in total hip BMD reflect some variation in the vBMD, the reduction in trabecular bone mineral density was not captured by the DXA scan. Consequently, fracture risk may be underestimated when relying on DXA, and further research into fracture risk assessment in T1D is warranted.

A Randomized Controlled Trial on the Effect of Luseogliflozin on Bone Microarchitecture Evaluated Using HR-pQCT in Elderly Type 2 Diabetes

INTRODUCTION

Bone fragility is a critical issue in the treatment of elderly people with type 2 diabetes (T2D). In the Canagliflozin Cardiovascular Assessment Study, the subjects with T2D who were treated with canagliflozin showed a significant increase in fracture events compared to a placebo group as early as 12 weeks post-initiation. In addition, it has been unclear whether sodium-glucose co-transporter 2 (SGLT2) inhibitors promote bone fragility. We used high-resolution peripheral quantitative computed tomography (HR-pQCT) to prospectively evaluate the short-term effect of the SGLT2 inhibitor luseogliflozin on bone strength and microarchitecture in elderly people with T2D.

METHODS

This was a single-center, randomized, open-label, active-controlled pilot trial for ≥ 60-year-old Japanese individuals with T2D without osteoporosis. A total of 22 subjects (seven women and 15 men) were randomly assigned to a Lusefi group (added luseogliflozin 2.5 mg) or a control group (added metformin 500 mg) and treated for 48 weeks. We used the second-generation HR-pQCT (Xtreme CT II®, Scanco Medical, Brüttisellen, Switzerland) before and 48 weeks after the treatment to evaluate the subjects' bone microarchitecture and estimate their bone strength.

RESULTS

Twenty subjects (Lusefi group, n = 9; control group, n = 11) completed the study, with no fracture events. As the primary outcome, the 48-week changes in the bone strength (stiffness and failure load) estimated by micro-finite element analysis were not significantly different between the groups. As the secondary outcome, the changes in all of the cortical/trabecular microarchitectural parameters at the radius and tibia from baseline to 48 weeks were not significantly different between the groups.

CONCLUSIONS

In the pilot trial, we observed no negative effect of 48-week luseogliflozin treatment on bone microarchitecture or bone strength in elderly people with T2D.

TRIAL REGISTRATION

UMIN-CTR no. 000036202 and jRCT 071180061.

Super-resolution of clinical CT: Revealing microarchitecture in whole bone clinical CT image data

Osteoporotic fractures, prevalent in the elderly, pose a significant health and economic burden. Current methods for predicting fracture risk, primarily relying on bone mineral density, provide only modest accuracy. If better spatial resolution of trabecular bone in a clinical scan were available, a more complete assessment of fracture risk would be obtained using microarchitectural measures of bone (i.e. trabecular thickness, trabecular spacing, bone volume fraction, etc.). However, increased resolution comes at the cost of increased radiation or can only be applied at small volumes of distal skeletal locations. This study explores super-resolution (SR) technology to enhance clinical CT scans of proximal femurs and better reveal the trabecular microarchitecture of bone. Using a deep-learning-based (i.e. subset of artificial intelligence) SR approach, low-resolution clinical CT images were upscaled to higher resolution and compared to corresponding MicroCT-derived images. SR-derived 2-dimensional microarchitectural measurements, such as degree of anisotropy, bone volume fraction, trabecular spacing, and trabecular thickness were within 16 % error compared to MicroCT data, whereas connectivity density exhibited larger error (as high as 1094 %). SR-derived 3-dimensional microarchitectural metrics exhibited errors <18 %. This work showcases the potential of SR technology to enhance clinical bone imaging and holds promise for improving fracture risk assessments and osteoporosis detection. Further research, including larger datasets and refined techniques, can advance SR's clinical utility, enabling comprehensive microstructural assessment across whole bones, thereby improving fracture risk predictions and patient-specific treatment strategies.

Fracture risk based on high-resolution peripheral quantitative computed tomography measures does not vary with age in older adults-the bone microarchitecture international consortium prospective cohort study

Fracture risk increases with lower areal bone mineral density (aBMD); however, aBMD-related estimate of risk may decrease with age. This may depend on technical limitations of 2-dimensional (2D) dual energy X-ray absorptiometry (DXA) which are reduced with 3D high-resolution peripheral quantitative computed tomography (HR-pQCT). Our aim was to examine whether the predictive utility of HR-pQCT measures with fracture varies with age. We analyzed associations of HR-pQCT measures at the distal radius and distal tibia with two outcomes: incident fractures and major osteoporotic fractures. We censored follow-up time at first fracture, death, last contact or 8 years after baseline. We estimated hazard ratios (HR) and 95%CI for the association between bone traits and fracture incidence across age quintiles. Among 6835 men and women (ages 40-96) with at least one valid baseline HR-pQCT scan who were followed prospectively for a median of 48.3 months, 681 sustained fractures. After adjustment for confounders, bone parameters at both the radius and tibia were associated with higher fracture risk. The estimated HRs for fracture did not vary significantly across age quintiles for any HR-pQCT parameter measured at either the radius or tibia. In this large cohort, the homogeneity of the associations between the HR-pQCT measures and fracture risk across age groups persisted for all fractures and for major osteoporotic fractures. The patterns were similar regardless of the HR-pQCT measure, the type of fracture, or the statistical models. The stability of the associations between HR-pQCT measures and fracture over a broad age range shows that bone deficits or low volumetric density remain major determinants of fracture risk regardless of age group. The lower risk for fractures across measures of aBMD in older adults in other studies may be related to factors which interfere with DXA but not with HR-pQCT measures.

Postmenopausal women with normal BMD who have fractures have deteriorated bone microarchitecture: A prospective analysis from The OFELY study

Most postmenopausal women who sustain fragility fracture (Fx) have their areal bone mineral density (BMD) above the osteoporosis threshold. A sizeable proportion of them have normal aBMD. This study aimed to prospectively investigate the association of fragility Fx with bone microarchitecture (MA) assessed by high-resolution peripheral computed tomography (HR-pQCT) in postmenopausal women without low BMD. At the 14th annual follow-up of the OFELY study, we measured bone MA at the distal radius and tibia with HR-pQCT in addition to areal BMD with DXA, in 586 postmenopausal women. Among them, 166 (29 %) women, mean (SD) age 65 (8) yr, had normal BMD defined as a T score ≥ -1 at the lumbar spine, femoral neck, and total hip. During a median [IQR] 15 [14-15] yr of follow-up, 46 of those women sustained incident fragility Fx, including 19 women with a major osteoporotic Fx (clinical spine, forearm, proximal humerus, hip). Women who sustained Fx did not differ for age, BMI, tobacco and alcohol use, diabetes, falls, FRAX®, aBMD, and TBS compared with women without incident Fx. In contrast, they had significant impairment of volumetric densities, cortical area (Ct. Ar) and thickness (Ct. Th), stiffness (K), and estimated failure load (FL) at the radius compared with women without incident Fx. At the radius, each SD decrease of volumetric densities, Ct.Ar, Ct.Th, K, and estimated FL were significantly associated with an increased risk of all fragility fractures with hazard ratios (HR) from 1.44 to 1.56 and of major osteoporotic fractures (HR from 1.66 to 2.57). Lesser impairment of bone MA was seen at the tibia. We conclude that even in women with normal areal BMD fragility fractures are associated with deterioration of bone microarchitecture.

Bone microarchitectural alterations associated with spinal cord injury: Relation to sex hormones, metabolic factors, and loading

CONTEXT

People living with spinal cord injury (SCI) are at high risk for bone fractures. Neural, hormonal and metabolic contributors to bone microarchitectural alterations are incompletely understood.

OBJECTIVE

To determine the relationship of physical, metabolic and endocrine characteristics with bone microarchitecture, characterized using high-resolution peripheral quantitative computed tomography (HRpQCT) in SCI.

DESIGN

Cross-sectional analyses of bone properties in people with SCI.

PARTICIPANTS

Twenty adults with SCI and paraplegia (12) or motor incomplete quadriplegia (8).

OUTCOME MEASURES

Distal tibia and radius HRpQCT parameters, including density, microstructure and strength by microfinite element anaysis (μFEA); sex hormones; metabolic and inflammatory markers.

RESULTS

The mean age of the participants with SCI was 41.5 ± 10.3 years, BMI 25.7 ± 6.2 kg/m2, time since injury 10.4 ± 9.0 years. Participants with SCI had significantly lower median total (Z score - 3.3), trabecular (-2.93), and cortical vBMD (-1.87), and Failure Load by μFEA (-2.48) at the tibia than controls. However, radius vBMD, aBMD and microarchitecture were similar in participants with SCI and un-injured controls. Unexpectedly, C-Reactive Protein (CRP) was positively associated with tibial trabecular vBMD (β = 0.77, p = 0.02), thickness (β = 0.52, p = 0.04) and number (β = 0.92, p = 0.02). At the radius, estradiol level was positively associated with total vBMD (β = 0.59, p = 0.01), trabecular thickness (β = 0.43, p = 0.04), cortical thickness (β = 0.63, p = 0.01) and cortical porosity (β = 0.74 p = 0.04).

CONCLUSIONS

Radius vBMD and microarchitecture is preserved but tibial total, cortical and trabecular vBMD, and estimated bone strength are markedly lower and bone microarchitectural parameters substantially degraded in people with SCI. The alterations in bone microarchitecture in people with SCI are likely multifactorial, however marked degradation of bone microarchitecture in tibia but not radius suggests that unloading is an important contributor of site-specific alterations of bone microarchitecture after SCI. Fracture prevention in SCI should focus on strategies to safely increase bone loading.

CLINICALTRIALS

gov registration #: (NCT03576001).

Deficits in volumetric bone mineral density, bone microarchitecture, and estimated bone strength in women with atypical anorexia nervosa compared to healthy controls

OBJECTIVE

Anorexia nervosa is associated with low bone mineral density (BMD) and deficits in bone microarchitecture and strength. Low BMD is common in atypical anorexia nervosa, in which criteria for anorexia nervosa are met except for low weight. We investigated whether women with atypical anorexia nervosa have deficits in bone microarchitecture and estimated strength at the peripheral skeleton.

METHOD

Measures of BMD and microarchitecture were obtained in 28 women with atypical anorexia nervosa and 27 controls, aged 21-46 years.

RESULTS

Mean tibial volumetric BMD, cortical thickness, and failure load were lower, and radial trabecular number and separation impaired, in atypical anorexia nervosa versus controls (p < .05). Adjusting for weight, deficits in tibial cortical bone variables persisted (p < .05). Women with atypical anorexia nervosa and amenorrhea had lower volumetric BMD and deficits in microarchitecture and failure load versus those with eumenorrhea and controls. Those with a history of overweight/obesity or fracture had deficits in bone microarchitecture versus controls. Tibial deficits were particularly marked. Less lean mass and longer disease duration were associated with deficits in high-resolution peripheral quantitative computed tomography (HR-pQCT) variables in atypical anorexia nervosa.

DISCUSSION

Women with atypical anorexia nervosa have lower volumetric BMD and deficits in bone microarchitecture and strength at the peripheral skeleton versus controls, independent of weight, and particularly at the tibia. Women with atypical anorexia nervosa and amenorrhea, less lean mass, longer disease duration, history of overweight/obesity, or fracture history may be at higher risk. This is salient as deficits in HR-pQCT variables are associated with increased fracture risk.

PUBLIC SIGNIFICANCE

Atypical anorexia nervosa is a psychiatric disorder in which psychological criteria for anorexia nervosa are met despite weight being in the normal range. We demonstrate that despite weight in the normal range, women with atypical anorexia nervosa have impaired bone density, structure, and strength compared to healthy controls. Whether this translates to an increased risk of incident fracture in this population requires further investigation.

Incident fractures of the distal radius: Dual-energy CT-derived metrics for opportunistic risk stratification

BACKGROUND

Dual-energy CT (DECT)-derived bone mineral density (BMD) of the distal radius and other CT-derived metrics related to bone health have been suggested for opportunistic osteoporosis screening and risk evaluation for sustaining distal radius fractures (DRFs).

METHODS

The distal radius of patients who underwent DECT between 01/2016 and 08/2021 was retrospectively analyzed. Cortical Hounsfield Unit (HU), trabecular HU, cortical thickness, and DECT-based BMD were acquired from a non-fractured, metaphyseal area in all examinations. Receiver-operating characteristic (ROC) analysis was conducted to determine the area under the curve (AUC) values for predicting DRFs based on DECT-derived BMD, HU values, and cortical thickness. Logistic regression models were then employed to assess the associations of these parameters with the occurrence of DRFs.

RESULTS

In this study, 263 patients (median age: 52 years; interquartile range: 36-64; 132 women; 192 fractures) were included. ROC curve analysis revealed a higher area under the curve (AUC) value for DECT-derived BMD compared to cortical HU, trabecular HU, and cortical thickness (0.91 vs. 0.61, 0.64, and 0.69, respectively; p <.001). Logistic regression models confirmed the association between lower DECT-derived BMD and the occurrence of DRFs (Odds Ratio, 0.83; p <.001); however, no influence was observed for cortical HU, trabecular HU, or cortical thickness.

CONCLUSIONS

DECT can be used to assess the BMD of the distal radius without dedicated equipment such as calibration phantoms to increase the detection rates of osteoporosis and stratify the individual risk to sustain DRFs. In contrast, assessing HU-based values and cortical thickness does not provide clinical benefit.

Digital wrist tomosynthesis (DWT)-based finite element analysis of ultra-distal radius differentiates patients with and without a history of osteoporotic fracture

Despite effective therapies for those at risk of osteoporotic fracture, low adherence to screening guidelines and limited accuracy of bone mineral density (BMD) in predicting fracture risk preclude identification of those at risk. Because of high adherence to routine mammography, bone health screening at the time of mammography using a digital breast tomosynthesis (DBT) scanner has been suggested as a potential solution. BMD and bone microstructure can be measured from the wrist using a DBT scanner. However, the extent to which biomechanical variables can be derived from digital wrist tomosynthesis (DWT) has not been explored. Accordingly, we measured stiffness from a DWT based finite element (DWT-FE) model of the ultra-distal (UD) radius and ulna, and correlate these to reference microcomputed tomography image based FE (μCT-FE) from five cadaveric forearms. Further, this method is implemented to determine in vivo reproducibility of FE derived stiffness of UD radius and demonstrate the in vivo utility of DWT-FE in bone quality assessment by comparing two groups of postmenopausal women with and without a history of an osteoporotic fracture (Fx; n = 15, NFx; n = 51). Stiffness obtained from DWT and μCT had a strong correlation (R2 = 0.87, p < 0.001). In vivo repeatability error was <5 %. The NFx and Fx groups were not significantly different in DXA derived minimum T-scores (p > 0.3), but stiffness of the UD radius was lower for the Fx group (p < 0.007). Logistic regression models of fracture status with stiffness of the nondominant arm as the predictor were significant (p < 0.01). In conclusion this study demonstrates the feasibility of fracture risk assessment in mammography settings using DWT imaging and FE modeling in vivo. Using this approach, bone and breast screening can be performed in a single visit, with the potential to improve both the prevalence of bone health screening and the accuracy of fracture risk assessment.

High-resolution peripheral quantitative computed tomography: research or clinical practice?

High-resolution peripheral quantitative CT (HR-pQCT) is a low-dose three-dimensional imaging technique, originally developed for in vivo assessment of bone microarchitecture at the distal radius and tibia in osteoporosis. HR-pQCT has the ability to discriminate trabecular and cortical bone compartments, providing densitometric and structural parameters. At present, HR-pQCT is mostly used in research settings, despite evidence showing that it may be a valuable tool in osteoporosis and other diseases. This review summarizes the main applications of HR-pQCT and addresses the limitations that currently prevent its integration into routine clinical practice. In particular, the focus is on the use of HR-pQCT in primary and secondary osteoporosis, chronic kidney disease (CKD), endocrine disorders affecting bone, and rare diseases. A section on novel potential applications of HR-pQCT is also present, including assessment of rheumatic diseases, knee osteoarthritis, distal radius/scaphoid fractures, vascular calcifications, effect of medications, and skeletal muscle. The reviewed literature seems to suggest that a more widespread implementation of HR-pQCT in clinical practice would offer notable opportunities. For instance, HR-pQCT can improve the prediction of incident fractures beyond areal bone mineral density provided by dual-energy X-ray absorptiometry. In addition, HR-pQCT may be used for the monitoring of anti-osteoporotic therapy or for the assessment of mineral and bone disorder associated with CKD. Nevertheless, several obstacles currently prevent a broader use of HR-pQCT and would need to be targeted, such as the small number of installed machines worldwide, the uncertain cost-effectiveness, the need for improved reproducibility, and the limited availability of reference normative data sets.

A Fracture Risk Assessment Tool for High Resolution Peripheral Quantitative Computed Tomography

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).

Bone microstructure in proton pump inhibitor users

OBJECTIVES

We assessed skeletal microstructure and stiffness in proton pump inhibitor (PPI) users compared to non-users with high resolution peripheral quantitative computed tomography (HRpQCT) and microfinite element analysis (μFEA) and other modalities. Relationships between PPI dose/frequency and bone parameters were evaluated.

METHODS

We cross-sectionally assessed skeletal health in 601 older (≥age 65 years) adults (130 PPI users and 471 non-users) participating in a multi-ethnic population-based study of aging.

RESULTS

PPI users tended to have more comorbidities and take more medications than non-users. Female PPI users (n = 100) were more likely to be non-Caucasian, shorter with higher BMI, and more likely to have diabetes, lower physical activity and be using anti-depressants and thiazide diuretics compared to non-users (n = 302). Male PPI users (n = 30) were more likely to have liver disease than non-users (n = 169). In women, historical fractures (53.0 % vs. 43.4 %, p = 0.05) and falls (38 % vs. 26.8 %, p = 0.04) tended to be more frequent in PPI users compared to non-users. Number of falls was higher in women reporting daily rather than intermittent PPI use (1.8/year vs. 1.0/year, p < 0.001). In women, there were no differences in any HRpQCT or μFEA parameter. By HRpQCT, covariate-adjusted cortical volumetric bone density (Ct.vBMD) was 4.2 % lower in male PPI users vs. non-users at the tibia (p = 0.04), but this did not result in reduced stiffness. There were no other differences by HRpQCT at the tibia or radius.

CONCLUSIONS

PPI use was not associated with altered skeletal microstructure or stiffness in elderly men and women. The results do not support a relationship between PPI use and microstructure.

Do bone turnover markers reflect changes in bone microarchitecture during treatment of patients with thyroid dysfunction?

PURPOSE

This study aimed to compare changes in the bone turnover markers (BTMs)-C-terminal telopeptide of type I collagen (CTX-I) and procollagen I N-terminal peptide (PINP)-with changes in the bone microarchitecture, assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT), during treatment of patients with thyroid dysfunction.

METHODS

In women with newly diagnosed hypo- or hyperthyroidism, HR-pQCT variables, obtained from the tibia and the radius, were compared with BTMs. Data were collected at diagnosis and after at least 12 months of euthyroidism.

RESULTS

73 women completed the study (hypothyroidism, n = 27; hyperthyroidism, n = 46). Among hyperthyroid patients, correlations were found between changes in BTMs and HR-pQCT variables, primarily for cortical variables in the tibia, i.e. cortical thickness (CTX-I, p < 0.001; PINP, p < 0.001), and volumetric bone mass density (vBMD) (CTX-I, p < 0.001; PINP, p < 0.001). Moreover, correlations between BTMs and estimated bone strength were found. In the hypothyroid subgroup, no significant findings existed after adjustment. Following treatment, less decrease in tibial vBMD was seen among patients with increasing CTX-I compared to those with a decreasing CTX-I level (p = 0.009). Opposite findings applied to PINP, as patients with decreasing PINP showed an increase in tibial vBMD, in contrast to a decline in this parameter among patients with increasing PINP (p < 0.001).

CONCLUSION

Changes in CTX-I and PINP correlated with HR-pQCT variables during the treatment of women with thyroid dysfunction. To some extent, these BTMs reflected the restoration of bone microarchitecture. CTX-I seems to be the most sensitive BTM in treatment-naïve thyroid diseases, while PINP is more useful for monitoring during treatment.

TRIAL REGISTRATION NUMBER

NCT02005250. Date: December 9, 2013.

Bone fragility: conceptual framework, therapeutic implications, and COVID-19-related issues

Bone fragility is the susceptibility to fracture even for common loads because of structural, architectural, or material alterations of bone tissue that result in poor bone strength. In osteoporosis, quantitative and qualitative changes in density, geometry, and micro-architecture modify the internal stress state predisposing to fragility fractures. Bone fragility substantially depends on the structural behavior related to the size and shape of the bone characterized by different responses in the load-deformation curve and on the material behavior that reflects the intrinsic material properties of the bone itself, such as yield and fatigue. From a clinical perspective, the measurement of bone density by DXA remains the gold standard for defining the risk of fragility fracture in all population groups. However, non-quantitative parameters, such as macro-architecture, geometry, tissue material properties, and microcracks accumulation can modify the bone's mechanical strength. This review provides an overview of the role of different contributors to bone fragility and how these factors might be influenced by the use of anti-osteoporotic drugs and by the COVID-19 pandemic.

Compartment-specific effects of muscle strength on bone microarchitecture in women at high risk of osteoporosis

BACKGROUND

It is well known that skeletal integrity is influenced by the musculature. Poor muscle strength (i.e. sarcopenia) is considered a major predictor of fragility fractures. While this observation appears particularly relevant for older women with increased risk of osteoporosis, there has been no comprehensive investigation to determine the influence of muscle performance on compartment-specific bone microarchitecture in multiple body regions.

METHODS

We retrospectively analysed data from different muscle performance and bone microarchitecture assessments in 230 women (aged 21 to 87 years) at high risk of osteoporosis. Muscle performance tests included grip strength and chair rising test (CRT) combined with mechanography. Balance was determined by Romberg posturography. Areal bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) at the hip and lumbar spine. Compartment-specific volumetric BMD, microarchitecture, and geometry were assessed by second-generation high-resolution peripheral quantitative computed tomography (HR-pQCT) at multiple skeletal sites (distal radius, tibia, and fibula). Regression models were applied to test for interactions between muscle and bone parameters. Subgroups were defined to compare women with osteoporosis and osteosarcopenia regarding BMD and microarchitecture.

RESULTS

While osteoporosis was diagnosed in 115/230 (50.0%) women, sarcopenia was detected in 38/230 (16.5%). Positive associations of both grip strength and CRT maximum force with cortical geometric and microarchitectural parameters were detected at all measured sites, with the strongest effect applying to CRT maximum force and tibial parameters (e.g. tibial cortical area R2  = 0.36, P < 0.0001, and tibial cortical thickness R2  = 0.26, P < 0.0001). Balance parameters showed much weaker or no associations with HR-pQCT parameters. Major associations between muscle strength and trabecular parameters could not be confirmed. Age and body mass index were confirmed as negative and positive predictors for several microarchitectural parameters, respectively. An independent predictive value of grip strength on radial, tibial, and fibular (all P < 0.01) cortical area and of CRT maximum relative force on cortical thickness (all P < 0.05) was revealed. Women with osteosarcopenia showed significantly reduced cortical HR-pQCT parameters but no differences in DXA values compared with women with osteoporosis but no sarcopenia. Stratification by fracture and treatment status revealed that vertebral fractures and denosumab treatment altered the muscle-bone interaction.

CONCLUSIONS

A systemic interaction between muscle strength and bone microarchitecture was demonstrated, and this interaction appears to be primarily with the cortical bone compartment. The value of muscle assessments in fracture risk evaluation may be partly mediated by their effects on bone microarchitecture.

Self-reported Resistance Training Is Associated With Better HR-pQCT-derived Bone Microarchitecture in Vegan People

CONTEXT

A plant-based lifestyle is a global trend; lower bone mineral density and increased fracture risk in vegan people are reported.

OBJECTIVE

The primary objective was to assess trabecular and cortical bone microarchitecture in vegans and omnivores. Secondary objectives were to evaluate relationships between bone microarchitecture, nutrition parameters, and physical activity.

METHODS

This was an observational study at the Medical Department II, St. Vincent Hospital (tertiary referral center for gastrointestinal, metabolic, and bone diseases, and teaching hospital of the Medical University of Vienna), including 43 healthy nonobese female and male subjects on a plant-based diet for at least 5 years, and 45 healthy nonobese female and male subjects on an omnivore diet for at least 5 years. The main outcome measures were the parameters of trabecular and cortical bone microarchitecture (high-resolution peripheral quantitative computed tomography), serum markers of bone turnover, nutrient intake (nutrition protocol), and self-reported resistance training (physical activity questionnaires).

RESULTS

In the vegan group, trabecular and cortical structure were altered compared with omnivores. Vegans not reporting resistance training had diminished bone microarchitecture compared with omnivores not reporting resistance training. In vegans and omnivores reporting resistance training, bone structure was similar. In both vegan subgroups (resistance training and not resistance training), a small number of correlations between nutrient intake and bone microarchitecture were observed without a conclusive pattern.

CONCLUSION

Bone microarchitecture in vegans differed from matched omnivores but could not be explained solely by nutrient uptake. These differences were attenuated between the subgroups reporting resistance training. In addition to a well-planned diet, progressive resistance training on a regular basis should be part of the vegan lifestyle.

High-Intensity Exercise and Geometric Indices of Hip Bone Strength in Postmenopausal Women on or off Bone Medication: The MEDEX-OP Randomised Controlled Trial

To compare the effects of high-intensity resistance and impact training (HiRIT) to low-intensity, Pilates-based exercise (LiPBE) on proximal femur geometry and explore the influence of antiresorptive medication on those effects. Postmenopausal women with low bone mass, on or off antiresorptive bone medications were randomly allocated, stratified on medication intake, to eight months of twice-weekly, supervised HiRIT (Onero™) or LiPBE (Buff Bones®). 3D hip software was used to analyse proximal femur DXA scans. Outcomes included femoral neck (FN) and total hip (TH), volumetric (e.g. vBMC, vBMD) and geometric (e.g. cortical thickness, cross-sectional area [CSA], section modulus [Z]) indices of bone strength. Data were analysed using analysis of variance. Scans of 102 women were examined: LiPBE, 43; HiRIT, 37; LiPBE-med, 11; HiRIT-med, 11. HiRIT improved TH trabecular vBMC and vBMD (3.1 ± 1.1% versus - 1.2 ± 1.2%, p = 0.008; and 1.5 ± 1.0% versus - 1.6 ± 1.2%, p = 0.042, respectively) and FN and TH total vBMC (2.0 ± 0.8% versus - 0.2 ± 0.7%, p = 0.032; and 0.7 ± 0.4% versus - 0.8 ± 0.6%, p = 0.032, respectively), compared to losses in LiPBE. HiRIT also increased Z while LiPBE did not (p = 0.035). The combination of HiRIT and medication achieved greater improvements in FN total and trabecular vBMD, total BMC, CSA and Z than HiRIT alone. HiRIT improved geometric parameters of proximal femur strength, while LiPBE exercise was largely ineffective. Medication may enhance some HiRIT effects. Findings suggest reduced hip fracture risk in response to HiRIT.Trial registration number ACTRN12617001511325.

Diabetes and osteoporosis - Treating two entities: A challenge or cause for concern?

People with T1D and T2D have an increased risk of fractures than the general population, posing several significant pathophysiologic, diagnostic, and therapeutic challenges. The pathophysiology is still not fully elucidated, but it is considered a combination of increased skeletal fragility and falls. Diagnostics issues exist, as regular and even newer scan methods underestimate the true incidence of osteoporosis and thus the fracture risk. Therefore, co-managing diabetes and osteoporosis by using top-line strategies is essential to preserve bone health and minimize the risk of falls. The therapeutic focus should start with lifestyle implementation and physical exercise interventions to reduce diabetic complications, strengthen bones, and improve postural control strategies. In addition, osteoporosis should be treated according to current guidelines by including bisphosphonates and antidiabetic drugs that support bone health. Finally, potentially modifiable risk factors for falls should be managed.

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

INTRODUCTION

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.

MATERIALS AND METHODS

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.

RESULTS

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 ≥ 60 years. 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 ≥ 60 years. No significant correlations were seen between QUS and biochemical markers.

CONCLUSIONS

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.

Bone microarchitecture impairment in prolactinoma patients assessed by HR-pQCT

PURPOSE

Prolactinoma may reduce bone mineral density (BMD) and increase fracture risk, but its influence on bone microarchitecture remains to be elucidated. The purpose of this study is to evaluate bone microarchitecture parameters by high-resolution peripheral quantitative computed tomography (HR-pQCT) in prolactinoma patients.

METHODS

31 prolactinoma patients and 62 age- and sex-matched healthy controls in our center were included, and HR-pQCT was used to evaluate their bone microarchitecture at the radius and tibia. Z-scores for bone microarchitecture parameters were calculated based on previously published reference.

RESULTS

After adjusting for height and weight, prolactinoma patients had lower trabecular (- 0.011 mm, p = 0.005) and cortical thickness (- 0.116 mm, p = 0.008) and cortical area (- 6.0 mm2, p = 0.013) at radius, as well as lower trabecular (- 0.014 mm, p = 0.008) and cortical (- 0.122 mm, p = 0.022) thickness at tibia compared with the controls. Patients with higher prolactin level had more severe bone microarchitecture impairments. After adjusting for prolactin level and age, male patients had lower trabecular volumetric BMD (vBMD), trabecular number, trabecular thickness, and cortical porosity at radius, as well as lower trabecular vBMD, trabecular bone volume fraction, trabecular number, and cortical area, and higher trabecular separation at tibia compared with female patients. Z-score for radius vBMD was correlated with Z-score for areal BMD (aBMD) at lumbar and femoral neck, while Z-score for tibia vBMD was correlated with Z-score for lumbar aBMD, and some patients with vBMD Z-score below - 2.0 had aBMD Z-score within normal range.

CONCLUSION

Peripheral bone microarchitecture was impaired in prolactinoma patients, especially in patients with higher prolactin level. We compared the bone microarchitecture of prolactinoma patients and healthy controls by high-resolution peripheral quantitative computed tomography (HR-pQCT), and found that many bone microarchitecture parameters were impaired among prolactinoma patients. Such impairment was more prominent among patients with higher prolactin level.

Bone architecture, bone material properties, and bone turnover in non-osteoporotic post-menopausal women with fragility fracture

Macro- and microarchitectural, bone material property, dynamic histomorphometric, and bone turnover marker data were studied in normal bone mineral density (BMD) post-menopausal women with fragility fracture. Women with fracture had thinner iliac cortices and more homogeneous bone material properties in cortical bone than age/BMD-matched non-fracture women. Low cortical thickness and bone tissue heterogeneity in normal BMD women are associated with prevalent fragility fracture.

INTRODUCTION

Bone mass (bone mineral density, (BMD)) of the spine and hip is today's best single measurement for evaluating future fragility fracture risk. However, the majority of fragility fractures occur in women with BMD T-score above the WHO osteoporotic BMD threshold of - 2.5, indicating that non-BMD endpoints may play a role in their fragility fractures. We hypothesize that in non-osteoporotic women, bone micoarchitecture, bone material properties, dynamic histomorphometric endpoints, and bone turnover markers are related to fragility fracture.

METHODS

Two groups (N = 60 each) of post-menopausal women with total hip BMD T-score ranging from + 0.3 to -2.49 were recruited: fragility fracture and age/BMD-matched, non-fragility fracture women. Normal (T-score >  - 0.99) and osteopenic (T-score ≤  - 1.0) BMD cohorts were designated within both the fracture and non-fracture groups. Transiliac biopsy specimens were obtained to evaluate dynamic histomorphometric and microarchitectural endpoints and bone material properties by static and dynamic nanoindentation testing. All variables for fracture and non-fracture women within each BMD cohort were compared by the Wilcoxon signed-rank test (P < 0.01).

RESULTS

Compared to non-fracture/normal BMD women, fracture/normal BMD women display lower iliac cortical thickness (- 12%, P = 0.0041) and lower heterogeneity of hardness (- 27%, P = 0.0068), elastic modulus (- 35%, P = 0.0009), and storage modulus (- 23%, P = 0.0054) in the cortical bone tissue, and lower heterogeneity of hardness (- 13%, P = 0.0088) in the trabecular bone tissue. Osteopenic women had no abnormalities related to fracture status.

CONCLUSION

Post-menopausal women with normal BMD and fragility fracture have low cortical thickness and heterogeneity of several bone material properties in cortical and trabecular mineralized bone tissue. These differences may explain a portion of the excess bone fragility in women with normal BMD and fragility fracture.

The bone strain index predicts fragility fractures. The OFELY study

Recently, the bone strain index (BSI), a new index of bone strength based on a finite element model (FEA) from dual X-ray absorptiometry (DXA), has been developed. BSI represents the average equivalent strain inside the bone, assuming that a higher strain level (high BSI) indicates a condition of higher risk. Our study aimed to analyze the relationship between BSI and age, BMI and areal BMD in pre- and postmenopausal women and to prospectively investigate fracture prediction (Fx) by BSI in postmenopausal women. Methods. At the 14th annual follow-up of the OFELY study, BSI was measured at spine (Spine BSI) and femoral scans (Neck and Total Hip BSI), in addition to areal BMD with DXA (Hologic QDR 4500) in 846 women, mean (SD) age 60 yr (15). The FRAX® (fracture risk assessment tool) for major osteoporotic fractures (MOF) was calculated with FN areal BMD (aBMD) at baseline; incident fragility fractures were annually registered until January 2016. Results. In premenopausal women (n = 261), Neck and Total Hip BSI were slightly negatively correlated with age (Spearman r = -0.13 and -0.15 respectively, p = 0.03), whereas all BSIs were positively correlated with BMI (r = +0.20 to 0.37, p < 0.01) and negatively with BMD (r = -0.69 to -0.37, p < 0.0001). In postmenopausal women (n = 585), Neck and Total Hip BSI were positively correlated with age (Spearman r = +0.26 and +0.31 respectively, p < 0.0001), whereas Spine BSI was positively correlated with BMI (r = +0.22, p < 0.0001) and all BSIs were negatively correlated with BMD (r = -0.81 to -0.60, p < 0.0001). During a median [IQ] 9.3 [1.0] years of follow-up, 133 postmenopausal women reported an incident fragility Fx, including 80 women with a major osteoporotic Fx (MOF) and 26 women with clinical vertebral Fx (VFx). Each SD increase of BSI value was associated with a significant increase of the risk of all fragility Fx with an age-adjusted HR of 1.23 for Neck BSI (p = 0.02); 1.27 for Total Hip BSI (p = 0.004) and 1.35 for Spine BSI (p < 0.0001). After adjustment for FRAX®, the association remained statistically significant for Total Hip BSI (HR 1.24, p = 0.02 for all fragility Fx; 1.31, p = 0.01 for MOF) and Spine BSI (HR 1.33, p < 0.0001 for all fragility Fx; 1.33, p = 0.005 for MOF; 1.67, p = 0.002 for clinical VFx). In conclusion, spine and femur BSI, an FEA DXA derived index, predict incident fragility fracture in postmenopausal women, regardless of FRAX®.

Finite element analysis of trabecular bone microstructure using CT imaging and continuum mechanical modelling

Purpose

Osteoporosis is a bone disease associated with enhanced bone loss, microstructural degeneration, and fracture‐risk. Finite element (FE) modeling is used to estimate trabecular bone (Tb) modulus from high‐resolution three‐dimensional (3‐D) imaging modalities including micro‐computed tomography (CT), magnetic resonance imaging (MRI), and high‐resolution peripheral quantitative CT (HR‐pQCT). This paper validates an application of voxel‐based continuum finite element analysis (FEA) to predict Tb modulus from clinical CT imaging under a condition similar to in vivo imaging by comparing with measures derived by micro‐CT and experimental approaches.

Method

Voxel‐based continuum FEA methods for CT imaging were implemented using linear and nonlinear models and applied on distal tibial scans under a condition similar to in vivo imaging. First, tibial axis in a CT scan was aligned with the coordinate z‐axis at 150 μm isotropic voxels. FEA was applied on an upright cylindrical volume of interests (VOI) with its axis coinciding with the tibial bone axis. Voxel volume, edge, and vertex elements and their connectivity were defined as per the isotropic image grid. A calibration phantom was used to calibrate CT numbers in Hounsfield unit to bone mineral density (BMD) values, which was then converted into calcium hydroxyapatite (CHA) density. Mechanical properties at each voxel volume element was defined using its ash‐density defined on CT‐derived CHA density. For FEA, the bottom surface of the cylindrical VOI was fixed and a constant displacement was applied along the z‐direction at each vertex element on the top surface to simulate a physical axial compressive loading condition. Finally, a Poisson's ratio of 0.3 was applied, and Tb modulus (MPa) was computed as the ratio of average von Mises stress (MPa) of volume elements on the top surface and the applied displacement. FEA parameters including mesh element size, substep number, and different tolerance values were optimized.

Results

CT‐derived Tb modulus values using continuum FEA showed high linear correlation with the micro‐CT‐derived reference values (r ∈ [0.87 0.90]) as well as experimentally measured values (r ∈ [0.80 0.87]). Linear correlation of computed modulus with their reference values using continuum FEA with linear modeling was comparable with that obtained by nonlinear modeling. Nonlinear continuum FEA‐based modulus values (mean of 1087.2 MPa) showed greater difference from their reference values (mean of 1498.9 MPa using micro‐CT‐based FEA) as compared with linear continuum methods. High repeat CT scan reproducibility (intra‐class correlation [ICC] = 0.98) was observed for computed modulus values using both linear and nonlinear continuum FEA. It was observed that high stress regions coincide with Tb microstructure as fuzzily characterized by BMD values. Distributions of von Mises stress over Tb microstructure and marrow regions were significantly different (p < 10^–8).

Conclusion

Voxel‐based continuum FEA offers surrogate measures of Tb modulus from CT imaging under a condition similar to in vivo imaging that alleviates the need for segmentation of Tb and marrow regions, while accounting for bone distribution at the microstructural level. This relaxation of binary segmentation will extend the scope of FEA application to assess mechanical properties of bone microstructure at relatively low‐resolution imaging.

Bone Microarchitecture Phenotypes Identified in Older Adults Are Associated With Different Levels of Osteoporotic Fracture Risk

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 individuals 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).

Reference microarchitectural values measured by HR-pQCT in a Franco-Swiss cohort of young adult women

Bone microarchitecture assessed by high-resolution peripheral quantitative computed tomography varies across populations of different origin. The study presents a reference dataset of microarchitectural parameters in a homogeneous group of participants aged within 22-27 range determined by a discriminant analysis of a larger cross-sectional cohort of 339 women.

INTRODUCTION

High-resolution peripheral quantitative computed tomography (HR-pQCT) non-invasively measures three-dimensional bone microarchitectural parameters and volumetric bone mineral density. Previous studies established normative reference HR-pQCT datasets for several populations, but there were few data assessed in a reference group of young women with Caucasian ethnicity living in Western Europe. It is important to obtain different specific reference dataset for a valid interpretation of cortical and trabecular microarchitecture data. The aim of our study was to find the population with the most optimal bone status in order to establish a descriptive reference HR-pQCT dataset in a young and healthy normal-weight female cohort living in a European area including Geneva, Switzerland, Lyon and Saint-Etienne, France.

METHODS

We constituted a cross-sectional cohort of 339 women aged 19-41 years with a BMI > 18 and < 30 kg/m². All participants had HR-pQCT measurements at both non-dominant distal radius and tibia sites.

RESULTS

We observed that microarchitectural parameters begin to decline before the age of 30 years. Based on a discriminant analysis, the optimal bone profile in this population was observed between the age range of 22 to 27 years. Consequently, we considered 43 participants aged 22-27 years to establish a reference dataset with median values and percentiles.

CONCLUSION

This is the first study providing reference values of HR-pQCT measurements considering specific age bounds in a Franco-Swiss female cohort at the distal radius and tibia sites.

Gait speed and spasticity are independently associated with estimated failure load in the distal tibia after stroke: an HR-pQCT study

This HR-pQCT study was conducted to examine bone properties of the distal tibia post-stroke and to identify clinical outcomes that were associated with these properties at this site. It was found that spasticity and gait speed were independently associated with estimated failure load in individuals with chronic stroke.

PURPOSE

(1) To examine the influence of stroke on distal tibia bone properties and (2) the association between these properties and clinical outcomes in people with chronic stroke.

METHODS

Sixty-four people with stroke (age, 60.8 ± 7.7 years; time since stroke, 5.7 ± 3.9 years) and 64 controls (age: 59.4 ± 7.8 years) participated in this study. High-resolution peripheral quantitative computed tomography (HR-pQCT) was used to scan the bilateral distal tibia, and estimated failure load was calculated by automated finite element analysis. Echo intensity of the medial gastrocnemius muscle and blood flow of the popliteal artery were assessed with ultrasound. The 10-m walk test (10MWT), Fugl-Meyer Motor Assessment (FMA), and Composite Spasticity Scale (CSS) were also administered.

RESULTS

The percent side-to-side difference (%SSD) in estimated failure load, cortical area, thickness, and volumetric bone mineral density (vBMD), and trabecular and total vBMD were significantly greater in the stroke group than their control counterparts (Cohen's d = 0.48-1.51). Isometric peak torque and echo intensity also showed significant within- and between-groups differences (p ≤ 0.01). Among HR-pQCT variables, the %SSD in estimated failure load was empirically chosen as one example of the strong discriminators between the stroke group and control group, after accounting for other relevant factors. The 10MWT and CSS subscale for ankle clonus remained significantly associated with the %SSD in estimated failure load after adjusting for other relevant factors (p ≤ 0.05).

CONCLUSION

The paretic distal tibia showed more compromised vBMD, cortical area, cortical thickness, and estimated failure load than the non-paretic tibia. Gait speed and spasticity were independently associated with estimated failure load. As treatment programs focusing on these potentially modifiable stroke-related impairments are feasible to administer, future studies are needed to determine the efficacy of such intervention strategies for improving bone strength in individuals with chronic stroke.

Cortical bone structure of the proximal femur and incident fractures

PURPOSE

Fracture risk is most frequently assessed using Dual X-ray absorptiometry to measure areal bone mineral density (aBMD) and using the Fracture Risk Assessment Tool (FRAX). However, these approaches have limitations and additional bone measurements may enhance the predictive ability of these existing tools. Increased cortical porosity has been associated with incident fracture in some studies, but not in others. In this prospective study, we examined whether cortical bone structure of the proximal femur predicts incident fractures independent of aBMD and FRAX score.

METHODS

We pooled 211 postmenopausal women with fractures aged 54-94 years at baseline and 232 fracture-free age-matched controls based on a prior nested case-control study from the Tromsø Study in Norway. We assessed baseline femoral neck (FN) aBMD, calculated FRAX 10-year probability of major osteoporotic fracture (MOF), and quantified femoral subtrochanteric cortical parameters: porosity, area, thickness, and volumetric BMD (vBMD) from CT images using the StrAx1.0 software. Associations between bone parameters and any incident fracture, MOF and hip fracture were determined using Cox's proportional hazard models to calculate hazard ratio (HR) with 95% confidence interval.

RESULTS

During a median follow-up of 7.2 years, 114 (25.7%) of 443 women suffered one or more incident fracture. Cortical bone structure did not predict any incident fracture or MOF after adjustment for age, BMI, and previous fracture. Each SD higher total cortical porosity, thinner cortices, and lower cortical vBMD predicted hip fracture with increased risk of 46-62% (HRs ranging from 1.46 (1.01-2.11) to 1.62 (1.02-2.57)). After adjustment for FN aBMD or FRAX score no association remained significant. Both lower FN aBMD and higher FRAX score predicted any incident fracture, MOF and hip fractures with HRs ranging from 1.45-2.56.

CONCLUSIONS

This study showed that cortical bone measurements using clinical CT did not add substantial insight into fracture risk beyond FN aBMD and FRAX. We infer from these results that fracture risk related to the deteriorated bone structure seems to be largely captured by a measurement of FN aBMD and the FRAX tool.

Influence of loading conditions in finite element analysis assessed by HR-pQCT on ex vivo fracture prediction

Many fractures occur in individuals with normal areal Bone Mineral Density (aBMD) measured by Dual X-ray Absorptiometry (DXA). High Resolution peripheral Quantitative Computed Tomography (HR-pQCT) allows for non-invasive evaluation of bone stiffness and strength through micro finite element (μFE) analysis at the tibia and radius. These μFE outcomes are strongly associated with fragility fractures but do not provide clear enhancement compared with DXA measurements. The objective of this study was to establish whether a change in loading conditions in standard μFE analysis assessed by HR-pQCT enhance the discrimination of low-trauma fractured radii (n = 11) from non-fractured radii (n = 16) obtained experimentally throughout a mechanical test reproducing a forward fall. Micro finite element models were created using HR-pQCT images, and linear analyses were performed using four different types of loading conditions (axial, non-axial with two orientations and torsion). No significant differences were found between the failure load assessed with the axial and non-axial models. The different loading conditions tested presented the same area under the receiver operating characteristic (ROC) curves of 0.79 when classifying radius fractures with an accuracy of 81.5%. In comparison, the area under the curve (AUC) is 0.77 from DXA-derived ultra-distal aBMD of the forearm with an accuracy of 85.2%. These results suggest that the restricted HR-pQCT scanned region seems not sensitive to loading conditions for the prediction of radius fracture risk based on ex vivo experiments (n = 27).

The role of advanced glycation end products in fracture risk assessment in postmenopausal type 2 diabetic patients

OBJECTIVE

The objective of this study was to analyze the quantitative association between advanced glycation end products (AGEs) and adjusted FRAX by rheumatoid arthritis (FRAX-RA) in postmenopausal type 2 diabetic (T2D) patients. The optimal cutoff value of AGEs was also explored, which was aimed at demonstrating the potential value of AGEs on evaluating osteoporotic fracture risk in postmenopausal T2D patients.

METHODS

We conducted a cross-sectional study including 366 postmenopausal participants (180 T2D patients [DM group] and 186 non-T2D individuals [NDM group]). All the subjects in each group were divided into three subgroups according to BMD. Physical examination, dual-energy x-ray absorptiometry (DXA), and serum indicators (including serum AGEs, glycemic parameters, bone turnover markers and inflammation factors) were examined. The relationship between FRAX-RA, serum laboratory variables, and AGEs were explored. The optimal cutoff value of AGEs to predict the risk of osteoporotic fracture was also investigated.

RESULTS

Adjusting the FRAX values with rheumatoid arthritis (RA) of T2D patients reached a significantly increased MOF-RA and an increasing trend of HF-RA. AGEs level was higher in the DM group compared to the NDMs, and was positively correlated with MOF-RA (r=0.682, P<0.001) and HF-RA (r=0.677, P<0.001). The receiver operating characteristic curve analysis revealed that the area under the curve was 0.804 (P<0.001), and the optimal AGEs cut-off value was 4.156mmol/L. Subgroup analysis for T2D patients revealed an increase in TGF-β, IL-6 and SCTX in the osteoporosis group, while a decreased PINP in the osteoporosis group compared to the other two subgroups. AGEs were positively associated with FBG, HbA1c, HOMA-IR, S-CTX, IL-6 and TGF-β in T2D patients, and negatively associated with PINP.

CONCLUSIONS

RA-adjusted FRAX is a relevant clinical tool in evaluating fracture risk of postmenopausal T2D patients. Our study analyzed the relationship between AGEs and FRAX-RA, and explored the threshold value of AGEs for predicting fracture risk in postmenopausal T2D patients. AGEs were also associated with serum bone turnover markers and inflammation factors, indicating that the increasing level of AGEs in postmenopausal T2D patients accelerated the expression of inflammatory factors, which led to bone metabolism disorders and a higher risk of osteoporotic fractures.

Best Performance Parameters of HR-pQCT to Predict Fragility Fracture: Systematic Review and Meta-Analysis

Osteoporosis is a systemic skeletal disease characterized by low bone mass and bone structural deterioration that may result in fragility fractures. Use of bone imaging modalities to accurately predict fragility fractures is always an important issue, yet the current gold standard of dual-energy X-ray absorptiometry (DXA) for diagnosis of osteoporosis cannot fully satisfy this purpose. The latest high-resolution peripheral quantitative computed tomography (HR-pQCT) is a three-dimensional (3D) imaging device to measure not only volumetric bone density, but also the bone microarchitecture in a noninvasive manner that may provide a better fracture prediction power. This systematic review and meta-analysis was designed to investigate which HR-pQCT parameters at the distal radius and/or distal tibia could best predict fragility fractures. A systematic literature search was conducted in Embase, PubMed, and Web of Science with relevant keywords by two independent reviewers. Original clinical studies using HR-pQCT to predict fragility fractures with available full text in English were included. Information was extracted from the included studies for further review. In total, 25 articles were included for the systematic review, and 16 articles for meta-analysis. HR-pQCT was shown to significantly predict incident fractures and/or major osteoporotic fractures (MOFs). Of all the HR-pQCT parameters, our meta-analysis revealed that cortical volumetric bone mineral density (Ct.vBMD), trabecular thickness (Tb.Th), and stiffness were better predictors. Meanwhile, HR-pQCT parameters indicated better performance in predicting MOFs than incident fractures. Between the two standard measurement sites of HR-pQCT, the non-weight-bearing distal radius was a more preferable site than distal tibia for fracture prediction. Furthermore, most of the included studies were white-based, whereas very few studies were from Asia or South America. These regions should build up their densitometric databases and conduct related prediction studies. It is expected that HR-pQCT can be used widely for the diagnosis of osteoporosis and prediction of future fragility fractures. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

The clinical application of high-resolution peripheral computed tomography (HR-pQCT) in adults: state of the art and future directions

High-resolution peripheral computed tomography (HR-pQCT) was developed to image bone microarchitecture in vivo at peripheral skeletal sites. Since the introduction of HR-pQCT in 2005, clinical research to gain insight into pathophysiology of skeletal fragility and to improve prediction of fractures has grown. Meanwhile, the second-generation HR-pQCT device has been introduced, allowing novel applications such as hand joint imaging, assessment of subchondral bone and cartilage thickness in the knee, and distal radius fracture healing. This article provides an overview of the current clinical applications and guidance on interpretation of results, as well as future directions. Specifically, we provide an overview of (1) the differences and reference data for HR-pQCT variables by age, sex, and race/ethnicity; (2) fracture risk prediction using HR-pQCT; (3) the ability to monitor response of anti-osteoporosis therapy with HR-pQCT; (4) the use of HR-pQCT in patients with metabolic bone disorders and diseases leading to secondary osteoporosis; and (5) novel applications of HR-pQCT imaging. Finally, we summarize the status of the application of HR-pQCT in clinical practice and discuss future directions. From the clinical perspective, there are both challenges and opportunities for more widespread use of HR-pQCT. Assessment of bone microarchitecture by HR-pQCT improves fracture prediction in mostly normal or osteopenic elderly subjects beyond DXA of the hip, but the added value is marginal. The prospects of HR-pQCT in clinical practice need further study with respect to medication effects, metabolic bone disorders, rare bone diseases, and other applications such as hand joint imaging and fracture healing. The mostly unexplored potential may be the differentiation of patients with only moderately low BMD but severe microstructural deterioration, which would have important implications for the decision on therapeutical interventions.

Comparative effect of eldecalcitol and alfacalcidol on bone microstructure: A preliminary report of secondary analysis of a prospective trial

Objectives

To compare the effect of eldecalcitol and alfacalcidol on skeletal microstructure by high-resolution peripheral QCT (HR-pQCT).

Methods

This was a substudy of a randomized, double-blind, active comparator trial. Five female osteoporotic patients with 1-year 0.75 μg/day eldecalcitol and 5 with 1-year 1.0 μg/day alfacalcidol completed HR-pQCT scans before and after treatment were enrolled.

Results

Total vBMD [1.67 ± 1.06% (mean ± SD), P = 0.043 versus baseline] and trabecular vBMD (2.91 ± 1.72%, P = 0.043) at the radius increased in eldecalcitol group, while total, trabecular, and cortical vBMD tended to decrease in alfacalcidol group, with a significant reduction in cortical vBMD at the tibia (0.88 ± 0.62%, P = 0.043). Cortical area (1.82 ± 1.92%, P = 0.043) at the radius and thickness (0.87 ± 1.12%, P = 0.043) at the tibia increased in eldecalcitol group, while these parameters decreased with alfacalcidol at the tibia (1.77 ± 1.72%, P = 0.043 for cortical area; 1.40 ± 2.14%, P = 0.042 for cortical thickness). Trabecular thickness at the radius (1.97 ± 1.93%, P = 0.042) and number at the tibia (3.09 ± 3.04%, P = 0.043) increased by eldecalcitol but did not increase by alfacalcidol. Trabecular separation decreased by eldecalcitol (2.22 ± 2.43%, P = 0.043) but tended to increase by alfacalcidol at the tibia.

Conclusions

Eldecalcitol has the greater potential to improve cortical and trabecular microstructure at the peripheral bone than alfacalcidol which needs further more studies.

Level and change in bone microarchitectural parameters and their relationship with previous fracture and established bone mineral density loci

BACKGROUND

Osteoporosis is characterised by a reduction of bone mineral density (BMD) and predisposition to fracture. Bone microarchitecture, measured by high resolution peripheral quantitative computed tomography (HR-pQCT), has been related to fragility fractures and BMD and has been the subject of large-scale genome-wide analysis. We investigated whether fracture was related to baseline values and longitudinal changes in bone microarchitecture and whether bone microarchitecture was associated with established BMD loci.

METHODS

115 males and 99 females (aged 72-81 at baseline) from the Hertfordshire Cohort Study (HCS) were analysed. Fracture history was determined in 2011-2012 by self-report and vertebral fracture assessment. Participants underwent HR-pQCT scans of the distal radius and tibia in 2011-2012 and 2017. Previous fracture in relation to baseline values and changes in tibial HR-pQCT parameters was examined using sex-adjusted logistic regression with and without adjustment for age, sociodemographic, lifestyle and clinical characteristics; baseline values and changes in parameters associated with previous fracture were then examined in relation to four established BMD loci after adjustment for sex and age.

RESULTS

Previous fracture was related to: higher trabecular area (fully-adjusted odds ratio [95% CI] per SD greater baseline value: 2.18 [1.27,3.73], p = 0.005); lower total volumetric BMD (0.53 [0.34,0.84], p = 0.007), cortical area (0.53 [0.30,0.95], p = 0.032), cortical BMD (0.56 [0.36,0.88], p = 0.011) and cortical thickness (0.45 [0.27,0.77], p = 0.004); and greater declines in trabecular BMD (p = 0.001). Associations were robust in sex- and fully-adjusted analysis. Relationships between BMD loci and these HR-pQCT parameters were weak: rs3801387 (WNT16) was related to decline in trabecular BMD (p = 0.011) but no other associations were significant (p > 0.05).

CONCLUSION

Baseline values of HR-pQCT parameters and greater decline in trabecular BMD were associated with fracture. Change in trabecular BMD was associated with WNT16 which has been demonstrated to influence bone health in murine models and human genome-wide association studies (GWAS).

Assessment of Skeletal Strength: Bone Density Testing and Beyond

A bone fractures when a force applied to it exceeds its strength. Assessment of bone strength is an important component in determining the risk of fracture and guiding treatment decisions. Dual-energy X-ray absorptiometry is used to diagnosis osteoporosis, estimate fracture risk, and monitor changes in bone density. Fracture risk algorithms provide enhanced fracture risk predictability. Advanced technologies with computed tomography (CT) and MRI can measure parameters of bone microarchitecture. Mathematical modeling using CT data can evaluate the behavior of bone structures in response to external loading. Microindentation techniques directly measure the strength of outer bone cortex.

A prospective case-control pilot study to evaluate bone microarchitecture in children and teenagers on long-term parenteral nutrition using HR-pQCT

Long-term parenteral nutrition (PN) may induce bone complications. Tridimensional bone imaging techniques such as high-resolution peripheral quantitative computed tomography (HR-pQCT) allow the assessment of both compartmental volumetric densities and microarchitecture. Our aim was to evaluate these parameters in children and teenagers receiving long-term PN. This cross-sectional, case–control study included children older than 9 years undergoing PN for at least 2 years. They were age-, gender- and puberty-matched with healthy controls (1:2). Evaluation included biological assessment of bone metabolism (serum calcium, phosphate, and albumin; urinary calcium and creatinine; 25-OH vitamin D, osteocalcin and PTH), dual X-ray absorptiometry (DXA) and HR-pQCT at the ultradistal tibia and radius. Results are presented as median [range]. Eleven patients (3 girls) with a median age of 16 [9–19] years were included. Bone parameters assessed by HR-pQCT at the ultradistal radius and tibia were similar in patients and controls. Parathyroid hormone (PTH) levels were higher (14 [7–115] vs 16 [12–27]) and osteocalcin levels were lower (44 [15–65] vs 65 [38–142]) in patients than in controls, although within the normal range. Conclusions: there were no differences for compartmental bone densities and microarchitecture in patients undergoing chronic PN. Further longitudinal studies are required to confirm these quite reassuring preliminary results.

High Cortico-Trabecular Transitional Zone Porosity and Reduced Trabecular Density in Men and Women with Stress Fractures

To determine whether stress fractures are associated with bone microstructural deterioration we quantified distal radial and the unfractured distal tibia using high resolution peripheral quantitative computed tomography in 26 cases with lower limb stress fractures (15 males, 11 females; mean age 37.1 ± 3.1 years) and 62 age-matched healthy controls (24 males, 38 females; mean age 35.0 ± 1.6 years). Relative to controls, in men, at the distal radius, cases had smaller cortical cross sectional area (CSA) (p = 0.012), higher porosity of the outer transitional zone (OTZ) (p = 0.006), inner transitional zone (ITZ) (p = 0.043) and the compact-appearing cortex (CC) (p = 0.023) while trabecular vBMD was lower (p = 0.002). At the distal tibia, cases also had a smaller cortical CSA (p = 0.008). Cortical porosity was not higher, but trabecular vBMD was lower (p = 0.001). Relative to controls, in women, cases had higher distal radial porosity of the OTZ (p = 0.028), ITZ (p = 0.030) not CC (p = 0.054). Trabecular vBMD was lower (p = 0.041). Distal tibial porosity was higher in the OTZ (p = 0.035), ITZ (p = 0.009), not CC. Stress fractures are associated with compromised cortical and trabecular microstructure.

Bone health assessment via digital wrist tomosynthesis in the mammography setting

Bone fractures attributable to osteoporosis are a significant problem. Though preventative treatment options are available for individuals who are at risk of a fracture, a substantial number of these individuals are not identified due to lack of adherence to bone screening recommendations. The issue is further complicated as standard diagnosis of osteoporosis is based on bone mineral density (BMD) derived from dual energy x-ray absorptiometry (DXA), which, while helpful in identifying many at risk, is limited in fully predicting risk of fracture. It is reasonable to expect that bone screening would become more prevalent and efficacious if offered in coordination with digital breast tomosynthesis (DBT) exams, provided that osteoporosis can be assessed using a DBT modality. Therefore, the objective of the current study was to explore the feasibility of using digital tomosynthesis imaging in a mammography setting. To this end, we measured density, cortical thickness and microstructural properties of the wrist bone, correlated these to reference measurements from microcomputed tomography and DXA, demonstrated the application in vivo in a small group of participants, and determined the repeatability of the measurements. We found that measurements from digital wrist tomosynthesis (DWT) imaging with a DBT scanner were highly repeatable ex vivo (error = 0.05%-9.62%) and in vivo (error = 0.06%-10.2%). In ex vivo trials, DWT derived BMDs were strongly correlated with reference measurements (R = 0.841-0.980), as were cortical thickness measured at lateral and medial cortices (R = 0.991 and R = 0.959, respectively) and the majority of microstructural measures (R = 0.736-0.991). The measurements were quick and tolerated by human patients with no discomfort, and appeared to be different between young and old participants in a preliminary comparison. In conclusion, DWT is feasible in a mammography setting, and informative on bone mass, cortical thickness, and microstructural qualities that are known to deteriorate in osteoporosis. To our knowledge, this study represents the first application of DBT for imaging bone. Future clinical studies are needed to further establish the efficacy for diagnosing osteoporosis and predicting risk of fragility fracture using DWT.

Determinants of estimated failure load in the distal radius after stroke: An HR-pQCT study

Bone health is often compromised after stroke and the distal radius is a common site of fragility fractures. The macro- and mircoproperties of bone tissue after stroke and their clinical correlates are understudied. The objectives of the study were to use High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT) to investigate the bone properties at the distal radius, and to identify the correlates of estimated failure load for the distal radius in people with chronic stroke. This was a cross-sectional study of 64 people with stroke (age: 60.8 ± 7.7 years, stroke duration: 5.7 ± 3.9 years) and 64 age- and sex-matched controls. Bilateral bone structural, densitometric, geometric and strength parameters of the distal radius were measured using HR-pQCT. The architecture, stiffness and echo intensity of the bilateral biceps brachii muscle and brachial artery blood flow were evaluated using diagnostic ultrasound. Other outcomes included the Fugl-Meyer Motor Assessment (FMA), Motor Activity Log (MAL), and Composite Spasticity Scale (CSS). The results revealed a significant side (paretic vs non-paretic for the stroke group, non-dominant vs dominant for controls) by group (stroke vs control) interaction effect for estimated failure load, cortical area, cortical thickness, trabecular number and trabecular separation, and all volumetric density parameters. Post-hoc analysis showed percent side-to-side differences in bone outcomes were greater in the stroke group than the control group, with the exception of trabecular thickness and intracortical porosity. Among the HR-pQCT variables, percent side-to-side difference in trabecular volumetric bone mineral density contributed the most to the percent side-to-side difference in estimated failure load in the stroke group (R² change = 0.334, β = 1.106). Stroke-related impairments (FMA, MAL, CSS) were found to be significant determinants of the percent side-to-side difference in estimated failure load (R² change = 0.233, β = -0.480). This was the first study to examine bone microstructure post-stroke. We found that the paretic distal radius had compromised bone structural properties and lower estimated failure load compared to the non-paretic side. Motor impairment was a determinant of estimated bone strength at the distal radius and may be a potential intervention target for improving bone health post-stroke.

Bone mineral density assessment by DXA in rheumatic patients with end-stage osteoarthritis undergoing total joint arthroplasty

BACKGROUND

Patients with rheumatic diseases have a high risk for joint destruction and secondary osteoarthritis (OA) as well as low bone mineral density (BMD, i.e., osteoporosis). While several factors may lead to low BMD in these patients, the value of BMD measurements in rheumatic patients with end-stage OA scheduled for total joint arthroplasty is unknown.

METHODS

In this retrospective cross-sectional study of 50 adults with secondary OA due to rheumatic diseases, we evaluated dual energy X-ray absorptiometry (DXA) measurements of both hips and the spine performed within 3 months prior to arthroplasty (n = 25 total hip arthroplasty, THA; n = 25 total knee arthroplasty, TKA). We analyzed various demographic and disease-specific characteristics and their effect on DXA results by using group comparisons and multivariate linear regression models.

RESULTS

Although patients undergoing TKA were younger (63.2 ± 14.2 vs. 71.0 ± 10.8 yr., p = 0.035), osteoporosis was observed more frequently in patients scheduled for TKA than THA (32% vs. 12%). Osteopenia was detected in 13/25 patients (52%) in both the THA and TKA cohort. In the THA cohort, female sex, lower BMI and prednisolone use were associated with lower T-score in the hip. In TKA patients, higher OA grade determined by Kellgren-Lawrence score was associated with lower T-score in the hip of the affected side.

CONCLUSIONS

Osteoporosis is present in a considerable frequency of rheumatic patients with end-stage OA, and THA and TKA patients show distinct frequencies and risk factors of low BMD. Our findings point to a potential value of DXA regarding preoperative evaluation of bone status.

Consequences of Hyperthyroidism and Its Treatment for Bone Microarchitecture Assessed by High-Resolution Peripheral Quantitative Computed Tomography

Background: Hyperthyroidism is associated with bone mass reduction and increased fracture risk, but the effects on other important bone parameters have been sparsely examined. Therefore, we investigated bone microarchitecture and estimated bone strength by high-resolution peripheral quantitative computed tomography (HR-pQCT) in hyperthyroid patients at diagnosis and after being euthyroid for at least one year. Methods: Two approaches were used: (A) a case-control study comparing 61 hyperthyroid women with 61 euthyroid women matched for age and menopause status; (B) a follow-up study, in which 46 of the 61 women were re-examined after having been euthyroid for one year. HR-pQCT of the distal radius and tibia, and dual-energy X-ray absorptiometry (DXA) of the lumbar spine and the hip were performed. Results: In analysis A: In the radius, compared with the healthy controls, hyperthyroid patients had higher total area (16.9% ± 29.5%; p < 0.001), trabecular area (28.6% ± 45.7%; p < 0.001), and lower cortical area (-11.7% ± 23.2%; p < 0.001). Total volumetric bone mineral density (vBMD) (-13.9% ± 26.5%; p < 0.001), cortical vBMD (-5.8% ± 7.9%; p < 0.001), cortical thickness (-16.7% ± 26.0%; p < 0.001), and estimated bone strength (-6.6% ± 19.5%; p < 0.01) were lower. No significant differences were found in the tibia or in the DXA parameters. In analysis B: In the radius, significant improvements were observed in the cortical area (2.1% ± 4.6%; p < 0.01), cortical thickness (2.5% ± 5.1%; p < 0.001), and total vBMD (0.8% ± 3.0%; p < 0.05). Trabecular area decreased (-0.5% ± 1.0%; p < 0.01) and trabecular separation increased (2.0% ± 8.3%; p < 0.05). In the tibia, cortical area (3.6% ± 7.3%; p < 0.01) and cortical thickness (3.8% ± 7.6%; p < 0.01) increased, and trabecular area decreased (-0.5% ± 1.1%; p < 0.01). Areal BMD, measured by DXA, increased in the spine (1.1% ± 3.4%; p < 0.05) and in the hip (2.0% ± 3.8%; p < 0.01). Conclusions: Compared with the healthy control group, hyperthyroid women had lower vBMD, lower estimated bone strength, and compromised cortical microarchitecture in the radius. After restoration of euthyroidism, significant improvements in vBMD and cortical microarchitecture were observed, highlighting the importance of achieving and maintaining euthyroidism.