The discriminatory capacity of BMD measurements by DXA and dual X-ray and laser (DXL) at the calcaneus including clinical risk factors for detecting patients with vertebral fractures

The influence of diet and physical activity on bone density of children aged 5-7 years: The Belfast HAPO family study

OBJECTIVE

Osteoporosis is a global health issue, and modifiable behavioural factors need to be identified in childhood to reduce the risk of osteoporosis in later life. The aim of this study was to investigate the influence of diet and physical activity on bone density of children aged 5-7 years participating in the Belfast Hyperglycaemia and Adverse Pregnancy Outcome (HAPO) Family study.

DESIGN AND METHODS

Pregnant women were recruited to the Belfast centre of the HAPO study at 24-32 weeks gestation. Offspring were followed up at 5-7 years as part of the Belfast HAPO Family Study. Heel bone mineral density (BMD) and bone mineral apparent density (BMAD) were measured and calculated, respectively. Physical activity in the offspring was measured by accelerometery and dietary intakes were measured using a 4-day food diary.

RESULTS

Results from 793 offspring were analysed. Mean age of the offspring ± standard deviation was 6.4 ± 0.5 years. A mean of 48.3 ± 22.4 min each day was spent in moderate to vigorous physical activity (MVPA). Median (interquartile range) dietary calcium and vitamin D intakes were 844 (662-1073) mg/day and 1.7 (1.1-2.5) μg/day, respectively. Neither dietary vitamin D nor calcium intakes were significantly associated with offspring heel BMD or BMAD in multiple regression. However, controlling for confounders, a 30-min greater MVPA was associated with significantly larger heel BMD (0.018 g/cm² in boys and 0.010 g/cm² in girls) and BMAD (0.005 g/cm³ in boys and 0.003 g/cm³ in girls).

CONCLUSION

Physical activity was associated with better BMD and BMAD in 5-7-year-old children. Dietary calcium and vitamin D were not predictive of BMD and BMAD.

Osteoporosis treatment in Austria-assessment of FRAX-based intervention thresholds for high and very high fracture risk

The adoption of the management pathway proposed by the National Osteoporosis Guideline Group (NOGG), UK applied using the Austrian FRAX® tool in a referral population of Austrian women categorises 22-29% of women age 40 years or more eligible for treatment of whom 28-34% are classified at very high risk.

PURPOSE

The aim of this study is to provide a reference document for the further development of existing guidelines for the management of osteoporosis in Austria, considering FRAX-based intervention thresholds for high and very high fracture risk.

METHODS

The model development was based on two Austrian hospital referral cohorts. Baseline information was collected to compute the 10-year probability (using the Austrian FRAX model) of a major osteoporotic fracture (MOF) and hip fracture both with and without the inclusion of femoral neck bone mineral density (BMD). Assessment thresholds for BMD testing were defined, as well as intervention thresholds. In addition, thresholds that characterise men and women at high and very high fracture risk were established. The management pathway followed that currently recommended by the UK National Osteoporosis Guideline Group (NOGG).

RESULTS

The two cohorts comprised a total of 1306 women and men with a mean age of 66.7 years. Slightly more than 50% were eligible for treatment by virtue of a prior fragility fracture. In those women without a prior fracture, 22% (n = 120) were eligible for treatment based on MOF probabilities. Of these, 28% (n = 33) were found to be at very high risk. When both MOF and hip fracture probabilities were used to characterise risk, 164 women without a prior fracture were eligible for treatment (29%). Of these, 34% (n = 56) were found to be at very high risk. Fewer men without prior fracture were eligible for treatment compared with women.

CONCLUSION

The management pathway as currently outlined is expected to reduce inequalities in patient management. The characterisation of very high risk may aid in the identification of patients suitable for treatment with osteoanabolic agents.

MRI-based vertebral bone quality score effectively reflects bone quality in patients with osteoporotic vertebral compressive fractures

OBJECTIVE

The present study is aimed to validate the ability of the vertebral bone quality (VBQ) score to evaluate bone quality in patients with osteoporotic vertebral compression fractures (OVCF) and to compare it with the ability of T-score by DXA. In addition, the sensitivity of VBQ score with cerebrospinal fluid (CSF) of L2 and L3 segments as baseline is evaluated.

METHODS

196 inpatients were collected and assigned into OVCF and Non-OVCF groups, respectively. For each patient, the VBQ score was calculated by the signal intensity of the L1-L4 vertebral bodies and CSF at L3 or L2 level from T1-weighted MRIs, while T-score from DXA was also obtained. The VBQ and T-score was compared between OVCF and non-OVCF groups, and among age groups. The OVCF ORs by VBQ score and T-score were calculated using logistic regression.

RESULTS

OVCF group was significantly different to the non-OVCF group in the T-score (- 2.9 vs. - 0.7) and VBQ score (4.0 vs. 3.5). VBQ score and T-score in patient aged 60-79 years old could indicate the bone quality, but only T-score in patients aged 50-59 years old. OVCF are associated with both higher VBQ score and lower T-score. The VBQ scores calculated by L2 CSF and L3 CSF were similar.

CONCLUSIONS

The VBQ score is an effective indicator of bone quality in OVCF patients and comparable to T-score, particularly in people over 60 years old. The VBQ score is not sensitive to CSF of different segments as a baseline.

Bone Stress Injuries Are Associated With Differences in Bone Microarchitecture in Male Professional Soldiers

Bone stress injuries are commonly due to repetitive loading, as often described in competitive athletes or military recruits. The underlying pathophysiology of bone stress injuries is multifactorial. The present cross-sectional study investigated (i) cortical and trabecular bone microstructure as well as volumetric bone mineral density in subjects with bone stress injuries at the tibial diaphysis, measured at the distal tibia and the distal radius by means of high-resolution peripheral quantitative computed tomography (CT), (ii) areal bone mineral density using dual-energy X-ray absorptiometry as well as calcaneal dual X-ray absorptiometry and laser, and (iii) the influence on bone turnover markers of formation and resorption at the early phase after injury. A total of 26 Caucasian male professional soldiers with post-training bone stress injury at the tibial diaphysis were included (case group). A total of 50 male, Caucasian professional soldiers from the same military institution served as controls (control group). High-resolution peripheral quantitative CT revealed a higher total area at the radius within the case group. Cortical bone mineral density was reduced at the radius and tibia within the case group. The trabecular number and trabecular thickness were reduced at the tibia in the case group. The trabecular network was more inhomogeneous at the radius and tibia within the case group. Calcaneal dual X-ray absorptiometry and laser was significantly reduced in the case group. This study quantified differences in bone microstructure among otherwise healthy individuals. Differences in bone microarchitecture may impair the biomechanical properties by increasing the susceptibility to sustain bone stress injuries. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2516-2523, 2019.

Less strict intervention thresholds for the FRAX and TBS-adjusted FRAX predict clinical fractures in osteopenic postmenopausal women with no prior fractures

Little is known about the clinical relevance of treating post-menopausal women with no prior history of fragility fracture and bone mineral densities (BMD) within the osteopenic range. In recent years, in addition to BMD and FRAX fracture probability assessments, a surrogate measure of bone micro-architecture quality, called the trabecular bone score (TBS), has been proven to predict future fragility fractures independently of both BMD and the FRAX. In this retrospective analysis of a follow-up study, we compared three risk assessment instruments-the FRAX, the TBS, and a TBS-adjusted FRAX score-in their ability, to predict future fragility fractures over a minimum of five years of follow-up among post-menopausal osteopenic women with no prior fragility fractures. We also sought to determine if more- versus less-stringent criteria were better when stratifying patients into higher-risk patients warranting osteoporosis-targeted intervention versus lower-risk patients in whom intervention would usually be deemed unnecessary. Over a mean 5.2 years follow-up, 18 clinical fragility fractures were documented among 127 women in the age 50 years and older (mean age = 66.1). On multivariate analysis utilizing regression models and Kaplan-Meier curve analysis, less-stringent criteria for the FRAX and TBS-adjusted FRAX were capable of predicting future fractures (with sensitivity/specificity of 83/31; 39/77 and 78/50% for TBS, FRAX and TBS-adjusted FRAX, respectively), while more-stringent criteria were incapable of doing so (with sensitivity/specificity of 56/60; 39/77 and 39/74 for TBS, FRAX and TBS-adjusted FRAX, respectively). Neither TBS threshold alone was a significant predictor of future fracture in our study. However, hazard ratio analysis revealed slight superiority of the TBS-adjusted FRAX over the FRAX alone (HR = 3.09 vs. 2.79). Adjusting the FRAX tool by incorporating the TBS may be useful to optimize the detection of post-menopausal osteopenic women with no prior fractures who warrant osteoporosis-targeted therapy.

Epidemiology of Vertebral Fractures

Vertebral fractures are one of the most common fractures associated with skeletal fragility and can cause as much morbidity as hip fractures. However, the epidemiology of vertebral fractures differs from that of osteoporotic fractures at other skeletal sites in important ways, largely because only one quarter to one-third of vertebral fractures are recognized clinically at the time of their occurrence and otherwise require lateral spine imaging to be recognized. This article first reviews the prevalence and incidence of clinical and radiographic vertebral fractures in populations across the globe and secular trends in the incidence of vertebral fracture over time. Next, associations of vertebral fractures with measures of bone mineral density and bone microarchitecture are reviewed followed by associations of vertebral fracture with various textural measures of trabecular bone, including trabecular bone score. Finally, the article reviews clinical risk factors for vertebral fracture and the association of vertebral fractures with morbidity, mortality, and other subsequent adverse health outcomes.

Bone structure assessed by HR-pQCT, TBS and DXL in adult patients with different types of osteogenesis imperfecta

Bone microarchitecture by high-resolution peripheral quantitative computed tomography (HR-pQCT) was assessed in adult patients with mild, moderate, and severe osteogenesis imperfecta (OI). The trabecular bone score (TBS), bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), and dual X-ray and laser (DXL) at the calcaneus were likewise assessed in patients with OI. Trabecular microstructure and BMD in particular were severely altered in patients with OI.

INTRODUCTION

OI is characterized by high fracture risk but not necessarily by low BMD. The main purpose of this study was to assess bone microarchitecture and BMD at different skeletal sites in different types of OI.

METHODS

HR-pQCT was performed in 30 patients with OI (mild OI-I, n = 18 (41.8 [34.7, 55.7] years) and moderate to severe OI-III-IV, n = 12 (47.6 [35.3, 58.4] years)) and 30 healthy age-matched controls. TBS, BMD by DXA at the lumbar spine and hip, as well as BMD by DXL at the calcaneus were likewise assessed in patients with OI only.

RESULTS

At the radius, significantly lower trabecular parameters including BV/TV (p = 0.01 and p < 0.0001, respectively) and trabecular number (p < 0.0001 and p < 0.0001, respectively) as well as an increased inhomogeneity of the trabecular network (p < 0.0001 and p < 0.0001, respectively) were observed in OI-I and OI-III-IV in comparison to the control group. Similar results for trabecular parameters were found at the tibia. Microstructural parameters were worse in OI-III-IV than in OI-I. No significant differences were found in cortical thickness and cortical porosity between the three subgroups at the radius. The cortical thickness of the tibia was thinner in OI-I (p < 0.001), but not OI-III-IV, when compared to controls.

CONCLUSIONS

Trabecular BMD and trabecular bone microstructure in particular are severely altered in patients with clinical OI-I and OI-III-IV. Low TBS and DXL and their significant associations to HR-pQCT parameters of trabecular bone support this conclusion.

TBS reflects trabecular microarchitecture in premenopausal women and men with idiopathic osteoporosis and low-traumatic fractures

Transiliac bone biopsies, while widely considered to be the standard for the analysis of bone microstructure, are typically restricted to specialized centers. The benefit of Trabecular Bone Score (TBS) in addition to areal bone mineral density (aBMD) for fracture risk assessment has been documented in cross-sectional and prospective studies. The aim of this study was to test if TBS may be useful as a surrogate to histomorphometric trabecular parameters of transiliac bone biopsies. Transiliac bone biopsies from 80 female patients (median age 39.9 years-interquartile range, IQR 34.7; 44.3) and 43 male patients (median age 42.7 years-IQR 38.9; 49.0) with idiopathic osteoporosis and low traumatic fractures were included. Micro-computed tomography values of bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), structural model index (SMI) as well as serum bone turnover markers (BTMs) sclerostin, intact N-terminal type 1 procollagen propeptide (P1NP) and cross-linked C-telopeptide (CTX) were investigated. TBS values were higher in females (1.282 vs 1.169, p< 0.0001) with no differences in spine aBMD, whereas sclerostin levels (45.5 vs 33.4 pmol/L) and aBMD values at the total hip (0.989 vs 0.971 g/cm(2), p<0.001 for all) were higher in males. Multiple regression models including: gender, aBMD and BTMs revealed TBS as an independent, discriminative variable with adjusted multiple R(2) values of 69.1% for SMI, 79.5% for Tb.N, 68.4% for Tb.Sp, and 83.3% for BV/TV. In univariate regression models, BTMs showed statistically significant results, whereas in the multiple models only P1NP and CTX were significant for Tb.N. TBS is a practical, non-invasive, surrogate technique for the assessment of cancellous bone microarchitecture and should be implemented as an additional tool for the determination of trabecular bone properties.

Laser-Supported Dual Energy X-Ray Absorptiometry (DXL) Compared to Conventional Absorptiometry (DXA) and to FRAX as Tools for Fracture Risk Assessments

Dual X-ray and Laser (DXL) adds a measure of the external thickness of the heel, measured by laser, to a conventional measurement of bone mineral density (BMD) of the calcaneus, using Dual energy X-ray Absorptiometry (DXA). The addition of heel thickness aims at a better separation of fatty tissue from bone than the standard method of DXA, which may mistake fatty tissue for bone and vice versa. The primary aim of this study was to evaluate whether DXL of the calcaneus can be used to assess the 10-year risk of fractures. Secondary aims were to compare the predictive ability of DXL with the two most established methods, Dual energy X-ray Absorptiometry (DXA) of the hip and spine and the WHO fracture risk assessment tool, FRAX. In 1999 a cohort of 388 elderly Swedish women (mean age 73.2 years) was examined with all three methods. Prospective fracture data was collected in 2010 from health care registers. One SD decrease in BMD of the heel resulted in an age-adjusted Hazard Ratio (HR) of 1.47 for a hip fracture (95% CI 1.09–1.98). Harrell’s C is the Cox regression counterpart of the Area Under Curve (AUC) of the Receiver Operating Characteristic (ROC) as a measure of predictive accuracy. Harrell’s C for BMD of the calcaneus was 0.65 for prediction of hip fractures. These results were not significantly different from those for BMD of the femoral neck or for FRAX. The HR for a hip fracture, for one SD decrease in BMD at the femoral neck, was 1.72 (95% CI 1.21–2.44. Harrell’s C was 0.67 for BMD at the femoral neck and 0.59 for FRAX. We conclude that DXL of the calcaneus could be a useful tool for fracture risk assessments.

A pilot study of change in fracture risk in patients with acute respiratory distress syndrome

Introduction

Acute skeletal muscle wasting is a major contributor to post critical illness physical impairment. However, the bone response remains uncharacterized. We prospectively investigated the early changes in bone mineral density (BMD) and fracture risk in critical illness.

Methods

Patients were prospectively recruited ≤24 hours following intensive care unit (ICU) admission to a university teaching or a community hospital (August 2009 to April 2011). All were aged >18 years and expected to be intubated for >48 hours, spend >7 days in critical care and survive ICU admission. Forty-six patients were studied (55.3% male), with a mean age of 54.4 years (95% confidence interval (CI): 49.1 to 59.6) and an APACHE II score of 23.9 (95% CI: 22.4 to 25.5). Calcaneal dual X-ray absorptiometry (DXA) assessment of BMD was performed on day 1 and 10. Increase in fracture risk was calculated from the change in T-score.

Results

BMD did not change between day 1 and 10 in the cohort overall (0.434 (95% CI: 0.405 to 0.463) versus 0.425 g/cm² (95% CI: 0.399 to 0.450), P = 0.58). Multivariable logistical regression revealed admission corrected calcium (odds ratio (OR): 1.980 (95% CI: 1.089 to 3.609), P = 0.026) and admission PaO₂-to-FiO₂ ratio (OR: 0.916 (95% CI: 0.833 to 0.998), P = 0.044) to be associated with >2% loss of BMD. Patients with acute respiratory distress syndrome had a greater loss in BMD than those without (−2.81% (95% CI: −5.73 to 0.118%), n = 34 versus 2.40% (95% CI: 0.204 to 4.586%), n = 12, P = 0.029). In the 34 patients with acute respiratory distress syndrome, fracture risk increased by 19.4% (95% CI: 13.9 to 25.0%).

Conclusions

Patients with acute respiratory distress syndrome demonstrated early and rapid bone demineralisation with associated increase in fracture risk.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0892-y) contains supplementary material, which is available to authorized users.

Dual-energy X-ray absorptiometry of human metatarsals: precision, least significant change and association to ex vivo fracture force

BACKGROUND

Fractures are common in foot bones, but clinicians lack adequate indices of bone strength.

OBJECTIVES

We used dual-energy X-ray absorptiometry (DXA) to measure bone mineral density (BMD) and content (BMC) of excised human metatarsals, determined intra- and inter-rater measurement precision, and assessed associations between BMD/BMC and ex vivo bone fracture strength.

METHODS

Two raters each made two measurements of whole-bone and sub-regional BMD and BMC in both second and third metatarsals from 10 cadavers. Variance components analysis was used to assess variability attributable to repeat measurements, raters, sub-regions, bones, sides, and cadavers. Root-mean-square standard deviation (RMS-SD) and least-significant change (LSC) were used to assess rater precision and ultimate forces during 3-point bending were tested for correlations with BMD and BMC.

RESULTS

Variation due to repeat measurements and rater was low (<1% combined) for BMD and BMC. RMS-SD for whole metatarsal BMD of both metatarsals ranged from 0.004 to 0.010 g/cm(2) and 0.062 to 0.086 g for BMC. Whole metatarsal and sub-region BMD and BMC were strongly correlated to ex vivo fracture force (r(2)=0.67-0.93).

CONCLUSIONS

DXA measurements of BMD and BMC have high intra- and inter-rater precision and are strongly correlated to ex vivo bone strength.