X-ray-verified fractures are associated with finite element analysis-derived bone strength and trabecular microstructure in young adult men

Trabecular bone microstructure analysis on data from a novel twin robotic X-ray device

Background

Bone strength is related to both mineral density (BMD) and the bone microstructure. However, only the assessment of BMD is available in clinical routine care today.

Purpose

To analyze and study the correlation of trabecular bone microstructure from the imaging data of a prototype Multitom Rax system, using micro-computed tomography (CT) data as the reference method (Skyscan 1176).

Material and Methods

Imaging data from 14 bone samples from the human radius were analyzed regarding six bone structure parameters, i.e. trabecular nodes, separation, spacing, and thickness as well as bone volume (BV/TV) and structural model index (SMI).

Results

All six structure parameters showed strong correlations to micro-CT with Spearman correlation coefficients in the range of 0.83–0.93. BV/TV and SMI had a correlation >0.90. Two of the parameters, namely, separation and number, had mean values in the same range as micro-CT. The other four were either over- or underestimated.

Conclusion

The strong correlation between micro-CT and the clinical imaging system, indicates the possibility for analyzing bone microstructure with potential to add value in fracture assessment using the studied device in a clinical workflow.

Is repeated childhood fracture related to areal bone density or body composition in middle age?

Childhood fracture is common, but whether it predicts adult fracture is not clear. Repeat childhood fracture was associated with adult (≤ 45 years) fracture, and in women, lower areal bone density was associated with repeat childhood fracture. Identifying fracture-prone children can modify adult fracture risk management.

INTRODUCTION

A quarter of boys and 15% of girls will suffer multiple fractures, but it is not clear whether multiple fractures during growth predict fracture risk and areal bone density in adulthood. This study evaluated whether children who repeatedly fracture were at increased risk of low areal bone density, abnormal body composition, and fractures by age 45.

METHODS

A subsample of a large birth cohort study with childhood fracture cases had areal bone density assessed at age 45 years. Participants were questioned regularly across their lifetime about fractures during childhood (ages 0-18 years of age) and adulthood (any fracture between 18 and 45 years). The number of fractures was collapsed into three categories: no fractures; 1 fracture; and > 1 fracture, separately for child and adult groups.

RESULTS

At age 45 years, areal bone mineral density (g/cm2) and body composition were measured with dual X-ray absorptiometry in n = 555 participants. Compared to no fractures, twice as many girls (14% vs 7%, P = 0.156) and boys (31.4% vs 14.1%, P = 0.004) who repeatedly fractured in childhood sustained multiple fractures as adults. Both girls and boys who were fracture-free tended to remain fracture-free as adults (79.8% compared with 62.8%, P = 0.045, and 64.8% compared with 51.4%, P = 0.025, in males and females, respectively). Participants were more than twice as likely to fracture repeatedly as adults if they had sustained multiple fractures as a child (OR 2.5 95% CI: 1.4, 4.6). Women who repeatedly fractured during childhood had lower areal bone density, whereas repeated fracturing during childhood was not associated with areal bone density or body composition in men, even after adjustment for other factors known to influence fracture history.

CONCLUSION

Childhood fracture history is associated with persistent skeletal fragility in adulthood (≤ 45 years), even after adjustment for behavioral and demographic factors known to influence fracture history.

HR-pQCT imaging in children, adolescents and young adults: Systematic review and subgroup meta-analysis of normative data

We aimed to investigate the methodologies on image acquisition of normative data of high-resolution peripheral quantitative computed tomography (HR-pQCT) in children, adolescents and/or young adults (up to 25 years) and to determine their normative data based on available literature. A literature search was conducted in MEDLINE, EMBASE and Web of Science from 1947 to July 2019. Quality of articles was assessed using Standards for Reporting of Diagnostic Accuracy (STARD) scoring system and Modified Newcastle-Ottawa scale (NOS). Articles which fitted the following criteria were combined to meta-analysis: age range (15 to 22.6 years), references at tibia (22.5mm) and/or radius (9.0 to 9.5mm). Eight articles were ultimately included in the systematic review and 4 of them that filled the criteria were summarised in meta-analysis. The results of random effects model of HR-pQCT parameters of the 4 articles were as follows: 1)Radius: bone volume fraction (BT/BV) [estimate 0.17:0.1229(lower)-0.2115 (upper); trabecular number (Tb_N):2.08(2.03–2.12); trabecular thickness (Tb.Th):0.07 (0.07–0.0.08); trabecular separation (Tb.Sp):0.41 (0.38–0.42); cortical thickness (Ct.Th):0.85 (0.76–0.94); cortical porosity (Ct.Po):1.53 (0.63–2.44); total area (Tt.Ar):263.66(-385.3–912.6); total bone density (Tt-vBMD):280.5 (73.1–487.7); Trabecular density (Tb-vBMD):223.6 (47.1–400.09), and cortical density (CT.vBMD):765.9 (389.1–1142.8). 2)Tibia: BT/BV:0.18 (0.17–0.19); Tb_N:2.02 (1.83–2.2); Tb.Th:0.08 (0.80–0.09); Tb.Sp:0.40(0.36–0.44); Ct.Th:1.32(1.26–1.38); Ct.Po:3.15 (1.1–5.2); Tt.Ar:693.1(150.2–1235.8); Tt-vBMD:343.76 (335.5–352.1); Tb-vBMD:223.6 (213.37 (193.5–233.2), and CT.vBMD:894.3 (857.6–931.1). There is overall ‘fair’ evidence on reporting of results of normative data of HR-pQCT parameters in children, adolescents and/or young adults. However, data are scarce pointing out to the urgent need for standardization of acquisition parameters and guidelines on the use of HR-PQCT in these populations.

The Association between First Fractures Sustained during Childhood and Adulthood and Bone Measures in Young Adulthood

OBJECTIVE

To describe the association between fractures sustained at different stages of growth and bone measures in early adulthood.

STUDY DESIGN

Participants (n = 201) in southern Tasmania were at birth at a higher risk of sudden infant death syndrome; they were followed to age 25. Outcomes were areal bone mineral density at the spine, hip, and total body (by dual-energy x-ray absorptiometry) and trabecular and cortical bone measures at the radius and tibia (by high-resolution peripheral quantitative computed tomography). Fractures were self-reported and confirmed by radiographs at 8, 16, and 25 years of age. Multivariable linear regression was used to analyze the association of the occurrence of prepubertal (<9 years of age), pubertal (9-16 years of age), and postpubertal (17-25 years of age) fractures with all bone measures.

RESULTS

Over 25 years, 99 participants had at least 1 fracture. For high-resolution peripheral quantitative computed tomography measures at age 25, prepubertal fractures were negatively associated with cortical and trabecular volumetric bone mineral density and most microarchitecture measures at both the tibia and radius. Prepubertal fractures had a significant association with smaller increase of areal bone mineral density from age 8 to 16 years and at 25 years of age compared with participants with no fractures. Pubertal fractures had no association with any bone measures and postpubertal fractures were only associated with a lower trabecular number at the tibia.

CONCLUSIONS

Prepubertal fractures are negatively associated with areal bone mineral density increases during growth and high-resolution peripheral quantitative computed tomography bone measures in young adulthood. There is little evidence that fractures occurring from age 8 years onward with bone measures in young adulthood, implying that prepubertal fractures may be associated with bone deficits later in life.

Association of High-resolution Peripheral Quantitative Computed Tomography (HR-pQCT) bone microarchitectural parameters with previous clinical fracture in older men: The Osteoporotic Fractures in Men (MrOS) study

High-resolution peripheral quantitative computed tomography (HR-pQCT) assesses both volumetric bone mineral density (vBMD) and trabecular and cortical microarchitecture. However, studies of the association of HR-pQCT parameters with fracture history have been small, predominantly limited to postmenopausal women, often performed limited adjustment for potential confounders including for BMD, and infrequently assessed strength or failure measures. We used data from the Osteoporotic Fractures in Men (MrOS) study, a prospective cohort study of community-dwelling men aged ≥65 years, to evaluate the association of distal radius, proximal (diaphyseal) tibia and distal tibia HR-pQCT parameters measured at the Year 14 (Y14) study visit with prior clinical fracture. The primary HR-pQCT exposure variables were finite element analysis estimated failure loads (EFL) for each skeletal site; secondary exposure variables were total vBMD, total bone area, trabecular vBMD, trabecular bone area, trabecular thickness, trabecular number, cortical vBMD, cortical bone area, cortical thickness, and cortical porosity. Clinical fractures were ascertained from questionnaires administered every 4 months between MrOS study baseline and the Y14 visit and centrally adjudicated by masked review of radiographic reports. We used multivariate-adjusted logistic regression to estimate the odds of prior clinical fracture per 1 SD decrement for each Y14 HR-pQCT parameter. Three hundred forty-four (19.2%) of the 1794 men with available HR-pQCT measures had a confirmed clinical fracture between baseline and Y14. After multivariable adjustment, including for total hip areal BMD, decreased HR-pQCT finite element analysis EFL for each site was associated with significantly greater odds of prior confirmed clinical fracture and major osteoporotic fracture. Among other HR-pQCT parameters, decreased cortical area appeared to have the strongest independent association with prior clinical fracture. Future studies should explore associations of HR-pQCT parameters with specific fracture types and risk of incident fractures and the impact of age and sex on these relationships.

Fracture Prospectively Recorded From Prepuberty to Young Adulthood: Are They Markers of Peak Bone Mass and Strength in Males?

Fractures are common in otherwise healthy children and adolescents. They result from trauma of varying severity. Some reflect a greater skeletal fragility. A long-term implication of these fractures is their potentiality to predict adult bone fragility and increased risk of osteoporosis in later life. Using dual-energy X-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and micro-finite element analysis (μFEA) measurements, we previously found in 124 healthy females, followed from the age of 7.9 to 20.4 years, substantial deficits in both structural and strength components of the radius in the 42 girls who sustained a fracture during skeletal development. The objective of the current study was to assess in healthy males the relationship between fracture during development and expression of bone fragility in adulthood. A cohort of 152 boys was followed from age 7.4 ± 04 (mean ± SD) to 22.6 ± 0.7 years, ie, when peak bone mass is attained. Ninety participants (59.2%) sustained at least one fracture during growth, with highest incidence within the 10- to 13-year age range. Forearm was the most frequent site of fractures. At 7.4 years, several bone DXA-measured variables (areal bone mineral density [aBMD], bone mineral content [BMC]) were lower in the group with a positive fracture history during skeletal development compared with the non-fractured group. In contrast, at 22.6 years, no DXA-measured sites, including forearm, indicated a deficit in the fractured group compared with the non-fractured group. Likewise, at 22.6 years, neither HR-pQCT nor μFEA measurements, including distal radius, showed a structural or strength deficit in the fractured group. These results markedly contrast with a similar prospective study using the same technical and clinical design in 124 healthy girls. In conclusion, our prospective studies suggest a sex difference in the predictability of bone fragility in young adults who sustained fractures during childhood and adolescence. This difference might be related to the degree of trauma severity, usually lower in girls than in boys. © 2017 American Society for Bone and Mineral Research.

Current Physical Activity Is Independently Associated With Cortical Bone Size and Bone Strength in Elderly Swedish Women

Physical activity is believed to have the greatest effect on the skeleton if exerted early in life, but whether or not possible benefits of physical activity on bone microstructure or geometry remain at old age has not been investigated in women. The aim of this study was to investigate if physical activity during skeletal growth and young adulthood or at old age was associated with cortical geometry and trabecular microarchitecture in weight-bearing and non-weight-bearing bone, and areal bone mineral density (aBMD) in elderly women. In this population-based cross-sectional study 1013 women, 78.2 ± 1.6 (mean ± SD) years old, were included. Using high-resolution 3D pQCT (XtremeCT), cortical cross-sectional area (Ct.CSA), cortical thickness (Ct.Th), cortical periosteal perimeter (Ct.Pm), volumetric cortical bone density (D.Ct), trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp) were measured at the distal (14% level) and ultra-distal tibia and radius, respectively. aBMD was assessed using DXA (Hologic Discovery A) of the spine and hip. A standardized questionnaire was used to collect information about previous exercise and the Physical Activity Scale for the Elderly (PASE) was used for current physical activity. A linear regression model (including levels of exercise during skeletal growth and young adulthood [10 to 30 years of age], PASE score, and covariates) revealed that level of current physical activity was independently associated with Ct.CSA (β = 0.18, p < 0.001) and Ct.Th (β = 0.15, p < 0.001) at the distal tibia, Tb.Th (β = 0.11, p < 0.001) and BV/TV (β = 0.10, p = 0.001) at the ultra-distal tibia, and total hip aBMD (β = 0.10, p < 0.001). Current physical activity was independently associated with cortical bone size, in terms of thicker cortex but not larger periosteal circumference, and higher bone strength at the distal tibia on elderly women, indicating that physical activity at old age may decrease cortical bone loss in weight-bearing bone in elderly women. © 2016 American Society for Bone and Mineral Research.

Synchrotron Imaging Assessment of Bone Quality

Bone is a complex hierarchical structure, and its principal function is to resist mechanical forces and fracture. Bone strength depends not only on the quantity of bone tissue but also on the shape and hierarchical structure. The hierarchical levels are interrelated, especially the micro-architecture, collagen and mineral components; hence, analysis of their specific roles in bone strength and stiffness is difficult. Synchrotron imaging technologies including micro-CT and small/wide angle X-ray scattering/diffraction are becoming increasingly popular for studying bone because the images can resolve deformations in the micro-architecture and collagen-mineral matrix under in situ mechanical loading. Synchrotron cannot be directly applied in vivo due to the high radiation dose but will allow researchers to carry out systematic multifaceted studies of bone ex vivo. Identifying characteristics of aging and disease will underpin future efforts to generate novel devices and interventional therapies for assessing and promoting healthy aging. With our own research work as examples, this paper introduces how synchrotron imaging technology can be used with in situ testing in bone research.

Predicting Trabecular Bone Stiffness from Clinical Cone-Beam CT and HR-pQCT Data; an In Vitro Study Using Finite Element Analysis

Stiffness and shear moduli of human trabecular bone may be analyzed in vivo by finite element (FE) analysis from image data obtained by clinical imaging equipment such as high resolution peripheral quantitative computed tomography (HR-pQCT). In clinical practice today, this is done in the peripheral skeleton like the wrist and heel. In this cadaveric bone study, fourteen bone specimens from the wrist were imaged by two dental cone beam computed tomography (CBCT) devices and one HR-pQCT device as well as by dual energy X-ray absorptiometry (DXA). Histomorphometric measurements from micro-CT data were used as gold standard. The image processing was done with an in-house developed code based on the automated region growing (ARG) algorithm. Evaluation of how well stiffness (Young’s modulus E3) and minimum shear modulus from the 12, 13, or 23 could be predicted from the CBCT and HR-pQCT imaging data was studied and compared to FE analysis from the micro-CT imaging data. Strong correlations were found between the clinical machines and micro-CT regarding trabecular bone structure parameters, such as bone volume over total volume, trabecular thickness, trabecular number and trabecular nodes (varying from 0.79 to 0.96). The two CBCT devices as well as the HR-pQCT showed the ability to predict stiffness and shear, with adjusted R²-values between 0.78 and 0.92, based on data derived through our in-house developed code based on the ARG algorithm. These findings indicate that clinically used CBCT may be a feasible method for clinical studies of bone structure and mechanical properties in future osteoporosis research.

Relationship between Fetuin A, Vascular Calcification and Fracture Risk in Dialysis Patients

Background

Fractures are a common morbidity that lead to worse outcomes in dialysis patients. Fetuin A inhibits vascular calcification (VC), potentially promotes bone mineralization and its level positively correlates with bone mineral density in the general population. On the other hand, the presence of VC is associated with low bone volume in dialysis patients. Whether the fetuin A level and VC can predict the occurrence of fractures in dialysis patients remains unknown.

Methods

We performed this prospective, observational cohort study including 685 dialysis patients (629 hemodialysis and 56 peritoneal dialysis) from a single center in Taiwan for a median follow-up period of 3.4 years. The baseline fetuin A level and status of presence of aortic arch calcification (VC) and incidence of major fractures (hip, pelvis, humerus, proximal forearm, lower leg or vertebrae) were assessed using adjusted Cox proportional hazards models, recursive partitioning analysis and competing risk models.

Results

Overall, 177 of the patients had major fractures. The incidence rate of major fractures was 3.29 per 100 person-years. In adjusted analyses, the patients with higher baseline fetuin A levels had a lower incidence of fractures (adjusted hazard ratio (HR), 0.3; 95% CI, 0.18‒0.5, fetuin A tertile 3 vs. tertile 1 and HR, 0.52; 95% CI, 0.34‒0.78, tertile 2 vs. tertile 1). The presence of aortic arch calcification (VC) independently predicted the occurrence of fractures (adjusted HR, 1.95; 95% CI, 1.34‒2.84) as well. When accounting for death as an event in competing risk models, the patients with higher baseline fetuin A levels remained to have a lower incidence of fractures (SHR, 0.31; 95% CI, 0.17‒0.56, fetuin A tertile 3 vs. tertile 1 and 0.51; 95% CI, 0.32‒0.81, tertile 2 vs. tertile 1).

Interpretations

Lower baseline fetuin A levels and the presence of VC were independently linked to higher risk of incident fractures in prevalent dialysis patients.

Alterations of bone mineral density, bone microarchitecture and strength in patients with ankylosing spondylitis: a cross-sectional study using high-resolution peripheral quantitative computerized tomography and finite element analysis

Introduction

Ankylosing spondylitis (AS) is an inflammatory disease associated with new bone formation and an increased risk of osteoporosis and fractures. The negative effects of AS on bone microarchitecture and strength are unclear. Thus, we conducted an observational study to analyze the effect of AS on bone microarchitecture and strength.

Methods

Patients with AS (n = 53) and non-AS subjects (n = 85) were recruited for the study. All subjects underwent clinical evaluation, DXA and high-resolution peripheral quantitative CT scans (HRpQCT).

Results

The AS patients were aged 44 ± 12 (mean ± standard deviation) years and had a median disease duration of 17 (interquartile range: 7–27) years. They were found to have lower cortical, trabecular and total vBMD at the distal radius and tibia than non-AS subjects on multivariable regression analysis. Cortical parameters such as cortical thickness and porosity, and bone strength parameters such bone stiffness and stress as estimated by finite element analysis (FEA) in AS patients were significantly worse than that of-non-AS subjects. Among patients with AS, male sex, mSASSS greater than zero and HLA-B27 negative status were associated with worse bone microarchitecture.

Conclusions

Patients with AS have worse bone mineral density, microarchitecture and strength when compared to non-AS subjects. More research is needed to understand the mechanisms underlying bone pathology in AS and to assess the effect of treatments such as TNF inhibitors on bone quality and fracture risk.

Osteoporosis: the evolution of a diagnosis

The global trend towards increased longevity has resulted in ageing populations and a rise in diseases or conditions that primarily affect older persons. One such condition is osteoporosis (fragile or porous bones), which causes an increased fracture risk. Vertebral and hip fractures lead to increased morbidity and mortality and result in enormous healthcare costs. Here, we review the evolution of the diagnosis of osteoporosis. In an attempt to separate patients with normal bones from those with osteoporosis and to define the osteoporosis diagnosis, multiple factors and characteristics have been considered. These include pathology and histology of the disease, the endocrine regulation of bone metabolism, bone mineral density (BMD), fracture type or trauma severity, risk models for fracture prediction, and thresholds for pharmacological intervention. The femoral neck BMD -2.5 SDs cut-off for the diagnosis of osteoporosis is arbitrarily chosen, and there is no evidence to support the notion that fracture location (except vertebral fractures) or severity is useful to discriminate osteoporotic from normal bones. Fracture risk models (including factors unrelated to bone) dissociate bone strength from the diagnosis, and treatment thresholds are often based on health-economic considerations rather than bone properties. Vertebral fractures are a primary feature of osteoporosis, characterized by decreased bone mass, strength and quality, and a high risk of another such fracture that can be considerably reduced by treatment. We believe that the 2001 definition of osteoporosis by the National Institutes of Health Consensus Development Panel on Osteoporosis is still valid and useful: 'Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture'.

Prior fracture as a risk factor for future fracture in an Australian cohort

SUMMARY

This study investigated the influence of prior fracture on the risk of subsequent fracture. There was a higher risk of subsequent fracture in both young and older adult age groups when Australian males or females had already sustained a prior fracture. Fracture prevention is important throughout life for both sexes.

INTRODUCTION

The purpose of this study was to determine the impact of prior fracture on the risk of subsequent fracture across the adult age range in Australian males and females.

METHODS

All-cause fractures were grouped into age categories for males and females enrolled in the Geelong Osteoporosis Study (Australia) using retrospective self-report data and prospective radiology-confirmed data. For all age categories, the relative risk (RR and 95% confidence interval (CI)) of subsequent fracture in a later age category was compared between those with prior fracture and those without.

RESULTS

For both sexes, childhood fracture increased the risk of subsequent fracture in adolescence (males: RR 21.7; 95% CI 16.0, 27.4; females: RR 8.1; 3.5, 12.8). Males with adolescent fracture had increased risk of subsequent fracture in early adulthood (RR 11.5; 5.7, 17.3) and mid-adulthood (RR 13.0; 6.3, 19.7). Additionally, males with young adulthood or mid-adulthood fracture had increased risk of subsequent fracture in the following age group (RR 11.2; 4.4, 17.9, and RR 6.2; 0.8, 11.7, respectively). Mid-adult fractures increased the risk of subsequent fracture in older adulthood (RR 6.2; 0.8, 11.7). Females with childhood or adolescent fracture had an increased risk of fracture in young adulthood (RR 4.3; 0.7, 7.9, and RR 10.5; 4.4, 16.6), and prior fracture in older adult life increased the risk of subsequent fracture in old age (RR 14.9; 6.4. 23.3).

CONCLUSIONS

Fracture prevention strategies may be more effective if attention is directed towards individuals with prior fracture at any age as they have a higher likelihood of sustaining a subsequent fracture later in life.

Changes in cortical volumetric bone mineral density and thickness, and trabecular thickness in lactating women postpartum

CONTEXT

Lactation is associated with decreased areal bone mineral density (aBMD). Replenishment occurs especially after ceased lactation. Changes in volumetric bone mineral density (vBMD), microstructure, and dimensional parameters are unknown and may clarify the role of lactation for skeletal health. OBJECTIVE AND MAIN OUTCOMES: The objective of the study was to test the hypothesis that lactation is associated with changes in aBMD, vBMD, microstructure, and dimensional parameters.

DESIGN

At baseline (0.5 mo after delivery) and 4, 12, and 18 months thereafter, bone was assessed using dual-energy x-ray absorptiometry and high-resolution peripheral quantitative computed tomography.

PARTICIPANTS AND SETTING

Eighty-one fair-skinned postpartum women and 21 controls aged 25-40 years were recruited. The completion ratio was 73%. Postpartum women were categorized depending on duration of lactation: 0-3.9, 4-8.9, and 9 months or longer.

RESULTS

During the first 4 months, aBMD decreased at several sites (geometric mean ± SE; -0.73% ± 0.21% to -3.98% ± 0.76%) in women lactating at least 4 months. During the same time, cortical vBMD at the ultradistal tibia decreased in women lactating 4-8.9 months (-0.26% ± 0.08%) and 9 months or longer (-0.49% ± 0.10%). At 12 months postpartum, cortical thickness (≥ 9 mo, -2.48% ± 0.41%) and trabecular thickness (4-8.9 mo, -2.14% ± 0.92%; ≥ 9 mo, -2.56% ± 1.21%) also were lower than baseline. No decreases were found in women lactating less than 4 months or in controls in these parameters. At 18 months postpartum, both cortical vBMD (≥ 9 mo, -0.77% ± 0.17%) and trabecular thickness (4-8.9 mo, -2.25% ± 1.25%; ≥ 9 mo, -3.21% ± 1.41%) were lower in women with long lactation.

CONCLUSIONS

Decreases in cortical vBMD, thickness, and trabecular thickness at the ultradistal tibia were found in women lactating 4 months or longer. Longer follow-up is needed to confirm whether women with extended lactation recover fully or whether the changes could potentially lead to an increased risk of fracture in later life.

Age- and sex-related patterns of first fracture and fracture prevalence

There are few data documenting the pattern of prevalent fracture across the entire adult age range, so we aimed to address this gap by investigating the prevalence of fractures in an Australian cohort. All-cause (ever) fractures were identified for males and females enrolled in the Geelong Osteoporosis Study (Australia) using a combination of radiology-confirmed and self-reported data. First fractures were used to generate age-related frequencies of individuals who had ever sustained a fracture. Of 1,538 males and 1,731 females, 927 males and 856 females had sustained at least one fracture since birth. The proportion of all prevalent fractures in the 0-10 year age group was similar for both sexes (~10%). In males, the proportion with prevalent fracture increased to 34.1% for age 11-20 year. Smaller increases were observed into mid-life, reaching a plateau at ~50% from mid to late life. The age-related prevalence of fracture for females showed a more gradual increase until mid-life. For adulthood prevalent fractures, approximately 20% of males had sustained a first adulthood fracture in the 20-30 year age group, with a gradual increase up to the oldest age group (49.1%), while females showed an exponential pattern of increase from the 20-30 year age group (6.8%) to the oldest age group (60.4%). In both sexes, those who had not sustained a fracture in childhood or early adulthood generally appeared to remain fracture-free until at least the sixth decade. When considering the prevalence of adulthood fractures across the age groups, males showed a gradual increase while females showed an exponential increase.

Diminished bone strength is observed in adult women and men who sustained a mild trauma distal forearm fracture during childhood

Children and adolescents who sustain a distal forearm fracture (DFF) owing to mild, but not moderate, trauma have reduced bone strength and cortical thinning at the distal radius and tibia. Whether these skeletal deficits track into adulthood is unknown. Therefore, we studied 75 women and 75 men (age range, 20 to 40 years) with a childhood (age < 18 years) DFF and 150 sex-matched controls with no history of fracture using high-resolution peripheral quantitative computed tomography (HRpQCT) to examine bone strength (ie, failure load) by micro-finite element (µFE) analysis, as well as cortical and trabecular bone parameters at the distal radius and tibia. Level of trauma (mild versus moderate) was assigned using a validated classification scheme, blind to imaging results. When compared to sex-matched, nonfracture controls, women and men with a mild trauma childhood DFF (eg, fall from standing height) had significant reductions in failure load (p < 0.05) of the distal radius, whereas women and men with a moderate trauma childhood DFF (eg, fall while riding a bicycle) had values similar to controls. Consistent findings were observed at the distal tibia. Furthermore, women and men with a mild trauma childhood DFF had significant deficits in distal radius cortical area (p < 0.05), and significantly lower dual-energy X-ray absorptiometry (DXA)-derived bone density at the radius, hip, and total body regions compared to controls (all p < 0.05). By contrast, women and men with a moderate trauma childhood DFF had bone density, structure, and strength that did not differ significantly from controls. These findings in young adults are consistent with our observations in children/adolescents with DFF, and they suggest that a mild trauma childhood DFF may presage suboptimal peak bone density, structure, and strength in young adulthood. Children and adolescents who suffer mild trauma DFFs may need to be targeted for lifestyle interventions to help achieve improved skeletal health.

Exercise during growth and young adulthood is independently associated with cortical bone size and strength in old Swedish men

Previous studies have reported an association between exercise during youth and increased areal bone mineral density at old age. The primary aim of this study was to investigate if exercise during growth was independently associated with greater cortical bone size and whole bone strength in weight-bearing bone in old men. The tibia and radius were measured using both peripheral quantitative computed tomography (pQCT) (XCT-2000; Stratec) at the diaphysis and high-resolution pQCT (HR-pQCT) (XtremeCT; Scanco) at the metaphysis to obtain cortical bone geometry and finite element-derived bone strength in distal tibia and radius, in 597 men, 79.9 ± 3.4 (mean ± SD) years old. A self-administered questionnaire was used to collect information about previous and current physical activity. In order to determine whether level of exercise during growth and young adulthood or level of current physical activity were independently associated with bone parameters in both tibia and radius, analysis of covariance (ANCOVA) analyses were used. Adjusting for covariates and current physical activity, we found that men in the group with the highest level of exercise early in life (regular exercise at a competitive level) had higher tibial cortical cross-sectional area (CSA; 6.3%, p < 0.001) and periosteal circumference (PC; 1.6%, p = 0.011) at the diaphysis, and higher estimated bone strength (failure load: 7.5%, p < 0.001; and stiffness: 7.8%, p < 0.001) at the metaphysis than men in the subgroup with the lowest level of exercise during growth and young adulthood. Subjects in the group with the highest level of current physical activity had smaller tibial endosteal circumference (EC; 3.6%, p = 0.012) at the diaphysis than subjects with a lower current physical activity, when adjusting for covariates and level of exercise during growth and young adulthood. These findings indicate that exercise during growth can increase the cortical bone size via periosteal expansion, whereas exercise at old age may decrease endosteal bone loss in weight-bearing bone in old men.

Serum estradiol levels are inversely associated with cortical porosity in older men

CONTEXT

The key role of serum estradiol (E2) for bone health in men is well established. The effect of serum sex steroids on bone microstructure, measured by high-resolution peripheral quantitative computed tomography, remains unknown in elderly men.

OBJECTIVE

The objective of the study was to examine the associations between serum sex steroids and bone microstructural parameters in older men.

METHODS

Trabecular and cortical bone microstructure at the tibia was measured by high-resolution peripheral quantitative computed tomography in 440 men (mean 80 y of age) participating in the population-based Osteoporotic Fractures in Men Sweden cohort. Serum levels of E2 and T were analyzed with mass spectrometry and free E2 and free T levels were calculated using law-of-mass-action equations.

RESULTS

Age-adjusted models demonstrated that E2 and free E2 but not T or free T associated significantly inversely with cortical porosity. The associations between E2 and free E2 and cortical porosity remained significant after further adjustment for height, weight, physical activity, calcium intake, and smoking. Models including both serum E2 and T demonstrated that E2 (standardized β = -.12, P < .05) but not T associated independently with cortical porosity. A similar independent association was found for free E2 (standardized β = -.12, P < .05) but not free T. Free E2 associated significantly with trabecular bone volume fraction in the age-adjusted models, but this association did not remain significant after further adjustment.

CONCLUSIONS

Serum E2 levels associated inversely with cortical porosity in 80-year-old men. We propose that low serum E2 may reduce cortical bone strength, at least partly, by increasing cortical porosity and thereby increase fracture risk in older men.