Bone density and geometry in assessing hip fracture risk in post-menopausal women

Study on the scanning protocols for measuring bone mineral density by gemstone CT spectral imaging based on European spine phantom

BACKGROUND

Gemstone spectral computed tomography (GSCT) has been used to measure bone mineral density (BMD) in human vertebrae and animal models gradually.

PURPOSE

To investigate the effect of scanning protocols for BMD measurements by GSCT using the European spine phantom (ESP) and its accuracy and precision.

MATERIAL AND METHODS

The ESP number 145 containing three hydroxyapatite (HAP) inserts with densities of 50, 100, and 200 mg/cm³ were labeled as L₁, L₂, and L₃, respectively. Quantitative CT (QCT) protocol and 14 groups of scanning protocols configured by GSCT were used to repeatedly scan the ESP 10 times. Their measurements were compared with the true values of ESP and their relative standard deviation and relative error were calculated.

RESULTS

The measured values of the three inserts at different exposure levels were statistically significant (P < 0.05). The measured values in the 0.8 s/r 260 mA group, 0.5 s/r 630 mA group, and 0.6 s/r 640 mA group were not significantly different from the actual ESP values for L₁ and L₂. However, the measured values at all the parameters were significantly different from the actual values for the L₃.

CONCLUSION

CT gemstone spectral imaging can accurately and quantitatively measure the HAP value of ESP, but the results of BMD will be affected by the scanning protocols. The best scanning parameter of ESP measured by GSCT was 0.8 s/r 260 mA, taking dose into consideration, and the measurement accuracy of vertebrae with low BMD was higher than that of QCT under this parameter.

Age Related Trends in Structural Indices of Proximal Femur in Women Aged 20-70 in Southern Sri Lanka

Age related trends of the indices of hip structure help understanding how bone strength changes with age and the increased bone fragility in old age. Community-dwelling women aged 20-70years (n = 419) were selected by stratified random method and divided into age categories; 20-29years (n-69), 30-39years (n = 60), 40-49years (n = 69), 50-59years (n = 107) and 60-70years (n = 114). All subjects underwent dual energy x-ray absorptiometry (DXA) and hip structure analysis using Hologic Discovery scanner (Hologic Inc, Bedford, USA). Measured indices included hip axis length (HAL) and neck shaft angle (NSA) of the proximal femur. Cross sectional area (CSA), cross sectional moment of inertia (CSMI), section modulus (SM), cortical thickness (CT), buckling ration (BR) of three regions of interest; narrow neck, intertrochanteric region and femoral shaft, were also measured. Age related trends of all indices were studied with Locally Weighted Scatterplot Smoothing lines (LOESS) and ANOVA. Mean HAL and NSA values were not different between age categories. CSA, CSMI, SM and CT in three different regions showed curvilinear relationships with age. These indices gradually increased with age between 20-50 years and the maximum values were seen in the 40-49years age category and they declined afterwards. The decline of these indices was more rapid in the narrow neck and intertrochanter regions when compared with femoral shaft and the lowest mean CSA, CSMI, SM and CT in these two regions were seen in the 60-70 age category. BR showed a gradual decrease with age between 20-50 years and the lowest mean value was seen in the 40-49 age category. BR increased afterwards and the maximum mean value was seen in the 60-70 age category. This study demonstrates the dynamics of structural properties of proximal femur in the three selected cross sections of community-dwelling women aged 20-70 years and the increased bone fragility in old age.

Risk factors for contralateral hip refractures in patients aged over 80 years with intertrochanteric femoral fractures

Purpose

The purpose of this study was to identify which of the risk factors would contribute to the contralateral fracture in very elderly patients after intramedullary nail fixation.

Methods

Clinical data of 227 intertrochanteric fracture patients aged 80 years or older were retrospectively reviewed. Intramedullary nails (IMNs) were used on all of the patients. Potential risk factors for contralateral hip refractures were determined using univariate and logistic regression analyses.

Results

Contralateral hip refractures occurred in 11 patients (4.84%). Univariate analysis revealed that age, gender, body mass index, fracture classification, hematocrit, D-dimer, and CRP level were not associated with contralateral fractures (P > 0.05). However, neurological diseases, cardiovascular disease, and visual impairments were significantly associated with contralateral fractures (P < 0.05). Multivariate analysis further revealed that neurological diseases (OR 4.25, P = 0.044) and visual impairments (OR 5.42, P = 0.015) were independent risk factors associated with contralateral refractures.

Conclusion

To prevent contralateral refractures, more attention should be paid to elderly intertrochanteric fracture patients with underlying neurological disease and visual impairments.

Does hip structural analysis confer additional benefit to routine BMD assessment in postmenopausal women with hip fracture? A study from a tertiary center in southern India

This study from southern India showed that proximal hip geometry was significantly impaired in postmenopausal women with femoral neck fracture. The trabecular bone score (TBS), which is reflective of bone microarchitecture, was also significantly impaired in patients with fracture.

INTRODUCTION

There is limited information with regard to comprehensive bone health in Indian postmenopausal women with neck of femur fracture. We studied the bone mineral density (BMD), trabecular bone score (TBS), proximal hip geometry, and bone mineral biochemistry in postmenopausal women with and without femoral neck fractures.

METHODS

This was a cross-sectional study conducted at a tertiary care center in South India. BMD, TBS, and hip structural analysis (HSA) were assessed using a dual-energy X-ray absorptiometry (DXA) scanner. Bone mineral biochemical profiles were also studied.

RESULTS

A total of 90 postmenopausal women with acute femoral neck fracture with mean (SD) age of 63.2 (6.1) years and 90 age-matched controls were included. The prevalence of osteoporosis was higher among cases as compared to controls (83.3% vs 47.8%; P < 0.001). Degraded bone microarchitecture (TBS value < 1.200) was more frequent among women with hip fracture as compared to controls (46.7% vs 31.1%; P = 0.032). Cross-sectional moment of inertia (CSMI) was significantly lower at the narrow neck (NN) and inter-trochanteric (IT) region in cases (P < 0.05) and buckling ratio (BR) was significantly higher at all three sites in postmenopausal women with femoral neck fracture as compared controls. Multivariate logistic regression analysis showed that femoral neck osteoporosis, low CSMI at NN and high BR at NN and femoral shaft emerged as factors significantly associated with femoral neck fractures.

CONCLUSION

This study highlights that impaired parameters of proximal hip geometry and a low trabecular bone score may be significantly associated with femoral neck fractures in postmenopausal women.

Association of body composition with predicted hip bone strength among Chinese postmenopausal women: a longitudinal study

Body composition and bone strength are closely associated. How lean mass (LM) and fat mass (FM) contribute to bone strength remains ambiguous. We investigated the associations of total body LM and FM with changes in predicted hip bone strength over a period of 3 years in 1,743 postmenopausal Chinese women from the communities of Guangzhou, China. The body compositions of the women were obtained with dual-energy X-ray absorptiometry. We used the hip structure analysis program to obtain the bone parameters at the femoral neck region, including the bone mineral density (BMD), cross-sectional area (CSA), cortical thickness (CT), section modulus (SM) and buckling ratio (BR). We found the FM and LM were positive predictors for hip bone strength (β > 0, P < 0.05). The LM had a larger contribution to the BMD, CSA, CT, SM and/or their annual percent changes (βLM > βFM), while the contribution of FM to the BR and its annual percent change was higher than LM (|βFM| > |βLM|). Further analysis found that the associations of FM and LM with bone parameters were stronger in the underweight and normal weight participants (|βBMI1| > |βBMI2|). Overall, FM and LM had positive but differential effects on predicted hip bone strength, with a higher impact in the thinner participants.

Tea Consumption Is Associated with Increased Bone Strength in Middle-Aged and Elderly Chinese Women

OBJECTIVES

Previous studies found that tea consumption was related to a reduction in the risks of some chronic diseases, but limited data are available on bone health. This study aimed to examine the associations of tea consumption with hip bone strength in Chinese women.

DESIGN

Cross-sectional study.

SETTING

The participants were from the ongoing Guangzhou Nutrition and Health Study. This was a cohort study started in 2008. The examination data conducted between June 2010 and December 2013 were used.

PARTICIPANTS

A total of 1,495 Chinese women aged more than 40 years were included.

MEASUREMENTS

Tea consumption, socio-demographic information and lifestyle habits were collected by a face-to-face questionnaire. Hip bone mineral density (BMD) and geometric parameters, i.e. cross-sectional area (CSA), section modulus (Z) and buckling ratio (BR), were generated by dual-energy X-ray absorptiometry. The associations of tea consumption with bone phenotypes were detected by analysis of covariance and multiple linear regression models after adjusting for age, body mass index, years since menopause, physical activity, dietary-protein intake, dietary-calcium intake, calcium tablet intake, drinking status and smoking status.

RESULTS

Tea drinkers (n = 732) had approximately 1.9% higher BMD (p < 0.05) and 3.6% lower BR (p < 0.05) than non-tea drinkers (n = 763). The dose-response relationships of BMD, BR or CSA with total tea consumption were identified (p-trend < 0.05). Tea drinking was found to be a significant and independent predictor of BMD (β = 0.068, p < 0.05) or BR (β = -0.079, p < 0.05).

CONCLUSION

Tea consumption was associated with increased bone strength in middle-aged and elderly Chinese women.

Cortical thickness in the intertrochanteric region may be relevant to hip fracture type

Background

This study assessed the differences in femoral geometry and bone mineral density between femoral neck fragility fractures and trochanteric fractures.

Methods

One hundred and seventeen patients were divided into femoral neck and trochanteric fracture groups. There were 69 patients with femoral neck fractures, 20 men and 49 women with an average age of 75.1 ± 9.6 years and an average body mass index (BMI) value of 21.6 ± 4.1 kg/m². The trochanteric group consisted of 48 patients, 16 men and 32 women with an average age of 78.1 ± 9.1 years and an average BMI value of 21.5 ± 4.3 kg/m². All patients underwent dual-energy X-ray absorptiometry (DXA) of the contralateral hip; hip structural analysis (HSA) software was used to analyze the femoral geometry parameters, including hip axis length (HAL), neck-shaft angle (NSA), cross-sectional area (CSA), the cross-sectional moment of inertia (CSMI), the buckling ratio (BR), and cortical thickness.

Results

The cortical thickness in the intertrochanteric region was reduced in the trochanteric fractures group compared to the femoral neck fracture group (P < 0.05). There were no statistically significant differences (P > 0.05) in gender, age, height, weight, or BMI between the two groups. In addition, no statistically significant differences (P > 0.05) were found in the CSA, CSMI, or BR of the femoral neck or the intertrochanteric region between the two groups. There were no statistically significant differences (P > 0.05) in femoral neck cortical thickness between the two groups.

Conclusions

Cortical thickness thinning in the intertrochanteric region may be one of the relevant factors causing different types of hip fractures, especially in elderly patients.

Gemstone spectral imaging for measuring adult bone mineral density

The present study aimed to detect the bone Ca²⁺ content of L3 vertebrae in adults by gemstone spectral computed tomography. In total, 235 patients were selected and divided into age groups of 10 years each. The scanning data were used to detect the water-based and Ca²⁺-based substance levels on the L3 vertebral cancellous bone images. The results indicated that there were significant differences in vertebral Ca²⁺-water and water-Ca²⁺ densities determined by gemstone spectral imaging (GSI) between males and females in subjects aged 50-59 years, 60-69 years, 70-79 years and ≥80 years (P<0.05). The ages of male and female participants were negatively correlated with vertebral Ca²⁺-water density (P<0.01) and water-Ca²⁺ density (P<0.01). In conclusion, GSI may be used as a novel method of measuring the vertebral adult bone mineral density.

Femoral neck-shaft angle in humans: variation relating to climate, clothing, lifestyle, sex, age and side

The femoral neck-shaft angle (NSA) varies among modern humans but measurement problems and sampling limitations have precluded the identification of factors contributing to its variation at the population level. Potential sources of variation include sex, age, side (left or right), regional differences in body shape due to climatic adaptation, and the effects of habitual activity patterns (e.g. mobile and sedentary lifestyles and foraging, agricultural, and urban economies). In this study we addressed these issues, using consistent methods to assemble a global NSA database comprising over 8000 femora representing 100 human groups. Results from the analyses show an average NSA for modern humans of 127° (markedly lower than the accepted value of 135°); there is no sex difference, no age-related change in adults, but possibly a small lateral difference which could be due to right leg dominance. Climatic trends consistent with principles based on Bergmann's rule are evident at the global and continental levels, with the NSA varying in relation to other body shape indices: median NSA, for instance, is higher in warmer regions, notably in the Pacific (130°), whereas lower values (associated with a more stocky body build) are found in regions where ancestral populations were exposed to colder conditions, in Europe (126°) and the Americas (125°). There is a modest trend towards increasing NSA with the economic transitions from forager to agricultural and urban lifestyles and, to a lesser extent, from a mobile to a sedentary existence. However, the main trend associated with these transitions is a progressive narrowing in the range of variation in the NSA, which may be attributable to thermal insulation provided by improved cultural buffering from climate, particularly clothing.

Ethnic variability in bone geometry as assessed by hip structure analysis: findings from the hip strength across the menopausal transition study

Racial/ethnic origin plays an important role in fracture risk. Racial/ethnic differences in fracture rates cannot be fully explained by bone mineral density (BMD). Studies examining the influence of bone geometry and strength on fracture risk have focused primarily on older adults and have not included people from diverse racial/ethnic backgrounds. Our goal was to explore racial/ethnic differences in hip geometry and strength in a large sample of midlife women. We performed hip structure analysis (HSA) on hip dual-energy X-ray absorptiometry (DXA) scans from 1942 premenopausal and early perimenopausal women. The sample included white (50%), African American (27%), Chinese (11%), and Japanese (12%) women aged 42 to 52 years. HSA was performed using software developed at Johns Hopkins University. African American women had higher conventional (8.4% to 9.7%) and HSA BMD (5.4% to 19.8%) than other groups with the exception being Japanese women, who had the highest HSA BMD (9.7% to 31.4%). HSA indices associated with more favorable geometry and greater strength and resistance to fracture were more prevalent in African American and Japanese women. Femurs of African American women had a smaller outer diameter, a larger cross-sectional area and section modulus, and a lower buckling ratio. Japanese women presented a different pattern with a higher section modulus and lower buckling ratio, similar to African American women, but a wider outer diameter; this was offset by a greater cross-sectional area and a more centrally located centroid. Chinese women had similar conventional BMD as white women but a smaller neck region area and HSA BMD at both regions. They also had a smaller cross-sectional area and section modulus, a more medially located centroid, and a higher buckling ratio than white women. The observed biomechanical differences may help explain racial/ethnic variability in fracture rates. Future research should explore the contribution of hip geometry to fracture risk across all race/ethnicities.

Femoral geometric parameters and BMD measurements by DXA in adult patients with different types of osteogenesis imperfecta

OBJECTIVES

Osteogenesis imperfecta (OI) is an inherited disorder characterized by increased bone fragility with recurrent fractures that leads to skeletal deformities in severe cases. Consequently, in most OI patients, the hip is the only reliable measuring site for estimating future fracture risk. The aim of the study was to assess the applicability of hip structure analysis (HSA) by DXA in adult patients with osteogenesis imperfecta.

MATERIALS AND METHODS

We evaluated bone mineral density (BMD) and hip structure analysis (HSA) by DXA, including cross-sectional area (CSA), cross-sectional moment of inertia (CSMI) and femoral strength index (FSI) in 30 adult patients with different types of OI and 30 age-matched healthy controls (CO). The OI total group (OI-tot) was divided into two subgroups: the mild OI I group (OI-I) and the more severe OI III and IV group (OI-III-IV).

RESULTS

The mean neck BMD of OI-I and OI-III-IV were significantly lower compared to CO (-15.9 %, p < 0.005 and -37.5 %, p < 0.001 respectively). Similar results were observed at trochanter and total hip. CSA and the CSMI value were significantly lower for OI-I (-23.2 %, p < 0.001) and OI-III-IV (-45.9 %, p < 0.001) in comparison to CO. In addition, significant differences were found between the mild OI-I and the severe OI-III-IV group (-29.6 %, p < 0.05). FSI was significantly decreased in the OI-III-IV (25.7 %, p < 0.05) in comparison to the CO. Furthermore, significant correlations between BMD and HSA and between HSA and height and weight were found in osteogenesis imperfecta and controls.

CONCLUSION

BMD measurement in osteogenesis imperfecta patients is very critical. The combination of BMD and geometric structural measurements at the hip in osteogenesis imperfecta patients may represent an additional helpful means in estimating bone strength and fracture risk.

Proximal hip geometry and hip fracture risk assessment in a Korean population

The association between proximal femoral geometry and hip fracture risk were investigated. The risk of intertrochanteric fractures increased 1.64-fold and 2.32-fold with 1 standard deviation (sd) increase of hip axis length and neck-shaft angle, respectively, while the risk of femur neck fracture 2.03-fold with 1 sd decrease in femoral head offset.

INTRODUCTION

The purpose of this study was to determine the association between proximal femoral geometry (PFG) and the risk of hip fracture in femur neck (FN) and intertrochanteric (IT) fractures in a Korean population.

METHODS

The study included 151 patients (57 patients with IT fractures, 43 patients with FN fractures, and 51 control patients). Data on BMD, PFG parameters (hip axis length [HAL], neck-shaft angle [NSA], neck length, femoral head offset, neck diameter, shaft diameter (SD), and demographics [age, gender, height, and body weight]) were collected. Descriptive statistics and odds ratios of PFG parameters corrected with demographic variables were obtained using logistic regressions.

RESULTS

HAL (p = 0.046) and NSA (p = 0.003) were significantly greater in the patients with IT fracture than in the control patients, while neither parameter was significantly greater in patients with FN fractures than the control patients. The femoral head offset was significantly shorter in the patients with FN fractures (p = 0.003) compared with the control patients. In patients with IT fractures, the fracture risk increased 1.64-fold (p = 0.048) with a 1 sd increase of the HAL, while it increased 2.32-fold (p = 0.003) with a 1 sd increase of the NSA. In FN fractures, the fracture risk increased 2.03-fold (p = 0.012) with a 1 sd decrease in femoral head offset.

CONCLUSIONS

Our study showed that some PFG parameters as well as BMD values predict hip fractures in a Korean population, and their evaluation may be useful in the understanding of the biomechanics of hip fractures.

The differences of femoral neck geometric parameters: effects of age, gender and race

This study aims at investigating the effects of age, sex, and ethnicity on five femoral neck geometric parameters (FNGPs): femoral neck periosteal diameter, cross-sectional area, cortical thickness, sectional modulus, and buckling ratio and found that the three factors would influence the FNGPs.

INTRODUCTION

Bone geometry is one of the most important predictors of bone strength and osteoporotic fractures. This study aims at investigating the effects of age, sex, and ethnicity on five femoral neck geometric parameters (FNGPs): femoral neck periosteal diameter (W), cross-sectional area (CSA), cortical thickness (CT), sectional modulus (Z), and buckling ratio (BR).

METHODS

In the studied 861 Caucasian subjects and 3,021 Chinese individuals, CSA, CT, and Z displayed trends of decrease with age, but W and BR showed increasing trends with age in both Chinese and Caucasian females and males (p < 0.05). W, CSA, CT, and Z were significantly higher (p <or= 0.001) in Caucasians than in Chinese and higher in males than in females except for BR between Chinese males and Chinese females.

CONCLUSION

In conclusion, the differences of FNGPs according to gender and ethnicity provide important implications in the different prevalence of osteoporotic fracture among different gender and ethnic groups.

The effect of telomere length, a marker of biological aging, on bone mineral density in elderly population

Telomere length (TL), as a reflection of aging and inflammatory processes, may be associated with bone mineral density (BMD). This study examines the association between TL and BMD cross-sectionally and the rate of bone loss over a 4-year period in 1,867 Chinese elderly community living subjects. After adjusting for confounding factors, no association was observed with BMD or bone loss. The decline in BMD with aging is not reflected by corresponding changes in telomere length.

INTRODUCTION

Bone mineral density (BMD) is influenced by the dynamics of aging, inflammatory, and bone remodeling processes. Telomere length (TL) is a reflection of the former two processes and may also be associated with bone loss.

METHODS

Hip BMD was measured in 1,867 Chinese elderly community living subjects and the relationship between leukocyte TL measured using quantitative real-time polymerase chain reaction, and bone loss after 4 years was examined.

RESULTS

Women had greater bone loss than men. In women, age of menopause, menarche, estrogen treatment/replacement therapy, and history of previous fracture were also among the significant covariates. However, in multivariate analyses, TL was not associated with BMD in either sex.

CONCLUSIONS

TL was not associated with either baseline BMD or bone loss over 4 years and accounted for less than 1.6% of the baseline BMD.

A comparative study between corresponding structural geometric variables using 2 commonly implemented hip structural analysis algorithms applied to dual-energy X-ray absorptiometry images

Hip structural analysis (HSA) has been developed over 20 yr, applied extensively in research, and has demonstrated useful outcomes associating bone structural geometry with bone fragility (research-HSA or r-HSA). In 2007, Hologic Inc. (Bedford, MA) incorporated HSA with some modifications as an option for Hologic dual-energy X-ray absorptiometry (DXA) scanners (clinical HSA or c-HSA). This brought HSA from the research environment into the clinical environment. This article reports a comparison of r-HSA and c-HSA implementations using DXA scans from a group of 191 females. Bland-Altman plots at the narrow-neck (NN) HSA region indicated higher r-HSA areal bone mineral density (mean difference: 0.27 g/cm(2); 21.7% [of mean]); cross-sectional area (0.63 cm(2); 18.7%); cross-sectional moment of inertia (0.26 cm(4); 11.1%), and section modulus (0.22 cm(3); 14.5%) compared with c-HSA. The converse was observed for NN subperiosteal width (-0.09 cm; 3.1%). High linear correlations (r(2) > 0.81) were found between r-HSA and c-HSA NN structural geometric outcomes, with the exception of neck shaft angle (r(2) > 0.47). As differences were significant (p < 0.001), slopes and intercepts are provided to enable linear transformations from r-HSA to corresponding c-HSA structural geometric data.

Does obesity really make the femur stronger? BMD, geometry, and fracture incidence in the women's health initiative-observational study

Heavier individuals have higher hip BMD and more robust femur geometry, but it is unclear whether values vary in proportion with body weight in obesity. We studied the variation of hip BMD and geometry across categories of body mass index (BMI) in a subset of postmenopausal non-Hispanic whites (NHWs) from the Women's Health Initiative Observational Cohort (WHI-OS). The implications on fracture incidence were studied among NHWs in the entire WHI-OS. Baseline DXA scans of hip and total body from 4642 NHW women were divided into BMI (kg/m(2)) categories: underweight (<18.5), healthy weight (18.5-24.9), overweight (25-29.9), and mild (30-34.9), moderate (35-39.9), and extreme obesity (>40). Femur BMD and indices of bone axial (cross-sectional area [CSA]) and bending strength (section modulus [SM]) were extracted from DXA scans using the hip structure analysis (HSA) method and compared among BMI categories after adjustment for height, age, hormone use, diabetes, activity level, femur neck-shaft angle, and neck length. The association between BMI and incident fracture was studied in 78,013 NHWs from the entire WHI-OS over 8.5 +/- 2.6 (SD) yr of follow-up. Fracture incidence (cases/1000 person-years) was compared among BMI categories for hip alone, central body (hip, pelvis, spine, ribs, and shoulder girdle), upper extremity (humerus and distal), and lower extremity (femur shaft and distal but not hip). Femur BMD, CSA, and SM were larger in women with higher BMI, but values scaled in proportion to lean and not to fat or total body mass. Women with highest BMI reported more falls in the 12 mo before enrollment, more prevalent fractures, and had lower measures of physical activity and function. Incidence of hip fractures and all central body fractures declined with BMI. Lower extremity fractures distal to the hip trended upward, and upper extremity incidence was independent of BMI. BMD, CSA, and SM vary in proportion to total body lean mass, supporting the view that bones adapt to prevalent muscle loads. Because lean mass is a progressively smaller fraction of total mass in obesity, femur BMD, CSA, and SM decline relative to body weight in higher BMI categories. Traumatic forces increase with body weight, but fracture rates at the hip and central body were less frequent with increasing BMI, possibly because of greater soft tissue padding. There was no evident protective effect in fracture rates at less padded distal extremity sites. Upper extremity fractures showed no variation with BMI, and lower extremity fracture rates were higher only in the overweight (BMI = 25-29.9 kg/m(2)).

Race and sex differences in bone mineral density and geometry at the femur

INTRODUCTION

Differences in osteoporotic hip fracture incidence between American whites and blacks and between women and men are considered to result, in part, from differences in bone mineral density and geometry at the femur. The aim of this study was to quantify differences in femoral bone density and geometry between a large sample of healthy American white and black women and men.

SUBJECTS AND METHODS

Healthy American white (n=612) and black (n=164) premenopausal women, aged 23 to 57 years, and healthy American white (n=492) and black (n=169) men, aged 20 to 63 years, had volumetric bone mineral density (vBMD) and geometry variables measured at the femur by computerized tomography (CT), and areal bone mineral density (aBMD) at femoral neck measured by dual X-ray absorptiometry (DXA).

RESULTS

American blacks had higher vBMD at the femoral neck and femoral shaft cortex than American whites whereas femoral axis length and femoral neck area were not different. Men had lower vBMD at the femoral neck and femoral cortex than women but had greater femoral axis length and femoral neck area than women. The higher aBMD in American blacks than whites persisted after correction for measured area whereas the higher aBMD in men than women disappeared.

CONCLUSIONS

At the femoral neck, American whites have lower bone density than American blacks but similar geometry. Women have higher bone density than men in both races but have smaller geometry variables. The differences in bone density may account in part for the differences in hip fracture incidence between American blacks and whites, whereas the differences in femur size may account for the differences in hip fracture rates between men and women.

High-resolution pQCT analysis at the distal radius and tibia discriminates patients with recent wrist and femoral neck fractures

We depict a fragility bone state in two primitive osteoporosis populations using 3D high-resolution peripheral in vivo QCT (HR-pQCT). Postmenopausal women (C, controls, n = 54; WF, wrist, n = 50; HF, hip, n = 62 recent fractured patients) were analyzed for lumbar and hip DXA areal BMD (aBMD), cancellous and cortical volumetric BMD (vBMD), and microstructural and geometric parameters on tibia and radius by HR-pQCT. Principal component analysis (PCA) allowed extracting factors that best represent bone variables. Comparison between groups was made by analysis of covariance (ANCOVA). Two factors (>80% of the entire variability) are extracted by PCA: at the radius, the first is a combination of trabecular parameters and the second of cortical parameters. At the tibia, we found the reverse. Femoral neck aBMD is decreased in WF (8.6%) and in HF (18%) groups (no lumbar difference). WF showed a approximately 20% reduction in radius trabecular vBMD and number. Radius cortical vBMD and thickness decrease by 6% and 14%, respectively. At the tibia, only the cortical compartment is affected, with approximately 20% reduction in bone area, thickness, and section modulus and 6% reduction in vBMD. HF showed same radius trabecular alterations than WF, but radius cortical parameters are more severely affected than WF with reduced bone area (25%), thickness (28.5%), and vBMD (11%). At the tibia, trabecular vBMD and number decrease by 26% and 17.5%, respectively. Tibia cortical bone area, thickness, and section modulus showed a >30% decrease, whereas vBMD reduction reached 13%. Geometry parameters at the tibia displayed the greatest differences between healthy and fractured patients and between wrist and hip fractures.