Sexual dimorphism of femoral neck cross-sectional bone geometry in athletes and non-athletes: a hip structural analysis study

Femora of women with premature ovarian insufficiency exhibit reduced strength and misalignment with the transmitted vertical forces from the upper body

BACKGROUND

Women with premature ovarian insufficiency (POI) lack oestrogen, which is a key determinant of bone growth, epiphyseal closure, and bone tissue organisation. Although dual-energy X-ray absorptiometry (DXA)-derived areal bone mineral density (BMD) remains the gold standard for fracture risk evaluation, it does not fully characterise the skeletal abnormalities present in these women. Hence, we aimed to assess hip/femur anatomy, strength, and geometry and femoral alignment using advanced hip analysis (AHA).

METHODS

We conducted a cross-sectional, case-control study including 89 women with spontaneous normal karyotype POI (s-POI) or iatrogenic POI (i-POI), aged 20-50 years compared with 89 age- and body mass index (BMI)-matched population-based female controls. Hip anatomy, strength, geometrical parameters, and femur alignment were measured using hip DXA images and Lunar AHA software. Femoral orientation angle (FOA) was quantified as the overall orientation of the femur with respect to the axis of the forces transmitted from the upper body.

RESULTS

The median age of POI diagnosis was 35 (18-40) years; the mean POI duration at the time of DXA was 2.07 (range 0-13) years, and 84% of POI women received oestrogen therapy. Areal BMD at all sites was significantly lower in the POI group (all P < .05). Indices of compressive and bending strength were lower in women with POI compared with controls, specifically the cross-sectional area (CSA, mm2) and section modulus (SM, mm3) (139.30 ± 29.08 vs 157.29 ± 22.26, P < .001 and 665.21 ± 129.54 vs 575.53 ± 150.88, P < .001, respectively). The FOA was smaller (124.99 ± 3.18) in women with POI as compared with controls (128.04 ± 3.80; P < .001) at baseline and after adjusting for height and femoral neck BMD.

CONCLUSION

Alongside lower BMD at multiple sites, the femora of women with POI demonstrate reduced strength and a misalignment with forces transmitted from the upper body. Further research is needed to establish the role of these newly identified features and their role in fracture risk prediction in this population.

New Insights on Bone Tissue and Structural Muscle-Bone Unit in Constitutional Thinness

While few studies pointed out low bone mineral densities in constitutionally thin women, little is known about potential explanations. The objective was to further explore bone architecture in both women and men with constitutional thinness to investigate their mechanical muscle-bone coupling (or uncoupling). Thirty constitutionally thin people and 31 normal weight controls participated in the study. Body composition, hip structural analysis, and trabecular bone score were assessed by dual-energy X-ray absorptiometry, bone architecture using high-resolution peripheral quantitative computed tomography, and muscle explorations through histological staining on muscle biopsies. Thirty-two out of the 48 indexes relative to density, geometry, texture, and architecture of bones were found significantly lower (p < 0.05) in constitutionally thin individuals compared with controls. This observation was particularly pronounced in constitutionally thin men. Bone microarchitecture was more altered in weight-supporting bone (tibia) than in non-weight-supporting (radius) bone, which might refer to a normal physiological adaptation (Frost’s mechanostat theory). Yet, the heat-maps of correlations analyses showed many alterations of body weight or muscle associations with bone parameters in constitutionally thin individuals contrary to controls. Present results might support the idea of intrinsic disturbances of bone cells independently to the small muscle structure, particularly in men.

Bone mineral density and hip structure changes over one-year in collegiate distance runners and non-athlete controls

Modification of bone is continuous throughout life and influenced by many factors, including physical activity. This study investigated changes in areal bone mineral density (aBMD) and hip structure among male and female collegiate distance runners and non-athlete controls over 12 months. Using dual-energy x-ray absorptiometry (DXA) and hip structure analysis (HSA) software, aBMD at the posterior-anterior (PA) and lateral spine, femoral neck, total hip (TH), whole body (WB), and bone geometry at the narrow neck (NN) of the femur was measured three times over 12 months. HSA included cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and Z-section modulus (Z). Male runners had significantly higher aBMD at TH and WB and greater CSA, CSMI, and Z than male controls at the end of 12 months. Female controls had higher aBMD at the PA spine than female runners at the end of 12 months. Male runners had significant increases in aBMD at the PA (p = 0.003) and lateral spine (p = 0.002), and TH (p = 0.002), female runners had significant decreases in aBMD at TH (p = 0.015) and WB (p = 0.002), male controls had significant increases in aBMD at the PA spine (p < 0.001) and WB (p < 0.001), and female controls had significant decreases in aBMD at lateral spine and TH (p = 0.008) over the year. When applying covariates of bone-free lean mass and vitamin D, male distance runners demonstrated significant improvement in CSA (3.602 ± 0.139 vs. 3.675 ± 0.122 cm², p = 0.05), CSMI (3.324 ± 0.200 to 3.467 ± 0.212 cm⁴, p < 0.05), and Z (1.81 ± 0.08 to 1.87 ± 0.08 cm³, p = 0.05) during the study. No other changes in hip structure occurred over the year. Distance running may be beneficial to aBMD and hip structure in college-age males but not females. Further research is needed on potential influences of weight-bearing activity, energy availability, and hormonal status on aBMD and hip structure in males and females.

Sex-specific relationship between vascular calcification and incident fracture in patients with end-stage renal disease

Background

Vascular calcification (VC) is a major component of mineral bone disorders in patients with end-stage renal disease (ESRD). Bone metabolism is affected by various factors, including sex hormones. This study investigated whether there was a sex-specific relationship between VC and incident fracture in patients with ESRD.

Methods

This was a retrospective cohort study of dialysis patients from a single center. VC was assessed by the aortic calcification index (ACI) using abdominal computed tomography. Patients were grouped by sex and stratified into low or high ACI groups, according to the median ACI value. The association between ACI and incident fracture was analyzed.

Results

Data from 593 patients (male n = 328, median ACI, 14.57; female n = 265, median ACI, 19.44) were included. During a median follow-up of 36.7 months, 71 patients (12.0%) developed fractures. The fracture-free survival rate was significantly lower in the high ACI group versus the low ACI group, both in males (P = 0.021) and females (P = 0.001). In males, multivariate analysis showed that the high ACI group and ACI per se were not significant risks for fracture. However, in females, both the high ACI group (adjusted hazard ratio, 2.720; P = 0.003) and ACI per se (adjusted hazard ratio, 1.768; P = 0.035) were independently associated with fracture after adjustment for confounding variables.

Conclusion

VC was independently associated with incident fracture in female patients with ESRD. There may be a sex-specific relationship between VC and fracture in patients with ESRD.

Impact of sleeve gastrectomy on hip structural analysis in adolescents and young adults with obesity

BACKGROUND

Sleeve gastrectomy (SG), the most commonly performed metabolic and bariatric surgery, is associated with reductions in areal bone mineral density at multiple sites, and changes in bone structure at the distal radius and tibia without reductions in strength estimates at these peripheral sites. Data are lacking regarding effects on hip strength estimates.

OBJECTIVE

To evaluate effects of SG on measures of hip structural analysis in adolescents and young adults over 12 months using dual-energy x-ray absorptiometry.

SETTINGS

Translational and Clinical Research Center.

METHODS

We enrolled 48 youth 14- to 22-years old with moderate-to-severe obesity; 24 underwent SG and 24 controls were followed without surgery (18 females, 6 males in each group). Hip structure was assessed using dual-energy x-ray absorptiometry at baseline and 12 months. Analyses are adjusted for age, sex, race, and the baseline bone measure.

RESULTS

The SG group lost 25.9% weight versus .3% in controls. Compared with controls, SG had reductions in narrow neck, intertrochanteric and femoral shaft bone mineral density Z-scores (P ≤ .012). Furthermore, SG had greater reductions in narrow neck and intertrochanteric region (but not femoral shaft) cross-sectional area, cortical thickness, cross-sectional moment of inertia and section modulus, and increases in buckling ratio (P ≤ .039). Differences were attenuated after adjusting for 12-month body mass index change. At 12 months, differences were minimal after adjusting for age, sex, race, and weight.

CONCLUSIONS

Over 12 months, SG had negative effects at the narrow neck and intertrochanteric regions of the hip, but not the femoral shaft. Reduced body mass index may compensate for these deleterious effects on bone.

Epidemiology of fractures in the United Kingdom 1988-2012: Variation with age, sex, geography, ethnicity and socioeconomic status

Rates of fracture worldwide are changing. Using the Clinical Practice Research Datalink (CPRD), age, and gender, geographical, ethnic and socioeconomic trends in fracture rates across the United Kingdom were studied over a 24-year period 1988-2012. Previously observed patterns in fracture incidence by age and fracture site were evident. New data on the influence of geographic location, ethnic group and socioeconomic status were obtained.

INTRODUCTION

With secular changes in age- and sex-specific fracture incidence observed in many populations, and global shifts towards an elderly demography, it is vital for health care planners to have an accurate understanding of fracture incidence nationally. We aimed to present up to date fracture incidence data in the UK, stratified by age, sex, geographic location, ethnicity and socioeconomic status.

METHODS

The Clinical Practice Research Datalink (CPRD) contains anonymised electronic health records for approximately 6.9% of the UK population. Information comes from General Practitioners, and covers 11.3 million people from 674 practices across the UK, demonstrated to be representative of the national population. The study population consisted of all permanently registered individuals aged ≥18years. Validated data on fracture incidence were obtained from their medical records, as was information on socioeconomic deprivation, ethnicity and geographic location. Age- and sex-specific fracture incidence rates were calculated.

RESULTS

Fracture incidence rates by age and sex were comparable to those documented in previous studies and demonstrated a bimodal distribution. Substantial geographic heterogeneity in age- and sex adjusted fracture incidence was observed, with rates in Scotland almost 50% greater than those in London and South East England. Lowest rates of fracture were observed in black individuals of both sexes; rates of fragility fracture in white women were 4.7 times greater than in black women. Strong associations between deprivation and fracture risk were observed in hip fracture in men, with a relative risk of 1.3 (95% CI 1.21-1.41) in Index of Multiple Deprivation category 5 (representing the most deprived) compared to category 1.

CONCLUSIONS

This study presents robust estimates of fracture incidence across the UK, which will aid decisions regarding allocation of healthcare provision to populations of greatest need. It will also assist the implementation and design of strategies to reduce fracture incidence and its personal and financial impact on individuals and health services.

Insights into relationships between body mass, composition and bone: findings in elite rugby players

Recent reports indicate that bone strength is not proportional to body weight in obese populations. Elite rugby players have a similar body mass index (BMI) to obese individuals but differ markedly with low body fat, high lean mass, and frequent skeletal exposure to loading through weight-bearing exercise. The purpose of this study was to determine relationships between body weight, composition, and bone strength in male rugby players characterized by high BMI and high lean mass. Fifty-two elite male rugby players and 32 nonathletic, age-matched controls differing in BMI (30.2 ± 3.2 vs 24.1 ± 2.1 kg/m²; p = 0.02) received 1 total body and one total hip dual-energy X-ray absorptiometry scan. Hip structural analysis of the proximal femur was used to determine bone mineral density (BMD) and cross-sectional bone geometry. Multiple linear regression was computed to identify independent variables associated with total hip and femoral neck BMD and hip structural analysis-derived bone geometry parameters. Analysis of covariance was used to explore differences between groups. Further comparisons between groups were performed after normalizing parameters to body weight and to lean mass. There was a trend for a positive fat-bone relationship in rugby players, and a negative relationship in controls, although neither reached statistical significance. Correlations with lean mass were stronger for bone geometry (r(2): 0.408-0.520) than for BMD (r(2): 0.267-0.293). Relative to body weight, BMD was 6.7% lower in rugby players than controls (p < 0.05). Rugby players were heavier than controls, with greater lean mass and BMD (p < 0.01). Relative to lean mass, BMD was 10%-14.3% lower in rugby players (p < 0.001). All bone geometry measures except cross-sectional area were proportional to body weight and lean mass. To conclude, BMD in elite rugby players was reduced in proportion to body weight and lean mass. However, their superior bone geometry suggests that overall bone strength may be adequate for loading demands. Fat-bone interactions in athletes engaged in high-impact sports require further exploration.

Hip structural analysis in adolescent boys with anorexia nervosa and controls

CONTEXT

We have reported lower hip bone mineral density (BMD) in adolescent boys with anorexia nervosa (AN) compared with controls. Although studies have described bone structure in girls with AN, these data are not available for boys. Hip structural analysis (HSA) using dual-energy x-ray absorptiometry is a validated technique to assess hip geometry and strength while avoiding radiation associated with quantitative computed tomography.

OBJECTIVE

We hypothesized that boys with AN would have impaired hip structure/strength (assessed by HSA) compared with controls.

DESIGN AND SETTING

We conducted a cross-sectional study at a clinical research center.

SUBJECTS AND INTERVENTION

We used HSA techniques on hip dual-energy x-ray absorptiometry scans in 31 previously enrolled boys, 15 with AN and 16 normal-weight controls, 12 to 19 years old.

RESULTS

AN boys had lower body mass index SD score (P < .0001), testosterone (P = .0005), and estradiol (P = .006) than controls. A larger proportion of AN boys had BMD Z-scores <-1 at the femoral neck (60% vs 12.5%, P = 0008). Using HSA, at the narrow neck and trochanter region, boys with AN had lower cross-sectional area (P = .03, 0.02) and cortical thickness (P = .02, 0.03). Buckling ratio at the trochanter region was higher in AN (P = .008). After controlling for age and height, subperiosteal width at the femoral shaft, cross-sectional moment of inertia (narrow neck and femoral shaft), and section modulus (all sites) were lower in AN. The strongest associations of HSA measures were observed with lean mass, testosterone, and estradiol. On multivariate analysis, lean mass remained associated with most HSA measures.

CONCLUSIONS

Boys with AN have impaired hip geometric parameters, associated with lower lean mass.

Hip structural analysis in adolescent and young adult oligoamenorrheic and eumenorrheic athletes and nonathletes

CONTEXT

Stress fractures are common in endurance athletes. Whereas studies have described distal tibia bone structure in athletes, there are few data regarding hip geometric parameters. Hip structural analysis (HSA) using dual-energy x-ray absorptiometry is a validated technique to assess hip bone structure.

OBJECTIVES

The purpose of this study was to compare hip geometry in young oligoamenorrheic athletes (AAs), eumenorrheic athletes (EAs), and nonathletes using HSA. We hypothesized that AAs would have impaired bone structure compared with that of EAs.

DESIGN

This was a cross-sectional study.

SETTING

The setting was a clinical research center.

SUBJECTS

We enrolled 55 AAs, 24 EAs, and 23 nonathletes of normal weight who were 14 to 22 years old. Athletes ran ≥20 miles/wk or were engaged in weight-bearing sports for ≥4 hours/wk.

MAIN OUTCOME MEASURES

Dual-energy x-ray absorptiometry was used for HSA and hip areal bone mineral density (aBMD).

RESULTS

Hip aBMD Z-scores were lower in AAs and in nonathletes than in EAs (P = .002). A larger proportion of AAs than EAs and nonathletes had hip Z-scores <-1 (30.9, 4.2, 17.4%, P = .01). At the narrow neck, trochanteric region, and femoral shaft, subperiosteal width, cross-sectional moment of inertia, and section modulus were higher in EAs than in nonathletes; values in AAs did not differ from those of nonathletes. Cross-sectional area was lower in AAs and in nonathletes than in EAs. Groups did not differ for cortical thickness or buckling ratio. Group differences were lost after adjustment for lean mass but not aBMD.

CONCLUSIONS

In an eugonadal state, athletic activity confers benefits for hip structure independent of aBMD. This advantage is lost in AAs, who do not differ from nonathletes for most parameters and fare worse than EAs for cross-sectional area.

The multicomponent anthropometric model for assessing body composition in a male pediatric population: a simultaneous prediction of fat mass, bone mineral content, and lean soft tissue

The aim of this study was to propose and cross-validate an anthropometric model for the simultaneous estimation of fat mass (FM), bone mineral content (BMC), and lean soft tissue (LST) using DXA as the reference method. A total of 408 boys (8-18 years) were included in this sample. Whole-body FM, BMC, and LST were measured by DXA and considered as dependent variables. Independent variables included thirty-two anthropometrics measurements and maturity offset determined by the Mirwald equation. From a multivariate regression model ((n)Y(m) = (n)x(r + 1)(r + 1)β(m) + (n)ε(m)), a matrix analysis was performed resulting in a multicomponent anthropometric model. The cross-validation was executed through the sum of squares of residuals (PRESS) method. Five anthropometric variables predicted simultaneously FM, BMC, and LST. Cross-validation parameters indicated that the new model is accurate with high R(PRESS)(2) values ranging from 0.94 to 0.98 and standard error of estimate ranging from 0.01 to 0.09. The newly proposed model represents an alternative to accurately assess the body composition in male pediatric ages.