Appendicular and whole body lean mass outcomes are associated with finite element analysis-derived bone strength at the distal radius and tibia in adults aged 40years and older

Development and validation of reference equations for dual-energy X-ray absorptiometry-derived measures of fat-free mass in adults aged 45-85 years: results from the Canadian Longitudinal Study on Aging

Reference equations for fat-free mass (FFM) and lean soft tissue mass (LM) measures obtained from dual-energy X-ray absorptiometry (DEXA) are important for the interpretation of body composition. This study developed and validated reference equations for FFM and LM using DEXA from the Canadian Longitudinal Study on Aging. Reference equations were developed using data from a random population-based sample of ostensibly healthy and functionally independent adults aged 45-85 years. Reference equations for absolute (accounting for age, sex, height, and body mass) and height-adjusted aka index (accounting for age, sex, and body mass index) measures of FFM and LM were developed using quantile regression. Reference equations were respectively developed and validated in derivation (80%) and validation cohorts (20%). Reference equations were applied to symptomatic adults with self-reported chronic obstructive pulmonary disease (COPD) or heart disease to assess discriminant validity; and compared with other published equations to assess performance. Bland-Altman analyses and Lin's concordance correlation coefficients were utilised to assess agreement. Reference equations for 5th, 10th, 50th, 90th, and 95th percentiles were developed for DEXA-derived estimates of FFM and LM based on 1881 healthy participants (57% male) aged 55 [IQR: 50-61] years. Reference equations performed comparably in the validation cohort and discriminated reference values between ostensibly healthy adults and people with symptomatic COPD or heart disease. Previously published reference equations tended to over- or under-predict estimates of LM compared with the current reference equations. This study provides a comprehensive and validated set of reference equations for estimating and interpreting FFM and LM from DEXA in Canadian adults aged 45-85 years, although additional validation may be required for those >75 years.

Indices of sarcopenic obesity are important predictors of finite element analysis-derived bone strength in older adults with obesity

Background

The expanding population of older adults with obesity is a public health challenge, in part, because of the increased risk of fractures despite normal or high bone mineral density. Potential factors predisposing to fractures in this group include sarcopenia associated with obesity and impaired bone quality. We aimed to determine the contribution of sarcopenic obesity (SO) indices to bone strength as assessed by microfinite element analysis (μFEA) of high-resolution peripheral quantitative computed tomography (HR-pQCT).

Methods

One-hundred eighty-nine older (age ≥ 65 years) adults with obesity (BMI ≥ 30 kg/m2) participated in lifestyle intervention trials at our medical center. All underwent baseline measurements of bone strength (failure load and stiffness) using μFEA from HR-pQCT of the distal radius and tibia. In addition, SO indices [appendicular lean mass/weight (ALM/W) and percent body fat (FM%)] by dual-energy X-ray absorptiometry and handgrip strength (HGS) by dynamometry were assessed. SO was diagnosed and staged based on the 2022 ESPEN and EASO expert consensus statement.

Results

Both ALM/W and HGS were positively correlated explaining 28% to 36% of the variance in failure load and stiffness at the distal radius and tibia (all p < 0.001). In contrast, FM% was negatively correlated explaining 22% to 31% of the variance in failure load and stiffness at the distal radius and tibia (all p < 0.001). The associations of SO indices with failure load and stiffness remained significant after controlling for age, sex, race/ethnicity, diabetes, and 25-OH vitamin D (ALM/W: R 2 = 0.301 to 0.448, HGS: R 2 = 0.346 to 0.472, FM%: R 2 = 0.299 to 0.432) (p < 0.001 to 0.011). SO was diagnosed in 75/189 (40%) participants with 66/75 (88%) having functional or metabolic complications (stage II). Participants with SO had lower failure load and stiffness at the distal radius than participants with no SO (both p < 0.05).

Conclusion

These findings demonstrate that lower muscle mass and strength and higher fat mass may impair bone quality. Therefore, interventions that focus on preserving muscle mass and strength while reducing fat mass may be important to decrease fracture risk when older adults with obesity undertake lifestyle intervention therapy.

Examining effects of habitual physical activity and body composition on bone structure in early post-menopausal women: a pQCT analysis

After menopause, bones decline in structure and can break more easily. Physical activity can strengthen bones. This study investigated how activity and body composition can impact bone structure in post-menopausal women. Higher levels of physical activity were positively associated with bone structure at the lower leg.

PURPOSE

The menopausal transition is characterized by dramatic bone loss, leading to an increased risk of fracture. Few studies have examined how modifiable risk factors influence bone structure. Thus, the objective of this cross-sectional study was to examine the relationship between habitual physical activity (PA), body composition, and bone structure in post-menopausal women with low bone mass.

METHODS

Data was analyzed from 276 post-menopausal women with low bone mass enrolled in the Heartland Osteoporosis Prevention Study. Body composition and bone structure measures were collected using dual X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) at the tibia. Habitual PA was collected using the Human Activity Profile questionnaire. Multiple regression analysis was used to determine the relative impact of habitual PA and body composition on bone structure measures (density, area, and strength). Direct and/or indirect effects of PA on bone outcomes were assessed by path analysis.

RESULTS

Mean (± SD) age of participants was 54.5 (± 3.2) years and average BMI was 25.7 (± 4.7). Mean T-score of the total lumber spine and hip were - 1.5 (± .6) and - 0.8 (± .59), respectively, with all women classified with low bone mass. Habitual PA had a significant positive effect on bone area and strength measures at the 66% site, and trend effects at the 4% site. Lean mass had a significant positive effect on area and strength at the 66% site and 4% site. Fat mass showed no effect at the 66% site, with a positive effect on density and strength at the 4% site.

CONCLUSION

Increased habitual activity was related to improved bone structure of the tibia. Our results in post-menopausal women emphasize that PA and lean mass preservation are important for maintaining bone structure in the years following menopause.

Adiposity and bone microarchitecture in the GLOW study

Low body mass index (BMI) is an established risk factor for fractures in postmenopausal women but the interaction of obesity with bone microarchitecture is not fully understood. In this study, obesity was associated with more favourable bone microarchitecture parameters but not after parameters were normalised for body weight.

INTRODUCTION

To examine bone microarchitecture in relation to fat mass and examine both areal bone mineral density (aBMD) and microarchitecture in relation to BMI categories in the UK arm of the Global Longitudinal Study of Osteoporosis in Women.

METHODS

Four hundred and ninety-one women completed questionnaires detailing medical history; underwent anthropometric assessment; high-resolution peripheral quantitative computed tomography (HRpQCT) scans of the radius and tibia and DXA scans of whole body, proximal femur and lumbar spine. Fat mass index (FMI) residuals (independent of lean mass index) were derived. Linear regression was used to examine HRpQCT and DXA aBMD parameters according to BMI category (unadjusted) and HRpQCT parameters in relation to FMI residuals (with and without adjustment for anthropometric, demographic and lifestyle covariates).

RESULTS

Mean (SD) age was 70.9 (5.4) years; 35.0% were overweight, 14.5% class 1 obese and 7.7% class 2/3 obese. There were significant increasing trends according to BMI category in aBMD of whole body, hip, femoral neck and lumbar spine (p ≤ 0.001); cortical area (p < 0.001), thickness (p < 0.001) and volumetric density (p < 0.03), and trabecular number (p < 0.001), volumetric density (p < 0.04) and separation (p < 0.001 for decreasing trend) at the radius and tibia. When normalised for body weight, all HRpQCT and DXA aBMD parameters decreased as BMI increased (p < 0.001). FMI residuals were associated with bone size and trabecular architecture at the radius and tibia, and tibial cortical microarchitecture.

CONCLUSION

Significant trends in HRpQCT parameters suggested favourable bone microarchitecture at the radius and tibia with increasing BMI but these were not proportionate to increased weight.

Differences in Trabecular Plate and Rod Structure in Premenopausal Women Across the Weight Spectrum

CONTEXT

Premenopausal women with anorexia nervosa (AN) and obesity (OB) have elevated fracture risk. More plate-like and axially aligned trabecular bone, assessed by individual trabeculae segmentation (ITS), is associated with higher estimated bone strength. Trabecular plate and rod structure has not been reported across the weight spectrum.

OBJECTIVE

To investigate trabecular plate and rod structure in premenopausal women.

DESIGN

Cross-sectional study.

SETTING

Clinical research center.

PARTICIPANTS

A total of 105 women age 21 to 46 years: (i) women with AN (n = 46), (ii) eumenorrheic lean healthy controls (HCs) (n = 29), and (iii) eumenorrheic women with OB (n = 30).

MEASURES

Trabecular microarchitecture by ITS.

RESULTS

Mean age (±SD) was similar (28.9 ± 6.3 years) and body mass index differed (16.7 ± 1.8 vs 22.6 ± 1.4 vs 35.1 ± 3.3 kg/m2; P < 0.0001) across groups. Bone was less plate-like and axially aligned in AN (P ≤ 0.01) and did not differ between OB and HC. After controlling for weight, plate and axial bone volume fraction and plate number density were lower in OB vs HC; some were lower in OB than AN (P < 0.05). The relationship between weight and plate variables was quadratic (R = 0.39 to 0.70; P ≤ 0.0006) (i.e., positive associations were attenuated at high weight). Appendicular lean mass and IGF-1 levels were positively associated with plate variables (R = 0.27 to 0.67; P < 0.05). Amenorrhea was associated with lower radial plate variables than eumenorrhea in AN (P < 0.05).

CONCLUSIONS

In women with AN, trabecular bone is less plate-like. In women with OB, trabecular plates do not adapt to high weight. This is relevant because trabecular plates are associated with greater estimated bone strength. Higher muscle mass and IGF-1 levels may mitigate some of the adverse effects of low weight or excess adiposity on bone.

Interaction of body fat percentage and height with appendicular functional muscle-bone unit

The interaction of body fat percentage and height with appendicular BMC for LBM was analyzed. Only body fat had significant negative correlation with the appendicular BMC for LBM.

PURPOSE/INTRODUCTION

For the clinical evaluation of the functional muscle-bone unit, it was proposed to evaluate the adaptation of the bone to the acting forces. A frequently used parameter for this is the total body less head bone mineral content (TBLH-BMC) determined by dual-energy X-ray absorptiometry (DXA) in relation to the total body lean body mass (LBM). Body fat percentage seemed to correlate negatively and height positively with TBLH-BMC for LBM. It was supposed that appendicular BMC for LBM is a more accurate surrogate for the functional muscle-bone unit since appendicular LBM does not incorporate the mass of internal organs. The aim of this study was to analyze the interaction of body fat percentage and height with appendicular BMC for LBM.

METHODS

As part of the National Health and Nutrition Examination Survey (NHANES) study, between the years 1999 and 2004, whole-body DXA scans on randomly selected Americans from 8 years of age were carried out. From all eligible DXA scans, three major US ethnic groups were evaluated (non-Hispanic Whites, non-Hispanic Blacks, and Mexican Americans) for further statistical analysis.

RESULTS

For the statistical analysis, the DXA scans of 8190 non-Hispanic White children and adults (3903 female), of 4931 non-Hispanic Black children and adults (2250 female), and 5421 of Mexican American children and adults (2424 female) were eligible. Only body fat had a significant negative correlation with the appendicular BMC for LBM.

CONCLUSIONS

Only body fat had significant negative correlation with appendicular BMC for LBM, and thus, should be addressed when evaluating functional muscle-bone unit.