Geometric Indices of Bone Strength Are Associated With Physical Activity and Dietary Calcium Intake in Healthy Older Women

Abstract

A population-based study on 1008 postmenopausal women identified that the 24% of women achieving high levels of PA and CI had 3.4-4.4% higher femoral bone strength in axial compression and 1.7-5.2% in bending than those achieving low levels, indicating that lifestyle factors influence bone strength in the proximal femur. Introduction:Extensive research has shown that increased physical activity (PA) and calcium intake (CI) decrease the rate of bone loss; however, there is little research on how these lifestyle variables affect bone geometry. This study was designed to investigate the effects of modifiable lifestyle variables, habitual PA and dietary CI, on femoral geometry in older women. Materials and Methods: Femoral geometry, habitual PA, and dietary CI were measured in a population-based sample of 1008 women (median age ± interquartile range, 75 ± 4years) enrolled in a randomized controlled trial (RCT) of calcium supplementation. Baseline PA and CI were assessed by validated questionnaires, and 1-year DXA scans (Hologic 4500A) were analyzed using the hip structural analysis technique. Section modulus (Z), an index of bending strength, cross-sectional area (CSA), an index of axial compression strength, subperiosteal width (SPW), and centroid position, the position of the center of mass, were measured at the femoral neck (NN), intertrochanter (IT), and femoral shaft (FS) sites. These data were divided into tertiles of PA and CI, and the results were compared using analysis of covariance (ANCOVA), with corrections for age, height, weight, and treatment (calcium/placebo). Results and Conclusions: PA showed a significant dose-response effect on CSA all hip sites (p < 0.03) and Z at the narrow neck and intertrochanter sites (p < 0.02). For CI, there was a dose-response effect for centroid position at the intertrochanter (p ‫ס‬ 0.03). These effects were additive, such that the women (n ‫ס‬ 240) with PA in excess of 65.5 kcal/day and CI in excess of 1039 mg/day had significantly greater CSA (NN, 4.4%; IT, 4.3%; FS, 3.4%) and Z (NN, 3.9%; IT, 5.2%). These data show a favorable association between PA and aspects of bone structural geometry consistent with better bone strength. Association between CI and bone structure was only evident in 1 of 15 variables tested. However, there was evidence that there may be additive effects, whereby women with high levels of PA and CI in excess of 1039 mg/day had significantly greater CSA (NN, 0.4%; FS, 2.1%) and Z (IT, 3.0%) than women with high PA but low CI. These data show that current public health guidelines for PA and dietary CI are not inappropriate where bone structure is the health component of interest.

Multivariate analysis of lifestyle, constitutive and body composition factors influencing bone health in community-dwelling older adults from Madeira, Portugal

“…bone strength index) measures of bone strength and PA in older adults populations. However, similar to our findings, Nurzenski et al (2007) and Uusi-Rasi, Sievä nen, Pasanen, Beck, and Kannus (2008) reported significant positive associations between aspects of femoral bone geometry and PA in older adults females, whereas there is only one report to our knowledge (Semanick et al, 2005), which likewise, indicated a weak positive relationship between walking and FN section modulus in older adults men.…”

Comparison of QCT-derived and DXA-derived areal bone mineral density and T scores

“…These structural geometrical variables, demonstrated to be useful in the understanding of bone fragility, are also available from analysis of DXA hip images [14].…”

Evaluation of Proximal Femoral Geometry in Plain Anterior-Posterior Radiograph in Eastern-Indian Population

“…In their study Chaubber & Singh showed higher value of various parameters on left side than that of right, as whether a person is right handed or left handed, more people use left lower limb for more weight bearing [6]. A population based study by Nurzenski et al, showed that life style factors also influence geometric indices of bone strength in the proximal femur [7]. So, to minimise post operative complications the implants should be designed by taking into account the parameters of the local population.…”