Determinants of forearm strength in postmenopausal XXXX .

@entity1 @entity251 @entity174 @entity53 @entity134 @entity230
Bone strength at the ultradistal radius, quantified by micro-finite element modeling, can be predicted by variables obtained from high-resolution peripheral quantitative computed tomography scans. The specific formula for this bone strength surrogate (-555.2 + 8.1   [trabecular vBMD] + 19.6   [cortical area] + 4.2   [total cross-sectional area]) should be validated and tested in @entity174 risk assessment. INTRODUCTION: The purpose of this study was to identify key determinants of ultradistal radius (UDR) strength and evaluate their relationships with age, sex @entity134 levels, and measures of habitual skeletal loading. METHODS: UDR failure load (~strength) was assessed by micro-finite element ( FE) modeling in 105 postmenopausal controls from an earlier @entity174 case-control study. Predictors of bone strength obtained by high-resolution peripheral quantitative computed tomography (HRpQCT) in this group were then evaluated in a population-based cohort of 214 postmenopausal @entity1 . Sex @entity230 were measured by mass spectrometry. RESULTS: A surrogate variable (-555.2 + 8.1   [trabecular vBMD] + 19.6   [cortical area] + 4.2   [total cross-sectional area]) predicted UDR strength modeled by  FE (R(2) = 0.81), and all parameters except total cross-sectional area declined with age. Evaluated cross-sectionally, the 21% fall in predicted bone strength between ages 40-49 years and 80+ years more resembled the change in trabecular volumetric bone mineral density (vBMD) (-15%) than that in cortical area (-41%). In multivariable analyses, measures of body composition and physical activity were stronger predictors of UDR trabecular vBMD, cortical area, total cross-sectional area, and predicted bone strength than were sex @entity134 levels, but bio-available @entity53 and @entity251 were correlated with body mass. CONCLUSIONS: Bone strength at the UDR, as quantified by  FE, can be predicted from variables obtained by HRpQCT. Predicted bone strength declines with age with changes in UDR trabecular vBMD and cortical area, related in turn to reduced skeletal loading and sex @entity134 levels. The predicted bone strength formula should be validated and tested in @entity174 risk assessment.
