J Bone Miner Res, 2018; 33(4): 580-588, PMID: 29083059

Do Visceral or Subcutaneous Fat Influence Peripheral Cortical Bone Strength During Adolescence? A Longitudinal Study.

Year: 2018

Glass NA, Torner JC, Letuchy EM, Burns TL, Janz KF, Eichenberger Gilmore JM, Schlechte JA, Levy SM
Department of Orthopaedic Surgery, The University of Iowa Hospitals & Clinics.

Abstract

This study evaluated the longitudinal relationships among visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and peripheral bone strength during adolescence. Fat and lean mass, VAT and SAT area and android/gynoid (A/G) ratio were estimated with DXA. Our main outcome was strength-strain index (SSI), an indicator of peripheral bone strength estimated by pQCT at the radius and tibia. Sex-specific analyses evaluated the longitudinal bone-fat relationship from ages 11-19 years with linear mixed models using biological age as the time variable and adjusted for limb length and lean mass in 182 girls and 167 boys. Variables were standardized (mean=0, SD=1) prior to model fitting and results shown are parameter estimates+/-SE. Fat mass and SAT were positively associated with SSI (radius: 0.07+/-0.02, p=0.003;0.05+/-0.02, 0.041, respectively; tibia:0.09+/-0.02, p<0.001;0.08+/-0.02, p<0.001, respectively) prior to, but not following adjustment for lean mass in girls. In contrast, fat mass and SAT were negatively associated with radial SSI, both before and after adjustment for lean mass in boys (fat mass:-0.05+/-0.01, p=0.001; SAT:-0.04+/-0.01, p=0.004). In full models, negative associations were limited to VAT in girls and included radial (-0.06+/-0.02, p=0.001) and tibial SSI (-0.04+/-0.02, p=0.033). For boys, there were no significant associations present between VAT and SSI at the radius or tibia. In analyses limited to obese participants, an A/G ratio was not significantly associated with SSI in girls, but was negatively associated with radial SSI regardless of adjustment for lean mass in boys (-0.06+/-0.02, p=0.018). These results that show a negative relationship between peripheral bone strength and VAT in girls, but greater total and central adiposity in boys, suggest these factors play a role in adequate acquisition of bone strength during adolescence. This article is protected by copyright. All rights reserved.

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