J Bone Miner Res, 2016; 31(7): 1455-65, PMID: 26861036

The Relationship between Greater Pre-Pubertal Adiposity, Subsequent Age of Maturation and Bone Strength During Adolescence.

Year: 2016

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

Abstract

This longitudinal study investigated whether greater pre-pubertal adiposity was associated with subsequent timing of maturation and bone strength during adolescence in 135 girls and 123 boys participating in the Iowa Bone Development Study. Greater adiposity was defined using BMI data at age 8 years to classify participants as overweight (OW, >/=85th percentile for age and sex) or healthy-weight, HW). Maturation was defined as the estimated age of peak height velocity (PHV) based on a series of cross-sectional estimates. Measurements were taken at ages 11, 13, 15 and 17 years for estimates of body composition by DXA, bone compression (bone strength index) and torsion strength (polar strength-strain index) at the radius and tibia by pQCT, and femoral neck bending strength (section modulus) by hip structural analysis. Bone strength in OW versus HW were evaluated by fitting sex-specific linear mixed models that included centered age (visit age - grand mean age of cohort) as the time variable and adjusted for change in fat mass, and limb length in Model 1. Analyses were repeated using biological age (visit age - age PHV) as the time variable for Model 1 with additional adjustment for lean mass in Model 2. BMI was negatively associated with age of maturation (p < 0.05). OW versus HW girls had significantly greater bone strength (p < 0.001) in Model 1, while OW versus HW boys had significantly greater bone strength (p < 0.001) at the tibia and femoral neck, but not radius (p > 0.05). Analyses were repeated using biological age, which yielded reduced parameter estimates for girls but similar results for boys (Model 1.) Differences were no longer present following adjustment for lean mass (Model 2) in girls (p > 0.05) while differences at the tibia were sustained in boys (p < 0.05). These findings demonstrate sex- and site-specific differences in the associations between adiposity, maturation and bone strength. This article is protected by copyright. All rights reserved.

Keywords: Bone-fat interactions; Bone QCT; Osteoporosis; General population study; DXA
GID: 4089; Last update: 16.02.2016