Original Article Geometric Indices of Hip Bone Strength in Obese, Overweight, and Normal-Weight Adolescent Girls Rawad El Hage, * ,1,2 Zaher El Hage, 1 Elie Moussa, 1 Christophe Jacob, 1 Gautier Zunquin, 2 and Denis Theunynck 2 1 Department of Physical Education, Laboratoire de Physiologie et de Biom ecanique de la Performance Motrice, Universit e de Balamand, Al Koura, Lebanon; and 2 Laboratoire RELACS, D epartement STAPS, Universit e du Littoral C^ ote d’Opale, Dunkerque, France Abstract The aim of this study was to compare hip bone strength indices in obese, overweight, and normal-weight ado- lescent girls using hip structure analysis (HSA). This study included 64 postmenarcheal adolescent girls (14 obese, 21 overweight, and 29 normal weight). The 3 groups (obese, overweight, and normal weight) were matched for maturity (years since menarche). Body composition and bone mineral density (BMD) of whole body, lumbar spine, and proximal femur were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate hip bone strength, DXA scans were analyzed at the femoral neck (FN) at its narrow neck (NN) region, the intertrochanteric (IT), and the femoral shaft (FS) by the HSA program. Cross-sectional area and section modulus were measured from hip BMD profiles. Total hip BMD and FN BMD were significantly higher in obese and overweight girls in compar- ison with normal-weight girls ( p ! 0.05). However, after adjusting for weight, using a one-way analysis of covari- ance, there were no significant differences among the 3 groups regarding HSA variables. This study suggests that in obese and overweight adolescent girls, axial strength and bending strength indices of the NN, IT, and FS are adapted to the increased body weight. Key Words: Body mass index; growth; hip geometry; lean mass. Introduction Obesity may protect against hip and vertebral fractures in the elderly (1,2). However, in children and adolescents, the relation between being obese or overweight on one hand and bone strength indices on the other hand may be influ- enced by gender, maturity, and site of bone mass measure- ment (3e20). For instance, fat mass is a stronger positive determinant of bone mineral content (BMC) and bone mineral density (BMD) among adolescent girls than adolescent boys (21). However, BMD is not a measure of bone strength; it is a surrogate of bone strength (22,23). Interestingly, Beck et al (24) developed a computer program to derive hip geom- etry from bone mineral data for an estimate of hip strength. The program, called hip structure analysis (HSA), was devel- oped originally to improve the predictive value of hip bone mineral data for osteoporosis fracture risk assessment (24). Bone strength may be better represented by HSA variables such as cross-sectional area (CSA), an index of axial com- pression, and section modulus (Z), an index of bending strength, than BMD or BMC (23,24). The hip is a weight- bearing site that is strongly influenced by mechanical factors such as body weight and lean mass (25). We have previously shown that in obese adolescent boys, intertrochanteric (IT) structural rigidity and femoral shaft (FS) structural rigidity and bending strength are not adapted to the increased body Received 03/07/12; Accepted 03/26/12. *Address correspondence to: Rawad El Hage, PhD, Faculty of Arts and Social Sciences, Division of Physical Education, University of Balamand, P.O. Box: 100 Tripoli, Lebanon. E-mail: rawadelhage21@hotmail.com 313 Journal of Clinical Densitometry: Assessment & Management of Musculoskeletal Health, vol. 16, no. 3, 313e319, 2013 Ó Copyright 2013 by The International Society for Clinical Densitometry 1094-6950/16:313e319/$36.00 http://dx.doi.org/10.1016/j.jocd.2012.03.010