Influence of the weight status on hip bone strength indices in a group of sedentary adolescent girls.

Objective: The aim of this study was to compare femoral shaft and intertrochanteric geometry in overweight and normal weight adolescent girls.

Methods And Results: This study included 22 overweight (Body mass index (BMI) > 25 kg/m2) adolescent girls (15.4 +/- 2.4 years old) and 20 maturation-matched (15.2 +/- 1.9 years old) controls (BMI < 25 kg/m2). Body composition and BMD were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate bone geometry, DXA scans were analyzed at the femoral shaft and the intertrochanteric region by the Hip Structure Analysis (HSA) program. Cross-sectional area (CSA), an index of axial compression strength, section modulus (Z), an index of bending strength, cross-sectional moment of inertia (CSMI), cortical thickness (CT) and buckling ratio (BR) were measured from bone mass profiles. Lean mass, body weight, fat mass and BMI were higher in overweight girls compared to controls (p < 0.001). CSA, Z, CSMI and CT were higher in overweight girls compared to controls (p < 0.05) at the two regions (femoral shaft and intertrochanteric). After adjustment for maturation index (years since menarche), CSA, Z, CSMI and CT of the intertrochanteric region and CSA of the femoral shaft were higher in overweight girls compared to controls (p < 0.05). After adjustment for either body weight, lean mass or BMI, using a one-way analysis of covariance (ANCOVA), there were no differences between the two groups (overweight and controls) regarding the HSA variables (CSA, CSMI, Z, CT and BR) at the femoral shaft and the intertrochanteric.

Conclusion: This study suggests that overweight adolescent girls have greater indices of bone axial and bending strength in comparison to controls at the intertrochanteric after adjustment for maturation index.