Femoral neck geometry in overweight and normal weight adolescent girls.

Being overweight is associated with increased bone mineral content, bone mineral density (BMD), and bone strength in adults. However, the effect of being overweight on bone strength during adolescence is poorly understood. The aim of this study was to compare femoral neck geometry in overweight and normal weight adolescent girls. This study included 22 overweight (BMI > 25 kg/m(2)) adolescent girls (15.4 +/- 2.4 years old) and 20 maturation-matched (15.2 +/- 1.9 years old) controls (BMI < 25 kg/m(2)). Body composition and BMD were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate bone geometry, DXA scans were analyzed at the femoral neck 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, and CSMI were higher in overweight girls compared to controls (P < 0.05; P < 0.01 and P < 0.01, respectively). CT and BR were not significantly different between the two groups. After adjustment for body weight, lean mass, or fat mass, using a one-way analysis of covariance (ANCOVA), there were no differences between the two groups (overweight and controls) regarding the HSA variables (CSA, Z, CSMI, CT, and BR). In conclusion, this study suggests that overweight adolescent girls have greater indices of bone axial and bending strength in comparison to controls at the femoral neck.