Radiographic Measurements, Bone Mineral Density, and the Singh Index in the Proximal Femur of White and Black Postmenopausal Women

Background: Radiographic measurements, bone mineral density (BMD), and the Singh Index were examined to assess ethnic differences in the architecture and trabecular patterns in the proximal femur.

Methods: We measured height (cm), weight (kg), and the following radiographic variables in 326 white and black postmenopausal women participating in the Women's Health Initiative at the Clinical Center in Detroit, MI: neck breadth, inferior neck cortical thickness, head diameter, subtrochanteric breadth, and subtrochanteric medial and lateral cortical thicknesses. Bone densitometry was performed by dual-energy x-ray absorptiometry (Hologic QDR 1000 plus; Hologic Inc, Bedford, MA) at 5 regional sites in the proximal femur. The Singh Index was read by its originator.

Results And Conclusions: There was no significant ethnic difference in mean age, height, or body mass index, but weight and BMD was higher in the black group at all regional sites. The inferior neck cortical thickness was significantly greater in the black group. The Singh Index was found to be grade VI (normal) in 87%, grade V in 9%, and grades II-IV in 4% of all subjects. Multiple regression models explained 35% to 60% of the variance in the regional BMDs; the Singh Index, weight, and subtrochanteric cortical thicknesses were significant contributors to all regional hip BMD models. Although there were ethnic differences in BMD, there were no ethnic differences in the distribution of the Singh Index scores.