Evaluation of Femur Angle Abduction/Adduction and Bone Mineral Density Values

Bone densitometry using fan-beam technology allows both femurs to be rapidly measured with the aid of a bilateral foot-positioning tool to keep both legs in internal rotation. The Lunar Prodigy® system uses a bilateral foot-positioning tool with a fixed interpedal width. The aim of this study was to determine whether the small degrees of femur abduction and adduction introduced by a fixed interpedal width-positioning tool influences the femur bone mineral density (BMD) measurements. Two-hundred patients had the total femur (FTot), femoral neck (FN), femoral shaft (FS), and femoral trochanter (FT) BMD, and angles of femoral abduction and adduction measured. Of all subjects, 26.5% had an absolute difference in femur angulation of #1°, 77.5% had #5° and 97% had #10°. There was no significant correlation between the right-to-left differences in femur angles and the absolute right-to-left differences in FTot, FN, FS, and FT BMD. The introduction of small degrees of femur angulation with the fixed interpedal width bilateral foot positioner does not significantly affect the measured BMD at the various femur regions.