Symmetry of bone mineral density at the proximal femur with emphasis on the effect of side dominance.

The symmetry and effect of side dominance on the bone mineral density (BMD) of proximal femur was evaluated in 266 normal Chinese women with a dual photon absorptiometer (DPA, Norland 2600). The BMDs of the femoral neck, trochanter, and Ward's triangle at the proximal femur in the dominant leg (BMDd) were compared with those of the nondominant side (BMDn). The linear regression of BMDd and BMDn of the corresponding regions at the proximal femur showed a good correlation (r = 0.893-0.941, SEE = 0.052-0.062 g/cm2). The paired difference of proximal femoral BMD was -0.002 +/- 0.062 g/cm2 for the femoral neck, 0.003 +/- 0.054 g/cm2 for the trochanter, and 0.008 +/- 0.062 g/cm2 for the Ward's triangle. The ratio of asymmetry for femoral neck BMD was mean +/- SD = -0.4 +/- 7.8%, for trochanter 0.6 +/- 8.1%, and for the Ward's triangle 1.3 +/- 9.7%. Both paired difference and ratio of asymmetry between BMDd and BMDn were approximately normally distributed, with a mean +/- 2 SD ranging from -0.126 to 0.122 g/cm2 for paired difference and -16.0% to 15.2% for the ratio of asymmetry in the femoral neck. These data revealed that dominance had little effect on the proximal femur BMDs. However, the wide range of paired difference and ratio of asymmetry of the proximal femur BMD in the normal individuals should be considered in the interpretation of the proximal femoral BMD.