Bilateral variation in radial bone speed of sound.

The aims of this study were to: (a) examine differences in speed of sound (SOS) between the right (SOS(R)) and left (SOS(L)) radius; (b) detect bone loss following proximal forearm fracture by SOS measurement at the radius; and (c) compare SOS(L) and bone mineral density (BMD) of one-third, mid-distal, ultra-distal and total region of the left radius. Two hundred eighty-seven Caucasian women (mean age 60.4+/-6.7 years) participated in this study. All subjects were right-handed. Twenty-seven women (mean age 63.6+/-8.0 years) had suffered a high-energy fracture of the right or left forearm. The SOS was assessed using a quantitative ultrasound device, whereas BMD was measured by dual energy X-ray absorptiometry (DXA). The SOS(R) was significantly higher than SOS(L) (4047.5+/-121.0 vs 4026.3+/-113.4 m/s; p<0.001). The contralateral absolute difference was 1.94% (95% confidence intervals: 1.73-2.15%). In women who had suffered a fracture of their right forearm, SOS(R) was not significantly higher than SOS(L )(3989.9+/-141.8 vs 3985.0+/-151.1 m/s), whereas the bilateral difference was reduced to 1.45%. In women with a previous fracture of the left forearm, SOS(R) was significantly higher than SOS(L) (4076.9+/-92.8 vs 3992.6+/-124.0 m/s; p<0.01) and the bilateral difference was increased to 2.61%. Of the 260 subjects without fracture, 155 had greater SOS in the right radius, 102 had greater SOS in the left radius and 3 patients had equal values of SOS in both bones. Calculated correlations between SOS and BMD were weak to moderate ( r=0.27-0.41; p<0.0001 for all comparisons). The SOS measurements should be performed on both radial bones. A high-energy forearm fracture results in a decrease in SOS measured at the radius. Radial-bone SOS measurements cannot predict forearm BMD.