The changes in bone mineral density of the forearm and distal radius–ulna subcortical bone due to ulnar variance

The aim of this study was to evaluate the changes in subcortical bone mineralization of the distal radius and ulna in the presence of negative ulnar variance. A total of 77 healthy right hand-dominant volunteers [34 women and 43 men of mean age 38 ± 14.8 years (range 14–71)] were enrolled in this study. Bilateral bone mineral density (BMD) and bone mineral density ratio (BMDR) measurements of the distal radius and ulna were performed by using dual energy X-ray absorptiometry. We found a significant decrease of ulnar subcortical BMD and BMDR subcortical in the dominant forearms of the subjects with negative ulnar variance when compared to that of subjects with neutral ulnar variance (P < 0.02). But this difference was not seen on the non-dominant side. There was no significant difference in BMDRs between the dominant and non-dominant forearms for all subjects. Radial and ulnar subcortical BMD values were significantly different between dominant and non-dominant forearms in subjects with bilateral neutral ulnar variance, whereas not significantly different in subjects with bilateral negative ulnar variance. The increase found in the BMD value of radial subcortical bone in subjects with negative ulnar variance may be due to the indirect shift of axial forces through the ulna to radius.