Bone composition in the distal forearm.

Recent data have indicated that measurements of bone mass in the very distal part of the forearm is superior to more proximal measurements in identifying osteoporosis. Bone slices from the distal part of the forearm were obtained from 16 necropsies and the trabecular fraction of the total dry bone weight was measured in adjacent bone slices, 8 mm thick. Prior to autopsy bone mass at the corresponding sites was measured using a multipath single photon absorptiometric method by which scans are obtained proximal (proximal BMC) and distal (distal BMC) to the site, where the ulna and radius are 8 mm apart. The accuracy of bone measurements at the two sites was virtually similar (r = 0.98 and r = 0.94, respectively). In both areas the amount of trabecular bone increased towards the metaphysis with a trabecular/cortical ratio ranging from 10 to 60% (wt/wt). If bone composition is known it is possible to estimate rates of bone loss from the two compartments.