Physical meaning of bone mineral content parameters and their relation to mechanical properties.

The relations between parameters obtained by clinical absorptiometric techniques, such as SPA, DPA, DXA and QCT, and geometrical and material parameters of bone structures are investigated. Two types of bone are considered: the diaphysis of a long bone, modelled as a hollow cylindrical structure consisting of compact bone, and secondly a cylindrical body consisting of trabecular bone. The latter is a model for the vertebral body and for the femoral neck. Parameters investigated are BMD (as gr/cm2) and BMC (as gr/cm). The modeling predicts good agreements between BMD and the wall thickness in the diaphysis of the bone, between BMC and the area of cross section of a long bone and between BMC and the effective area in a body of trabecular bone.