The ratio of the incidence of trochanteric to cervical fractures increased with age in the elderly female population, but the reason for this fact remain unclear.

The purposes of this study were to investigate whether or not there are specificities of the local distribution of mechanical properties at the trochanteric region of the elderly female using a scanning acoustic microscope (SAM). Human proximal femurs were harvested from seven female cadavers (67–88 years) and proximal femur was coronally sectioned into halves across the center of neck. The surface of the coronal section was polished in order to achieve flat surfaces of smoothness well below the surface resolution in scanning with SAM. Bone tissue density and elastic modulus were calculated from the acquired SAM data. Mechanical properties were measured at the lateral and medial trochanter. Cortical bone tissue of the lateral trochanter had significantly lower elastic modulus than that of the medial trochanter in the all specimen over 70s(p<0.05). Trabecular bone tissue of proximal region of the lateral trochanter had significantly lower elastic modulus than that of distal region in all 80s specimens (p<0.05). Decrease of the elastic modulus of cortical bone in the lateral trochanter and low value of the elastic modulus of trabecular bone in the proximal region of the lateral trochanter may be related to the increase of the ratio of trochanteric to cervical fractures with age in the elderly female population.