Mechanical properties of trabecular bone from the proximal femur: a quantitative CT study

We have investigated the relationships between trabecular bone compressive strength and elastic modulus and the directly measured apparent density and noninvasively measured CT equivalent mineral density for 49 cylindrical specimens harvested from fresh human proximal femora. Compressive strength demonstrated a high positive correlation with both densities, being proportional to the apparent density raised to the 1.8 power (R2 = 0.93) and equivalent mineral density to the 1.5 power (R2 = 0.89). Similarly, the compressive modulus demonstrated a high correlation with both density measures, being proportional to the apparent density raised to the 1.4 power (R2 = 0.91) and CT equivalent mineral density to the 1.2 power (R2 = 0.90). Though variations in architecture and bone marrow fat were observed to influence trabecular properties, the data presented here demonstrate that apparent density, compressive strength, and elastic modulus can be determined accurately using single energy quantitative CT. We expect that the use of these noninvasive data will result in improved estimates of that component of hip fracture risk that is attributable to bone strength.