We measured bone density in various parts of the femur by using single energy quantitative computed tomography. In the cadaver studies we found significant correlations between the trabecular and cortical bone density and the structural strength of the femur in bending and rotational loading. This was observed in parts of the femur distant from the fracture site in the femoral neck. Good reproducibility of the density measurements was obtained at the condylar level, a site easily accessible for clinical measurements. In a clinical study, we could record post-traumatic osteoporotic changes at 5% precision level.