Texture, stress and age in the human femur.

The way in which remodelling of human bone is determined by the mechanics of life is explored in a neutron diffraction study of the femur. The hydroxyapatite crystals provide ability to resist vertical stress by a preferred alignment which is low at birth, increases to a maximum at an age of about three years and then falls away steadily in later life. This vertical alignment is greater at the front of the femur than at the back.