The human proximal femur behaves linearly elastic up to failure under physiological loading conditions

► We tested to failure 12 human femurs to measure linearity of bone as a structure. ► Strain was measured (5 kHz). High-speed videos (up to 18,000 fps) were taken. ► Fracture started on the lateral side of the neck (tensile stress). ► Failure occurred abruptly in less than 0.25 ms. No permanent deformation was found on the bone fragments. ► Force-displacement and force-strain curves were highly linear (R2>0.98), with no sign of yield.