Figure 4:

Crack resistance of the femoral cortex. In fracture toughness tests, a crack is propagated by loading a femur mid-shaft with a micro-notch on the tension side of bending (A). The stress intensity to initiate the crack was estimated from the yield moment, and the work during crack growth (W_crack) per bone cross-sectional area (Ct.Ar) was estimated from the area under the moment vs. span-adjusted displacement curve (B). K_c,init (C) and W_crack/Ct.Ar (D) were lower for old than young adult mice in both sexes. ***p<0.001 and ****p<0.0001 within male. ##p<0.01 and ####p<0.0001 within female.