The influence of bone morphology on fracture toughness of the human femur and tibia

The influence of porosity, osteon density, osteonal area, osteonal lamellar area, osteon size, and haversian canal size on the tension and shear fracture toughness, that is, the mode I and mode II strain energy release rate (G(Ic) and G(IIc)), respectively, were investigated for the human femur and the tibia. The results suggest that porosity and osteon density were the best explanatory morphological parameters for G(Ic) and G(IIc). Both G(Ic) and G(IIc) significantly decrease with increasing porosity. They also increase with increasing osteon density, the increase being significant for the femur only. Morphological parameters, altogether, can explain 49%-68% of the variation in fracture toughness. We concluded that, although there must be other factors such as biochemical components and microdamage, osteon morphology has an important influence on fracture resistance of the cortical bone. (C) 1997 by Elsevier Science Inc. All rights reserved.