Font Size: 

Bone is a highly anisotropic material, having an easy crack growthdirection which is approximately parallel to the bone’s longitudinal axis. This createsanisotropy in its fracture toughness and strongly affects the orientation of naturallyoccurring cracks in vivo and the initial growth direction of cracks extending fromnotches. In this paper we show three examples to illustrate how fatigue and fracturebehaviour is affected by this anisotropy and how a knowledge of the crack path can helpin making fracture mechanics predictions of fatigue and fracture behaviour underdifferent external loading conditions.