Fatigue behaviour of titanium scaffolds with hierarchical porosity produced by material extrusion additive manufacturing

•Scaffolds with an open intrastrand pore network endured an order of magnitude more fatigue cycles than scaffolds with compact strands.•This unexpected behaviour is in contrast to traditional expectations in the field of metal fatigue.•Crack deflection and branching due to interactions with pores and small grains were responsible for fatigue life improvement.•Scaffolds produced by direct ink writing are competitive with those produced by other additive manufacturing methods.