Implantable pliable bone blocks comprising a solid block of cortical bone characterized by a length, width and thickness, having a first and a second face on opposite sides of the block. The first and second faces have a plurality slot features. The angle of incidence of the slot features of the first face and the x-axis and the angle of incidence of the slot features of the second face and the x-axis (a2) are such that the slots would intersect if they were in the same plane. Methods are provided for making implantable pliable bone blocks.