Identifying suitable 3D scaffolds for repair and regeneration of bone in critical size defects is challenging due to different, often contradictory, requirements imposed on these materials. Ceramic- and polymer-based materials have gained increasing use in bone tissue engineering due to their biocompatibility and mechanical competence. While scaffold mechanical properties are essential to support the defect at the repair site, the success of bone grafts strongly relies on its ability to guide blood vessels and cells into the scaffold pore structure. An optimum range of porosities needs to be identified where both the mechanical properties and scaffold perfusion are sufficiently high to warrant efficient bone repair. BSRG has developed a variety of mechanical and fluid-dynamical testing techniques to characterise bone scaffolds and identify optimal porosity values.