Infiltration cycles Besides the effects on the mechanical properties (crack propagation), polymer infiltration also affects the handling and integrity of the specimens. While noninfiltrated samples formed a lot of debris and collapse in multiple parts during mechanical testing, the PCL-infiltrated ones retained good integrity even when damaged (Fig. ). Unfortunately, it was not possible to evaluate the maximum deformation before final fracture because the samples came into contact with the sample holder. Peroglio et al. reported residual deflection higher than 1 mm (for a sample size of 6 × 10 × 60 mm 3 ) before total fracture in samples with comparable microstructures. The toughening effect obtained is intrinsic to the introduction of a highly deformable polymeric phase, which holds the structure together even when the ceramic structure collapses . This mechanism is analogous to the extensively reported crack bridging effect observed in cancellous bone . In the first stage, the ceramic scaffold withstands the stresses until its failure at a limited strain. Afterwards, in the plastic stage, the polymer phase controls the crack propagation until the polymer reaches its characteristic elongation to fracture producing a crack bridging effect. In our samples, PCL fibrils act in ice-templated scaffolds (see Fig. for a SEM micrograph of these fibrils in our material after fracture) like collagen fibrils in human bone. A similar effect has been shown by Currey et al. , who observed that the post-yield strain of bone is highly dependent on collagen content. The key mechanism responsible for the improvement of the mechanical properties in these highly porous materials is therefore the load redistribution enabled by the continuous polymer phase.