The aim of this proposal is to perform ultra-high-speed X-ray in-situ imaging of rapidly running cracks under impacts in (porcine and artificial) bone + scaffold systems. The goal is to understand how 3D-printed biodegradable scaffolds must be customized, patient-specifically, to stabilize and reinforce fractured bone, i.e., to be in mechanical and dynamical harmony with the surrounding bone while stimulating bone regeneration.