Titanium and stainless steel are currently used to stabilize bone fractures in children and adolescents. These permanent implants have to be removed otherwise impeding longitudinal bone growth. Magnesium (Mg)-based screws degrade after implantation, are mechanically similar to bone and could support bone fracture healing. However, Mg degradation has to be controlled and only previously, rare earth (RE) elements were added to slow down the degradation rate, although long-term effects are still unclear. Within this study, we evaluated fracture healing around a RE-free,
Mg-Zinc-Calcium alloy (ZX00, Mg-0.45Zn-0.45Ca) screw in an in vivo growing sheep tibia osteotomy model. We observed callus formation after 2 weeks, which was stable after 6 and progressed to resorption after 12 weeks, without qualitative differences compared to Ti implants. Increased bone mass was observed at the interface between bone and Mg. Moreover, Mg screws exhibited homogenous degradation and moderate hydrogen formation, which did not disturb surrounding tissue or healing. Fracture stabilization and bone fracture healing were comparable to Ti osteosynthesis. It is important to note, that the absence of RE in ZX00 makes these alloying system attractive for treating pediatric bone fractures.