Effect of mechanical stresses on degradation behavior of high-purity magnesium in bone environments

High-purity (HP) magnesium (Mg) has emerged as a promising biomaterial for supporting functional bone tissue. Our previous study found that mechanical stresses and the surrounding fibrotic tissue (subcutaneous) both play crucial roles in the degradation of HP Mg. However, due to challenges in the degradation and regeneration process in vivo, it remains unclear how stress affects HP Mg degradation in bone environments, limiting its further application. In this study, novel loading devices were designed and the effects of tensile and compressive stresses on HP Mg degradation in vivo and in vitro bone environments were quantitatively analyzed. In addition, bone osteointegration around HP Mg was explored preliminarily. Tensile stress increases the degradation rate of HP Mg in vivo and in vitro. HP Mg degradation in vivo is more sensitive to stress factors than in vitro, but the sensitivity decreases with corrosion time. The volume loss rate of HP Mg is multilinear with the applied stress and degradation time. The volume of bone tissue surrounding HP Mg is larger in the no-stress group compared to the stressed groups, which is more pronounced with increasing implantation time. These results provide valuable insights for optimizing the design of HP Mg-based implants considering load conditions. This will help to achieve a balance between the degradation rate of the implant and the regeneration rate of the surrounding bone.