In vivo behavior of biodegradable Mg-Nd-Y-Zr-Ca alloy

The aim of the this study is to evaluate the in vivo behavior of Mg-1.5%Nd-0.5%Y-0.5%Zr implants with and without 0.4%Ca in comparison with inert Ti-6Al-4V reference implants. This was carried out by implanting cylindrical disks at the back midline of Wister male rats within the subcutaneous layer of the skin for up to 12 weeks. The degradation of magnesium-based implants in terms of hydrogen gas bubble formation was evaluated by radiography assessment; corrosion rate was analyzed by visual examination and weight loss measurements. The physiological response of the rats post-implantation was obtained by evaluating their wellbeing behavior and blood biochemical analysis including serum Mg, blood urea nitrogen, and serum creatinine. In addition, histological analyses of the soft tissue around the implants were carried out to assess local lesions relating to the implants such as inflammation, tissue necrosis, granulation, mineralization, and tumor development. The results obtained clearly indicate that apart from the normal degradation characteristics and subsequent formation of hydrogen gas bubbles, the in vivo behavior of Mg implants was adequate and comparable to that of Ti-6Al-4V reference alloy. In addition, it was evident that the corrosion degradation of the magnesium alloys was strongly related to the location of the implant within the animal's body. The addition of 0.4%Ca improves the biodegradation corrosion resistance of the tested magnesium implants.