A Novel Device for Studying in Vivo Magnesium Degradation under Controllable Cyclic Load in the Rabbit Model

Abstract

Magnesium is an important material for medical implants due to its special properties including biocompatibility, low density, high mechanical property, and biodegradability. The in vivo implantation experiment of magnesium is an important experimental method to obtain its degradation characteristics. In recent years, although in vitro studies have found that the degradation of magnesium under cyclic loading is different from static loading, there is the lack of in vivo experiment to verify the above in vitro results, while the degradation characteristic of magnesium under load is an important factor to be considered when magnesium is used as orthopedic implant. We designed a novel device to apply controllable cyclic load onto the magnesium material implanted in the rabbit tibia, containing loading chamber, motor and gear reduction mechanism, and Singlechip Computer, etc. The conducted experiments have shown that the devices were able to apply load onto the implanted magnesium in rabbits in vivo during unrestricted cage activity for at least 16 days. Likewise, no distortion or infections were observed. Results demonstrated that the novel device was able to produce alteration of the mechanical environment in vivo rabbit tibia, which showed that the load device is suitable for in vivo loading degradation characteristics testing of magnesium or magnesium alloys.