Degradable Magnesium Implants - Assessment of the Current Situation
AbstractMg and its alloys degrade under physiological conditions. The great challenge here is to tailor the degradation in a manner that is suitable for a biological environment. Fast or uncontrolled corrosion is associated with strong hydrogen and ion release and severe pH changes, which can lead to a fast loss of mechanical stability and undesirable biological reactions. Since these processes are highly complex in a living system and sufficient data describing the degradation in vivo is missing, it is very difficult to produce knowledge based new alloys. Still, the endeavour is successful: one CE certified Mg-alloy compression screw (Magnezix, Syntellix AG, Germany) and a Mg-based drug-eluting stent (Magmaris, Biotronik AG, Germany) are on the market. In addition, in China and Korea patient trials (hip surgery and hand fracture) are reported. This paper gives a brief outline of the current status of Mg-implants and which obstacles still have to be mastered. As an example for the special nature of Mg and its interaction with cells, a comparison is made between the influence of osteoblasts (bone forming cells) and fibroblasts (the most abundant cells in connective tissue) on the degradation layer underneath the cells.