R Willumeit-Römer, L. Wu, M. Costantino, B. Luthringer
Helmholtz-Zentrum Geesthacht, Institut für Materialforschung, Division Metallische Biomaterialien, Geesthacht, D.
Aging populations, increasing obesity and rise in osteoporosis-related fractures will sustain a need for orthopaedic intervention. In addition, juvenile patients and active adults exhibiting risky sporting activities also require perfect care. So far these indications are treated mainly with non-degradable metal implants or in some cases also polymers. From the patient’s point of view, degradable implants would clearly be preferred. Here degradable Magnesium based implants could become an alternative to permanent metallic implants which have to be removed after healing, or to replace degradable polymers which do not always show the required mechanical properties.
Mg and its alloys degrade under physiological conditions. The great challenge here is to tailor the degradation to be 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 reactions4. 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. Therefore the development of new biodegradable Mg-based implants is strongly relying on the understanding of the degradation process in the living organism and the creation of an appropriate test system in vitro.
This presentation summarizes the influence Mg has on osteoblast, osteoclasts and macrophages. There are indications that indeed the release of locally high concentrations of Mg can stimulate bone remodelling. This is done in a multiple fashion: proteins responsible for bone matrix formation are strongly expressed but also the cross talk between osteoblasts and osteoclasts is influenced. In addition macrophages are directed into an anti-inflammatory and tissue remodelling pathway.