Monitoring degradation products and metal ions in vivo

The interaction of biomaterials with the human body not only affects the surrounding implantation tissue but also the integrity of biomaterial itself. The body fluid that contains aggressive chloride ions can trigger degradation of metallic biomaterials, leading to the release of metal ions and the formation of degradation products. This natural reaction has been heavily prevented from occurring on inert metallic biomaterials. However, a new type of metallic biomaterial, biodegradable metal, is intentionally made to degrade within the human body at a controllable manner. Monitoring the formation of degradation products and the release of metal ions therefore becomes essential. This chapter presents methods currently used for monitoring in vivo degradation of biodegradable metals from radiography, microcomputed tomography, magnetic resonance imaging, ultrasonography till blood, and histological analysis. In addition, new techniques capable of the online monitoring of local changes surrounding the implantation site and systemic changes in body fluid are also discussed. Both methods are important and complementary to gain comprehensive information of in vivo degradation of biodegradable metal implants.