Antibacterial properties of Mg – based alloys studied in a murine model of periprosthetic osteomyelitis

Abstract text (incl. figure legends and references)

Introduction: Periprosthetic infections remain a major challenge and a most difficult to treat complication for implants. Different strategies to avoid infections are followed, among them the complete degradation of the implant material. However, during the course of degradation bacteria might still be able to colonize the implant-tissue interface. Here magnesium-based biodegradable alloys are currently under eager attention as alternatives.

Objectives: Many in vitro studies reported profound antibacterial potential of pure magnesium and its alloys with improved bactericidal features, and some of the animal models of peri-implant osteomyelitis confirmed these results in vivo. However, to our knowledge, the susceptibility of magnesium and magnesium-silver alloys were previously not assessed in experimental settings for the hematogenous periprosthetic osteomyelitis.

Materials & methods: In the present study, we implemented a murine model for acute S.aureus bacteremia – related peri-implant bone infection to compare antibacterial activity of slowly degrading pure Mg and Mg-2Ag with that of medical grade Titanium.

Results: Directly on the surface of the explants only for Ti bacteria were detectable while the colonization efficiency of surrounding bone was found to be close between all three materials used as intramedullary implants.

Conclusion: Further material modifications e.g. a slightly increased in vivo degradation rate to 1-2 mm / year, which at the same time is not cytotoxic for the surrounding tissue, might be an option to improve the performance of magnesium and magnesium-silver implants for clinical implementation, especially for patients with high risks for S. aureus bacteremia.