Mechanical Integrity of Biodegradable Mg–HA Composite During In Vitro Exposure

Biodegradable metals are being frequently explored as a very potential replacement for bone implant and fixing accessories, owing to their superior mechanical and biological properties. In connection to this, biodegradable magnesium (Mg) and its alloys exhibit good biocompatibility for orthopedic applications. Nevertheless, the use of these biodegradable materials has been restricted due to their fast degradation rate in the physiological environment, even before the new tissue is adequately generated. So, it becomes necessary to bring down their corrosion rate to retain their mechanical integrity until the bone properly heals. A solution to this problem is found in hydroxyapatite (HA)-reinforced Mg-based composites. However, it is important to understand the mechanical behavior of these materials, after exposure to body environment. In this study, HA-reinforced composites of Mg-based (Mg-3Zn) matrix are evaluated for their mechanical integrity in simulated in vitro condition. Addition of 5 wt.% HA decreased the corrosion rate of Mg-3Zn, which in turn maintained the mechanical integrity of the structures even after 14 days of immersion. Mg-3Zn and Mg-3Zn-5HA composites have retained ~ 34 and 66% of ultimate compressive strength after 3 days of immersion. All these studies together establish the effect of HA on mechanical integrity of Mg-based composites in orthopedic application.