Magnesium Alloys for Orthopaedic Applications

Abstract

Magnesium alloys represent a promising class of temporary orthopaedic implants. Their mechanical and biocompatible properties, alongside with biodegradability, constitute an attractive field of innovative materials for load- bearing applications. However, the control of corrosion rates is still a challenge concerning the usage of magnesium alloys for bone healing. The slow release of products and the conservation of mechanical properties play a relevant role in the integration and recovery of the injured tissue. This work approached the corrosion of magnesium alloys at first by exploring the effects of heat treatments and microstructural features to the corrosion rates of Mg-Zn-Ca and Mg-Y-RE alloys. It was found that solution treatment and smaller grain sizes were beneficial for the reduction of Mg-Zn-Ca alloys corrosion rates, whereas Mg-RE alloys were in general less affected by these factors. After, the mechanical properties of different magnesium alloys -€“ including novel Mg-RE alloys -€“ were examined, showing to be substantially affected by the corrosive environment. However, the Mg-RE alloys studied showed high resistance to stress corrosion cracking. The corrosion of magnesium alloys in simulated body fluid showed the formation of different products depending on the alloy, and islands of non-corroded material containing Zr-rich precipitates were found in Mg-RE alloys. Finally, the biocompatibility of different magnesium alloys was assessed by direct cell culture of human osteoblasts for up to 21 days. Mg-RE alloys showed high cell viability and expression of matrix development and mineralisation markers, and no inhibition of alkaline phosphatase activity.

Date of Award	31 Dec 2018
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Joseph Robson (Supervisor), Dirk Engelberg (Supervisor) & Julie Gough (Supervisor)