In Vitro Biodegradation and Biocompatibility of Mg–HA-Based Composites for Orthopaedic Applications: A Review

Abstract

Magnesium (Mg)-based material systems offer great potential for healing bone fracture and defects, in terms of reduced stress shielding effect and non-toxicity, due to their biodegradability and biocompatibility. However, an issue with controlling degradation rate of Mg in an intraosseous (occurring within bone) environment has impeded their application in orthopaedics. As a solution to this problem, Mg can be combined with other corrosion-resistant and bioactive materials to form composite. Hydroxyapatite (HA) is an attractive bioceramic for implants due to its similar chemical composition to the apatite found in bone. Thus, incorporation of HA in Mg assists in enhancing multiple engineering properties that are critical for its widespread use in orthopaedic application. Tremendous improvement in the mechanical and degradation properties of HA-reinforced Mg composite, along with their impressive biocompatibility, has led to further interest in research, which has resulted in some clinical trials of Mg–HA-based composites, as well. This review article summarises researches, carried out till date on Mg–HA-based composite, with a special focus on significant role of HA in tuning the degradation and mechanical behaviour of Mg-based materials. The detailed summary on biocompatibility of Mg–HA-based composites has also been covered. A comprehensive understanding on biocompatibility and degradation behaviour of Mg–HA system is needed to assess the potential of these composites in orthopaedic application. However, such review is missing in available literatures. On the basis of current studies available on Mg–HA-based composites for orthopaedic application, guidelines for future application in clinical trials have also been framed and presented in this review article.