Research progress on biodegradable magnesium phosphate ceramics in orthopaedic applications

To overcome critical size bone defects, calcium phosphate (CaP)-based ceramics have been widely explored. The compositional similarity with bone matrix and degradability are the main reasons for their selection in orthopaedic biomaterials. However, the low solubility rate under in vivo conditions raises concerns about these CaP groups, particularly hydroxyapatite (HA) and tricalcium phosphate (TCP) ceramics. Therefore, reliable and suitable degradable ceramics for bone defect repair are always an important research direction for researchers. The magnesium phosphate (MgP) group of bioceramics has been studied for orthopaedic applications and is comparatively new compared to traditional CaP ceramics. The role of magnesium in different biochemical processes, such as DNA stabilization, bone density maintenance, regulating Ca and Na ion channels, and cell proliferation and differentiation enhancement, is a key parameter for the development of MgP bioceramics. This article aims to give a comprehensive review of MgP ceramics in bone tissue engineering. Here, we have highlighted several preparation techniques, the existence of porosity, and the impact of metal ion doping on MgP bioceramics. Finally, in vitro and in vivo responses of MgP bioceramics in bone formation are discussed.