Update on the research and development of magnesium-based biodegradable implants and their clinical translation in orthopaedics

Biodegradable magnesium(Mg)or its alloys are desirable materials for development into new-generation internal fixation devices or implants with high biocompatibility,adequate mechanical modulus,and osteopromotive properties,which may overcome some of the drawbacks of the existing permanent orthopaedic implants with regard to stress-shielding of bone and beam-hardening effects on radiographic images.This review summarises the current research status of Mg-based orthopaedic implants in animals and clinical trials.First,detailed information of animal studies including bone fracture repair and anterior cruciate ligament reconstruction with the use of Mg-based orthopaedic devices is introduced.Second,the repair mechanisms of the Mg-based orthopaedic implants are also reviewed.Afterwards,reports of recent clinical cases treated using Mg-based implants in orthopaedics are summarised.Finally,the challenges and the strategies of the use of Mg-based orthopaedic implants are discussed.Taken together,the collected efforts in basic research,translational work,and clinical applications of Mg-based orthopaedic implants over the last decades greatly contribute to the development of a new generation of biodegradable metals used for the design of innovative implants for better treatment of orthopaedic conditions in patients with challenging skeletal disorders or injuries.