Recent advancements in Fe-based biodegradable materials for bone repair

Degradable metallic biomaterials represent a new concept of bioactive biomaterials used for implants with temporary function. They should support the tissue healing process for a certain period and should progressively degrade thereafter. Degradable metallic materials could potentially replace the corrosion-resistant metals currently used for orthopaedic, cardiovascular, and paediatric implants. The interest in the study of degradable metallic biomaterials has dramatically increased in the last decade. This article reviews the current achievements in the design of biodegradable iron-based materials for orthopaedic load-bearing applications. It introduces a broad overview of the different alloying elements, coating materials, and processing methods used to improve the corrosion behaviour, mechanical properties, and biocompatibility of iron implant materials for temporary hard tissue scaffolds. An emphasis is set on Mn and Zn as the most promising alloying elements for Fe as well as on innovative calcium phosphate-based ceramic and polymeric coatings. In addition, the novel iron-ceramic composite biomaterials for orthopaedic implants are mentioned. Finally, recent challenges and future development direction for iron-based materials are proposed.