Iron and its alloys for bone regeneration scaffolds : a review

Abstract

Permanent implants and bone grafts have been used successfully to repair bone defects for a number of years. However, there are significant limitations, for example patients requiring revision surgery for implant removal, inadequate mechanical properties leading to stress-shielding and osteoporosis, as well as restricted bone development, particularly in paediatric patients. As a result, those implants with a more active involvement in the healing process than the original inert implants, were favoured. Biodegradable scaffolds are porous implants which are incorporated into sizeable bone defects in order to support the damaged area while the bone regenerates. In response to bone healing, the structure is expected to degrade at a controlled rate in vivo. Following the promising research published in relation to magnesium-based alloys for cardiovascular stents, iron and its alloys have recently been proposed for this application. An in vivo study published in 2001 showed that pure iron exhibited an inadequately slow degradation rate. Since then, research efforts have been focused on accelerating the corrosion rate by implementing various material design strategies. This review presents an overview of notable research work treating the tailoring of corrosion, mechanical and cytotoxic response as well as promising processing methods for the production of iron-based foam structures. To conclude, based on current research, the clinical potential for these materials will be analysed.