A review on bioactive porous metallic biomaterials

Abstract

Porous metallic biomaterials have been extensively studied for many bone tissue engineering applications because porous structures provided space for bone in-growth and vascularisation. Improvement on mechanical properties also leads to the increased popularity of porous materials for bone substitute applications, especially for load-bearing implants. However, they usually lack sufficient osseointegration for implant longevity. In addition, their biocompatibility is also an important concern in these applications due to adverse reactions of metallic ions with the surrounding tissues after these metallic ions are released from the implant surfaces. One consideration to accelerate the healing process is surface treatment, including application of bioactive coatings, e.g. hydroxyapatite and biomimetic creation of surface. Surface treatments on biomaterials will determine surface chemistry and topography, whereas these surface characteristics influence osseointegration process. To respond on the challenges of producing biocompatible and mechanical compatible biomaterials and lack of review studies on surface modifications on porous structures, a comprehensive literature review on surface modifications of various porous metallic materials is presented. This review covers various methods of surface treatment such as biomimetic, electrodeposition, alkali heat treatment, anodization and their effects on mechanical and structural properties which then provided insights into bone implants improvement studies. Biological responses (in vitro and In vivo) of porous material after surface treatment are thoroughly discussed.