Recent advances in 3D printing of metallic component-containing bone repairing materials

Although conventional metallic prostheses made through casting, forging and numerically controlled machining have been widely used to treat bone defects for permanent or long-term replacement, their insufficient model supply, mismatched mechanical properties, limited surface topographical features and inadequate osseointegration restrict their further wide use. Three-dimensional (3D) printing has emerged as a transformative technology to manufacture metal and metallic component-containing biomaterials into personalized prosthesis implants and bone regeneration scaffolds with tailored architectures, tunable mechanical strength and desirable biological responses. This mini-review introduces recent advances in 3D printed metallic bulk/porous prosthesis and metallic-component containing ceramic and/or polymeric composite scaffolds for bone repair/regeneration. The physical, chemical and biological requirements of 3D printed metallic-component containing bone repairing materials including bulk/porous prostheses for bone tissue replacement with/without bone in growth and biodegradable scaffolds for bone regeneration are presented. Afterwards, material selection principles for producing different types of metallic components containing bone repairing materials are compared. Then, core 3D printing technologies and post-treatment methods are reviewed. Subsequently, typical application cases using 3D printed bone repairing materials/scaffolds are sequentially discussed. Despite encouraging progress, multifunctional metallic component containing bone repairing materials/scaffolds should be continuously developed to simultaneously present biomimetic structural features, suitable mechanical properties, appropriate degradation rate, excellent functional agent delivery capability and desirable biological performance to elicit improved osseointegration, enhanced vascularization, excellent antibacterial/anti-inflammation capability. In addition, translational barriers such as standardization, large-scale manufacturing, and regulatory approval should be also resolved.