Reviewing the literature of 3D printing of bones and cartilage: Evidence and practice

The cutting-edge innovations offer diverse opportunities in medicine; one such inductive approach is 3D bio-printing, in which cells and desired biomaterials cohesively synthesize living macro tissues. The rapidly increasing demand for reconstruction and restoration of highly intricate and responsive bone implants has encouraged bone tissue engineering to yield implants that substitute the native bone, both physically and biologically. As this technology is still in its infancy, different limitations can be encountered, such as the lack of in-depth characterization of scaffolds and limited visualization of a general framework, which can be overcome with further explorative studies. With computerized bio-fabrication, 3D printing aims to perfectly adapt implants, individually analyzing data at the level of cells, tissues, organs, and organic systems, ending this entire process under pre-bioprinting. The locus and susceptibility to bare load are primary considerations in selecting among widely available biomaterial options and printing techniques, including bio-ceramics, metals, bioinks, selective laser melting, directed energy deposition (laser or e-beam), and drop-on-powder printing. The addition of growth factors and mesenchymal stem cells allows the maintenance of the balance between osteoclasts and osteoblasts, the cartilage tissue formation, and contributes to the overall bone remodeling and regeneration processes. This review address and highlights relevant aspects on pre-bioprinting procedures, bio-materials selection, bio-printers, bone remodeling mechanism, and in-vivo responses of fibrin scaffold.