Additive manufacturing for bone tissue engineering scaffolds

Large bone defects, which occur due to various causes, have substantially affected people's health and quality of life. Bone tissue engineering (BTE) is a promising approach for repairing or replacing bone injuries. The aim of BTE scaffolds is to mimic the biological function and structure of the natural bone extracellular matrix (ECM), which provides a three-dimensional (3D) environment for cell adsorption, proliferation and differentiation. Significant advances in materials science, computer-aided design (CAD) and biomedical engineering have facilitated BTE scaffolds. This paper describes the requirements of BTE scaffolds and highlights the important role of additive manufacturing (AM) technologies in building bridges between biomaterials, CAD models and additives, and BTE scaffolds. It reviews various AM technologies that are used to fabricate BTE scaffolds. These technologies are divided into seven categories: (1) stereolithography (SLA), (2) powder bed fusion (PBF), (3) binder jetting (BJ), (4) material extrusion (ME), (5) material jetting (MJ), (6) volumetric printing (VP) and (7) 4D printing (4DP). The characteristics, raw materials, accuracy, cost, advantages and disadvantages of the AM technologies are discussed. Several recommendations for future research are presented.