Abstract:

There are more than 2 million bone grafting procedures performed annually in the US alone. Despite significant
efforts, the repair of large segmental bone defects is a substantial clinical challenge which
requires bone substitute materials or a bone graft. The available biomaterials lack the adequate mechanical
strength to withstand the static and dynamic loads while maintaining sufficient porosity to facilitate
cell in-growth and vascularization during bone tissue regeneration. A wide range of advanced biomaterials
are being currently designed to mimic the physical as well as the chemical composition of a bone by
forming polymer blends, polymer–ceramic and polymer–degradable metal composites. Transforming
these novel biomaterials into porous and load-bearing structures via three-dimensional printing (3DP) has
emerged as a popular manufacturing technique to develop engineered bone grafts. 3DP has been
adopted as a versatile tool to design and develop bone grafts that satisfy porosity and mechanical requirements
while having the ability to form grafts of varied shapes and sizes to meet the physiological requirements.
In addition to providing surfaces for cell attachment and eventual bone formation, these bone
grafts also have to provide physical support during the repair process. Hence, the mechanical competence
of the 3D-printed scaffold plays a key role in the success of the implant. In this review, we present
various recent strategies that have been utilized to design and develop robust biomaterials that can be
deployed for 3D-printing bone substitutes. The article also reviews some of the practical, theoretical and
biological considerations adopted in the 3D-structure design and development for bone tissue
engineering.