Hope is that tissue engineering will provide a solution to meet the growing needs for bone substitutes. Among the potential solutions, three-dimensional (3D) printing is a promising method to fabricate functional bone substitutes especially for treatment of complex and critical-sized bone defects. Despite its encouraging achievements, 3D printing of bone substitutes still faces serious challenges including mechanical strength, shape complexity, optimization of pore parameters, and vascularization. The newer approach, that is, 3D bioprinting, is also confronted with challenges, which have prevented the realization of the dream of fabricating functional patient-specific bone substitutes. This article reviews the major challenges toward 3D printing and bioprinting of bone substitutes and recent studies addressing them. Potential solutions for each challenge and future directions are also provided. Impact Statement This review provides a current overview of the challenges in 3D (bio)printing of bone substitutes and summarizes the potential solutions.

中文翻译：

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骨骼替代物的三维打印面临的挑战。

希望组织工程学将提供一种解决方案，以满足对骨替代物日益增长的需求。在潜在的解决方案中，三维（3D）打印是一种有前途的方法，可用于制造功能性骨替代品，尤其是用于治疗复杂和临界尺寸的骨缺损。尽管取得了令人鼓舞的成就，但骨骼替代物的3D打印仍然面临着严峻的挑战，包括机械强度，形状复杂性，孔参数的优化和血管化。较新的方法，即3D生物打印，也面临着挑战，这些挑战使实现针对患者的功能性骨替代物的梦想无法实现。本文回顾了骨替代物的3D打印和生物打印面临的主要挑战，以及针对这些替代物的最新研究。还提供了针对每个挑战和未来方向的潜在解决方案。影响力陈述该评论提供了有关骨骼替代物3D（生物）打印挑战的最新概述，并总结了潜在的解决方案。