Mechanical performance of 3D-printed Ti6Al4V bone scaffolds: A comprehensive review of design, processing, and post-treatment strategies

The repair of critical-sized bone defects remains a significant clinical challenge, driving the demand for advanced bone substitute materials. Titanium alloy (Ti6Al4V) has emerged as a material of choice for load-bearing orthopedic implants due to its excellent biocompatibility, corrosion resistance, and high strength-to-weight ratio. The advent of additive manufacturing, particularly techniques like selective laser melting (SLM), has revolutionized the field by enabling the fabrication of patient-specific porous scaffolds with precisely controlled architectures. This capability is crucial for mitigating the critical issue of stress shielding, which arises from the mechanical property mismatch between dense titanium and native bone. This review paper provides a comprehensive overview of the current state of knowledge regarding the mechanical performance of 3D-printed Ti6Al4V bone scaffolds. It begins by establishing the rationale for using porous structures to achieve an elastic modulus comparable to that of human cortical and trabecular bone. The paper then systematically examines the influence of key design parameters, including pore size, porosity, unit cell topology (e.g., strut-based, TPMS), and lattice configuration on the resulting mechanical properties such as compressive strength, stiffness, energy absorption, and fatigue behavior. The complex interplay between achieving sufficient mechanical integrity for load-bearing applications and providing an open, interconnected architecture for bone ingrowth and vascularization is a central theme. Furthermore, the review discusses the impact of SLM process parameters and post-processing treatments on the microstructural evolution and resultant mechanical performance of the scaffolds. By synthesizing findings from recent experimental and computational studies, this review aims to identify optimal design strategies that effectively balance mechanical demands with biological requirements.