Structural influence on titanium ion dissolution in 3D-printed Ti6Al4V orthopedic implants

Abstract

3D printed orthopedic implants have emerged as innovative solutions for treating bone tumors, offering advantages such as patient-specific customization and faster production compared to conventional manufacturing methods. However, elevated concentrations of titanium (Ti) ions in the bloodstream have frequently been observed following limb salvage surgery using 3D printed Ti6Al4V implants, which could lead to systemic toxicity and critical implant failure. In this study, we characterize the Ti dissolution phenomenon associated with 3D printed implants. Finite element analysis (FEA) of full-scale pelvic and tibial implants revealed that large mesh surface areas designed for implant-tissue integration can accelerate corrosion. Microstructural analyses of cubical Ti6Al4V samples with solid, mesh, and solid-mesh hybrid geometries revealed that galvanic coupling between the alpha (alpha) and beta (beta) phases drives localized corrosion. A notable difference in beta-phase content-ranging from 145% to 200%-was observed among the three cases, with the highest beta-phase content in the mesh structures. These findings indicate that although mesh structures are essential for implant-tissue bonding, they can significantly promote Ti ion release, potentially compromising the mechanical integrity of the implant over time. Careful design and surface treatment strategies are therefore needed to balance biological integration with long-term material stability.