Mechanical, electrochemical corrosion, and biocompatibility analysis of EBM-printed Ti6Al4V scaffolds to reduce stress shielding in medical implants

Abstract

Early loosening of implants, primarily caused by stress shielding, is a major challenge associated with almost all metal-based implants. Introducing ordered porosity is an effective approach to minimizing the stress shielding effect by reducing implant stiffness and promoting osteointegration. Apart from mechanical properties, other biomedical-related properties, such as corrosion resistance and osteointegration, are also dependent on pore morphology

therefore, evaluating each aspect is important. In this study, four Ti6Al4V scaffolds with porosity levels of 65%, 70%, 75%, and 80%, defined by a body-centred spherical cavity cubic unit cell with quantified trabecular thickness (1.16–0.68 mm) and trabecular space (2.169–2.400 µm), were fabricated by Electron Beam Melting (EBM). Further, these scaffolds were tested to study the effect of porosity on mechanical properties, corrosion behaviour, and in vitro biocompatibility. Quasi-static compression testing showed that Young’s modulus decreased from 6.18 GPa at 65% porosity to 2.87 GPa at 80% porosity, with the 70% and 75% porosity scaffolds falling within the modulus range of human cortical bone, indicating potential for stress-shielding reduction. Electrochemical characterization in simulated body fluid (SBF, 37 °C, pH 7.4) by linear potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) revealed that corrosion current density increased from 0.033 × 10⁻6 A/cm2 (bulk) to 2.55 × 10⁻6 A/cm2 at 80% porosity, while polarization resistance decreased from 21.65 kΩ (bulk) to 2.47 kΩ (80% porosity), attributed to increasing effective surface area and electrolyte penetration into interconnected pore networks. In vitro cytotoxicity assessment using BICR-10 fibroblast cells per ISO 10993–5 confirmed cell viability above 80% at day 7 for scaffolds with 70%, 75%, and 80% porosity, meeting the non-cytotoxicity threshold, while the 65% porosity scaffold exhibited a significant reduction in day-7 viability attributed to diffusion-limited nutrient transport within its smaller pore channels. Within the scope of this in vitro, quasi-static study, scaffolds with 70% and 75% porosity demonstrated a favourable balance of mechanical stiffness, corrosion resistance, and non-cytotoxicity. These findings establish a quantitative structure–property framework for EBM-fabricated Ti6Al4V scaffolds across a systematic porosity range. Although finding of this study suggests that 70% and 75% are suitable for implant application, validation through fatigue characterization, tribocorrosion testing, and in vivo animal model studies is also required before carrying the clinical study for load-bearing application. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2026.