Transactions on Additive Manufacturing Meets Medicine
Vol. 8 No. S1 (2026): Trans. AMMM Supplement
https://doi.org/10.18416/AMMM.2026.26062732
Impact of lattice-based Voronoi design and surface finishing on the functional performance of Ti-6Al-4V bone screws
Main Article Content
Copyright (c) 2026 Maddalena Bracchi; Clara Mapelli, Jacopo Fiocchi, Ausonio Tuissi, Chiara Colombo, Carlo Alberto Biffi
This work is licensed under a Creative Commons Attribution 4.0 International License.
Abstract
Ti6Al4V ELI bone screws are widely used in orthopedics for fracture fixation and osseointegration. Additive manufacturing (AM) enables the production of patient-specific implants with customized geometries and integrated trabecular lattice structures [1]. These porous architectures can enhance osseointegration, particularly in osteoporotic bone, while reducing implant stiffness to better match that of natural bone. In addition, the inherent micro-roughness of AM surfaces promotes osteoblast adhesion and spreading, supporting early bone integration [2,3].
In this study, bone screws manufactured via Laser Powder Bed Fusion (LPBF) with Voronoi lattice structure, placed in both longitudinal and transversal locations, were subjected to finishing treatments to optimize their surface characteristics. Morphological characterization was performed through surface profilometry on both the lattice regions and the threaded surfaces, and the results were compared with those of untreated screws to evaluate the surface modifications induced by the treatments. Mechanical performance was subsequently evaluated through insertion tests, axial pull-out tests to assess primary stability in solid polyurethane foam with a density comparable to osteoporotic bone. Additionally, torsional tests were also carried out until failure in accordance with the ASTM F543-17 standard to determine the influence of surface treatments on the mechanical properties of the three types of screws.
Secondary stability was also investigated by evaluating the mechanical behaviour of the screws embedded in PMMA bone cement, which simulates woven bone formed immediately after implantation by osteoblast activity. Finally, the experimental results were compared with Finite Element Method (FEM) simulations of the axial pull-out behaviour to validate the computational predictions and to determine the critical regions within the lattice structure, providing insights for further optimization of the screw design.