Enhanced biomechanical compatibility of 3D-printed polylactic acid lattice structures: Synergizing mechanical, topography, and microstructural properties for trabecular bone mimicry.

The design and mechanical performance of 3D-printed lattice scaffolds are critical for biomedical applications, particularly when replicating the trabecular architecture of bone. This study evaluated the mechanical and biological performance of collagen-infused PLA 3D-printed lattice scaffolds designed for trabecular bone regeneration. Four geometries-body-centered cubic (BCC), diamond, gyroid, and rhombic-were fabricated with cellular wall thicknesses of 1.5, 2.0, and 2.5 mm. BCC lattices achieved a maximum compressive strength of 14.66 MPa, while Diamond-2 samples recorded a yield strength of 2.61 MPa. Gyroid scaffolds, though not the strongest, exhibited optimal porosity (up to 9.98 %) and the highest surface roughness (Sa = 12.51 μm), features that enhance cell attachment. In vitro assays with L929 fibroblast cells revealed that transparent PLA analogues of the gyroid design achieved relative growth rates of 109.4 % and 125.7 % at 50 % and 100 % extraction concentrations, respectively, compared to 37.3 % and 31.1 % for green PLA analogues at 60 % and 100 % extraction concentrations. These results underscore that while BCC structures excel in mechanical support, gyroid lattices provide a superior balance between mechanical integrity and biological performance, rendering them promising candidates for bone tissue engineering. These findings offer important insights for optimizing collagen-enhanced, 3D-printed scaffolds tailored to meet the dual mechanical and biological demands of trabecular bone regeneration.