3D-Printed PLA/HA Composite Scaffolds: Balancing Mechanical Properties for Bone Tissue Engineering

Bone tissue engineering requires biomimetic materials, but pure polylactic acid (PLA) lacks osteoinductivity and produces acidic byproducts during degradation. To address these limitations, this study fabricated PLA scaffolds using fused-deposition modeling with four distinct lattice structures (rectangular, triangular, gyroid, and honeycomb) and incorporated hydroxyapatite (HA) at ratios of 0%, 10%, 20%, and 30% via injection molding. Mechanical properties were evaluated through compression, bending, and tensile testing. The results revealed that increasing HA content significantly reduced structural strength and increased brittleness. Specifically, specimens with 30% HA showed a 50% reduction in bending strength, while tensile strength dropped by approximately 46% at just 10% HA. Although the triangular lattice maximized absolute load capacity, the rectangular lattice provided a superior load-to-weight ratio and greater plastic deformation before fracture. Consequently, these findings suggest that the rectangular pattern with 70% infill density demonstrates the most suitable mechanical properties combined with limited HA addition (< 10%) to balance necessary mechanical integrity with the enhanced bioactivity required for repairing large bone defects. These PLA/HA composite scaffolds offer a promising approach for advanced bone tissue regeneration.