3D-printed CF-PLA bone plates with metamaterial structures: Design, fabrication, and mechanical evaluation.

This study presents the design, fabrication, and mechanical performance of carbon fiber-reinforced polylactic acid (CF-PLA) bone plates incorporating auxetic and non-auxetic metamaterial architectures. Four lattice-structured bone plates (re-entrant, rotating square, tetrachiral, and hexagonal) were evaluated for their flexural, tensile, and compressive properties. The specimens were fabricated using Fused Deposition Modelling (FDM). The tetrachiral structure demonstrated superior bending capacity, achieving a flexural stress of 17 MPa and a modulus of 1214 MPa. Under both tension and compression, it exhibited the highest strength (24.5 MPa and 40 MPa, respectively) and stiffness (1441 MPa in tension and 2352 MPa in compression), while the rotating square designs offered a favorable balance of flexibility and strength. CF-PLA metamaterial bone plates showed substantially lower stiffness compared to various metallic plates (e.g., Titanium (Ti), steel) indicating their potential to reduce stress shielding and promote bone healing. The auxetic geometries, particularly the tetrachiral and rotating square, exhibited superior tensile and compressive behavior compared to the non-auxetic hexagonal bone plates. The results underscore the potential of 3D-printed CF-PLA metamaterial structures as effective alternatives to metallic bone plates. With further optimization, such designs could enable patient-specific implants with improved biomechanical compatibility and healing outcomes.