Design of an Ultra-Low Modulus 3D Printed Titanium Bio-Metamaterials for Bone Replacement

Porous designs effectively reduce stress shielding in metallic orthopedic implants. However, current porous structures often fail to adequately meet the needs of patients with osteoporosis and low-modulus body regions. This study proposes a sinusoidal-based lattice structure for an ultralow and widely tunable modulus design, aiming to match diverse bone tissue requirements and enhance biomechanical compatibility. Parametric modeling and finite element analysis were used to evaluate the performance of this structure. Results show that, within the design range suitable for bone growth, the elastic modulus of this lattice structure is tunable over a wide range, from 0.09 to 32.67 GPa, outperforming existing porous structures. The lowest value closely matched the minimum mechanical properties of human cancellous bone among porous structures. Moreover, the structure exhibited distinct anisotropic characteristics, allowing for directional design based on mechanical requirements. The structure's permeability ranged from 1.19 × 10 –8 m² to 2.3 × 10 –7 m², making it highly compatible with human cancellous bone and meeting the requirements of orthopedic implants. Samples with porosities ranging from 46 % to 87 % were successfully fabricated using powder bed fusion additive manufacturing, validating the simulation predictions. This tunable low-modulus lattice structure provides a novel approach for developing personalized orthopedic implants, particularly for patients with specialized needs such as osteoporosis, and can potentially enhance biomechanical compatibility and long-term stability.