Optimizing Lattice Structure for Load Bearing Orthopedic Implants

Higher stiffness of commercially available femoral implants compared to the surrounding bone results in loosening of the femoral implant, which requires revision hip replacement surgery. To address this issue, 3D‐printed porous femoral implants have been explored to avoid early implant failure. These implants can minimize stress‐shielding effects by reducing the overall implant stiffness and facilitating bone ingrowth through interconnected pores, resulting in a high surface‐area‐to‐volume ratio. However, reducing stiffness often compromises the yield and fatigue strength of the implant. This article uses the design of experiments method for optimization of lattice structures, with analysis of variance to validate the results. Influence of design parameters, such as pore size, strut diameter, and lattice type, that is, octet and face body centered cubic (FBCCZ), is analyzed to achieve a high yield‐strength‐to‐stiffness ratio. The optimal configuration is identified as an octet lattice with a 0.4 mm strut diameter and 0.9 mm pore size, producing mechanical properties comparable to the surrounding bone. Optimized Ti6Al4V lattice structures are fabricated using selective laser melting and tested under quasistatic compression. The fatigue analysis is performed using finite element simulations, according to ISO 7204‐6, and the factor of safety as per Soderberg criterion is evaluated as 2.37, corresponding to 50 million cycles.