Numerical Evaluation of a Porous Tibial-Knee Implant using Gyroid Structure

Porous materials are recommended for orthopedic applications as they eliminate issues of interfacial instability with tissues and reduce mechanical mismatch of the young’s modulus. The current research provides a finite element analysis (FEA) to investigate porous gyroid Ti6Al4V structure compared to a solid stem model for human tibial-knee implantation of total knee replacement (TKR). In this study, the implant proximal portion was designed as porous gyroid Ti6Al4V structure with 500 µm pore size. CATIA V5R18 was used for modeling both gyroid and full solid models. Structural analysis was carried out using ANSYS R18.1 to evaluate the implant performance. After gyroid implantation, the maximum von-Mises stress obtained under the tibial tray was increased to 10.081 MPa. Also, the maximum shear stress at the stem/bone interface was reduced to 0.7347 MPa. The stress concentration at the stem tip and the bone strain energy were also improved. The minimum factor of safety is 4.6 for the gyroid porous implant. A proof of concept model was additively manufactured successfully with pore size 577.7733 ± 34.762 µm. The results indicated enhanced clinical performance of the porous tibial-knee implant compared to the solid titanium implant via increasing the maximum von-Mises bone stresses and decreasing the maximum shear stress at the bone/implant interface.