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

Background: 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. Objective: The current research provides a finite element analysis (FEA) to investigate porous gyroid Ti۶Al۴V structure compared to a solid stem model for human tibial-knee implantation of total knee replacement (TKR).Material and Methods: In this study, the implant proximal portion was designed as porous gyroid Ti۶Al۴V structure with ۵۰۰ µm pore size. CATIA V۵R۱۸ was used for modeling both gyroid and full solid models. Structural analysis was carried out using ANSYS R۱۸.۱ to evaluate the implant performance. Results: After gyroid implantation, the maximum von-Mises stress obtained under the tibial tray was increased to ۱۰.۰۸۱ MPa. Also, the maximum shear stress at the stem/bone interface was reduced to ۰.۷۳۴۷ MPa. The stress concentration at the stem tip and the bone strain energy were also improved. The minimum factor of safety is ۴.۶ for the gyroid porous implant. A proof of concept model was additively manufactured successfully with pore size ۵۷۷.۷۷۳۳ ± ۳۴.۷۶۲ µm. Conclusion: 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.

Keywords:

Total knee replacement , Porous , Knee Prosthesis , Titanium Alloy (Ti۶Al۴V) , Von-Mises Stress , Shear Stress