Modeling and simulation of a porous mobility total ankle arthroplasty implant: enhancing bone-in growth and reducing micromotion for improved fixation.

Abstract

<h4>Background</h4>Porous implant designs have been introduced in total ankle replacement (TAR) to enhance bone ingrowth and long-term fixation. However, their immediate mechanical stability remains a concern, this study aimed to evaluate and compare the biomechanical behavior of porous and non-porous TAR stem designs under physiological loading using finite element analysis.<h4>Methods and results</h4>Three-dimensional models of both designs were conducted using SolidWorks and analyzed in ANSYS. The proximal tibia was fully constrained in all degrees of freedom, and an axial compressive load of 3414 N was applied to simulate stance-phase conditions. The non-porous implant exhibited a maximum contact pressure of 11.5 MPa and micromotion of 49.6 µm, while the porous implant showed higher peak contact pressure (83.3 MPa) and micromotion (129.4 µm). Stress distribution in the non-porous model was more uniform, whereas localized stress concentrations appeared around the porous stem regions. Peri-implant cancellous in non-porous design generated a peri-implant von Mises stress of 9.54 MPa, whereas the porous model increased these values to 67.3 MPa.<h4>Conclusion</h4>Porosity enhanced mechanical stimulus to the surrounding cancellous bone and may support improved long-term osseointegration by reducing stress shielding; however, it also produced substantially higher micromotion and contact pressure, indicating compromised primary stability. The localized stress peaks around pore regions highlight the need for balanced implant stiffness and optimized pore architecture to prevent early instability while still promoting bone ingrowth.