Custom-made talar component of total ankle replacement implant, with or without lateral articular facet: A finite element analysis

Abstract

Background: The present patient dissatisfaction with and high failure rates of total ankle replacement (TAR) are likely due to current prosthesis designs, which are not patient-specific and anatomy-based, leading to unphysiological motion at the replaced joint. The design of customized prostheses is already possible by means of medical imaging and additive manufacturing technology.Methods: In this study, dome and geometric fixtures of custom-made talar components for TAR were designed, and we investigated two kinds of talar components: 2-surface contact type (Type-1, without lateral articular facet) and 3-surface contact type (Type-2, with lateral articular facet). The effects of the above two prostheses on the loading stress of the prosthesis contact surface were comparatively analysed with three-dimensional finite element models.Results: The maximum and average von Mises stress values of the 3-surface prosthesis were smaller than those of the 2-surface prosthesis. In terms of contact surface pressure, the maximum and average values of the 3-surface prosthesis are almost equal to those of the 2-surface type. In terms of the tangential slip distribution of the contact surface, the maximum and average values of the 3surface prosthesis were smaller than those of the 2-surface prosthesis.Conclusions: The custom-made talar component of the total ankle replacement implant reproduced the anatomical morphology of the natural articular surfaces well. The 3-surface contact type prosthesis with lateral articular facet, compared to the 2-surface contact type without lateral articular facet, offers better static stability by affecting the internal and external forces.