Comparative finite element analysis of contact and stress distribution in tibiotalar articular cartilage: Healthy versus varus ankles.

Background: The distribution of forces within the ankle joint plays a crucial role in joint health and longevity. Loading disorders affecting the ankle joint can have significant detrimental effects on daily life and activity levels. This study aimed to enhance our understanding of the mechanical behavior of tibiotalar joint articular cartilages in the presence of varus deformity using finite element analysis (FEA) applied to patient-specific models. Methods: Two personalized ankle models, one healthy and another with varus deformity, were created based on CT scan images. Four static loading scenarios were simulated at the center of pressure (COP), coupled to the hindfoot complex. The contact area, contact pressure, and von Mises stress were computed for each cartilage. Results: It was found that the peak contact pressure increased by 54% in the ankle with varus deformity compared to the healthy ankle model. Furthermore, stress concentrations moving medially were observed, particularly beneath the medial malleolus, with an average peak contact pressure of 3.5 MPa and 4.7 MPa at the tibial and talar articular cartilages, respectively. Conclusion: Varus deformities in the ankle region have been consistently linked to elevated contact pressure, increasing the risk of thinning, degeneration, and eventual onset of osteoarthritis (OA), emphasizing the need for prompt interventions aimed at mitigating complications.