Lercan Aslan, Omer Subasi, Bedri Karaismailoglu, Cemil Cihad Gedik, Batuhan Yuruk, Soheil-Ashkani Esfahani, Ilker Eren
Acta Orthopaedica et Traumatologica Turcica - 2025;59(6):361-367
Objective: This study aimed to computationally evaluate the effects of lesions of varying sizes and locations on stress distribution and ankle stiffness across the nine-zone grid of the talar dome in three different ankle positions. Methods: An adult ankle geometry was modeled with 1 mm of cartilage on both sides of the tibiotalar contact. Lesions with diameters of 4.5, 6.4, and 9 mm were created on the talar dome at each grid partition, ranging from section 1 (anteromedial) to 9 (posterolateral). The key innovation of the study was the use of tilted talar planes to account for the dome's curvature, enabling more accurate lesion modeling and biomechanical analysis. Percent changes in osteochondral von Mises stress distribution and ankle stiffness parameters were investigated using finite element analysis. Based on the designated design parameters, 81 different cases were modeled and simulated. Results: Zones 7 (posteromedial, -33.2% change in stiffness for a 9 mm defect), 3 (anterolateral, -24.2% change in stiffness for a 9 mm defect), and 8 (mid-posterior, -48.8% change in stiffness for a 9 mm defect) were found to be the most critical zones, showing evidence of decreased ankle stiffness in neutral, dorsiflexion, and plantarflexion positions, respectively. Zone 9 (posterolateral; neutral -4.7%, dorsiflexion 5.4%, plantarflexion 0.17% stiffness change for a 9 mm defect) was found to be the least critical zone in terms of biomechanical stiffness. Conclusion: From a clinical standpoint, since lesions in zones 8, 7, and 3 significantly impact joint biomechanics compared to other zones, more aggressive cartilage restoration or augmentation could be required while lesions in less problematic zones like zone 9 can be treated with microfracture surgery. Level of Evidence: Level V, prognostic study.
