Patient-Specific Anatomical Plate Outperforms Commercial Plate in Finite Element Analysis of Supramalleolar Osteotomy

Joint malalignment is a common reason for uneven stress distribution and articular cartilage damage, leading to osteoarthritis (OA) and post-traumatic osteoarthritis (PTOA) of the ankle. Supramalleolar osteotomy (SMOT) is a surgical approach to realign the ankle joint and normalize loading for patients with mild to moderate stage ankle OA. This study aimed to evaluate the biomechanical performance of SMOT using different fixation plate designs through finite element analysis (FEA). A patient-specific FE model was created using Computed Tomography (CT) scans to simulate a varus ankle joint. Two fixation plates, a commercial plate, and a custom-designed anatomical plate, were compared in terms of stress distribution, displacement, and load-sharing properties. The anatomical plate reduced intra-articular stress by 1.15 MPa compared to the commercial plate and carried $\mathbf{6 7 \%}$ of the total stress, compared to $43 \%$ for the commercial plate. The commercial plate exhibited an average displacement of 0.4 mm, while the anatomical plate showed a lower displacement of 0.29 $\mathbf{m m}$, indicating superior fixation. Additionally, the stress on the bone was $37 \%$ higher with the commercial plate, potentially impeding proper bone healing and fusion. The patient-specific anatomical plate demonstrated superior performance in redistributing stress, reducing bone stress, and minimizing displacement, highlighting the importance of anatomical precision in plate design for enhancing surgical outcomes. These findings suggest the need for further clinical validation and optimization of patient-specific plate fixation strategies for SMOT.