Objective Assessing the biomechanical differences of the artificial ankle joints of INBONE II and INFINITY after TAA to provide more scientific and individualized treatment options for patients. Methods Based on MSK MBD software AnyBody, a patient individualized TAA lower extremity MSK MBD model was established. Prediction of ankle joint contact force, ankle joint motion and contact characteristics of artificial ankle joint surface. Results The geometric shape of the articular surface of the artificial ankle has no significant effect on the ankle contact force, but it affects the range of motion and the contact characteristics of the articular surface. Compared to INBONE II, the coronal plane articular surface arc height of INFINITY is lower, with increased rotational mobility by 7.91% and 2.61%. The sagittal plane matching is lower, resulting in changes of 21.75%, 21.23%, and 49.26% in the range of motion. INFINITY exhibits lower matching, with corresponding reductions of 18.48%, 30.42%, and 26.36% in articular surface contact area. However, the center of pressure motion trajectory is concentrated on the medial side, avoiding edge contact stress concentration, reducing the risk of joint dislocation, and premature wear of the tibial component. Conclusion The smaller geometric constraints of the INFINITY artificial ankle joint demonstrate better biomechanical performance, promoting improved postoperative ankle joint functional recovery.