Total Ankle Arthroplasty Kinematics Using a Symmetric Bicondylar Talar Component Design: A Cadaveric Gait Simulation Short Report

Background: The availability of total ankle arthroplasty (TAA) systems with varying designs of talar condylar geometry has increased. However, it remains unclear how these features influence the motion of the ankle and hindfoot joints. This study assessed the ankle and hindfoot kinematics using a contemporary TAA system with a symmetric bicondylar talar component design. Methods: TAA was performed in eleven mid-tibia specimens. A 6–degree-of-freedom robot sequentially simulated the stance phase for the intact and post-TAA conditions. The kinematics and range of motion (ROM) of the ankle, subtalar, and talonavicular joints were calculated and compared between conditions. Results: The ankle demonstrated decreased dorsiflexion by 4.0 degrees (P = .041) and increased inversion by 1.5 degrees (P = .04) during early stance. The talonavicular joint was significantly more everted by 3.5 degrees during a portion of late stance (P = .016). There were no significant differences between conditions in the subtalar joint. The ankle ROM in the transverse plane increased 1.9 degrees post-TAA (P = .025), but no significant changes were observed in the subtalar or talonavicular joints. Conclusion: In this cadaveric stance‑phase simulation, ankle and hindfoot kinematics and ROM were modestly altered after TAA. Therefore, a TAA system with a symmetric talar condylar design may closely replicate native ankle and hindfoot joint motion. Clinical Relevance: Implant design may influence joint kinematics; in this cadaveric model, a symmetric bicondylar talar component showed smaller transverse‑plane ROM increases than those previously reported for one asymmetric design tested under similar conditions.