Accurate knowledge of the kinematics of the in vivo Ankle Joint Complex (AJC) is critical for understanding the biomechanical function of the foot and assessing postoperative rehabilitation of ankle disorders, as well as an essential guide to the design of ankle–foot assistant devices. However, detailed analysis of the continuous 3D motion of the tibiotalar and subtalar joints during normal walking throughout the stance phase is still considered to be lacking. In this study, dynamic radiographs of the hindfoot were acquired from eight subjects during normal walking. Natural motions with six Degrees of Freedom (DOF) and the coupled patterns of the two joints were analyzed. It was found that the movements of the two joints were mostly in opposite directions (including rotation and translation), mainly in the early and late stages. There were significant differences in the Range of Motion (ROM) in Dorsiflexion/Plantarflexion (D/P), Inversion/Eversion (In/Ev), and Anterior–Posterior (AP) and Medial–Lateral (ML) translation of the tibiotalar and subtalar joints (p < 0.05). Plantarflexion of the tibiotalar joint was coupled with eversion and posterior translation of the subtalar joint during the impact phase (R² = 0.87 and 0.86, respectively), and plantarflexion of the tibiotalar joint was coupled with inversion and anterior translation of the subtalar joint during the push-off phase (R² = 0.93 and 0.75, respectively). This coordinated coupled motion of the two joints may be a manifestation of the AJC to move flexibly while bearing weight and still have stability.

准确了解体内踝关节复合体（AJC）的运动学对于了解足部的生物力学功能和评估踝关节疾病的术后康复至关重要，也是设计踝足辅助装置的重要指南。然而，在整个站立阶段正常行走期间，对胫距和距下关节连续 3D 运动的详细分析仍然被认为是缺乏的。在这项研究中，从八名受试者正常行走期间获得了后足的动态射线照片。分析了六个自由度 (DOF) 的自然运动和两个关节的耦合模式。结果发现，两关节的运动多为相反方向（包括旋转和平移），主要发生在早期和晚期。p  < 0.05）。在撞击阶段，胫距关节的跖屈与距下关节的外翻和平移相结合（R ² 分别为 0.87 和 0.86），在撞击阶段，胫距关节的跖屈与距下关节的内翻和平移相结合。推出阶段（R ² 分别 = 0.93 和 0.75）。两个关节的这种协调耦合运动可能是AJC在承受重量的同时移动灵活且仍具有稳定性的体现。