所有运动系统损伤中，踝足四关节损伤最为常见。我们前期研究发现四关节存在多平面生理运动，并在时、空、力上相互偶联，远较髋膝关节复杂。以往静态、准动态及尸体环境下的实验很难反映四关节在活体、动态情况下的复杂运动，更不能反映其内在的偶联机制，这使得踝关节创伤后不稳、平足症及人工踝关节假体等难题至今无法突破。我们前期优化了双平面透视匹配系统，使其适用于踝足部小关节的在体、动态三维运动测量。本项目基于该优化系统，采集四关节在活体内及各种生理运动状态下的三维运动全过程；将同步化三维力学采集整合于该系统中，实现在体动态有限元模型的建立及四关节内部应力的连续分析。以此建立踝足四关节连续、完整的在体动态生物力学数据库，重点分析踝足四关节在时、空、力上的偶联机制；针对上述的四关节临床难点进行研究，以活体、生理状态下的生物力学证据分析疾病发展过程中四关节偶联机制及其病理变化，为临床治疗改进提供理论依据。

The ankle and hindfoot joints complex had the highest rate of injuries in the human locomation system. Our preliminary researches had revealed that the this joint complex was much more complicated than the hip and knee joints due to the multi-plane physiological motions and the coupling mechanism in terms of time, space and internal stress distributions. Previously, the in vitro, static or quasi-dynamic studies could hardly reflect its real biomechanical characteristics during the physiological and dynamic conditions. Therefore, the clinical challenges such as post-traumatic ankle instability, flatfoot deformity and ankle joint prosthesis still had no breakthrough. We have successfully modified the dual-orthogonal fluoroscopic imaging system which could accurately measure the in vivo kinematics of the small joints on foot and ankle under dynamic environment. Based on this modified system, the current program aiming to obtain the precise in vivo kinematics of the ankle and hindfoot joints complex. Moreover, combined with synchronized kinetic measurement devices, the successive data of joint internal stress distribution would be measured with the establishment of dynamic finite element models. A systematic in vivo biomechanical database of the joints complex would be built then and their coupling mechanisms during various physiological motions would be analyzed. We will strictly include the most controversial clinical pathologies to reveal their coupling mechanism changes during disease progressions through the in vivo and dynamic biomechanical analysis. The etiology of these pathologies and the efficiency of current treatments would be demonstrated based on the in vivo biomechanical evidences. This will provide theoretical support for improvement of clinical treatments.