KINEMATICS AND STABILITY OF THE ARCH OF THE FOOT

足弓在为负重提供稳定的基础、适应不同地面条件的灵活性以及分散负重负荷的活动中非常重要。弓部受骨骼和关节几何形状、韧带、关节囊和筋膜的限制。胫骨后肌腱功能障碍(PTTD)与这些约束的丧失有关，导致疼痛、功能受损和扁平足畸形。本研究将集中于与足弓功能和足部机械行为相关的四个具体目标，包括PTTD和扁平足矫形器或重建术。假设1：使用动态踝关节模拟器可以在体外观察到正常的步态。具体目标1：测定正常人水平行走时的足踝运动学、地面反作用力和压力推进中心。假设2：在水平行走中，胫后肌腱功能障碍和扁平足与足踝运动学、地面反作用力和压力中心推进明显异常相关。具体目的2：测定模拟胫后肌腱功能障碍和扁平足的身体足的足踝运动学，并与正常足进行比较。假设3：后足矫形器(HFO)改善了胫后肌腱功能障碍和平足水平行走的足部和脚踝功能。具体目的3：评价水平行走时关节和非关节HFO治疗后胫后肌腱功能障碍的足踝和扁平足的力学行为。假设4：不涉及广泛关节融合术的胫后肌腱功能障碍和扁平足的重建术改善了水平行走中的足踝功能。具体目的4：评估三种治疗胫后肌腱功能障碍和扁平足的手术方式：外侧柱延长术(LCL)、跟骨内侧移位截骨术(MDO)和Giannini距下植入术，以评估足踝的力学行为。

The arch of the foot is important in performing activities to provide a stable base for weight bearing, flexibility to accommodate different ground conditions, and also to dissipate loads from weight bearing. The arch is constrained by bony and articular geometry, ligaments, joint capsules, and fascia. Posterior tibial tendon dysfunction (PTTD) is associated with loss of these constraints, leading to pain, impaired function, and flatfoot deformity. This study will focus upon four specific aims related to function of the arch and to mechanical behavior of the foot with orthoses or reconstruction procedures for PTTD and flatfoot. Hypothesis 1: Normal gait may be observed in vitro with a dynamic ankle simulator. Specific Aim 1: To determine foot and ankle kinematics, ground reaction force, and center of pressure advancement in level walking in normals. Hypothesis 2: Posterior tibial tendon dysfunction and flatfoot are associated with markedly abnormal foot and ankle kinematics, ground reaction force, and center of pressure advancement in level walking. Specific Aim 2: To determine foot and ankle kinematics in cadaveric feet with simulated posterior tibial tendon dysfunction and flatfoot and compare results with normals. Hypothesis 3: Hindfoot orthoses (HFO) improve foot and ankle function in feet with posterior tibial tendon dysfunction and flatfoot on level walking. Specific Aim 3: To evaluate mechanical behavior of the foot and ankle with posterior tibial tendon dysfunction and flatfoot treated with articulated and nonarticulated HFO on level walking. Hypothesis 4: Reconstruction operations for posterior tibial tendon dysfunction and flatfoot which do not involve extensive arthrodesis improve foot and ankle function in level walking. Specific Aim 4: To evaluate mechanical behavior of the foot and ankle with three recently developed and yet to be proven operations for posterior tibial tendon dysfunction and flatfoot: lateral column lengthening (LCL), medial displacement calcaneal osteotomy (MDO), and Giannini subtalar implant.