Huashan Hospital, Departmentof Orthopedics, Fudan University, Shanghai200040, China.
Bone Joint Res. 2013 Dec 9;2(12):255-63. doi: 10.1302/2046-3758.212.2000220. Print 2013.
The objective of this study was to evaluate the rotation and translation of each joint in the hindfoot and compare the load response in healthy feet with that in stage II posterior tibial tendon dysfunction (PTTD) flatfoot by analysing the reconstructive three-dimensional (3D) computed tomography (CT) image data during simulated weight-bearing.
CT scans of 15 healthy feet and 15 feet with stage II PTTD flatfoot were taken first in a non-weight-bearing condition, followed by a simulated full-body weight-bearing condition. The images of the hindfoot bones were reconstructed into 3D models. The 'twice registration' method in three planes was used to calculate the position of the talus relative to the calcaneus in the talocalcaneal joint, the navicular relative to the talus in talonavicular joint, and the cuboid relative to the calcaneus in the calcaneocuboid joint.
From non- to full-body-weight-bearing condition, the difference in the talus position relative to the calcaneus in the talocalcaneal joint was 0.6° more dorsiflexed (p = 0.032), 1.4° more everted (p = 0.026), 0.9 mm more anterior (p = 0.031) and 1.0 mm more proximal (p = 0.004) in stage II PTTD flatfoot compared with that in a healthy foot. The navicular position difference relative to the talus in the talonavicular joint was 3° more everted (p = 0.012), 1.3 mm more lateral (p = 0.024), 0.8 mm more anterior (p = 0.037) and 2.1 mm more proximal (p = 0.017). The cuboid position difference relative to the calcaneus in the calcaneocuboid joint did not change significantly in rotation and translation (all p ≥ 0.08).
Referring to a previous study regarding both the cadaveric foot and the live foot, joint instability occurred in the hindfoot in simulated weight-bearing condition in patients with stage II PTTD flatfoot. The method used in this study might be applied to clinical analysis of the aetiology and evolution of PTTD flatfoot, and may inform biomechanical analyses of the effects of foot surgery in the future. Cite this article: Bone Joint Res 2013;2:255-63.
本研究旨在评估足后足各关节的旋转和位移，并通过分析模拟负重状态下重建的三维（3D）计算机断层（CT）图像数据，比较健康足和 II 期胫骨后肌腱功能不全（PTTD）平足的负重反应。
首先对 15 例健康足和 15 例 II 期 PTTD 平足患者进行非负重状态下的 CT 扫描，然后进行模拟全身体重负重状态下的 CT 扫描。将后足骨骼图像重建为 3D 模型。在三个平面上使用“两次配准”方法，计算距骨相对于跟骨在距跟关节中的位置、跟骨相对于舟骨在跗舟关节中的位置以及骰骨相对于跟骨在跟骰关节中的位置。
从非负重到全身体重负重状态，距骨相对于跟骨在距跟关节中的位置差异，PTTD 平足组背屈增加 0.6°（p = 0.032）、外展增加 1.4°（p = 0.026）、前向增加 0.9 毫米（p = 0.031）、近端增加 1.0 毫米（p = 0.004），与健康足相比。跗舟关节中跟骨相对于舟骨的位置差异，外展增加 3°（p = 0.012）、外侧增加 1.3 毫米（p = 0.024）、前向增加 0.8 毫米（p = 0.037）、近端增加 2.1 毫米（p = 0.017）。跟骰关节中骰骨相对于跟骨的位置差异在旋转和位移方面无明显变化（均 p≥0.08）。
参照之前对尸体足和活体足的研究，在模拟负重状态下，II 期 PTTD 平足患者后足出现关节不稳定。本研究中使用的方法可应用于 PTTD 平足病因和演变的临床分析，并为未来的足部手术生物力学分析提供信息。
Bone Joint Res 2013;2:255-63.
