Henry Jensen K, Hoffman Jeffrey, Kim Jaeyoung, Steineman Brett, Sturnick Daniel, Demetracopoulos Constantine, Deland Jonathan, Ellis Scott
Foot & Ankle Surgery, Hospital for Special Surgery, New York, NY, USA.
Biomechanics, Hospital for Special Surgery, New York, NY, USA.
Foot Ankle Int. 2022 Dec;43(12):1577-1586. doi: 10.1177/10711007221126736. Epub 2022 Oct 19.
Progressive collapsing foot deformity (PCFD) is a complex pathology associated with tendon insufficiency, ligamentous failure, joint malalignment, and aberrant plantar force distribution. Existing knowledge of PCFD consists of static measurements, which provide information about structure but little about foot and ankle kinematics during gait. A model of PCFD was simulated in cadavers (sPCFD) to quantify the difference in joint kinematics and plantar pressure between the intact and sPCFD conditions during simulated stance phase of gait.
In 12 cadaveric foot and ankle specimens, the sPCFD condition was created via sectioning of the spring ligament and the medial talonavicular joint capsule followed by cyclic axial compression. Specimens were then analyzed in intact and sPCFD conditions via a robotic gait simulator, using actuators to control the extrinsic tendons and a rotating force plate underneath the specimen to mimic the stance phase of walking. Force plate position and muscle forces were optimized using a fuzzy logic iterative process to converge and simulate in vivo ground reaction forces. An 8-camera motion capture system recorded the positions of markers fixed to bones, which were then used to calculate joint kinematics, and a plantar pressure mat collected pressure distribution data. Joint kinematics and plantar pressures were compared between intact and sPCFD conditions.
The sPCFD condition increased subtalar eversion in early, mid-, and late stance ( < .05), increased talonavicular abduction in mid- and late stance ( < .05), and increased ankle plantarflexion ( < .05), adduction ( < .05), and inversion ( < .05). The center of plantar pressure was significantly ( < .01) medialized in this model of sPCFD and simulated stance phase of gait.
Subtalar and talonavicular joint kinematics and plantar pressure distribution significantly changed with the sPCFD and in the directions expected from a PCFD foot. We also found that ankle joint kinematics changed with medial and plantar drift of the talar head, indicating abnormal talar rotation. Although comparison to an in vivo PCFD foot was not performed, this sPCFD model produced changes in foot kinematics and indicates that concomitant abnormal changes may occur at the ankle joint with PCFD.
This study describes the dynamic kinematic and plantar pressure changes in a cadaveric model of simulated progressive collapsing foot deformity during simulated stance phase.
进行性足塌陷畸形（PCFD）是一种复杂的病理状况，与肌腱功能不全、韧带失效、关节排列不齐及足底异常力分布相关。现有的PCFD知识基于静态测量，其提供了结构信息，但关于步态期间足踝运动学的信息较少。在尸体中模拟了PCFD模型（sPCFD），以量化在模拟步态站立期完整状态与sPCFD状态之间关节运动学及足底压力的差异。
在12个尸体足踝标本中，通过切断弹簧韧带和内侧距舟关节囊，随后进行周期性轴向压缩来创建sPCFD状态。然后使用机器人步态模拟器在完整状态和sPCFD状态下对标本进行分析，利用致动器控制外在肌腱，并在标本下方使用旋转测力板来模拟步行的站立期。使用模糊逻辑迭代过程优化测力板位置和肌肉力量，以收敛并模拟体内地面反作用力。一个8摄像头运动捕捉系统记录固定在骨骼上的标记物的位置，随后用于计算关节运动学，并且一个足底压力垫收集压力分布数据。比较完整状态和sPCFD状态之间的关节运动学和足底压力。
sPCFD状态在站立早期、中期和晚期增加了距下关节外翻（P<0.05），在站立中期和晚期增加了距舟关节外展（P<0.05），并增加了踝关节跖屈（P<0.05）、内收（P<0.05）和内翻（P<0.05）。在这个sPCFD模型及模拟步态站立期，足底压力中心显著向内侧移位（P<0.01）。
距下关节和距舟关节运动学以及足底压力分布随sPCFD发生了显著变化，且变化方向符合PCFD足的预期。我们还发现，踝关节运动学随距骨头的内侧和足底移位而改变，表明距骨旋转异常。尽管未与活体PCFD足进行比较，但这个sPCFD模型产生了足部运动学变化，并表明PCFD可能伴随踝关节发生异常变化。
本研究描述了在模拟站立期模拟进行性足塌陷畸形尸体模型中的动态运动学和足底压力变化。
