Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region.
Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region; The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China.
Gait Posture. 2021 Jul;88:54-59. doi: 10.1016/j.gaitpost.2021.05.009. Epub 2021 May 10.
The posterior tibialis tendon dysfunction (PTTD) is typically associated with progressive flatfoot deformity, which could be alleviated with foot orthosis. However, the evaluation of tibialis posterior (TP) weakness on lower limb mechanics of flatfoot adults with foot orthoses is scarce and requires further investigation.
This study aimed to examine the effects of TP weakness on lower limb mechanics in flatfoot adults with foot orthosis through gait analysis and musculoskeletal modelling.
Fifteen young adults with flatfoot were recruited from University to perform a gait experiment with and without foot orthoses. Data collected from the motion capture system were used to drive the musculoskeletal modelling for the estimation of the joint force and extrinsic muscle forces of the lower limb. A parametric analysis was conducted by adjusting the TP muscle strength from 40 % to 100 %. Two-way repeated measures ANOVA was used to compare the peak extrinsic foot muscle forces and joint forces among different levels of TP weakness and insole conditions.
TP weakness significantly increased ankle joint force superoinferiorly (F = 125.9, p < 0.001) and decreased anteroposteriorly (F = 125.9, p < 0.001), in addition to a significant increase in the muscle forces of flexor hallucis longus (p < 0.001) and flexor digitorum longus (p < 0.001). Besides, the foot orthosis significantly reduced most peak muscle forces whilst significantly reduced the second peak knee force and peak ankle force compared to the control condition (F = 8.79-30.9, p < 0.05).
The increased extrinsic foot muscle forces (flexor hallucis longus and flexor digitorum longus) and ankle joint forces in the TP weakness condition indicated that TP weakness may induce compensatory muscle activation and attenuated joint load. The abnormal muscle and joint mechanics in flatfoot adults with TP weakness might be restored by the orthosis.
胫骨后肌腱功能障碍（PTTD）通常与进行性扁平足畸形相关，可通过足矫形器缓解。然而，对于使用足矫形器的扁平足成年人，胫骨后肌（TP）力量减弱对下肢力学的影响评估较少，需要进一步研究。
本研究旨在通过步态分析和肌肉骨骼建模来研究 TP 力量减弱对使用足矫形器的扁平足成年人下肢力学的影响。
从大学招募了 15 名年轻的扁平足成年人，让他们在使用和不使用足矫形器的情况下进行步态实验。使用运动捕捉系统采集的数据用于驱动肌肉骨骼建模，以估计下肢关节力和外在肌肉力。通过调整 TP 肌肉力量从 40%到 100%进行参数分析。使用双因素重复测量方差分析比较不同 TP 力量减弱水平和鞋垫条件下的外在足部肌肉最大力量和关节力。
TP 力量减弱显著增加了踝关节的内外方向上的关节力（F=125.9，p<0.001），并降低了前后方向上的关节力（F=125.9，p<0.001），同时还显著增加了踇长屈肌（p<0.001）和趾长屈肌（p<0.001）的肌肉力量。此外，与对照条件相比，足矫形器显著降低了大多数最大肌肉力量，同时显著降低了第二峰值膝关节力和峰值踝关节力（F=8.79-30.9，p<0.05）。
TP 力量减弱时，外在足部肌肉力量（踇长屈肌和趾长屈肌）和踝关节力量增加，表明 TP 力量减弱可能导致代偿性肌肉激活和关节负荷减轻。TP 力量减弱的扁平足成年人的异常肌肉和关节力学可能通过矫形器得到恢复。
