Background

The tissue stress theory is commonly used to prescribe foot orthoses, however the mechanisms of foot orthoses are not understood well. The effect foot orthotics have on the plantar intrinsic muscles remains unclear. The study was designed to assess changes in muscle size and activity of the intrinsic muscles of individuals with pes planus after wearing custom-made foot orthotics for 12-weeks.

Methods

Eighteen young adults with pes planus were allocated by stratified sampling into the orthotic group (n = 9) or control group (n = 9). Ultrasonography measured the cross-sectional area of the flexor digitorum brevis, abductor digiti minimi, and abductor hallucis at baseline, 6 and 12-weeks. Subsequently, participants completed an unexpected gait termination protocol (12 of 50 trials unexpected) and average electromyography magnitude was recorded.

Findings

After 12-weeks the orthotic group cross-sectional area significantly decreased by 9.6% (P < .001) for the flexor digitorum brevis, 17.1% for abductor digiti minimi (P < .001) and 17.4% for abductor hallucis (P < .001). There were no significant differences of muscle activity magnitude for the intrinsic muscles.

Interpretation

The short-term use of custom-made foot orthoses created a decrease in muscle size of the flexor digitorium brevis, abductor digiti minimi and abductor hallucis plantar intrinsic muscles but had no effect on muscle activity. Clinically, these results help to understand the adaptations that are created when foot orthoses are supporting a pes planus foot structure when reducing plantar pressures. These findings may help enhance the prescription of foot orthoses by adding a strength program to prevent disuse atrophy of these muscles.

中文翻译：

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在步态终止期间，为期12周的自定义足部矫形器干预对年轻人的固有足部肌肉的大小和肌肉活动的影响。

背景

组织应力理论通常用于规定足部矫形器，但是人们对脚部矫形器的机理还不甚了解。足部矫形器对足底固有肌肉的影响尚不清楚。这项研究旨在评估在佩戴定制的脚部矫形器12周后，患有扁平苔藓的个体的肌肉大小和固有肌肉活动的变化。

方法

通过分层抽样，将18例扁平疣年轻人分为矫形组（n  = 9）或对照组（n = 9）。超声检查在基线第6周和第12周测量了短指屈肌，小指外展肌和外展幻觉的横截面积。随后，参与者完成了意想不到的步态终止方案（意想不到的50个试验中的12个），并记录了平均肌电图幅值。

发现

在 短短12周后，矫形器组的截面积对于短指屈肌明显降低了9.6％（P <.001），对于小指外展肌而言是17.1％（P  <.001），对于外展幻觉来说是17.4％（P  <。 001）。固有肌肉的肌肉活动强度没有显着差异。

解释

定制足部矫形器的短期使用可减少短指屈肌，小指外展肌和拇外展器plant肌固有肌肉的肌肉大小，但对肌肉活动没有影响。在临床上，这些结果有助于了解当脚矫形器在降低足底压力时支撑足踝足结构时产生的适应性变化。这些发现可能通过增加强度程序来防止这些肌肉萎缩而有助于增强脚部矫形器的处方。