Ultrasonographic Approach to Detect the Resonance Frequency of the Plantar Fascia
Date Issued
2004
Date
2004
Author(s)
Chang, Yu-Jen
DOI
en-US
Abstract
足底筋膜是足底部重要的受力構造。由於在日常生活或運動的活動中，足底筋膜易受到反覆且過度的張力牽張，足底筋膜炎成為臨床上常見的足部問題之一。要了解足底筋膜的成因及其致病機轉，必須先了解足底筋膜的機械特質。
過去對於足底筋膜的研究大多是以離體的方式進行，亦即將足底筋膜取下，利用外力拉伸以測得其機械性質。唯一以活體方式測得足底筋膜機械性質的實驗是用是以螢光攝影術，即連續的Ｘ射線取得受試者足部的影像。此法使受試者曝露於過度放射線的危險，因此不易成為臨床使用的檢測工具。
本研究目的在建立使用超音波影像儀及加速度計測量足底筋膜共振頻率的方法，並以此一創新的方法量測足部在不同負載狀態下，足底筋膜共振頻率的變化。計有十三位年輕的健康志願者參與本實驗。實驗的方式是在受試者的足背放置振動馬達及加速度計，並由足底部以杜卜勒超音波影像法觀察足底筋膜的振動速度，藉由加速度計所測得的振動馬達振動加速度以及杜卜勒超音波測得的足底筋膜振動速度，可分別求出振動馬達及足底筋膜的振幅，二者相除可得其頻率響應，取其峰值所對應的頻率即為足底筋膜的共振頻率。本研究的重測信度係於站姿進行，以組內相關係數及標準誤表示。受試者共進行三次的測試，分別於坐姿、站姿及負重狀況測量。不同姿勢下共振頻率的差異係以重覆量測變異數分析檢測，若α=.05則視為有統計上的顯著差異，將進一步以事後檢定來檢測任兩組間的差異，此時α值調整為0.167。
結果顯示本研究再測信度為尚可至良好，其相關係數為0.684，測量標準誤則為1.79 Hz。足底筋膜的共振頻率在坐姿為20.4
Plantar fascia is the main load-bearing structure beneath the foot, which is noted to be vulnerable to excessive or abnormal stress acting on it. It is essential to study the mechanical properties of the plantar fascia to reveal the patho-mechanism of plantar fasciitis. In the past, researchers explored the mechanical properties of the plantar fascia via in vitro methods, which may not be able to reflect the properties of the fascia in a living system. The only in vivo study used the fluoroscopy, a series of X-ray, to obtain the image of the foot. This method may risk the participants in radiation exposure, avoided this method to be widely or repetitively used in the clinic.
It is, therefore, necessary to develop a method to detect the mechanical properties of the plantar fascia. To measure the resonance frequency of the plantar fascia and to clarify the relationship between the resonance frequency and the load acting on the foot, 13 healthy young participants were recruited in this study. A vibrator mounted with accelerometer was attached to the dorsum of the foot. The Doppler ultrasonography was used to detect the vibration speed of the plantar fascia beneath the foot. Through the acceleration of the vibrator detected by the accelerometer and the speed of the vibrating plantar fascia from the Doppler ultrasonography, amplitudes of vibration of the vibrator and the plantar fascia could be determined. By dividing the amplitude of the plantar fascia by the amplitude of the accelerometer, the resonance frequency of the plantar fascia was determined as the peak value of the frequency spectrum. The reliability was tested in the standing condition repetitively. The intra-class correlation coefficient (ICC) and the standard error of measurement (SEM) were used to represent the reliability of the test. The resonance frequency was also detected for the sitting, standing, and loaded conditions. For the sitting condition, participants were asked to sit on a high chair with their foot place on the platform. Their hands were not allowed to place on their thighs to avoid unexpected loads on the foot. For the standing condition, the participants were asked to stand on two acrylic testing platforms with their feet apart at shoulder width and to keep their trunk upright when the data were collected. The loaded condition was the same as the standing condition except the participants were asked to wear a weight jacket in order to create a loaded condition of 50% of body weight on the body. ANOVA with repeated measures was used to examine the differences of various loading conditions. Level of significance was set at
Subjects
機械性質
足底筋膜
超音波影像法
共振頻率
ultrasonography
mechanical property
resonance frequency
plantar fascia
Type
other