探討扁平足與正常足者之平衡差異性研究

A comparison of Postural Stability between Normal Feet and Flat Feet People

許曉菁(Hsiao-Ching Hsu)

指導教授 ： 江行全

元智大學/工程學院/工業工程與管理學系/碩士(2012年)

https://doi.org/10.6838/YZU.2012.00314

摘要

足弓結構對於站立及行走是非常重要的，足弓具有吸震與維持平衡等重要性。對正常足弓者而言，在腳掌著地時會自然做出適當的旋前及旋後動作，使足部有良好的吸震、適應地形及發揮有效率的推進功能。然而扁平足者因缺乏正常內側縱弓與橫弓，造成足部構造長期過度承受負荷，重覆性的負荷集中用於某特定骨骼、關節及周圍組織，促使該組織傷害形成，使身體產生疼痛的現象進而導致平衡的失調，易造成跌倒情況發生。然而，目前許多文獻多在探討使用矯正輔具達到步態改善，避免扁平足併發症進一步惡化的情況發生。卻無直接衡量平衡改善方面數據化指標，以供臨床上參考，有鑑於此，如何將扁平足平衡表現以指標做為量化，以了解扁平足平衡力與正常足間差異性，為本研究之重點所在。
本研究針對18歲以上30歲以下成年人進行平衡力量測，依據實驗對象進行足型的分類，可分成37名正常足以及17名扁平足。量測所得的壓力中心點(COP)訊號透過經驗模態分解法(EMD)拆解後，可產生數個不同頻帶的本質模態函數(IMF)，並藉由維持平衡時兩族群施予能量的不同，找到兩族群能量具差異的頻率帶，主要位於IMF6至IMF7之低頻帶小於0.3Hz處，以此頻帶訊號導入多項評估平衡力指標，用以鑑別出扁平足與正常足在平衡上之差異。研究結果發現扁平足平衡力較正常足者為差，特別是在左右方向上，扁平足因足弓構造異常，使得平衡時形成如同雜訊般晃動，頻率區段分析結果顯示其訊號跳動的頻率也較正常足為低，因此在COP傳統指標及複雜度指標的表現上，出現了平衡晃動幅度較正常足者為大且複雜度指標較正常足為低的現象，為了維持姿態的平衡，扁平足在平衡上所耗用的總能量較正常足為大，約是正常足的2.07倍。因此本研究後續建議，未來針對扁平足的平衡感提升可以朝向左右方向做刺激及改善。

關鍵字

扁平足 ； 壓力中心點 ； 經驗模態分解法 ； 本質模態函數 ； 希伯特黃轉換 ； 頻率區段分析 ； 多尺度熵 ； 複雜度

並列摘要

Arch structure is very important for our standing and walking. It acts as a shock absorber and serves to adjust the body to balance. Because of flatfoot lacks the medial longitudinal arch of the foot, so adults with flat feet demonstrate several biomechanical sufficiencies in the foot and ankle, and a variety of gait abnormalities. The development of clinical problems is dependent on the levels of activity and the amount of repetitive stress the feet must endure. There are studies pointed out that use of orthotics can provide support for the medial longitudinal arch and improve the biomechanics of the foot to avoid further complications.. But there was no literature to provide a quantification indicator to measure the balance performance between flat feet and normal feet. In order to understand the stability differences between normal feet and flat feet, how to establish their stability indicator is the main purpose of this study.
In this study, 54 subjects (age between 18 and 30 yr) were divided into two groups by their foot print. Foot type classification according to subjects, divided into 37 normal feet and 17 flat feet. The center of pressure (COP) signals can be examined in two parts: medio-lateral (ML) and anterior-posterior (AP). This study used empirical mode decomposition (EMD) to decompose each part of the COP signal into several different frequency bands of intrinsic mode functions (IMF). Because there are different energy release between two groups to maintain their balance, lower-frequency signals with less than 0.3Hz are selected to be adopted for multi-scale entropy (MSE) analysis for finding the complexity for each part. Further analyses of using frequency analysis and Hilbert Huang transform (HHT) analysis were also conducted.
The results showed that flat feet subjects had poorer postural stability than the normal feet subjects, particularly in the ML direction. Lower medial longitudinal arch may deteriorate sensory capability and muscle activity as a compensatory response to increase postural sway for the flatfoot subjects. In order to maintain the balance, flat feet subjects released more energy to keep postural stability. at about 2.07 times the normal feet. So the flat feet performance of the COP traditional indicator and the complexity index (CI) are poorer than normal groups. A suggestion for Future research can move towards some stimulation mechanisms in the ML direction to enhance flat feet balance of postural stability.

並列關鍵字

Flat feet；Center of pressure (COP)；Empirical mode decomposition (EMD)；Intrinsic mode functions (IMF)；Hilbert Huang transform (HHT) ； Frequency band (FB)；Multi-scale entropy (MSE)；Complexity index (CI)

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