抗內旋彈性肌貼對脛後肌肌腱硬度的影響

Abstract

內旋足者在行走承重期間常出現足部距下關節過多的內旋動作，這樣的動作普遍被認為將導致脛後肌在承重活動中反覆遭受牽拉，導致肌腱產生傷害而形成脛後肌肌腱失能。脛後肌肌腱失能將影響足弓吸震能力，又因其肌腱本身血液循環不佳、傷後癒合不易，而易進入惡性循環，對內旋足者的生活品質影響甚巨。過去的動作分析或足壓研究顯示抗內旋貼紮能控制足部距下關節過多的內旋動作或降低足底內側受壓，藉此推估貼紮能改變內旋足者在承重活動中的脛後肌負荷；但迄今對於脛後肌的負荷尚未有直接的測量方式。近年來剪力波彈性超音波影像的發展迅速，以非侵入的方式量化人體器官與軟組織的硬度，若硬度超出待測組織之正常範圍，則其很可能已產生不正常的病理變化。因此本研究以剪力波彈性超音波影像儀來測量站立承重時脛後肌肌腱的硬度，並比較有無施用抗內旋彈性肌貼對脛後肌肌腱硬度的影響，用以探討肌貼的療效。 本研究為前瞻性、便利性取樣、隨機順序、前後測的實驗設計。共計招募31名年輕的健康人接受實驗，包含正中足者17名、內旋足者14名。每位受試者均接受抗內旋彈性肌貼，分別在有無肌貼時均接受3項評估，包含脛後肌肌腱的硬度、足踝姿勢指標、舟狀骨滑落程度，用以比較肌貼介入對承重時脛後肌肌腱硬度的影響以及足型的變化。而以剪力波彈性超音波影像儀測量脛後肌肌腱的硬度分別在3個不同狀況下執行，側躺時肌腱無承重、站立時承重無肌貼、以及站立時承重有肌貼。所得數據皆以SPSS統計套裝軟體第20版進行分析，並以2  2二因子混合設計變異數分析來計算肌貼介入前後及組別對介入所產生之變化的影響。顯著水準訂在α= 0.05，檢定力訂在0.8。 本研究主要結果為：(一)內旋足者承重時的脛後肌肌腱硬度與正中足者無顯著差異；(二)有抗內旋彈性肌貼時，內旋足者承重時的脛後肌肌腱硬度較無肌貼時小。研究結果顯示抗內旋彈性肌貼能調整足型並達到改善關節功能的效果；承重時能減緩足弓塌陷，並減少脛後肌肌腱硬度。而正中足者的脛後肌肌腱在抗內旋彈性肌貼時亦有類似效果，唯其足型在肌貼與否並無顯著改變。本研究同時建立了以剪力波彈性超音波影像儀測量脛後肌肌腱硬度的極佳信度(ICC>0.75)。本研究量化了肌貼在改變關節功能上的成效，發現抗內旋彈性肌貼可調整足型，進而改善足部肌腱的硬度，此結果可供臨床決策之實證參考。

Excessive pronation motion during the stance phase of a gait cycle is frequently noted in adults with pronated foot, which has been believed to result in tibialis posterior tendon dysfunction due to repetitive microtrauma. The facts that poor shock absorption of the medial longitudinal arch during walking is found in patients with tibialis posterior tendon dysfunction and poor blood supply of the insulted tendon retards its healing process affect patients’ quality of life. Previous motion analysis or foot pressure studies showed that anti-pronation taping may control excessive pronation or decrease foot pressure on the medial area of the foot during the stance phase of a gait cycle in adults with pronated foot, but so far it is still lack of strong evidence due to no reliable direct measurements for this tendon. Recently, a newly invasive method, shear wave elastography, can measure the stiffness of tissues or organs in human bodies. If stiffness of a tissue presents significantly higher than its normal value, some pathological changes in this tissues can be noted. This research, therefore, used the shear wave elastography to measure the stiffness of the tibialis posterior tendon in order to compare the difference between adults with neutral and pronated foot and to investigate the effect of elastic anti-pronation taping on stiffness of the tibialis posterior tendon. The research was a prospective, convenience sampling, randomized-order, single-blinded, and pretest/ posttest design. There were 31 healthy adults recruited for the research, 17 adults with neutral foot and 14 with pronated foot, respectively. All participants received the elastic anti-pronation taping, and received three outcome measures, including stiffness of tibialis posterior tendon, foot posture index, and navicular drop test. To investigate the effect of taping, all variables were tested before and after the intervention. The shear wave elastographic measurement was performed at non-weight-bearing status that the body in side-lying position, non-taped weight-bearing status in standing position, and taped weight-bearing status in standing position. A 2 × 2 two-way mixed ANOVA measures was used to compare the differences before and after the intervention and the group effect. All statistical analyses were executed using SPSS version 20. The significant level was set at α=0.05 while the power was 0.8. The main results showed that: (1) there was no statistically significant difference in the stiffness of the tibialis posterior tendon between adults with pronated foot and those with neutral foot during stance, (2) the stiffness of the tibialis posterior tendon in the taped condition was lesser than that in the non-taped condition in adults with pronated foot. It demonstrated that elastic anti-pronation taping could change the foot type in adults with pronated foot through controlling the collapse of the arch and decreasing the stiffness of the tibialis posterior tendon. Again, the adults with neutral foot also presented similar effects, but did not show any changes in foot type. The excellent intra-rater reliability in measuring of the tibialis posterior tendon using shear wave elastography (ICC>0.75) was also establish in this research. The research quantified the changes of elastic anti-pronation taping in improving joint function, decreasing the stiffness of the tibialis posterior tendon. It can be used in clinical decision making in evidence-based practice.