正常人與脊髓損傷病人使用交替式步行輔具及柺杖步行之能量流分析

下肢癱瘓者在行動輔具的選擇除了輪椅以外，習用的行動輔具例如RGO也可協助下肢癱瘓者行動，雖然使用RGO可增進下肢癱瘓者身心狀況，然而研究顯示使用RGO步行是一件相當耗能的活動，本文將藉由研究下肢癱瘓受試者使用RGO與正常人使用RGO步行策略之比較來找出下肢癱瘓受試者耗能的主要原因。本實驗招募一位SCI 下肢癱瘓受試者及五位正常受試者，並為每位受試者量身製作RGO，在充足的練習後每位受試者以自選速度步行五公尺，並在實驗中收取步態運動學及力學資料進行能量流模型分析，其中，能量流分析在步態中又分為三期，分別是雙腳站立期、加速期及減速期; 資料呈現將選取特徵相似性較高者作為代表，正常人能量流資料由五位受試者當中取出一位受試者作為代表，下肢癱瘓病人資料因差異性較大，無法平均每次試驗，固選取其中一次試驗作為代表。相較於正常人0.55m/s，下肢癱瘓病人步行速度0.06m/s是非常緩慢的，分析結果顯示正常人使用RGO在雙腳站立期及加速期都有明顯的動位能相互轉換的機制，因此能量可藉由此轉換機制避免耗損。下肢癱瘓者在雙腳站立期傾向將動能及位能同時降低以得取較佳的平衡，並在雙腳站立後期及加速期將身體的動位能同時提升，然而此動作已違反動位能轉換機制原理，能量無法有效轉換。下肢癱瘓者步行能量是在雙腳站立期後期至加速期由肩關節產生能量提供軀幹位能以利下肢甩盪，並在加速期後期至減速期由摩擦力吸收下肢動能及雙腳著地後由Trunk-Pelvis 關節吸收軀幹位能。該步行策略能量轉換效率低的主要原因是該下肢癱瘓者缺乏下肢肌肉動力導致代償性步態的產生。在雙腳站立期下肢癱瘓者以軀幹屈曲-伸張動作代償臀中肌無力，然而軀幹屈曲動作將會吸收身體位能; 在Preswing以肩關節代償踝關節將身體位能提升，加速期拐杖持續施力於肩關節，然而肩關節會同時提升身體動能及位能，使能量無法轉換，且加速期肩關節受力方向與行動方向相反，將造成倒單擺運動受到阻礙;在減速期由於膝鎖裝置使膝關節無法活動，該裝置限制下肢癱瘓者降低身體位能，此時期能量無法由位能順利轉為動能，且容易造成拖足的現象。因此本文建議對於下肢癱瘓者行動輔具設計須考慮步態動位能轉換效率，若能提供外在人工動力將可以大幅減少下肢癱瘓者的代償性動作，具體可嘗試的方法為髖、踝關節外加動力，膝關節感應解鎖裝置等等。

關鍵字

交替式步行輔具；能量流

並列摘要

Many benefits are associated with spinal cord injury patients using reciprocating gait orthoses instead of wheel chairs, such as fewer muscle contractures, reduced risk for bone fractures, better peripheral circulation, and less depression. However, high energy cost and a slow walking speed are two factors that limit the usage rate of reciprocating gait orthosis. In previous study, the data shows that SCI group walking with different gait patterns compared with normal subjects, they tend to flex the trunk to motivate the lower limbs into swing phase. The gait pattern might be the reasons why spinal cord injury patients walk inefficiently. Nevertheless, the reasons of high energy cost are still unclear. This article aims to figure out the cause of high energy cost by energy flow analysis. 1 SCI patient and 5 normal subjects were recruited for this study. All subjects practicd how to walk with the reciprocating gait orthosis and crutches before data collection. They walked at a self-selected speed along a 5 meter walkway equipped with an Optotrak system synchronized with AMTI force plates and single axis load-cells on the crutches. The kinetic, kinematic and temporal-spatial, energetic parameters were collected with this system and calculated by inversed dynamics. The energy flow parameters were then calculated from the kinetic and kinematic data. Finally, we discussed the energy flow data and walking strategy between two groups. The representative data showed one normal subject with RGO averaged over 5 trials; And we showed particular one trial without averaging for the SCI subject since the data varied too much from trial to trial. The representative trial shows most of the features found in the total data. The velocity of the SCI subject (0.06m/s) is very slow compared to the velocity of normal subject with RGO( 0.55m/s ), the result shows that normal subject with RGO use the mechanism of inverted pendulum that conserve energy by converting potential energy and kinetic energy to avoid energy consumption in double-limb support and acceleration period. However, the SCI subject reduce both potential energy and kinetic energy to the minimum in mid double-limb support period and rise both kinetic energy and potential energy up in late double-limb support period and acceleration period, thus, the energy can’t be conserved since the strategy contradict to the mechanism of inverted pendulum model. For SCI subject, power from the shoulder was used to create foot clearance during the preswing and acceleration period. The power would be consumed in deceleration (or late acceleration) period by friction and in double-limb support period by trunk-pelvis joint. The reason why the energy is not conserved but consumed is that the SCI subject adopt compensatory movements such as leaned forward trunk, simultaneously increases in PE and KE due to shoulder power, and a locked knee device that discourages the conversion of PE to KE, energy absorbed by joints or friction; If we can make the RGO equipped with artificial power source on hip or ankle joint and unlocked knee joint at good timing, that would help SCI subject to reduce of compensatory movement and friction.

並列關鍵字

reciprocal gait orthosis ； mechanical energy flow

參考文獻

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正常人與脊髓損傷病人使用交替式步行輔具及柺杖步行之能量流分析

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