Effects of Hip flexion/extension coupling ratio on gait

交替式步行矯具是給下肢癱瘓患者使用的一種輔具，能幫助患者行走。但由於患者本能肌力功能的缺失，以及輔具設計並不完善，使得患者使用輔具行走的時候十分耗能，且行走速度只有正常人行走的速度的六分之一，導致放棄使用而遷就於輪椅的機率極高。而舊式的交替式步行矯具，其髖關節機構為一限制雙邊髖關節只能做出1:1交替式運動的鉸鏈機構，在過往改進以及探討交替式行走矯具的研究中，發現使用2:1的伸屈耦合比例能降低能量消耗以及增加走路速度。雖然後來也有能自由調控伸屈耦合比例的設計，但尚無研究去探討什麼樣的伸屈耦合比例適合應用在髖關節輔具上，以及為何高伸屈耦合比例能改善步態效率。 本研究的目的是藉由觀察交替動作期間的髖關節耦合運動關係，並嘗試解釋為何有這樣的運動關係，其結果期許能做為日後改良髖關節輔具的設計參考。 實驗中我們利用Optotrak、AMTI測力板取得動態中9位年輕健康人的三度空間步行資料，在關節限制條件上取了膝踝關節轉動與全固定，並採取快、自選、慢三種步行速度，再以步態分析方法檢視左右髖關節的交替動作關係。接下來再使用力動學模型，來驗證於正常步態中交替動作期間裡高耦合比例的必要性。 在研究最後的結果，研究中的交替運動期間之耦合比例。在三種步行速度下，膝踝關節全固定的耦合比例均高於膝踝關節自由轉動情況(快：p=0.009、自選：p=0.003、慢：p=0.003)。同時也觀察出在交替動作期間的雙側髖關節耦合比例有隨速度提高而降低的趨勢，但並無統計中的顯著差異。在力動學模型中的模擬也在交替動作期間中，呈現雙邊髖關節耦合比例偏高的現象。 總結而言，由目前本研究實驗中所得的結果，發現在交替運動期間，由正常人來調節在各種關節條件與速度的結合情況，所產生的耦合比例均呈現大於1的現象。而從模擬的情況也提示，之所以需要較高的耦合比例有可能是為了達到較省力的效果。因此在未來輔具的髖關節設計上，或許可以藉由提高交替動作期間內的耦合比例以便達到擺盪的順暢性，進而達到省能的效果。RGO (reciprocating gait orthoses) were designed for paraplegic patients, the equipments could help them get up and gain physiological benefits as well. However, the orthoses were not well adopted because of the high energy cost and the slow walking speed, which led to a high abandon rate. Instead, patients would rather use wheelchair to go around. This designs of the old type reciprocating gait orthoses limited hip joints flexion and extension in 1:1 coupling ratio. In past studies, the researchers proved that using higher coupling ratio could decrease energy consumption and increase walking speed. Although there were a lot of new designs that could adjust coupling ratio, there was no related literature to prove the appropriate coupling ratio of the orthotic hip joint. And we wonder know if the higher coupling ratio could improve the gait efficiency or not. The purpose of this study is to demonstrate the relationship between coupling ratio and different walking conditions. We anticipated the results might be the guideline to improve hip joint mechanism design in the future. In our study, we used Optotrak to collect movement data and AMTI force plate data from 9 young health people to analyze their kinetic performance. We arrange different walking and joint conditions: slow to fast walking conditions and free to locked knee and ankle joint conditions. In the same time, we used the collective gait data to construct a biomechanical model to prove the mechanical role of the coupling ratio in normal gait. There were three statistically significant differences when we compared the coupling ratio under different conditions. The coupling ratio in joint-locked condition were higher than joint-free condition under three speed conditions (Slow: p=0.009, self-select: p=0.003, fast: p=0.003). And we observed that the coupling ratio decreased while the walking speed got faster, but there is no statistical significance. In the results of model simulation, the bilateral hip joint coupling ratios were higher. In conclusion, we found that normal people could adjust the coupling ratio higher than one in both joint-constrained conditions under three walking speed conditions in reciprocating period. And the modeling result shows that people might need higher coupling ratio for the energy-saving. So, for orthotic design in the future, the designed coupling ratio of orthosis in reciprocating period should be higher than one to achieve the smoothness of swing and energy-savin