人體下肢不對稱性對走路步態週期和動作特性之影響

Effects of bilateral lower limb discrepancies on gait phase and movement characteristics

緒論：當人體的雙側下肢肢段重量、結構狀態和肌力協調發生不均衡的情況時，會導致不對稱的走路動作，長期累積下來容易造成慢性的骨骼肌肉系統傷害。若是能提早發現這樣的情況，就可以減少相關傷害的發生。動作分析系統能夠精準的記錄走路步態的分期和動作，而具有易攜帶、不影響動作和可長期監控優點的慣性感測器，目前也越來越常被使用來量測人體的動作特性。但是若要使用慣性感測器來準確量測動作型態的改變，就必須要找出其適合的擺放位置還有具指標性意義的動作特徵值。本研究選擇健康受試者進行研究以量測單側下肢負荷加重、單側下肢加長所產生步態時間空間參數和動作特徵值的不對稱性，並期待未來應用慣性感測器的特徵值能更方便評估和監控健康族群走路的動作對稱性。方法：本研究利用動作分析系統來分析走路步態的時間和空間參數，並以放置於人體雙側上、下肢以及軀幹的慣性感測器，記錄15名健康受試者在正常狀態、下肢單側加重（5％體重）以及下肢單側加長（3公分）在自選行走速度和1.5m／s行走速度下的身體動作特徵值表現。結果：下肢不對稱性造成左右抬腳高度、支撐期時間、擺盪期時間和動作特徵值的不對稱性顯著增加，將慣性感測器放置在下肢與軀幹較能觀察出不對稱操弄的影響，支撐期和擺盪期的慣性感測器特徵值較容易量測到動作的不對稱性，軸向以矢狀面上的加速度與角速度較佳。結論：人體下肢不對稱性會造成不對稱的走路步態週期和動作特性，慣性感測器可以用來量測走路步態的不對稱性，下肢和軀幹是較適合的位置，支撐期和擺盪期較容易量測到動作的不對稱性，矢狀面上的加速度與角速度是較適合觀察的運動學參數。

Introduction: Bilateral discrepancies in human lower limb weight, length, and strength could lead to an asymmetrical gait pattern. Such a gait pattern could result in chronic musculoskeletal injuries. However, we can prevent injuries through the early detection of bilateral asymmetry. Motion analysis systems detect gait phase and movement precisely. Easy-portable, non-movement suppressing, and long-term monitoring inertial measurement unit (IMU) sensors may also provide a practical and reliable means to measure gait patterns during human movement. IMUs have been increasingly used in research to detect human movement characteristics. However, the suitable IMU placement on the body and the specific biomechanical parameters to measure the imbalanced gait patterns still require further investigation. Motion analysis systems and IMUs were used in this study to investigate the asymmetric kinematics indexes of imbalanced gait patterns induced by the intervention of unilateral lower limb adding weight and unilateral lower limb lengthening in healthy subjects. We hope the IMU indexes can be used for the future evaluation and monitoring of gait symmetry in healthy individuals. Methods: Fifteen healthy subjects were recruited and divided into able bodied, unilateral lower limb weight-bearing (5% body weight), and unilateral lower limb lengthening (3cm). A motion analysis system was used to measure the spatio-temporal gait movement parameters. The inertial measurement units (IMU) were placed on both sides of the upper limbs, lower limbs, and trunk of the subjects to measure the movement characteristics under self-selected and 1.5m/s walking speeds. Results: Bilateral lower limb discrepancies led to significant asymmetric maximal heel height, stance/swing time, and movement characteristics. The placement of IMUs on the lower limb and trunk, sagittal plane acceleration, and angular velocity during the stance/swing phase of the gait showed significant differences between a symmetrical and asymmetrical gait pattern. Conclusion: Bilateral lower limb discrepancies resulted in asymmetric gait phase and movement characteristics. IMUs placed on the lower limb and trunk are recommended to measure gait asymmetry. While the sagittal plane acceleration and angular velocity parameter during the stance/swing phase of the gait are more suitable for measuring the movement characteristics of asymmetric gait.