不同負荷阻力對 膝關節角度配對之影響

Abstract

目的：本體感覺提供人體重要的感覺輸入，能判斷肢體在空間的位置與動作方向，並可維持關節動態與靜態身體的姿勢及穩定度，因此本體感覺的好壞會影響人的肢體動作。近年來許多學者都在研究如何評估本體感覺，就有學者認為在負荷阻力下關節主動-主動配對模式測量應較能測出接近日常生活中本體感覺的狀況。過去不同學者在測試時，給予的阻力皆不同，但從未有同一研究用不同負荷阻力探討對本體感覺的影響。本研究目的在探討不同負荷阻力下，關節位置感主動-主動角度配對絕對誤差值之差異。研究方法：以40位健康年輕人為對象，負荷阻力量設為體重之25%、50%、75%和100%；目標角度設為膝關節彎曲0°-30°與30°-60°兩種，受試者採坐姿坐於負荷阻力儀上，以隨機方式給與不同阻力與角度的測試。利用電子量角器量測受試者兩膝之主動-主動關節角度配對之絕對誤差值（absolute angle error, AAE）。以二因子變異數分析方法分析不同阻力與不同角度對角度配對絕對誤差值之差異，其顯著水準訂在p<0.05。結果：40名受試者，男女性各20名（男性：24.8±4.6歲；女性：24.8±3.5歲），結果顯示關節角度配對之絕對誤差值在不同負荷阻力間有顯著差異（F=11.829，P=0.001）， 75％體重為負荷阻力的角度配對絕對誤差值最小，與以25％、100％體重為負荷阻力時的角度配對絕對誤差值間，各具有統計上顯著的差異（P75％-25％=0.0029；P75％-100％=0.0016）。另外兩不同目標角度0°-30°與30°-60°，其關節角度配對之絕對誤差值分別為1.1°±0.5°與1.3°±0.6°，也有顯著差異（P<0.001），膝關節屈曲在較小的目標角度可得到較小的關節角度配對之絕對誤差值。討論：隨著負荷阻力增加確實得到較小的角度配對絕對誤差值，此結果可能是負荷阻力的增加使源自膝關節周邊收縮與非收縮性軟組織內之本體感覺接受器傳入中樞更多本體感覺訊息。但以100％體重為負荷阻力時，卻可能因為負荷阻力過大影響到測試結果。0°-30°比30°-60°為目標角度可得到較小之角度配對絕對誤差值，其原因可能是膝關節螺旋歸位機制（screw home mechanism）的作用，造成關節囊與肌膜張力的增加，而導致傳入中樞的本體感覺訊息增加，因而使得角度配對絕對誤差值較小。另已被證實的原因是：小角度可激發較多關節附近的本體感覺接受器。結論：在受試者可輕鬆抗衡負荷阻力儀時，負荷阻力越大，關節角度配對絕對誤差值越小。膝關節屈曲30°以內比30°以上時，可得到較小的關節角度配對絕對誤差值。在未來量測膝關節空間位置感時，可將本研究測量參數列入臨床研究不同膝關節疾患及臨床評估操作的參考。

Background: “Proprioception” is generally referred as the perception of limb position in space. Poor proprioception may result in the inability of maintaining static and dynamic posture. Active-active knee reposition test under resistance condition simulates muscle activities in daily life and is suggested by researchers to be the most proper way to assess knee proprioception. Previous studies differed in their resistance conditions under which the active-active knee reposition tests were performed. However, no study has ever compared the influence of different resistance conditions and knee joint angles in assessing knee reposition. Thus, no consistent standardized protocol has yet been established for the assessment of knee proprioception. Purposes: The purpose of this study was to compare the difference of knee joint reposition test performed during closed kinetic chain in four resistance conditions and two target angles in healthy subjects. Methods: Forty-three healthy young adults participated in the study. Four resistances conditions (25%, 50%, 75%, and 100% of body weight) and two knee joint angles (0°-30°, 30°-60°flexion) were randomly assigned to the subjects. The absolute angle error (AAE) was calculated as the difference between each target and reposition angle measured by an electrogoniometer. Repeated two-way analysis of variance (two repeated factors, 4-resistance condition and 2-target knee angle) was performed to exam the main effect and interaction. A P value of 0.05 was considered significant. Results: Forty subjects, 20 men (24.8±4.6 years old) and 20 women (24.8±3.5 years old) completed this study. There was a significant difference of the AAE in 4-resistance conditions and 2-target knee angles with no interaction between these two factors. AAE was significantly smaller under the 75% of body weight resistance condition (p=0.001) compared with 25% and 100% of body weight conditions. There was a tendency toward AAE to be smaller at greater resistance, except during 100% of body weight. These data also indicated that the target angle of 0°-30° had more precise AAE than those of 30°-60°(p<0.001). Discussions: There was a tendency toward smaller AAE at greater resistance conditions; the minimal AAE appeared at 75% but not 100% of body weight. This might due to the increased sensory input led by more muscle activities at greater resistance conditions, but when the resistance reached the body weight, the results of the test would be hampered. On the other hand, a smaller AAE appeared at the target angle of 0°-30°. This might result from the “screw home mechanism”, that is the increase tension in the knee joint capsule and more sensory inputs are provided by non-contractile tissues. Conclusions: The range in which the subject could bear performing closed chain resisted knee extension, the larger resistance resulted in a smaller AAE and a target angle of 0°-30°had a smaller AAE than those of 30°-60°. Further studies of a more precise standardized protocol to assess knee joint reposition sense in different age groups or diseases are needed, and the parameters measured in our study could be taken into account.