實驗背景及目的 關節牽拉鬆動技巧在臨床上常被使用於治療盂肱關節活動度下降的病人.其手法是由治療師沿著所包含受試者的身體肢段施予一長軸方向的牽拉力量.雖然關節牽拉鬆動技巧的手法在臨床骨科物理治療上已常被使用，卻仍缺乏運動學描述以及科學證據來支持它的效果。因此本篇研究的目的即在於分析屍體盂肱關節樣本在不同關節位置(置中位置,休息位置,終端位置)下,進行關節牽拉鬆動技巧時肱骨頭中心的移動情形。實驗方法 在關節牽拉鬆動技巧程序方面，12位有三年以上骨科物理治療臨床經驗的物理治療師參與本實驗.他們在三種不同關節位置下對於盂肱關節樣本施行關節牽拉鬆動技巧的手法，本實驗量測施行牽拉動作時關節中心的移動情形(前/後, 上/下, 內/外)。同時也會測量施行牽拉動作時的力量以及關節角度.運動學的資料由VICON 370動作分析系統來擷取，力量則由AMTI六軸測力儀來量測.在關節牽拉鬆動技巧程序前後，我們用MTS系統來量測屍體樣本之活動度，包括向後滑動量、向前滑動量、向下滑動量、轉動角度及外展角度，藉由MTS的實驗可知道屍體樣本的活動度，在關節牽拉鬆動技巧前後是否有改變。至於計算關節轉動中心的方法，則依照Gamage及Lasenby所發展的最小平方法。資料分析方面，我們比較屍體盂肱關節樣本在不同關節位置下,進行關節牽拉鬆動技巧時肱骨頭的移動情形(前/後, 上/下, 內/外)。本研究使用Friedman 以及 Wilcoxon signed ranks test來檢定，顯著差異定在0.05，我們使用SPSS 11.0來做統計分析。結果 在進行第五回關節牽拉鬆動手法時,盂肱關節中心的總移動量在休息位置時最大(27.38 mm), 第二是置中位置(22.01 mm), 而在終端位置則是最小的(9.34 mm). 盂肱關節中心的總移動量在三種不同關節位置時具有統計學的顯著差異(Wilcoxon signed rank test, p < 0.002).另外動力學的資料方面,關節牽拉的力量在三種不同關節位置時也具有統計學的顯著差異(Wilcoxon signed rank test, p < 0.015).至於在MTS的資料分析, 則發現實驗前後樣本的活動度在向下滑動,外展角度,總旋轉角度三方面有增加情形。結論 由12位有經驗的治療師進行此實驗可幫助了解盂肱關節樣本在不同關節位置下,進行關節牽拉鬆動技巧時其動力學和運動學的特徵以及中間相關的機制,結果發現在進行關節牽拉鬆動手法時,肱骨頭中心的總移動量在休息位置時最大(27.38 mm), 第二是置中位置(22.01 mm), 而在終端位置則是最小的(9.34 mm),此實驗結果提供在臨床上如何選擇適當的關節位置以實行牽拉鬆動術的學理依據.

　　Background and Purpose. The distraction mobilization technique is commonly used for patients with glenohumeral joint hypomobility. Distraction procedures require the physical therapist to exert a long axis distraction force along the shaft of the involved segment of the treated subject. Even though distraction mobilization technique has been used in the clinic, there is a lack of kinematic description and the scientific evidence of its efficacy. The purpose of this study is to analyze the humeral head displacement while performing the distraction mobilization technique in three different joint positions (neutral position, resting position, and end range position) of the glenohumeral abduction. Methods. Twelve experienced orthopedic physical therapists were recruited for this study. They performed the distraction mobilization technique in three different joint positions on the glenohumeral joint of a fresh cadaveric specimen. Outcome measures were the displacements of glenohumeral joint center (anterior-posterior, superior-inferior, medial-lateral directions) during distraction mobilization. The applied distraction forces and joint angles of the glenohumeral joint were also monitored. Kinematic data was collected by VICON motion analysis system; distraction forces were measured by an AMTI 6-axis load cell. We used the least squares method developed by Gamage and Lasenby (2002) to calculate the joint center. We compared the parameter of the peak total displacements of the glenohumeral joint center in anterior-posterior, medial-lateral, and superior-inferior directions during distraction mobilization technique in three different joint positions. Before and after the distraction procedures, a biaxial material testing system equipped with an x-y table was used to measure the magnitudes of anterior-posterior gliding, posterior-anterior gliding, inferior gliding, rotation angles and abduction angles of the specimen. The purpose of the MTS procedures was to measure whether there were changes in the mobility of the shoulder specimen before and after the experimental sessions. These outcome measures were tested by Friedman and Wilcoxon signed rank test with an α level of 0.05. SPSS 11.0 was used for all statistical analyses. Results. The peak total displacement of the humeral head during the fifth distraction mobilization procedure was largest in resting position (27.38 mm) followed by neutral position (22.01 mm) and end range position (9.34 mm). There were significant differences in three different joint positions (Wilcoxon signed rank test, p < 0.002). The distraction forces used were significantly different among the three glenohumeral joint positions (Wilcoxon signed rank test, p < 0.015). The mobility data measured in MTS procedures showed an increase in inferior gliding, abduction angle, and total rotation angle. Conclusion. Data collected from the twelve experienced physical therapists helped us to understand the kinematic and kinetic characteristics of the glenohumeral joint and the relationship mechanism of the distraction mobilization technique in three different joint positions. During distraction mobilization, the peak total displacement of the humeral head was largest in resting position follow by neutral position and end range position. This result may provide the rationales for choosing distraction mobilization technique at appropriate joint position.

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