背景與實驗目的: 對骨科物理治療師而言，大拇指關節疼痛是常見職業傷害之一。而引起傷害的徒手治療手法中，常被提及的是後前向滑動徒手操作技巧(posteroanterior glide manipulation 簡稱PA glide)。不同後前向滑動徒手操作的手法經常被治療師運用在臨床的工作上，然而，到目前為止，既有文獻中尚未有探討使用不同的後前向徒手治療技巧時，對大拇指所造成的不同影響。所以，本篇研究主要為針對沒有經驗及有臨床經驗的治療師，探討徒手治療臨床經驗、不同柔軟度及不同的治療手法對指端施力大小(thumb tip force)與拇指運動學及肌電學的影響。
實驗方法: 參與受試者為15位(4男11女，平均年齡21.9±2.2歲)尚未有徒手治療臨床經驗的初學者與15位(5男10女，平均年齡28.0±2.1歲)有至少3年骨科臨床經驗的物理治療師。這些受試者在一年內使用拇指不能有疼痛的情形。每位受試者在六軸力板上執行3種不同的後前向滑動徒手技巧(不支撐後前向滑動(Unsupported PA glide)，四指支撐之後前向滑動(PA glide with digits support)，食指支撐拇指指間關節之後前向滑動(PA glide with interphalangeal joint supported by index))。藉由動作分析系統、肌電圖儀及六軸分力儀同步收取拇指指骨間關節(IP joint)、掌指關節(MCP joint)及腕掌關節(CMC joint)之運動學資料、指端力量、拇指肌肉的表面肌電活動以及每位受試者的身體柔軟度(Beighton Score)。
結果:兩組受試者拇指掌指關節與指骨間關節在矢狀面(sagittal plane)之角度都呈現顯著負相關(p<0.05)(但初學者在施行指間關節支撐後前向滑動技巧時除外)，而在有經驗受試中掌指關節和腕掌關節角度之間也呈現相同的趨勢(p<0.05)。柔軟度與最大指尖力量亦為負相關 (p<0.01)。在執行指間關節支撐之後前向滑動技巧時第一背側骨間肌(1stDI)有較大的肌電活動(p<0.05)，同時最大指尖力量也較大(p<0.05)。有經驗組在外展拇短肌(APB), 外展拇長肌(APL), 屈拇短肌(FPB), 屈拇長肌(FPL)的肌電活動平均值比無經驗組小(p<.05)。而伸拇長肌(EPL), 外展拇長肌(APL)及伸拇短肌(EPB)則在執行沒有支撐之後前向滑動技巧時比其它兩種徒手技巧有較大的肌電圖活動(p<0.01)。
結論:在執行後前向滑動技巧時拇指相鄰關節矢狀面之角度呈現負相關的趨勢，也就是當指骨間關節處在比較伸直的姿勢時，掌指關節就會呈現彎曲的姿勢，而腕掌關節會表現伸直的趨勢，反之亦然。柔軟度較小的受試者或是使用指間關節支撐之後前向滑動技巧都能夠產生較大的指尖力量。而有經驗的族群比初學者更能有效率的使用肌肉活動來維持大拇指關節的穩定度。
臨床意義: 對初學者或是關節柔軟度較大的治療師我們建議使用指間關節支撐之後前向滑動技巧，以增加大拇指穩定度並有效產生較大的力量來減少徒手治療

Background and Purpose: Pain in joints of the thumb is one of the major occupation- related disorders for orthopaedic physical therapists. Extensive manual tasks involved in their daily activity appear to be the major culprits; among these tasks are the posteroanterior (PA) glide techniques for spinal mobilization/manipulation. Several different PA glide techniques are commonly employed by manual therapists. The performance of these manual techniques is likely to be influenced by factors such as experience and general flexibility as well. However, the differential effects of these PA manipulative techniques on the kinematics and kinetics of the thumb and the EMG activities of related muscles have not yet been studied. The purpose of this study was to investigate the influence of clinical experience, general flexibility and different manipulative techniques on the performance in the thumb.
Methods: Fifteen novice subjects (4 males and 11 females, aged 21.9±2.2 yrs) with no clinical experience and fifteen clinical physical therapists (5 males and 10 females, aged 28.0±2.1 yrs) with at least 3 years of orthopaedic experience participated in this study. Each subject performed three different PA glide techniques (PA glide with the thumb unsupported, PA glide with digital support and the PA glide with interphalangeal joint supported by the index) on a force plate while interphalangeal (IP), metacarpophalangeal (MCP) and carpometacarpal (CMC) joints kinematics were tracked by a motion analysis system. The joint angles, maximum thumb-tip force, surface EMG activities of 8 thumb muscles and the Beighton score of each subject were recorded for analyses.
Results: There was a negative correlation between the sagittal plane angles (flexion/extension) of the IP and MCP joints except PA glide with IP support in Novice Group (p<0.05). Such relationship was also found between sagittal plane angles of MCP and CMC joints in the Experienced Group (p<0.05). A negative correlation was also found between the Beighton score and the maximum thumb-tip force (p<0.01). The thumb-tip force and EMG activity of the first dorsal interosseous muscle during PA glide with IP support were greater than those of the other two techniques (p<0.05). EMG values in the Experienced Group were smaller than the Novice Group in abductor pollicis brevis (APB), abductor pollicis longus (APL), flexor pollicis brevis (FPB), and flexor pollicis longus (FPL). EMG activities of the extensor pollicis longus (EPL), abductor pollicis longus (APL) and extensor pollicis brevis (EPB) were greater during the unsupported PA glide (p<0.01), comparing with the other two techniques.
Conclusions: The results of the present study revealed negative correlation between angles of the IP and MCP, and between those of the MCP and CMC. Subjects with less general flexibility (smaller Beighton score) or when using IP support techniques are capable of exerting greater thumb-tip force. Experienced therapists exhibited less EMG activities and, thus, more efficiency comparing with their novice counterparts in maintaining the stability of the thumb joints.
Clinical Relevance: Physical therapists with excessive thumb flexibility are advised to perform the PA glide with IP joint supported to protect the thumb joints from injury.

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