拇指掌腕關節在人類日常生活中扮演重要的角色，此關節的活動範圍大且靈活，使手掌可以有對掌動作，但掌腕關節因為其解剖上的特性，例如關節面較淺、韌帶較鬆，因此比較容易受傷造成不穩定，長期使用下容易造成退化性關節炎發生。臨床診斷拇指掌腕關節的方法為X光檢查，普通X光檢查可以看到基礎關節的關節間隙變窄、關節表面變得凹凸不平與程度不等的半脫位。現今臨床判斷拇指掌腕關節之退化性關節炎的標準大多依照Eaton分類法，然而目前有多篇文獻指出此方法可以再增進以及改善，且目前尚未有相關文獻指出腕掌關節脫位與脫位力量間之關係，因此本研究旨在探討腕掌關節半脫位的變化和不同姿勢對腕掌關節半脫位、受力的影響。
本研究運用量化之分析方法，藉由動態透視攝影觀察並計算腕掌關節半脫位之變化，主要探討拇指腕掌關節半脫位與關節受力之關聯。實驗開發一套機構，在靠墊上面裝置力量感測器，用來量測拇指腕掌關節半脫位的力量值。本研究共招募30位健康受測者，慣用手皆為右手。實驗內容為在不同的指定位置下拍攝腕掌關節從靜止到最大力的變化，量測關節受力以及計算腕掌關節半脫位之情形。
使用簡單直線回歸法計算力量量測器與黃金標準值之關係，決定係數R2 達0.9998，可證實裝在靠墊上的量測器具有良好效度，受試者使用靠墊進行三次測驗，脫位再測信度為0.919，力量再測信度為0.559，即靠墊具有良好及中度之信度；使用動態透視攝影拍攝三種不同受測姿勢皆會造成腕掌關節半脫位，而且腕掌關節半脫位與關節受力有高度之相關性(r = 0.8~0.989, p < 0.001)；不同位置施力會影響關節受力和腕掌關節脫位，發現在指側壓力下照有最大的關節受力，在拇指掌骨及指骨之壓力下照卻有較大的脫位，說明指側壓力下照在透視動態攝影的結果有誤差。
本研究使用動態透視攝影拍攝腕掌關節半脫位變化並且同時量測關節受力，能直接且明確地顯現兩者之間的關係。受測者為健康正常族群，故研究資料可以提供臨床與病人比較，作為診斷上之依據，未來研究若能擴大至臨床族群將會驗證實驗更多結果。

Thumb carpometacarpal (CMC) joint serves as an important role in daily living. The wide range of motion and flexibility of CMC joint reconstruct palmar opposition function. This joint is vulnerable and unstable due to its anatomical characteristics such as the shal-low articular surface and loose ligaments. Overusing for a long time might lead to osteoar-thritis (OA). The clinical diagnosis of the thumb CMC usually underwent the examination of x-ray, from which shows the narrow joint space, uneven articular surface and joint sub-luxation. Nowadays, clinical criterion for diagnosing the osteoarthritis of CMC joint is in accordance with the Eaton classification. However, several literatures indicated that the Eaton classification method needed to be reformed. Further, the study demonstrating the relationship between CMC joint subluxation and dislocated force was still limited. There-fore, the aim of this study attempted to investigate the changes of CMC joint subluxation and the influence of CMC joint subluxation/ dislocated force in different thumb positions.
In this study, we quantified the changes of CMC joint subluxation by fluoroscopy to investigate the relation between the force and CMC joint subluxation (SR). The dislocated forces were obtained from the force transducer within the hand-supported device. Thirty male volunteered participants with right handed were recruited in our study, age range from 20 to 40 years old. During the experiment, the changes of CMC joint subluxation from resting to maximum stressed among different positions were recorded using dynamic radiography and the dislocated force were measured simultaneously by the force transduc-er.
Using simple linear regression, the relationship between force transducer and gold standard from which the coefficient R2 was 0.9998, indicating good validity of the force transducer. The test-retest reliability of dislocated force and SR was 0.559 and 0.919 with three measures, which showed good reliability of hand-supported device. Through fluor-oscopy, stressing under three positions caused CMCMP subluxation and the correlation between the force and SR were highly significant (r = 0.8~0.989, p < 0.001). The SR and dislocated force would be affected by the positions of stressing. We found that the dislo-cated force was biggest under KEY-PIP, yet the positions of CMCMP and CMCIP had larger SR. According to the above, there might be some error existing in the position of KEY-PIP by fluoroscopy.
Our study utilized the fluoroscopy to detect the SR and the dislocated force in the same time, indicating the direct and clear relationship among them. Therefore, the findings of this study could provide information for further clinical uses, as a basis for the precise examination and diagnosis. Future studies should expand to the investigation of more con-siderable factors such as gender and age on the subluxation property of this joint. Explora-tion of the relationship between the subluxation and dislocated force of the OA popula-tions is also valuable in the future study.

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