扳機指為目前常見的手部疾病之一，患者之手功能可能會因而受限。本研究的目的是針對扳機指建立一生物力學模型以預測扳機現象時之肌腱張力，並且探討其手指運動學與動力學表現。
本研究針對扳機指發展一屈指肌腱阻力量測設備，藉由手指尖力量之感測，發展了一肌肉力學模型，利用最佳化方法，計算發生扳機現象時之屈指肌腱及腱鞘間之阻力和估計伸指肌腱之張力。在實驗中，受測者的手指進行被動屈曲-伸直運動，由指尖外力帶動手指之伸直運動，同時使用三維動作分析系統擷取動作中手指之位置，以進行關節活動度與活動平順度等運動學參數分析；然後再進行主動伸直動作之量測。
運動學分析結果：扳機現象發生處會有一標準化急動值之尖峰值，其值以三級患者較大；而四級患者患側之近端指關節活動度明顯受小於健側，且於術後獲得立即之改善。
由肌力模型演算結果知扳機現象發生時，二級患者之肌腱張力分別為屈指深肌1.4~5.3N，屈指淺肌4.6~10.9N，伸指末端肌1.5~5.9N，指總伸肌5.5~14.9N，橈側分枝0.8~3.1N，尺側分枝0.7~2.8N；三級患者為屈指深肌24.1N，屈指淺肌57.5N，伸指末端肌26.4N，指總伸肌74.8N，橈側分枝14.0N，尺側分枝12.3N。可知扳機指嚴重程度越高，發生扳機現象時之肌腱張力也越大。
本研究提出一客觀、量化之扳機指力學特性描述，結果可與目前之臨床觀察相互應證；也為日後扳機指分級標準或治療方法之創新，提供了一有價值之研究資料。

Trigger thumb or finger is a very common hand disease nowadays and it might impair the functional activities of daily life greatly. The purpose of the study is to develop a biomechanical model to predict the tendon forces to quantify the functional performance of the trigger finger.
A custom device to measure the resistance forces of the flexor tendons for the trigger fingers was developed. In terms of the measured finger tip forces in passive movement of trigger fingers, a muscle model of the trigger finger was developed to predict the resistance force between the flexor tendons and A1 pulley and the extensor tendon forces. A motion analysis system was used to capture the motion trajectories of the fingers while fingers moving actively and passively. Kinematical variables including joint range of motion (ROM) and smoothness of movements were analyzed.
The results revealed that there was a peak value of normalized jerk while the triggering effect happened. Patients who were graded as III showed a larger peak flexor tendon forces than those in grades I, II, and IV. For the patients in grade IV, they had a limited ROM of proximal phalange joint in affected hand. After the surgery, the follow-up evaluation showed that ROM was improved.
The tendon forces at the instant of triggering for the flexor digitorum profundus, flexor digitorum superficialis, terminal extensor, extensor digitorum communis, radial band, and ulnar band were 1.4~5.3N, 4.6~10.9N, 1.5~5.9N, 5.5~14.9N, 0.8~3.1N, 0.7~2.8N, respectively, in grade II patients, as well as 24.1N, 57.5N, 26.4N, 74.8N, 14.0N, and 12.3N in grade III patients. The trigger finger patients at higher level showed greater tendon forces while triggering.
This study provided an objective and quantitative method in functional evaluation of trigger fingers. These results will be helpful to verify the clinical study, new classification, and innovation treatments.

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