腕隧道症候群和板機指為臨床上兩種常見的手部疾病。腕隧道症候群的病因是橫腕韌帶壓迫到正中神經，導致手掌橈側會有麻痺或刺痛等感覺異常的症狀；板機指也稱作狹窄性腱鞘炎，病因為屈指肌腱與腱鞘之結構尺寸不合，導致肌腱滑動不順暢。然而研究發現腕隧道症候群病患在接受腕隧道解離手術後，罹患板機指的機率增加，其中以大拇指發生機率最高，中指跟食指次之。因此過去也有許多研究針對此現象的成因加以探討，根據先前研究指出患者在腕隧道解離手術後，手指在施力時，腕隧道內的屈指肌腱會朝掌側移動，而在掌指關節處，屈指肌腱進入第一環狀腱鞘時的角度也會比術前大。目前認為造成這些改變的原因可能是解離橫腕韌帶後所導致的拉弓現象，然而在臨床上這些肌腱的改變可能會產生的影響是尚未明確的。
本研究的目的是發展一個生物力學模型去預測患者在解離手術後，中指抓握的生物力學表現，並且將此結果與健康成人相比較；同時，也量化拉弓現象對肌腱腱鞘系統所造成的影響；除此之外，此模型也建立屈指肌腱跟第一環狀腱鞘的力學關係式。本研究透過調整肌腱進入的角度、改變肌腱力臂和調整掌指關節角度來進一步了解並解析拉弓現象對中指的生物力學所造成的影響。本研究中引用的參數皆以過往實驗數據作為基礎，並利用程式最佳化出此模型中各項數據的可能值。
在此模型中，健康成人與模擬病人的結果在肌腱張力與關節受力上沒有顯著差異，這可能代表模擬病人與健康成人在進行抓握動作時，出力型態並沒有太大差異。但在肌腱作用於第一環狀腱鞘上的正向力，模擬病人的正向力相較於健康成人增加百分之三十，說明屈指肌腱進入第一環狀腱鞘的角度增加的確會使病人的腱鞘承受較大的作用力。除此之外，本研究藉由調整肌腱進入角度探討肌腱張力、關節受力與正向力的改變，結果發現肌腱張力跟關節受力無顯著變動，然而正向力則隨著角度增加而顯著上升。本研究的結果提供患者在腕隧道解離手術之後手指生物力學的相關資訊，並且對於術後罹患板機指的可能原因有進一步的釐清，說明了因為解離手術造成拉弓效應，使患者罹患板機指風險提高，期許未來能提供給臨床參考並且進一步發展出術後預防板機指發生的策略。

The common surgical treatment for carpal tunnel syndrome is carpal tunnel release, which divides the transverse carpal ligament to release the compression on the median nerve. Previous studies have demonstrated that morphological changes would occur both in the carpal tunnel and at the first annular pulley level after carpal tunnel release. These changes may increase the risk of trigger finger occurring. However, the exact influence of these morphological changes on biomechanics is still unclear. Moreover, the most frequently affected trigger finger after carpal tunnel release is the long finger, followed by the ring finger.
The purpose of the current study is to develop a biomechanical model to compare the different biomechanics of the tendon-pulley system during grasping between healthy individuals and patients after carpal tunnel release. The input of the model from grasping posture was collected by a motion capture system and custom-designed cylindrical simulator. The model simulated the grasping posture of patients after carpal tunnel release by combining the grasping postures of healthy individuals with the morphological changes observed in previous studies. Consequently, the model was able to predict the internal forces of healthy individuals and patients during grasping, including tendon tensions and joint constraints. Besides, by varying the entrance angle and increasing the moment arms of the flexors at MCP joint, the current study could evaluate the influence of the bowstring effect after carpal tunnel release
Unobvious differences in the tendon tensions and joint constraints were found by a comparison of the results between health individuals and patients. The influence of the bowstring effect on the moment arms of the flexor tendons at MCP joints could be neglected under the lower applied force. However, patients would suffer from larger normal force acting on the first annular pulley. The occurrence of the entrance angle after carpal tunnel release clearly affected the normal force.
Our findings provide information about the different biomechanics of the tendon-pulley system for patients after carpal tunnel release and healthy individuals. The results offer a probable solution to the question as to why patient might encounter trigger finger after carpal tunnel release. Besides, the current study suggests that patients after carpal tunnel release should avoid the posture that may suffer from larger normal force for a period of time.

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