大腳趾外翻是常見的足部疾病，除了有不正常的足部外觀，持續受到不正常壓力的蹠趾關節易趨於惡化，其所帶來的疼痛更使患者生活造成負面影響。目前醫界雖已發展各式大腳趾外翻治療手術，但其帶來的後遺症或併發症卻仍未有令人滿意的解決方案，因此患者接受手術之意願低落，而對於症狀輕微患者，為了減緩疼痛與避免症狀再度惡化，患者通常較能接受保守治療。趾間墊矯具是目前具方便性並接受度高之保守治療方法，過往文獻也證明於使用趾間墊過程能夠改善疼痛，但對於趾間墊是否具有矯正效用一直無法有明確之解答，因此本研究的目的是透過有限元素法進行大腳趾外翻以及使用趾間墊之生物力學分析。
本研究使用CAD軟體建立包含骨骼、軟骨、軟組織之大腳趾外翻模型，接著使用有限元素軟體ABAQUS建立韌帶以及肌肉肌腱系統以完成大腳趾外翻之完整有限元素模型，分析首先驗證所建立之肌肉肌腱系統對大腳趾外翻的影響，再以肌肉肌腱系統角度探討大腳趾外翻與趾間墊矯正生物力學關係。
以塞入不同厚度的趾間墊比較，分析結果顯示使用趾間墊的過程能夠矯正HVA，且厚度越厚的趾間墊，其HVA矯正效果越佳，以8 mm厚趾間墊為例，可降低HVA達1.76%，但趾間墊無法改善IMA。塞入趾間墊時內收足拇肌上的力量增加，且越厚的趾間墊，力量增加越明顯，長期使用可使該肌肉張力降低，推測此生物力學現象為趾間墊具有長期矯正效用之原因。因此越厚的趾間墊會有更好的矯正效果，但其在內收足拇肌上增加的張力對於患者而言也更容易帶來不適感。

Hallux valgus is one of the most common diseases of foot. The normal life can be affected a lot due to pain of the hallux valgus. There have been more surgeries developed for hallux valgus. However, there is no satisfied solutions for the sequelae and complications of the surgeries have been proposed. Therefore, the conservative treatments are usually more acceptable for patients. The toe spacer is one of which that provides convenience and acceptance for a hallux valgus patient. However, there is no clear answer to the effectiveness of the toe spacer for correcting the hallux valgus. The aim of this study is to conduct a biomechanics analysis for hallux valgus and toe spacer correction by using the finite element analysis.
In this study, the CAD models for the bones, cartilages and soft tissues of a foot was established. The ligaments, muscle and tendons were added in the model by using finite element software ABAQUS. In the analysis, the effects of the muscle and tendon systems to the hallux valgus were verified by the model. Then the biomechanics analysis of the use of the toe spacer on the hallux valgus is based on the muscle and tendon system.
The analysis results show that the use of the toe spacer can decrease the hallux valgus angle. It is found that the correction effect is better by increasing the thickness of the toe spacer. By taking the toe spacer with thickness of 8 mm as an example, it can reduce the HVA by 1.76%. However, the numerical results show that the IMA cannot be corrected by using the toe spacer. It is also found that the forces in adductor hallucis muscle decrease with the use of the toe spacer. This decrease is more obvious if a thicker toe spacer is used. After a long term usage, the tensions in adductor hallucis muscle can effectively decrease. It is inferred that this tension decrease is one of the reasons to correct the hallux valgus.

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