肩關節大結節骨折屬於肱骨近端骨折的一種，它是常見的肱骨損傷，常伴隨著肩關節脫位與旋轉肌群撕裂傷，治療較嚴重明顯的骨折可採用骨螺絲、鎖定式骨板、縫合式固定鉚釘、以及張力帶等方式固定骨折塊；雖然目前已有少數研究利用有限元素法來評估大結節骨折植入物之固定強度，但其數值模型的評估僅一外展動作。因此，本研究目的是以有限元素分析方法探討大結節骨折治療，分別以骨螺絲與鎖定式骨板固定後做復健動作時的生物力學性能。

本研究使用SolidWorks繪圖，由鎖骨、肩胛骨、肱骨、植入物組成，並將鎖骨隱藏以利後續分析；完成模型建構後將模型匯入電腦數值分析軟體ANSYS Workbench 19.2進行模擬分析，共有84個模型評估不同的手術治療策略之生物力學結果；本研究依據螺絲數目和固定方式分組進行穩定度與植入物應力評估，最後將所有結果進行正規化合併討論。

結果顯示，骨螺絲與鎖定式骨板在選擇螺絲固定位置時，螺絲排列呈倒三角形，其中兩支骨螺絲固定在骨折塊上，另一支骨螺絲則固定在肱骨上，使骨板橫跨骨折面，此方法使骨折處擁有較佳的穩定度以及較低的植入物破壞風險；螺絲呈倒三角排列但三支螺絲皆在骨折塊上，骨板並無橫跨骨折面，此固定方式使得骨板存在可有可無，甚至會有較糟的穩定度及應力表現，而非倒三角排列但骨板橫跨骨折面的固定方式使得骨折處的穩定度較差。這項研究可以提供外科醫師了解植入物的不同固定位置，其對於肱骨大結節骨折之生物力學結果與原理。

Greater tuberosity fracture of the humerus is a common injury, which is often accompanied by shoulder joint dislocation and rotator cuff tears. Patients with severe greater tuberosity fracture of humerus patterns more often underwent surgery. Multiple surgical strategies include the use of locking plates and screws, suture anchors, and tension bands. In previous studies, the finite element analysis (FEA) for fixation strategies of greater tuberosity fracture only considered shoulder abduction; however, considering only one shoulder posture was not enough to mimic the movement of multi-axial shoulder joint. Thus, the purpose of this study was to evaluate biomechanics on 2 treatments for 3 rehabilitation movements in 4 angles using three-dimensional FE models.

Seven types of implant fixation models, two types of screw fixation and five types of locking compression plate (LCP) fixation, were established using SolidWorks and ANSYS Workbench 19.2. In the boundary conditions, the scapula and the cartilage were fully constrained, the cartilage and the humerus were assumed to be no separation, the humerus and the implants were also assumed to be no separation, and the frictionless contact was applied between the interface of the greater tuberosity fracture. The force generated by the rotator cuff muscles in different postures were applied on humerus as the loading conditions. In post-processing, the bone fixation stability and the stress of implant were calculated and discussed.

The result showed that the screw insertion position had significant effect on fixation outcome. The screw insertion position arranged as a triangle and on both sides of the fracture line were more likely to provide better stability and less risk of implant failure. In contrast, the screw arrangements either without triangle position or only on one side of the fracture line had less stability or less functional outcome. This study could provide surgeons some useful information and biomechanics on the treatment of greater tuberosity fracture.

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