肩關節是人體中唯一連接著人體軀幹與臂膀之重要結構，一旦衝撞就會導致肱骨與肌肉損傷，在近幾年來近端肱骨骨折被列為第三常見之老年人疾病，容易因摔倒等原因受到衝擊受損，造成不可逆之後遺症，在臨床上會針對其症狀嚴重性進行不同程度的治療，其中骨板固定術是臨床上常見的治療之一，也是學術研究常見探討的對象，希望可以穩定其傷部能夠恢復術前之功能性，在有限元素模擬逐漸成熟的現今，雖然常見關於近端肱骨骨折的治療策略模擬，卻鮮少關於復健動作的生物力學影響，以及探討的動作單一並沒有給予肌肉力量，因此本研究將利用數值模擬去探討近端肱骨骨折在使用鎖定式骨板固定術後於旋轉肌群作用下之生物力學影響。
　　本研究利用Solidworks繪圖，建立肱骨、肩胛骨、肩胛軟骨、鎖定式骨板與骨螺絲組合成一個完整的數值模擬模型，將肱骨模擬成三種不同骨折情形並匯入電腦分析軟體ANSYS中進行數值模擬分析，將評估三種不同復健動作，每一個動作討論四種肱骨角度，故共計有36個數值分析模型，取得骨頭與植入物的應力負載評估其失效風險，同時會比對肩關節總位移與肌肉力量反力討論關聯性。
　　結果顯示錯位性近端肱骨骨折具有較高的負載，在於骨頭與骨螺絲上會比其他骨折情況有高應力產生，從骨板應力分佈得知骨缺損會導致應力過度集中在近端骨板區域，因此具有良好的內側支撐可以降低其應力集中現象，而復健動作中的水平內收動作是相對容易造成肱骨負擔，認為並不適合做為初始復健動作，會容易造成復原失效與對病人的負擔。

Proximal humerus fractures are frequent type of humeral fracture and account for about 5% of all fractures in adults. Open reduction and internal fixation with plates is one of the leading modes of operative treatment for these fractures. Previous studies have numerically investigated plate fixation to provide fracture stabilization and improve fixation mobility. However, few numerical studies have examined the fixation strategy in rehabilitation activity with simplified loading and boundary conditions. Therefore, the purpose of this study is to evaluate the biomechanical outcome of plate fixations with three types of proximal humerus fractures and three types of shoulder rehabilitation activities using finite element analysis.
　　Three-dimensional finite element models of the shoulder joint with three types of rehabilitations and three types of proximal humerus fractures were developed in this study.
The locking plate system and screw were established using SolidWorks. In the boundary condition, the medial border of scapula was fully constrained. The locations of the rotator cuff insertion on the humerus model were defined rotator cuff footprint and developed three local coordinate systems. The rotator cuff muscle forces from the previous study were applied on corresponding location. In the post-processing, the bone stress and implant stress were calculated, and the correlation between muscle reaction force and total deformation was also obtained.
　　The result showed that the displaced proximal humerus fractures were the highest stress in bone and screw. In the presence of a fracture gap, maximal stresses in the plates appeared above the fracture gap. So, a good medial contact is recommended to reduce the implant stress at the proximal region of the plate. Additionally, the outcome of this study indicated that horizontal flexion of rehabilitation activities increased bone stress, so it may increase the possibility of bone failure during early rehabilitation. Hence, horizontal flexion of rehabilitation activities may be suggested in the latter stages.

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