依據國內統計，平均每1分鐘就有一人因意外事故而骨折就醫，其中長骨(股骨與脛骨)骨折的病患每年就高達三萬人。目前最常使用的長骨骨折固定方式為於骨髓內腔植入骨髓內釘。植入骨髓內釘後，在骨髓內釘近端及遠端的固定孔鎖上固定螺釘，可以防止骨頭的旋轉及移位，幫助穩定骨頭使其自然癒合，但現行的手術方法在遠端固定的階段，會因為骨髓內釘在打入長骨骨髓腔時，外型受制於骨髓腔形狀而改變，導致依照骨釘規格製作之鑽孔導引器具與目標位置產生誤差，使醫師在進行遠端固定時必須高度仰賴C-arm(X光設備)，過程中造成手術時間拉長，病患與醫療人員也因而吸收高放射線劑量，且不見得順利鎖入固定螺絲。
本研究以C-arm影像輔助導引系統為基礎，應用於股骨骨折之骨髓內釘遠端螺絲鎖定系統，目標在於找出骨髓內釘遠端固定孔軸向方位。首先拍攝二張不同角度之C-arm影像，用於找出骨髓內釘在空間中的位置與方向，依照計算出的位置與方向將骨髓內釘模型擺放在建立好的C-arm投影模式下，模擬出骨髓內釘固定孔影像，以固定孔重疊區域之橢圓形長軸方向與骨髓內釘軸向之夾角作為比較特徵，將模擬之骨髓內釘固定孔影像與C-arm所拍攝之實際影像進行比對，找出最相似的模擬影像，即可得到固定孔軸向的位置與方向。
由於骨髓內釘固定孔孔徑只有5mm，徒手易造成鑽孔方向有所偏移，故設計一具有微調功能的鑽孔輔助器，使醫生能順利完成器械鑽孔。實驗誤差以C-arm拍攝夾角為28.3度中，最小的角度誤差為0.28°，位移誤差為0.78mm；最大角度誤差為1.90°，位移誤差為1.92mm。

According to national statistics result, people go for medical care due to the bone fracture in accident almost one person per minute. And there are around 30,000 cases of long bone fracture (femur and tibia) patients every year. Currently the most commonly treatment for long bone fracture fixation is implanting an intramedullary nail into marrow cavity of the long bone. For the therapeutic effect, intramedullary nail will be fastened with bone by locking screws in both proximal and distal sides of the nail. The bone is drilled by using K-wire instrument to pass through the locking hole, but usually the distal side locking holes are hard to be located because they are visible only under X-ray exposures and the nail deforms during the insertion process. So the surgeon must rely on fluoroscopy images to locate distal locking hole during surgery. The surgeon needs to spend a lot of time to figure out the positions and orientations of the locking holes and usually explore high radiation dosage.This project's goal is to develop an image-based surgical navigation system for the distal locking of intramedullary nails, which can locate the positions and orientations of the distal locking holes.
First of all, taking two fluoroscopy images in different angle, which can determine the positions and orientations of the intramedullary nail axis in space. The 3D model of the intramedullary nail will be placed according to the calculate positions and orientations under the C-arm projection mode, and simulate C-arm projection to produce the distal locking holes image of intramedullary nails. The angle between the nail axis and the locking holes projections overlap area of the ellipse’s long axis have to be determined. The simulate images are compared with the actual image are taken from C-arm to find the most similar simulate images, and get a axis position and orientation of locking holes.Because the diameter of locking hole only have 5mm, freehand drilling holes could easily cause the wrong direction, so design a aid-drill which have a fine-tuning that can help the surgeon to complete the drilling surgery successfully. Experimental accuracy with C-arm shooting angle of 28.3 degrees ,the smallest is 0.28 in rotation, 0.78 mm translation; the largest is 1.90 in rotation, 1.92 mm translation.

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