臺灣博碩士論文加值系統

單側遠端股骨骨板固定失效的發生率約為7%，在開放式骨折裡更佔了12%之多，此部位的主要功能為支撐身體重量並輔助下肢運動，因此對於遠端股骨骨板之生物力學現象，仍然值得探討。股骨為人體最大的骨頭，其又名大腿骨，目前治療遠端股骨骨折的方式有很多種，其中以骨板較適合治療遠端股骨骨折，在臨床上已經證實出使用鎖定式骨板有良好的治療效果，但對較嚴重之粉碎性骨折之患者，即使以鎖固式骨板進行固定，但仍有骨折產生未癒合與固定失效之情形。探究其失效的原因，可能為讓骨折處過早受力，理論上，若提供內外兩側或前外兩側之骨板固定，應可以增加骨折前期整體骨折處之穩定度，提升骨折的治療率。本研究選擇的雙側骨板固定包括了前外側骨板固定跟內外側骨板固定兩種，前外側骨板固定在手術上比內外側骨板固定來的容易進行，但是內外側骨板固定則是在力學上較有優勢。而過去文獻中並沒有探討單側和雙側鎖固式骨板固定的生物力學評估，之此，本研究使用有限元素法，評估三種不同固定方式在不同時期的骨痂和不同骨折類型中對於遠端股骨骨板固定之生物力學表現。
本篇研究使用的模型，外側骨板為Zimmer出產的Distal Lateral Femoral Locking Plate，在骨幹處用5根bicortical locking screw固定，在股骨遠端使用5根metaphyseal screw和1根斜向螺釘固定，前側骨板和內側骨板則是使用Stryker出產的Reconstruction plate，使用6根bicortical locking screw固定，骨頭模擬第四代的人造骨。
本篇研究是利用結構剛度來驗證本研究模型可靠度，驗證的研究是近年來使用相同骨板並且同樣為探討遠端股骨骨折之研究，其研究是使用拉身試驗機進行實驗，實驗骨頭為第四代人造骨，在人造骨上切出骨折型態，鎖上本研究之骨板，之後將其固定在拉身試驗機上，股骨近端和股骨遠端使用樹酯包埋，在拉身試驗機，近端和遠端都有ball bearing joint，其作用為避免實驗過程中骨頭產生扭矩和彎矩，並沿著mechanical axis施加軸向力，模擬人體受力的情況。
本篇研究分析三種不同固定方式，分別為單外側、前外側和內外側，骨痂的時期分別為0週、4週和8週，骨折類型則有AO33-A3和AO33-C1兩種類型。 結果的部分會探討骨折處變形型態、骨板應力、結構剛度。
本研究之驗證模型結果，比對的研究是近年來探討遠端股骨骨折並且使用相同骨板的研究。比對研究的結果，其結構剛度為 127.1N/mm 標準差為5.7N/mm。本研究模擬之模型，其結構剛度為 141.54N/mm ，在結構剛度兩者差異為10%左右，藉此驗證本研究模型之可靠度。
本研究結果顯示，評估三種不同時期的骨痂，在0週骨痂和4週骨痂時，骨折處的變形型態、骨板應力和結構強度，並沒有明顯的差異，由此表示在4週的骨痂所提供的強度跟0週的骨痂是差不多的，0週骨痂和4週骨痂其強度並不能提供骨折處穩定的固定，但是在8週時期的骨痂，其骨痂強度明顯不同於0週骨痂跟4週骨痂，8週骨痂可以比0週和4提供骨折處更好的穩定。雙側骨板固定可以在骨折前期提供比較好的穩定，在AO33-A3骨折時前外側骨板固定跟內外側骨板固定結果顯示是沒有太大差異，但是在AO33-C1骨折時內外側骨板固定優於前外側骨板固定。由研究結果發現，雙側骨板固定，前側和內側骨板的應力值會比外側骨板來的高，探究其原因有兩種因素，其一，可能是因為股骨內外側負載的分佈，本研究探討股骨內外側力的分佈，在使用單外側骨板固定時，股骨內外側力的分佈為1比5，雙側骨板固定時，股骨內外側力的分佈為1比1，骨折處結構越穩定股骨內側的負載就會增加，進而影響前側和內側骨板應力值，其二，可能是因為本研究使用兩種徑度差異太大的骨板，所以造成內側和前側骨板應力升高。因此，本研究建議，在使用雙側骨板固定時，要選擇徑度相近的骨板，可以讓應力平均分佈，避免骨板發生破壞。

Evaluation of Unilateral and Bilateral Locking Plate Fixation of Distal Femur Fracture: Finite Element Analysis
Hui-wen Yu
Chih-han Chang
Department of Biomedical Engineering/ National Cheng Kung University
SUMMARY
The incidence of distal femur locking plate failure was 7% and in open fractures increased 12% of plate failure. In clinical treatment, using locking plate to stabilize and treat the distal femur fractures has shown good results. In spite of its improved fixation, in certain cases like comminuted fracture or bone loss, fracture non-union even implant failure still occurred.. Theoretically, the union rate should be increased with the improved stability if this fracture construct is buttressed bilaterally by plates. The purpose of this study was to evaluate the biomechanical of different fixation on different period of callus and on different fracture type by using finite element method.
The results showed that in different callus condition, 0 week and 4 week callus can’t provide enough strength in fracture site and 8 week callus can. On AO33-A3 fracture type that lateral- medial and lateral- anterior locking plate fixation can provide fracture side more stable avoided locking plate failure. On AO33-C1 fracture type that lateral- anterior may also fail because the stress was too high to support but lateral- medial plate fixation can avoid failure occurrence. This study suggests that using bilateral fixation the two plates of stiffness cannot be very different and may cause more stress to one plate. Using similar stiffness of plate can avoid bone plate failure.
Keywords: Distal femur locking plate; Finite element analysis; Lateral plate fixation; Lateral- anterior plate fixation; Lateral- medial plate fixation
INTRODUCTION
The incidence of distal femur locking plate failure was 7% and in open fractures, it increased to 12% of plate failure. The main function of this site is to support the body weight and assist lower limb movement. Therefore, it is necessary to discuss the biomechanical performance of distal femur locking plate. The femur, another called thigh bone, is the strongest, longest, and heaviest bone in human. It is between hip bone and tibia. The main function is to sustain the weight of the body receiving from the hip bone and passing to the tibia. In clinical treatment, use of the locking plate to stabilize and treat distal femur fractures has shown good results. Despite its improved fixation, in certain cases involving comminuted fracture or bone loss, fracture non-union even implant failure still occurred. Their failure mode suggested insufficient support from the laterally implanted device before the solid union of fracture. Theoretically, the union rate should be increased with improved stability if this fracture construct is buttressed bilaterally by plates. This study used two types of bilateral fixation including anterior-lateral fixation and medial-lateral fixation. Anteriorolateral fixation is more easy with open reduction and internal fixation (ORIF). Medial-lateral fixation is a mechanical advantage. In the past literature, there was no information on the biomechanical analysis of unilateral and bilateral locking plate fixation on distal femur fractures. The purpose of this study was to evaluate the biomechanical analysis of two different fixations on different periods of callus and on different fracture type by using the finite element method.
MATERIALS AND METHODS
The model of this study, distal lateral femoral locking plate is fixed on lateral. Distal femoral locking plate was fixed with four 4.5 mm solid bicortical locking screws to the shaft. At the distal femoral locking plate segment, 5 of the metaphyseal screw holes were fixed with 5.5 mm locking screws, plus the oblique screw. A total of 6 locking screws were fixed at the distal site. Reconstruction plate was fixed on the anterior and medial positions. The reconstruction plate used in this study was fixed with six 4.5 mm bicortical locking. The bone model is a fourth-generation of sawbone.
A previous study shows the validation of the current study in terms of construct stiffness. In other studies, authors have used MTS experiment. The bone is a fourth-generation sawbone. The fracture type was cut on the sawbone and bone plate was fixed. The proximal half and distal end were held with polymethylmethacrylate and exerted axial force through mechanical axis to simulate body weight. In addition, ball bearing joints were used proximally and distally to avoid torque or bending moment during testing.
This study evaluated three different fixations, including lateral locking plate fixation, lateral-medial locking plate fixation, and lateral-anterior locking plate fixation. The period of callus included 0-week callus, 4-week callus, and 8-week callus. The fracture types were AO33-A3 and AO33-C1. The result evaluates the deformed mode of fracture site, plate stress, and structure stiffness.
RESULTS AND DISCUSSION
Using the results of model verification, this study compared construction stiffness with a recent study, using the same distal femur locking plate to validate model reliability. In another study, the stiffness of model construction was 127.1 N/mm and standard deviation was 5.7 N/mm. In this study, the stiffness of model construction was 141.54 N/mm that the loading was 495.41 N and the displacement was 3.5 mm. Stiffness between other studies and this study was almost the same; thus validating our model reliability.
The results of this study evaluated different periods of callus. In the 0-week and 4-week callus, there was no difference in the deformed mode than the plate stress and construction stiffness, but in the 8-week callus there was an obvious difference as compared with the 0-week and 4-week callus. A period of 8 weeks can provide better stability than that in the 0-week callus and 4-week callus on fracture site. This study showed that bilateral fixation can provide more stability in the early stage on fracture site. On AO33-A3 fracture types, the lateral- medial and lateral- anterior locking plate fixation can provide a fracture side that is more stable avoiding locking plate failure. The result shows that the reconstruction plate suffers high stress on bilateral fixation due to two factors. The first was the force distribution on femur. Unilateral fixation and force distribution on femur was 1 to medial and 5 to lateral. Bilateral fixation and force distribution on femur was 1 to medial and 1 to lateral. The other reason was that the size was very different than that of the distal femoral locking plate and reconstruction. On AO33-C1 fracture types, lateral- anterior may also fail because the stress was too high to support, but the lateral- medial plate fixation can avoid failure occurrence. This study suggests that using bilateral fixation the two plates of stiffness cannot be very different and may cause more stress to one plate. Using similar stiffness of plate can avoid bone plate failure.

中文摘要 I
Abstract IV
致謝 VII
第一章 簡介 1
1.1股骨解頗結構與特徵 1
1.1.1 股骨解剖構造 1
1.1.2 骨頭的特徵 3
1.2股骨骨折 3
1.2.2遠端股骨骨折的發生率 4
1.2.3 遠端股骨骨折植體破壞發生率 7
1.2.4 遠端股骨骨折類型 8
1.2.5 治療遠端股骨骨折的方法 9
1.3 骨板介紹 9
1.3.1 骨板類型 10
1.4 遠端股骨骨折骨板固定方式 11
1.4.1 單側骨板固定 11
1.4.2 雙側骨板固定 12
1.5 動機與目的 13
第二章　材料與方法 14
2.1 研究過程 14
2.2遠端股骨骨折骨板固定: 有限元素法 15
2.2.1 建立3D骨頭模型 15
2.2.2建立3D骨板模型 15
2.2.3 建出骨折3D 術後模型 19
2.2.4 模型驗證 21
2.2.5有限元素法–驗證模型之材料特性 22
2.2.6有限元素法–驗證模型之邊界條件與施力模式 22
2.2.7有限元素法–本研究之材料特性邊界條件與施力模式 23
2.2.8 有限元素法–本研究之邊界條件與施力模式 24
2.3 模擬參數 25
第三章 結果 27
3.1驗證模型結果 27
3.2 本研究之生物力學結果 27
3.2.1使用三種固定方式對AO33-A3骨折之變形型態、骨板應力、結構強度之影響 28
3.2.2使用三種固定方式對AO33-C1骨折之變形型態、骨板應力、結構強度之影響 34
第四章 討論 41
4.1本研究之討論 41
4.2 Limtations 43
第五章 結論 44
文獻 45

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