臺灣博碩士論文加值系統

椎弓根螺釘在後方腰椎固定術中已成為標準的手術方法之ㄧ，且可應用於許多不同的脊椎問題而達到重建脊椎穩定度的目的。雖然椎弓根螺釘是各種後方腰椎內固定器中固定效果最好、最強的一種內固定方式，然而當病患有骨質疏鬆時，椎弓根螺釘的固定效果就明顯地減低，如此一來就會造成手術的高失敗率。有許多方法被利用來解決這個問題，包括使用外加椎板骨鈎、椎板下鋼絲固定，及利用不同材質的骨泥加強固定螺釘等等。近年來便有許多中空骨釘產品上市，此類型產品主要訴求可先將骨釘植入椎體，再將骨水泥透過骨釘中間的內孔道注入，藉由骨釘的側孔使骨水泥出流至椎體的特定位置，避免預注方式骨水泥分佈難以控制的風險。雖然中空骨釘的應用目前在國際上逐漸受到重視，然而，許多的中空骨釘本身仍存在嚴重的缺陷-即骨釘本身結構的安全性不足。由於椎體內部壓力通常較大，且骨水泥本身的黏度亦會隨時間而增加，因此，部分市面上的中空骨釘設計為使骨泥能順利注入椎體中而擴大內徑與側孔的孔徑，但此舉卻犧牲了骨釘的結構強度。於臨床使用時可觀察到中空骨釘的同區段側孔密度過高時，即有可能在骨釘鎖入椎體時因剪力斷裂。另外，若中空骨釘於臨床使用卻無搭配骨水泥時，亦可能在長期負載的情況下造成應力破壞。此外，截至目前為止，沒有任何一個關於中空椎弓根螺釘最理想之內徑與外徑比率及理想的側孔數之探討。所以我們設計了一個生物力學實驗及有限元素分析，試圖找出最理想之內徑與外徑之比率及理想的側孔數的設計概念，進而提高手術的安全性。本計畫研究結果顯示，具側孔的中空骨釘會因扭力造成斷裂風險，且風險隨著側孔數量增加而提高。另外，中空骨釘的孔徑增大亦會使骨釘植入後所受到的最大應力上升，可能使其在週期應力下的疲勞強度有降低的風險。根據本研究結果顯示，市面的側孔骨鬆釘以孔數較少為佳；另外在中空孔徑設計上應儘量搭配較細且具功能的K-Wire為考量，範圍控制在2.0mm以內，以避免造成過度應力集中的情況。

Pedicle screws fixation has become one of the standard operations in lumbar spine fusion. It has been used in treatment of various diseases of lumbar spine to reestablish spinal stability. Pedicle screws fixation is considered the most stable one among posterior fixation devices. However, when it apply to patients with osteoporosis, the effect of pedicle screws fixation significantly decreased, and the risk of failure significantly increased. Many methods had been tried to resolve the problem, such as laminar hooks, sublaminar wiring and reinforce with bone cement. Recently, various kinds of cannulated-fenestrated pedicle screws were designed. After insertion of the screws, bone cement can be injected through the central canal and the side holes, filling between trabecular bone of vertebral body and the screw. Therefore, the screw bone interface can be reinforced. Although widely used, the problem of the structural weakness of the cannulated-fenestrated pedicle screws should be concerned. To overcome the pressure in vertebral body and the viscosity of bone cement, some products with larger central canal and side holes were designed. These products make it easier to inject bone cement at the cost of the structural strength of the screws. There were some cases with failure of the cannulated-fenestrated screws observed in clinical practice. To our knowledge, there is no study aiming to define the ideal central canal diameter and ideal number of side holes. Therefore, we designed a biomechanical experiment and finite element analysis, trying to find out the ideal central canal diameter and the ideal number of side holes to minimize the risk of screw failure.
The result of the experiment showed that the risk of screw failure enlarged with the number of side holes. Besides, the stress increased with the enlargement of the central canal. We recommend limit the number of side hole to four and the diameter of the central canal between 1.5-2.0mm.

誌謝…………………………………………………………………………….……...i
中文摘要………..……………………………………………………………….……iii
Abstract…………......………………………………………………………….……..iv
目錄…..……………………………………………………………………………….vi
圖目錄……………………….……………………………….…….……………….viii
表目錄…………………………………………………………….…..………………x
第一章 前言………………………………………………………………….………1
1.1脊椎的解剖學構造………………………….……………………….………….1
1.1.1 脊柱……………………………………………………………….…………1
1.1.2 脊椎骨的構造……………………………………………………………….2
1.1.3 椎間盤………………………………………………………………………..3
1.2 骨質疏鬆症………………………………….…………………………………..3
1.3 脊椎退化症……………………………….……………………………………..5
1.3.1 椎間盤疾病......................................................................................................5
1.3.2 脊椎狹窄症………………………………………………….………………6
1.3.3 脊椎滑脫症………………………………………………….………………6
1.4 脊椎融合手術……………………………………………..……………………7
1.5 研究背景、動機與目的……………………………………………………..…..7
第二章 材料與方法……………………….………………………………………..12
2.1 中空椎弓根骨釘孔徑分析…………………………….……………………...12
2.1.1 腰椎模型建立…………………………….…………………………..…….12
2.1.2模型收斂………………………………………..…………………………..14
2.1.3施力與邊界條件…………………………….……………………………...18
2.2 骨鬆式中空椎弓根骨釘側孔分佈分析……………….……………….……..18
2.2.1有限元素分析………………………………………………………………19
2.2.2拔出測試…………………………….…………………….………….……..23
第三章 結果…………………………….…………………………………………...26
3.1 不同內徑中空椎弓根骨釘的生物力學特性……………………………....….26
3.1.1 骨釘的von-Mises應力值……………………………………………..……26
3.1.2 固定節段的勁度值與鄰近節的椎間盤受力………………………………32
3.2 不同側孔分佈型態的骨鬆中空骨釘的機械特性……………………….……39
3.2.1 骨釘破壞扭矩與破壞彎矩有限元素分析……………………….….….….39
3.2.2骨釘抗拔出強度與勁度…………………………………….…….………..40
3.2.3 骨鬆式椎弓根骨釘拔出測試…………………………………….…….…..41
第四章 討論 ..……………………………………………….……………..……… 43
4.1 中空骨釘內徑的影響.…………………….………………………….……….43
4.2 側孔分佈對骨鬆式中空骨釘的影響………………………………..….……..46
4.3 未來研究方向…………………………………….……………………………50
第五章 結論…………………………………………………………………………51
參考文獻……………………….………………………….…………………………52

圖目錄
圖1.1、脊柱構造……………………………………………………………………...1
圖1.2、 椎骨示意圖…………………………………………………………………2
圖1.3、椎間盤構造示意圖……………………………………………………….......3
圖1.4、在術中發生斷裂的中空骨鬆用骨釘，其發生位置為骨釘遠端側孔處…..9
圖1.5、術中斷裂的骨釘，透過電子顯微鏡證實其破壞模式以剪力為主…….….10
圖1.6、植入後半年的骨釘斷裂，其發生位置於骨釘近端………………………10圖2.1、腰椎影像檔數位化的重建…..……………………………………………..13
圖2.2、匯入軟體後重建的有限元素模型…………………..……………………..14
圖2.3、以正常腰椎模型進行收斂測試……………………………………………16
圖2.4、在正常的腰椎有限元素模型上模擬椎弓根固定器植入…………..……..19
圖2.5、研究共採用3種不同的側孔分佈型態: 4孔、9孔、12孔………………...….21
圖2.6、骨釘三點彎曲測試示意圖…………………………………………………22
圖2.7、以4孔骨釘進行收斂測試…………………………………………………22
圖2.8、試驗所選擇的骨鬆測試塊，其結構呈現蜂巢狀……………………………23
圖2.9、將不同孔洞分佈型態的骨釘鎖入骨鬆測試塊並注入骨水泥……………24
圖2.10、骨釘拉出測試裝置圖……………………………………………………..24
圖3.1、四組骨釘模型S0、S1.5、S2.0、S2.5……………………….……………27
圖3.2、扭轉時，L4骨釘(下節)的最大von-Mises應力分佈……………………….28
圖3.3、側彎時，L4骨釘的最大von-Mises應力分佈…………………………….29
圖3.4、伸展時，L3骨釘的最大von-Mises應力分佈………………….………..30
圖3.5、彎曲時，L4骨釘的最大von-Mises應力分佈……………………………..31
圖3.6、各種內徑骨釘於彎曲受力下的模型力學特性表現………………………33
圖3.7、3款骨鬆用中空釘於扭矩下的受力狀況………………………………….39
圖3.8、三種側孔分佈的骨釘於灌入骨水泥前、後的拉出強度值…………………40
圖3.9、經由CT重建各款骨釘於灌注骨水泥後的包覆情況…………………….41
圖4.1、Chen等學者所設計的1種實心骨釘與5種中空骨釘……………………49

表目錄
表2.1、有限元素模型所使用的各元件材料性質…………………………………..16
表3.1、四種骨釘在腰椎活動條件下最大von-Mises應力值……………………..32
表3.2、不同型態骨釘固定節段在運動時所呈現的勁度值………………………34
表3.3、正常腰椎及骨釘固定後在扭轉時活動角度及整體活動度…………..……34
表3.4、正常腰椎及骨釘固定後在側彎時活動角度及整體活動度………………35
表3.5、正常腰椎及骨釘固定後在伸展時活動角度及整體活動度……………….35
表3.6、正常腰椎及骨釘固定後在彎曲時活動角度及整體活動度……………….36
表3.7、扭轉時椎間盤最高應力值與小面關節接觸力值………………………….37
表3.8、側彎時椎間盤最高應力值與小面關節接觸力值…………………………37
表3.9、伸展時椎間盤最高應力值與小面關節接觸力值………………………….38
表3.10、彎曲時椎間盤最高應力值與小面關節接觸力值…………………………38
表3.11、Mann-Whitney檢定顯示無顯著差異性……………………………………41
表3.12、Mann-Whitney檢定顯示骨水泥包覆長度僅S4與S9有顯著差異……….42

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45. 中華民國骨質疏鬆症學會彙編 2015台灣成人骨質疏鬆症防治之共識及指引