Effect of Fatigue Loading on The Static and Dynamic Response of Spinal Column Post Vertebroplasty

目的：探討脊骨整型術後之椎骨經疲勞負載後之力學反應變化景簡介：骨質疏鬆症是導致椎骨發生壓迫性骨折的因子，而脊骨整型手術是治療此病症的方法。在臨床結果中，這些病患在術後經過一段時間，有可能再次發生骨折。每天各式的活動都會對脊椎造成疲勞負載，這是導致椎骨壓迫性骨折的原因之一，也是脊骨整型手術後再次骨折的重要因素之一。我們希望能從脊椎受到疲勞負載過程的力學反應變化，了解造成椎骨再破壞的原因，或許能夠用來預測及預防椎骨的再破壞。料與方法：採用人體胸椎之運動元共十組，每一試樣為四節椎骨。在去除軟組織後，將試樣第一與第四節椎骨包覆強化樹脂並架設加速度計。完成後將試樣置於實驗機台進行衝擊測試，量測試樣之剛性與振動加速度。試樣在不同的階段接受衝擊測試，首先模擬椎骨的壓迫性骨折，接下來注射骨水泥對破壞節椎骨補強。等待骨水泥硬化後，試樣進行疲勞負載的階段。實驗中共模擬三組不同載重情況下的疲勞負載，試樣依序接受650 牛頓、950牛頓及1150 牛頓的疲勞破壞，每一組負載時間皆為5 小時，各組之間會有12 小時的休息。果：在椎骨模擬壓迫性骨折後，椎骨試樣剛性下降13.5% (P = 0.14)，第二節椎骨加速度上升25.8% (P = 0.00)，而使用骨水泥補強後，可以椎骨的剛性及加速度回復至接近破壞前。在5 小時的疲勞負載後，椎骨運動元之剛性增加26% (P = 0.00)，而第一節椎骨加速度下降了14% (P = 0.00)，休息可以使之回復。在負載大的組別中，加速度與剛性的變化速度較快，在第1 小時疲勞負載造成的變化最大。論：本研究顯示破壞會造成椎骨受衝擊時的剛性降低而加速度上升，破壞節椎骨處於不穩定的狀態，而經皮脊椎整型手術能夠恢復椎骨的穩定度。隨著疲勞負載的時間，脊椎有剛性增加與加速度下降的現象，而休息可使脊椎性能回復。從數學模型計算脊椎受力變，結果顯示在經過5 小時疲勞負載後，脊椎受力增加了1.46%，而在負重較高的情況中，脊椎受力增加的比較快速。因此，長時間疲勞負載是造成脊椎再破壞的因子，在負重較高的情況中，休息顯得更為重要。Objective: To investigate the effect of fatigue loading on the biomechanical responses of spinal column post vertebroplasty.ummary of Background Data: Fatigue loading is one of the risk factors for vertebral compression fracture. Vertebroplasty is a minimal invasive surgery for spinal compression fracture. It is believed that the fatigue loading is also an important factor for the vertebrale-fracture post vertebroplasty. We hope we can explore the mechanical response of augmented vertebra secondary to the fatigue loading. The results may help to predict or prevent the vertebral refracture.ethods: Ten human thoracic motion segments (T4-T7, T5-T8, T9-T12) were used and set up accelerometer on 1st and 2nd level. Specimens were applied with impulse testing to measure the stiffness and acceleration after fractured, augmented, and fatigue loading. The fatigue loadingsere 650N, 950N, and 1150N at 5Hz for 1, 2, 3, 4, and 5 hours (18,000, 36,000, 54,000, 72,000, and 90,000 cycles), and 12-hours rest was applied between different loadings. The paired-t test was respectively performed to evaluate the variations of stiffness and acceleration after a seriesf fatigue loading. The independent t-test was performed to evaluate the variation of acceleration on 1st and 2nd level.esults: After fractured, the stiffness decreased 13.5% (P = 0.14), and acceleration of level 2 increased 25.8% (P = 0.00). The variations of these properties were recovered after cement injection. After 5-hours fatigue loading, the stiffness increased 26% (P = 0.00) but acceleration ofevel 1 decreased 14% (P = 0.00), and both recovered after 12-hours rest. Under high loading condition, the changing rates of acceleration and stiffness is higher, especially in the first hour.onclusion: Spinal stability was decreased after vertebral compression fracture, and recovered post vertebroplasty. The stiffness increased but acceleration decreased after fatigue loadings, and rest could restore these mechanical properties. The results of numerical model indicated thenternal force of spinal column increased 1.46% after 5-hours fatigue loading. The internal force of spinal column increased rapidly under high loading condition. Therefore, a long-term activity is a risk factor for vertebral refracture.第一章 序論.............................................. 1-1 脊椎的基本構造....................................... 1-2 骨質疏鬆症........................................... 3-3 經皮脊骨整型手術..................................... 4-4 脊椎生物力學......................................... 5-5 文獻探討............................................. 6-5-1 疲勞負載與振動對人體脊椎之影響..................... 6-5-2 脊骨整型手術後脊椎力學性質之量測................... 7-5-3 脊椎振動加速度之研究............................... 8-6 實驗目的............................................. 9二章 實驗材料與測試方法............................... 10-1 實驗儀器............................................ 10-1-1 連續衝擊測試平台.................................. 10-1-2 往復式衝擊模組.................................... 11-1-3 單軸向加速度計與訊號處理器........................ 11-2 實驗階段............................................ 12-2-1 衝擊測試.......................................... 13-2-2 疲勞負載.......................................... 13-2-3 椎骨試樣準備...................................... 13-2-4 模擬椎骨壓迫性骨折................................ 15-2-5 骨水泥注射........................................ 15-3 資料分析............................................ 16-3-1 剛性分析.......................................... 16-3-2 加速度訊號分析.................................... 17-3-3 統計分析方法...................................... 18三章 實驗結果......................................... 19-1 椎骨運動元之剛性變化................................ 19-1-1 負載時間與休息之剛性變化.......................... 19-1-2 破壞前後及骨水泥補強後剛性比較.................... 19-1-3 負載大小與剛性變化量之關係........................ 20-2 椎骨運動元之加速度變化.............................. 21-2-1 第一與第二節椎骨加速度比較........................ 21-2-2 負載時間與休息之加速度變化........................ 22-2-3 加速度之頻域...................................... 23-4 脊椎受力之數學分析.................................. 24四章 討論............................................. 26-1 實驗設計之討論...................................... 26-2 剛性變化之討論...................................... 26-3 加速度變化之討論.................................... 27-6 實驗限制............................................ 27五章 結論與未來展望................................... 28-1 結論................................................ 28-2 未來展望............................................ 28amp;#63851;考文獻................................................ 2