經皮椎骨整型手術中骨水泥溢流之危險因子分析

Analysis of Risk Factors of Cement Leakage in Vertebroplasty

歐任凱(Jen-Kai Ou)

指導教授 ： 王兆麟

國立臺灣大學/工學院/醫學工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.02947

摘要

目的：探討經皮椎骨整型手術中，椎骨密度、骨折程度、骨水泥濃度對骨水泥注射力量以及骨水泥流動型態的影響。
背景簡介：經皮椎骨整型手術( Vertebroplasty )是一種微創的脊椎手術，主要用於治療因骨質疏鬆症所導致的椎骨骨折。不同的骨折程度與骨質疏鬆程度皆會影響骨水泥在椎骨中流動的情形，不同濃度的骨水泥也會影響手術中之注射力量。因此，針對不同的骨折程度，選擇相對應的手術方法與設定，將有助於手術順利進行並且預防骨水泥溢流。
材料與方法：實驗分為兩階段，在第一階段使用三種矽油(黏滯性分別為30, 60, 100 Pa*s )分別注射入三種人工假骨(骨質密度分別為0.33, 0.53, 1.18 g/cm2 )，觀察不同結構和黏滯性對注射力量的影響，以及矽油在人工假骨中的流動情形。第二階段實驗使用20個人體胸椎 ( T1 N=5, T2 N=5, T3 N=2, T5 N=5, T6 N=2, T7 N=1)，試樣分成2組，分別壓縮成原始高度的30%與60%，以模擬兩種楔形骨折的嚴重度。接著仿照經皮椎骨整型術的手術過程，從試樣左邊的椎弓根部位鑽出注射管道，將2種濃度的骨水泥(粉末與溶劑比分別為1.3與1.6 )注射入椎骨中，探討不同骨折程度與骨水泥濃度，對注射力量以及骨水泥溢流的影響。實驗中，矽油或骨水泥的注射容量為3 mL，注射速率為1.62 mL/min。楔形骨折的形成過程，以及矽油和骨水泥的注射過程，都由電腦斷層掃瞄機拍攝下來，事後以影像處理軟體分析矽油和骨水泥隨著時間於試樣內的擴散型態。之後以游標卡尺量測椎骨在骨水泥注射前後的高度變化，並將椎骨進行切片，觀察骨水泥於椎骨內的分佈狀態與溢流現象。最後以單變異數檢驗法及線性迴歸法，探討影響骨水泥注射力量的參數。
結果：在第一階段實驗中，矽油的注射力量只跟黏滯性有關，與人工假骨的孔洞比無關，三種矽油(30, 60, 100Pa*s)的注射力量分別為31 (10) N、63 (4) N以及81 (12) N，黏滯性越高的矽油所需要的注射力量越大。矽油在中、低密度的人工假骨內，擴散型態呈現圓球狀，黏滯性低的矽油因容易往前方流動，故擴散型態稍微類似橢圓球狀，而矽油在高密度的人工假骨內，則呈現不規則狀分佈。第二階段實驗中，注射力量隨骨水泥濃度增加而升高，濃骨水泥與稀骨水泥的平均注射力量分別為208 (39) N以及115 (38) N。椎骨的破壞程度與骨質密度皆不會影響注射力量。骨水泥是否溢流出椎體，與椎體的骨折程度有關，與骨水泥的濃度以及椎骨密度無顯著相關性。破壞程度30%的試樣中，有三個發生骨水泥溢流，溢流處分別為術中鑽出的注射管道以及椎體破裂處。破壞程度60%的試樣皆發生骨水泥溢流，溢流處分別為表面破裂處、椎終板破裂處、往神經腔方向的椎體靜脈通道，以及注射管道。稀的骨水泥於破壞程度較低的椎體內有較好的分佈狀態。破壞後的椎體經骨水泥注射過後，高度有顯著的回復。
結論：本研究顯示經皮椎骨整型手術的注射力量主要取決於骨水泥的濃度。骨水泥溢流則跟椎體的骨折程度有關，椎體破壞越嚴重就越容易引發骨水泥溢流，骨水泥的溢流位置較常發生於椎體表面破裂處、椎終板破裂處、往神經腔方向的椎體靜脈通道以及注射管道。若椎體無明顯破裂，選擇稀的骨水泥可方便注射，亦無明顯骨水泥溢流；若椎體有明顯破裂，注射濃骨水泥並避開皮質骨破裂處，或是在骨水泥即將觸及破裂處時停止注射，應可降低骨水泥發生溢流的機會。

【關鍵詞】骨質疏鬆症、壓迫性骨折、經皮椎骨整型手術、骨水泥、注射力量、溢流、滲透

關鍵字

骨質疏鬆症 ； 壓迫性骨折 ； 經皮椎骨整型手術 ； 骨水泥 ； 注射力量 ； 溢流 ； 滲透

並列摘要

Objective: To investigate the effect of cement viscosity, bone mineral density, and fracture level on the injection force and on the cement spreading pattern within the vertebrae during percutaneous vertebroplasty.
Summary of Background Data: Vertebroplasty is a minimal invasive surgery for spinal compression fracture. Cement viscosity, bone mineral density, and fracture level have been suspected to influence the injection force and spreading pattern of the cement; hence, further affect the risk of cement leakage.
Materials and Methods: Two experiments were conducted in this study. The first one was to find the effect of bone structure, bone porosity, and viscosity on the injection force and spreading patterns of the silicon oil. Three types of sawbones (BMD= 0.33 g/cm2, open cell; BMD= 0.53 g/cm2, open cell; BMD= 1.18 g/cm2, closed cell) and silicon oil (η=30, 60, 100 Pa*s ) were used. The second experiment was to find the effect of the fracture level and the cement viscosity on the injection force and spreading pattern of the bone cement. Ten cadaveric thoracic vertebrae were compressed to 30% of original height, and another 10 vertebrae were compressed to 60% of original height. Two kinds of bone cement with different viscosity were made by setting the powder-monomer ratio to be 1.3 and 1.6. In the first and the second experiment, 3 mL of silicon oil and bone cement was injected into the specimen at speed of 1.62 mL/min using the standard vertebroplasty procedure. The process of bone deformation and silicon oil /cement injection was scanned using cine-CT. The spreading patterns of silicone oil / bone cement within the sawbones and vertebrae were analyzed with an in-house image processing software. The specimens were sliced to find the spreading patterns and leakage pathway. The parameters that significantly influenced the injection force were determined by one-way ANOVA.
Results: In the first experiment, the injection force increased with viscosity of silicone oil. The injection force was 31(10) N for 30 Pa*s, 63(4) N for 60 Pa*s, and 81(12) N for 100 Pa*s silicone oil. The porosity and structure of sawbones did not affect the injection force. The spreading patterns of silicon oil were “bulb”shape within low- and median-density sawbones, but spreading patterns were irregular within high-density sawbones. In the second experiment, injection force also increased with viscosity of bone cement. The injection force was 208(39) N for high viscosity and 115(38) N for low viscosity. Bone mineral density and fracture level did not affect the injection force. The incidence of cement leakage increased with level of fracture. The cement was leaked in 3 out of 10 low fractured specimens, while all cement was leaked in high fractured specimens. The leakage pathway included fractured site of cortical shell, endplate fissure, basivertebral foramina and needle track. Bone mineral density and cement viscosity did not affect the cement leakage. The lower viscous cement spread wider and further in the vertebrae with lower fracture level. The height of vertebrae was recovered significantly after the vertebroplasty.
Conclusion: The injection force increases with viscosity of bone cement. The incidence of cement leakage is highly related to the level of fracture, while the fractured cortical shell, endplate fissures, basivertebral foramina and needle track are possible leakage sites. For the vertebrae without defects on cortical surface, injecting lower viscous cement is suggested, because the injection force is lower and the cement will not leak out of the vertebrae. For the vertebrae with defects on cortical surface, injecting higher viscous cement, keeping the injection track away from the defects and stopping injection when cement reaches the defects are suggested to avoid leakage.

【Keyword】osteoporosis, compression fracture, vertebroplasty, bone cement, leakage, injection force

並列關鍵字

osteoporosis ； compression fracture ； vertebroplasty ； bone cement ； leakage ； injection force

參考文獻

2. Aebli N, Krebs J, Davis G, et al. Fat embolism and acute hypotension during vertebroplasty: an experimental study in sheep. Spine 2002;27:460-6.

3. Baroud G, Bohner M, Heini P, et al. Injection biomechanics of bone cements used in vertebroplasty. Biomed Mater Eng 2004;14:487-504.

4. Baroud G, Crookshank M, Bohner M. High-viscosity cement significantly enhances uniformity of cement filling in vertebroplasty: an experimental model and study on cement leakage. Spine 2006;31:2562-8.

5. Baroud G, Falk R, Crookshank M, et al. Experimental and theoretical investigation of directional permeability of human vertebral cancellous bone for cement infiltration. J Biomech 2004;37:189-96.

6. Baroud G, Vant C, Giannitsios D, et al. Effect of vertebral shell on injection pressure and intravertebral pressure in vertebroplasty. Spine 2005;30:68-74.