Bone filling mesh container repairs vertebral compression fractures: biomechanical changes

doi:10.3969/j.issn.2095-4344.2014.16.005

Abstract

Abstract:

BACKGROUND: Percutaneous vertebroplasty and percutaneous kyphoplasty have become the mainstream clinical methods for the treatment of vertebral compression fractures. However, both of them have several shortcomings such as bone cement leakage, spinal stenosis, nerve compression, pulmonary embolism and other issues.

OBJECTIVE: To verify the possibility of bone filling mesh container prepared by polyethylene terephthalate for the treatment of vertebral compression fractures.

METHODS: The biological properties of bone filling mesh container were examined according to GB/T16886. After sample aging test, the tensile properties of the aged samples and the fresh prepared samples were compared. The expansion and bone cement leakage were evaluated by injecting bone cement into the bone filling mesh container and measuring the pressure. The initial strength and stiffness of the fresh pig vertebrae with calcium phosphate cement injection or with bone filling mesh container filled with calcium phosphate cement were compared. The in vivo bone tissue growth was periodically observed after the lumbar vertebra of 4-month-old pigs was implanted with the bone filling mesh container that was then full of bone cement.

RESULTS AND CONCLUSION: The bone filling mesh container had good biocompatibility. Bone filling mesh containers after 2-year storage had the same tensile strength to the fresh bone filling mesh containers. At ambient conditions, after bone cement injection, bone filling mesh containers could be expanded at 5-10 atm and therefore could play the role of uplift; at 7-10 atm, bone cement could leak out from the bone filling mesh container and enter into the interspace between surrounding bone tissues, thus playing the role of adhesion and fixation. The vertebrae after bone cement injection with or without bone filling mesh containers had the same initial strength and stiffness and exhibited bigger initial strength and stiffness than untreated vertebrae. The in vivo animal experiments proved that bone filling mesh container had no obvious effect on the vertebrae. These findings indicate that the bone filling mesh container can be used to restore the height and strength of the fractured vertebrae. Moreover, it may eliminate bone cement leakage and therefore increase the surgery safety.

中国组织工程研究杂志出版内容重点：生物材料；骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性；组织工程

全文链接：

Key words: biocompatible materials, fractures, compression, biomechanics, polyethylene terephthalates

CLC Number:

R318

Liu Xun-wei, Kong Xiao-yan, Zhong Jian, Yang Wen-zhou, Wei Dai-xu, Peng Xiang-tao, Ye Yong, Du Yan-xia, Sun Gang. Bone filling mesh container repairs vertebral compression fractures: biomechanical changes[J]. Chinese Journal of Tissue Engineering Research, 2014, 18(16): 2487-2492.

Figures/Tables 5

2.1 骨填充网袋生物性能测试骨填充网袋内毒素含量<10 EU/套，无急性全身毒性反应；皮内刺激试验为无刺激性；无致敏反应；溶血率为0.1%；细胞毒性1级；无遗传毒性；无慢性毒性；骨植入实验符合规定要求。 2.2 骨填充网袋老化处理后强度 5个骨填充网袋老化处理后的断裂强度分别为351.92，327.01，342.43，329.24，338.83 N；5个新骨填充网袋的断裂强度分别为346.87，359.24，329.52，334.71，343.25 N。新旧骨填充网袋的断裂强度比较差异无显著性意义(P > 0.05)，证明骨填充网袋经老化处理后仍具有相同的力学强度，可长期保持强度性能稳定。 2.3 骨填充网袋包裹及渗漏测试在外界直接灌注骨水泥时，灌注压力在5 atm时骨水泥自骨填充网袋体部网眼溢出，骨填充网袋前缘及后缘无骨水泥外溢。在承压测试时，骨水泥灌注压力为10 atm(图1)。骨填充网袋松解并待骨水泥凝固后，取出网袋，可见通过骨填充网袋溢出的骨水泥与周围尼龙颗粒粘连牢固，容器边缘无骨水泥黏附，证实骨填充网袋对骨水泥外溢的可控性。X射线片显示溢出骨水泥呈线条状伸入至尼龙颗粒间隙(图1)。正常状况下恢复椎体高度需要的压力为9 atm[14]，骨填充网袋在10 atm灌注压力下骨水泥从孔隙内呈线样溢出，足以保证抬升伤椎高度和整复塌陷的终板，恢复椎体压缩前的排列，减少额外屈曲力矩，提高椎间盘均衡分散负荷的能力[18-19]。灌注压力保持或略超过10 atm，线样溢出的骨水泥逐渐伸入到骨小梁间隙，与骨小梁交叉联结形成微观绞锁，达到固定骨折椎体，增加稳定性和对抗压力、剪切力的能力[20-21]。 2.4 骨填充网袋力学性能测试由图2可见实验组椎体其生物力学测量接近骨水泥组，高于正常椎体组。 3组椎体的断裂强度和刚度测试结果见表1，实验组与骨水泥组椎体强度及刚度比较差异无显著性意义(P > 0.05)，实验组及骨水泥组椎体强度及刚度与正常椎体比较差异有显著性意义(P < 0.05)。"

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