一种新型记忆合金椎体撑开器的设计

The design of new-type memory alloy vertebral sping

目的设计一种新型记忆合金椎体撑开器，测试其弹性系数和金属结构疲劳性能，探索该设计的合理性和可行性。方法采用记忆合金板材，设计并加工厚度分别为0．25mm和0．30mm、宽度为12mm椎体撑开器，在材料实验机上进行弹性系数和金属结构疲劳性能测试。制作猪椎体标本压缩骨折模型，记录椎体前缘高度的变化、椎体的压力-形变曲线，以及使用记忆合金椎体撑开器前后椎体前缘高度的变化、经椎弓根注入骨水泥后椎体的压力-形变曲线。结果该型撑开器最大撑开力量高达70N左右，椎体撑开器的撑开高度和撑开力呈线性关系，卷曲次数与最大高度、撑开力之间亦呈线性关系。使用双叶“S”形记忆合金椎体撑开器后，椎体前缘高度、压缩椎体内空间和其耐压强度，都明显增加，具有统计学意义（P〈0．05）。结论双叶“S”形设计的记忆合金椎体撑开器，能提供足够大撑开力，可以在猪压缩骨折椎体内部创造一定空间，增加椎体前缘高度，椎体内填塞骨水泥后可以明显增强椎体耐压强度。

Objective To design＇a new-type memory alloy vertebral sping,testing elasticity coefficients and metal fatigue characteristics, exploring sping rationality and feasibility. Methods Designed and produced double ＇ s＇ shaped vertebral springs using shape memory alloy with respective heights of 0.25 mm and 0.30 mm, width 12 mm,testing spring elasticity coefficients and metal fatigue characteristics by material testing system（MTS）. Induced compression fractures in our swine spine models, and recorded anterior vertebral height changes and compression-deformation curve. Recorded anterior vertebral height changes before and after implanting vertebral spring and compression-deformation curve after injecting polymethylmethaerylate（PMMA） into compressive vertebrae. Results The new type of vertebral spring design provides a force of as high as 70 N. Forming a linear distraction height and distraction strength relationship ,the same linear relationship was also observed in regards to curve characteristics versus vertebral height and distraction strength. Vertebral anterior height varied significantly before and after distraction （ P 〈 0.05 ） , compressive vertebral inner space and compression resistance also varied significantly before and after distraetion（P 〈 0.05 ）. Conclusion Memory alloy double ＇ s＇ shaped vertebral spring is a reasonable design,it can provide enough distraction strength, produce vertebral inner space, increase anterior vertebral height as well as provide access for PMMA injection into our swine spine models.