课题背景：采用人工髓核能通过恢复髓核摘除后脊柱的稳定性和运动性紊乱，减少椎间盘手术长期并发症，是目前脊柱外科的研究方向之一。聚乙烯醇水凝胶人工髓核有良好的生物相容性和生物力学特性，有望应用于临床。本实验通过观察两种不同模量聚乙烯醇水凝胶人工髓核植入对椎间盘黏弹性的并影响建立相应的力学模型，为人工髓核的研制提供科学依据。

偏倚或不足：本实验为体外力学实验，而且剔除了腰椎上附着的肌肉，无法完全模拟正常人体腰椎活动时的静态和动态变化。由于受到尸体来源限制，本实验中腰椎标本数量不足，且均为青年脊柱标本，与老年性退变脊柱的实际情况存在一定差别。

同行评价：文章选题紧贴临床，采用实验的方法对正常和植入人工髓核的椎间盘分别进行了蠕变和松弛测试，比较分析了两种不同弹性模量的聚乙烯醇水凝胶人工髓核的粘弹性性能，证实了人工髓核置换的生物力学意义，并得到这两种水凝胶假体的粘弹性性能比正常椎间盘差，有待在假体研制过程中进一步对材料加以改进，为人工髓核研制提供了科学依据。

摘要
背景：人工髓核假体在理论上能够恢复脊柱的稳定性，减少椎间盘髓核摘除后的并发症，但目前对其黏弹性的研究却甚少。
目的：与正常腰椎间盘的黏弹性特性对比，评估两种不同弹性模量（3 MPa和1 MPa）水凝胶人工髓核对黏弹性变化的影响。
设计、时间及地点：自身对照实验，于2002-11/2003-03在上海大学生物力学研究所试验室完成。
材料：弹性模量为3 MPa和1 MPa的两种聚乙烯醇水凝胶人工髓核由美国Everblooming公司提供。7具新鲜青壮年腰椎脊柱标本L4~5脊柱功能单元
方法：在完整椎间盘和分别植入两组不同的水凝胶人工髓核。3种状态下，利用实验应力分析方法进行蠕变和松弛特性研究，并通过建立三参数力学模型计算蠕变和应力松弛方程。
主要观察指标：①完整椎间盘和分别植入两组不同的水凝胶人工髓核后脊柱功能单元的蠕变和应力松弛曲线。②三参数力学模型的数学公式。
结果：蠕变和应力松弛曲线变化和数学公式均表明弹性模量为3 MPa和1 MPa的人工髓核植入后的椎间盘均与正常椎间盘有相似的蠕变和应力松弛规律，其中3 MPa假体与正常椎间盘更为接近。
结论：水凝胶人工髓核具有良好的黏弹性特性，弹性模量为3 MPa的髓核假体更加适合。
关键词：人工髓核；人工器官；椎间盘；黏弹性；生物材料

吴靖平，陈统一，陈中伟 ，王以进.两种不同弹性模量聚乙烯醇水凝胶人工髓核的黏弹性性质评估[J].中国组织工程研究与临床康复，2008，12(19):3655-3658 [www.zglckf.com/zglckf/ejournal/upfiles/08-19/19k-3655(ps).pdf]

Viscoelasticity of the polyvinyl hydrogel prosthetic nucleus pulposus with two different kinds of elastic modulus

Abstract
BACKGROUND: Prosthetic nucleus can restore the stability of the spine and reduce the complication after intervertebral disc nucleus pulposus excision. But, researches on the viscoelasticity of the prosthesis are few.
OBJECTIVE: To compare with the viscoelastic characteristic of normal lumbar intervertebral disc, and to assess the effect of the two different kinds of hydrogel nucleus prostheses (elastic modulus are 3 MPa and 1 MPa) on the viscoelasticity.
DESIGN, TIME AND SETTING: The self-control observation experiment was conducted at the Laboratory of Institute of Biomechanics, Shanghai University from November 2002 to March 2003.
MATERIALS: Two kinds of polyvinyl alcohol hydrogel nucleus with elastic modulus of 3 MPa and 1 MPa were provided by Everblooming, USA. Seven L4-5 functional spinal units (FSU) from fresh young cadavers were used in the test.
METHODS: Under three different conditions (intact and the two different groups of prostheses after implantation), the characteristic of creep and stress relaxation were analyzed by measuring the deformation and the stress. A three-parameter mechanical model was established to calculate the formulae of creep and relaxation.
MAIN OUTCOME MEASURES: ①The creep and stress relaxation curve of the FSU in the intact group and the other two groups after different prostheses implantation. ②The formulae of three-parameters mechanical model.
RESULTS: The curves of creep and stress relaxation and the mathematic formulae indicated that after the two groups of prostheses were implanted separately, the trends of the replaced disc were similar to that of the intact discs, especially the 3 MPa prosthesis.
CONCLUSION: The two kinds of nucleus prostheses have a good viscoelastic characteristic. The prosthesis whose elastic modulus is 3 MPa is better.

Wu JP, Chen TY, Chen ZW , Wang YJ.Viscoelasticity of the polyvinyl hydrogel prosthetic nucleus pulposus with two different kinds of elastic modulus.Zhongguo Zuzhi Gongcheng Yanjiu yu Linchuang Kangfu 2008;12(19):3655-3658(China)
[www.zglckf.com/zglckf/ejournal/upfiles/08-19/19k-3655(ps).pdf]