Viscoelastic behaviour of acrylic bone cements.
Viscoelastic behaviour of acrylic bone cements.
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丙烯酸骨水泥的粘弹性行为。
DOI：
10.1016/s0142-9612(97)00115-4
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发表时间：
1998
期刊：
影响因子：
14
通讯作者：
Litsky,AS
中科院分区：
文献类型：
--
作者：
Yetkinler,DN;Litsky,AS
骨-骨水泥界面处的局部接触应力被认为在部件松动的开始中起重要作用。低模量骨水泥可以降低这些局部接触应力。这种骨水泥的粘弹性引起了植入物系统长期下沉的问题。在这项研究中，使用应力松弛试验将低模量骨水泥的粘弹性与标准聚甲基丙烯酸甲酯（PMMA）骨水泥进行了比较。在37′C的水环境中，通过对骨水泥样本施加1%、2.5%和5%的应变并监测递减载荷100 h，进行无约束应力松弛试验。分析了在第一个小时内发生的初始快速应力松弛和在15和100 h之间发生的稳态应力松弛。PBMMA样本中出现快速应力减小，表明在全髋关节置换术应用中，PBMMA骨水泥将快速转移应力并将其分布在骨内膜骨表面的更大区域。稳态应力松弛实验表明，PMMA和PBMMA试样在2.5%和5%应力松弛值时差异显著（P<0.05），而在1%应力值时差异不显著。长度测量表明，粘弹性PBMMA标本表现出很小的恢复后，100小时的施加应变，而弹性PMMA标本表现出实质性的恢复。这似乎表明与PMMA样本相比，无限制PBMMA样本的下沉率相对较大。在体内，骨水泥外侧被骨内膜骨包围，内侧被植入物包围。因此，有必要进行约束蠕变试验，以获得评估体内沉陷所需的数据。
Local contact stresses at the bone–cement interface are thought to play an important role in the initiation of component loosening. A reduced-modulus bone cement can lower these local contact stresses. The viscoelastic properties of such a cement raised the question of long term subsidence of the implant system. In this study, the viscoelastic properties of a reduced-modulus bone cement were compared with standard polymethylmethacrylate, PMMA, bone cement using stress relaxation tests. Unconstrained stress relaxation tests were performed at 37′C in an aqueous environment by applying 1%, 2.5%, and 5% strains on bone cement specimens and monitoring the diminishing load for 100 h. The initial rapid stress relaxation occurring over the first hour and the steady state stress relaxation occurring between 15 and 100 h were analyzed. A fast stress diminution occurred in PBMMA specimens indicating that, in a total hip arthroplasty application, PBMMA bone cement would transfer the stress quickly and distribute it over a larger area of endosteal bone surface. Steady state stress relaxation experiments showed a significant difference in 2.5% and 5% stress relaxation values (P<0.05) between PMMA and PBMMA specimens, but not at the 1% stress values. Length measurements indicated that the viscoelastic PBMMA specimens demonstrated little recovery after 100 h of imposed strain whereas the elastic PMMA specimens showed substantial recovery. This seems to indicate relatively larger subsidence rates in unconstrained PBMMA specimens compared to PMMA specimens. In vivo, the cement is surrounded by endosteal bone at the outer side and by an implant on the inner side. Therefore, constrained creep tests are necessary to obtain the data required for an assessment of in vivo subsidence.