Race Amos, Miller Mark A, Mann Kenneth A
Musculoskeletal Science Research Center, Institute for Human Performance (3217), SUNY Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210, USA.
J Biomech. 2008 Oct 20;41(14):3017-23. doi: 10.1016/j.jbiomech.2008.07.016. Epub 2008 Sep 5.
Pre-clinical screening of cemented implant systems could be improved by modeling the longer-term response of the implant/cement/bone construct to cyclic loading. We formulated bone cement with degraded fatigue fracture properties (Sub-cement) such that long-term fatigue could be simulated in short-term cadaver tests. Sub-cement was made by adding a chain-transfer agent to standard polymethylmethacrylate (PMMA) cement. This reduced the molecular weight of the inter-bead matrix without changing reaction-rate or handling characteristics. Static mechanical properties were approximately equivalent to normal cement. Over a physiologically reasonable range of stress-intensity factor, fatigue crack propagation rates for Sub-cement were higher by a factor of 25+/-19. When tested in a simplified 2 1/2-D physical model of a stem-cement-bone system, crack growth from the stem was accelerated by a factor of 100. Sub-cement accelerated both crack initiation and growth rate. Sub-cement is now being evaluated in full stem/cement/femur models.
通过对植入物/骨水泥/骨结构对循环载荷的长期响应进行建模，可以改进骨水泥固定植入系统的临床前筛查。我们配制了具有降低疲劳断裂性能的骨水泥（亚骨水泥），以便在短期尸体试验中模拟长期疲劳。亚骨水泥是通过向标准聚甲基丙烯酸甲酯（PMMA）骨水泥中添加链转移剂制成的。这降低了珠间基质的分子量，而不改变反应速率或操作特性。静态力学性能与普通骨水泥大致相当。在生理合理的应力强度因子范围内，亚骨水泥的疲劳裂纹扩展速率高出25±19倍。在一个简化的柄-骨水泥-骨系统二维半物理模型中进行测试时，柄部的裂纹扩展加速了100倍。亚骨水泥加速了裂纹的萌生和扩展速率。目前正在全柄/骨水泥/股骨模型中对亚骨水泥进行评估。
