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首页> 外文期刊>Acta biomaterialia >Mechanisms underlying the limited injectability of hydraulic calcium phosphate paste. Part II: particle separation study.
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Mechanisms underlying the limited injectability of hydraulic calcium phosphate paste. Part II: particle separation study.

机译：液压磷酸钙浆料有限可注射性的机制。 第二部分：颗粒分离研究。

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Calcium phosphate cements (CPCs) are of great interest for bone augmentation procedures. In these a hydraulic calcium phosphate paste is injected through a small bore needle into the bone. The injectability of these pastes is relatively poor, resulting into partial injection only. In earlier studies we have shown that phase separation brings the injection process to a halt. Phase separation is characterized by a faster flow of the liquid than of the solid during paste extrusion. So far it is unclear whether or not particle separation contributes to the poor injectability of such hydraulic pastes. It is hypothesized that fine particles behave like a liquid and thus separate under the injection pressure, leaving larger particles behind. A factorial experimental design was used to examine this hypothesis. The particle size distribution (PSD) of the extrudate was measured over the course of each injection experiment using laser diffraction. The solid content of the paste was further inspected using scanning electron microscopy. A total of 48 experiments covering four factors at two levels each were performed. One factor was the ultrasound exposure duration, to ensure the dispersion quality of the particles during the PSD measurements. Another factor was the location of the samples over the course of the injection, so as to compare the extrudate with the PSDs remaining in the syringe. The liquid:powder ratio (LPR) in the injected paste was another factor investigated. Specifically, two different pastes with 40% and 50% LPR were examined. The dispersal medium was a fourth factor investigated, to ensure adequate dispersion of the particles during the PSD measurements. Analysis of variance showed that sample location did not significantly affect PSD. No apparent PSD change for the extruded paste and the paste remaining in the syringe could be detected by scanning electron microscopy. In conclusion, the present study did not show any evidence suggesting that particle separation occurred over the course of injection and thus that phase separation remains the main phenomenon leading to the poor injectability of CPCs.
机译：磷酸钙水泥（CPC）对骨增强程序具有很大的兴趣。在这些中，将液压钙糊剂通过小孔针注入骨中。这些浆料的可注射性相对较差，导致仅部分注射。在早期的研究中，我们已经表明，相分离使注射过程停止。相分离的特征在于液体在糊状挤出期间的固体更快地流动。到目前为止，目前尚不清楚颗粒分离是否有助于这种液压浆料的可注射性差。假设细颗粒表现得像液体，从而在注射压力下分离，留下较大的颗粒。阶乘实验设计用于检查这一假设。使用激光衍射在每个注射实验的过程中测量挤出物的粒度分布（PSD）。使用扫描电子显微镜进一步检查浆料的固体含量。共有48个实验，每个实验占两个层次的四个因素。一个因素是超声曝光持续时间，以确保在PSD测量期间颗粒的分散质量。另一个因素是样品在注射过程中的位置，从而将挤出物与残留在注射器中的PSD进行比较。液体：注射浆料中的粉末比（LPR）是另一种研究的另一个因素。具体地，检查了两种不同的糊状物，含有40％和50％LPR。分散培养基是研究的第四因素，以确保在PSD测量期间颗粒充分分散。方差分析表明，样品位置没有显着影响PSD。没有明显的PSD改变挤出的糊状物，并且可以通过扫描电子显微镜检测留在注射器中的糊剂。总之，本研究没有显示出暗示在注射过程中发生颗粒分离的任何证据，因此相分离仍然是导致CPC可注射差的主要现象。

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