新型多孔聚甲基丙烯酸甲酯骨水泥的制备及性能分析

Preparation and characterization of novel porous polymethyl methacrylate bone cements

背景:多孔磷酸三钙/聚甲基丙烯酸甲酯(polymethyl methacrylate,PMMA)骨水泥可改善传统PMMA骨水泥骨传导性差的不足,但加入的大量致孔剂显著降低了复合骨水泥的力学性能。目的:为改善多孔磷酸三钙/PMMA骨水泥的力学性能,制备含不同比例纳米磷酸三钙、甲基丙烯酸羟乙酯的复合PMMA骨水泥,观察其力学性能、凝固性能、成孔性能及生物安全性。方法:向PMMA骨水泥固相中加入不同比例的纳米磷酸三钙(质量分数40%,50%,60%),液相中加入不同比例的甲基丙烯酸羟乙酯(质量分数0%,5%,10%,15%,20%),混合固相与液相,制备不同组分的复合骨水泥,检测各组分骨水泥的抗压强度、抗弯强度、凝固最高温度及凝固时间,筛选优选比例组分骨水泥。将优选组分骨水泥浸泡在模拟人细胞外液中12周,扫描电镜观察成孔性能。采用优选组分骨水泥浸提液培养成骨前体细胞,24 h后利用CCK-8法检测吸光度,计算细胞活力。结果与结论:(1)在固相中加入40%,50%的磷酸三钙,可增强复合骨水泥的抗压强度,但当其比例达到60%时,复合骨水泥的抗压强度明显下降;磷酸三钙可明显降低复合骨水泥的抗弯性能,呈线性关系;在液相中加入甲基丙烯酸羟乙酯,可加强复合骨水泥的抗压、抗弯强度,但当浓度超过15%时,复合骨水泥的力学性能不再增强;(2)复合骨水泥的凝固最高温度约为80℃,与磷酸三钙、甲基丙烯酸羟乙酯比例无关;复合骨水泥的凝固时间随磷酸三钙比例的增加而缩短,随甲基丙烯酸羟乙酯比例的增加而延长;(3)优选组分骨水泥比例,纳米磷酸三钙为50%,甲基丙烯酸羟乙酯为0%,5%,10%,此3种复合骨水泥在模拟人细胞外液中浸泡12周后,表面可形成孔径约为100μm的多孔结构;(4)在3种优选复合骨水泥浸提液中,成骨前体细胞活力均大于75%,无细胞毒性;(5)综合以上结果发现,在加入PMMA固相中加入50%磷酸三钙、液相中加入10%甲基丙烯酸羟乙酯为最优复合骨水泥配方。

BACKGROUND:Porous tricalcium phosphate/polymethyl methacrylate bone cement can overcome the poor osteoconduction of traditional polymethyl methacrylate bone cement.But the addition of porogens may cause a significant reduction in the mechanical properties of composite bone cements.OBJECTIVE:To improve the mechanical properties of porous tricalcium phosphate/polymethyl methacrylate at different proportions,and to observe the mechanical properties,agglomeration,porosity and biosafety of composite bone cements.METHODS:Different groups of composite bone cements were prepared by adding different contents of tricalcium phosphate(40%,50%,60%)in solid phase and hydroxyethyl methylacrylate(0%,5%,10%,15%,20%)in liquid phase.The compressive strength,bending strength,maximum setting temperature,and setting time were measured,and screened the optimal ratio preliminarily.Then the pore formation properties of the optimal specimens were observed by scanning electron microscopy at 12 weeks after soaking in simulated body fluid.The osteogenic precursor cells were co-cultured with the preferred composite bone cement extract for 24 hours.The absorbance was then measured by cell counting kit-8 assay,and the cell viability was calculated.RESULTS AND CONCLUSION:The compressive strength of composite bone cement was increased when adding 40%and 50%of tricalcium phosphate in solid phase,but decreased when tricalcium phosphate concentration reached 60%.The bending strength was significantly decreased after adding tricalcium phosphate,showing a linear relationship.Addition of hydroxyethyl methylacrylate in liquid phase could strengthen the compressive strength and bending strength of composite bone cements,but no longer enhanced the mechanical properties when the concentration exceeded 15%.The maximum setting temperature of the composite bone cement was about 80 oC,regardless of the contents of tricalcium phosphate and hydroxyethyl methylacrylate.The setting time prolonged with the increasing of tricalcium phosphate and shortened with the increasing of hydroxyethyl methylacrylate.The formulas containing 50%tricalcium phosphate in the solid phase and 0%,5%and 10%hydroxyethyl methylacrylate,respectively in liquid phase were chosen as preferable groups.After immersing in the simulated body fluid for 12 weeks,there was porous structure whose pore size was approximately 100μm formed on the surface of composite bone cement.The cell viabilities of the preferable composite bone cement extract were all more than 75%,showing there was no cytotoxicity.In conclusion,the addition of 50%tricalcium phosphate in solid phase and 10%hydroxyethyl methylacrylate A in liquid phase into polymethyl methacrylate from the optimal composite bone cement formulation.