聚甲基丙烯酸甲酯与磷酸钙和庆大霉素复合型骨水泥的生物力学研究

Biomechanical Study of Bone Cement of Polymethyl Methacrylate with Calcium Phosphate and Gentamicin

目的研究不同比例聚甲基丙烯酸甲酯(polymethyl methacrylate,PMMA)、β-磷酸三钙(β-tricalcium phosphate,β-TCP)和一定比例的庆大霉素(gentamicin,GM)组成的复合骨水泥生物力学性能,筛选出理想的配比比例。方法将β-TCP粉末按15%、25%、35%的总质量比分别与对应的PMMA粉末混合,再将GM粉末按4%的总质量比分别加入到上述三组中制成复合骨水泥粉末,按厂家推荐的2︰1固液比混合后制成样本,测量各组的注射时间与干燥后的抗压强度,再将各组的样本按1︰5的比例浸泡于磷酸盐缓冲生理盐水中,分别于1d、3d、5d、1周、2周、3周、4周取出对应的各组样本,并测量各组浸泡液的pH值、GM释放量、样本干燥后的降解率和抗压强度。结果复合骨水泥的抗压强度浸泡后缓慢降低,复合骨水泥的体外降解率和GM释放量,随着浸泡时间的增加而增加,且随着β-TCP含量的增加而增加,复合骨水泥浸泡液的pH值,随着浸泡时间的增加而减小,且随着β-TCP含量的增加而减小。结论复合骨水泥中β-TCP含量在35%时可最大程度将两组骨水泥的性能结合在一起,有较理想的抗压强度、降解率、GM释放量,是较理想的混合比例。

Objective To study the biomechanical properties of bone cement which composed of different proportions of polymethyl methacrylate(PMMA),β-Tricalcium phosphate(β-TCP)and gentamicin Gentamicin(GM)and to screen out the proportion of ideal composite bone cement.Methods Theβ-TCP powder was mixed with the corresponding PMMA powder at a total mass ratio of 15%,25%,and 35%,and then the GM powder was separately added to the above three groups at a total mass ratio of 4%to prepare a composite bone cement powder and the bone cement was prepared with 2︰1 solid-liquid ratio as suggested by the manufacture.The injection time of each group of composite bone cement and the strength of the bone cement sample after drying were measured.The samples of each group were immersed in phosphate buffered saline at a ratio of 1︰5,and the corresponding numbered samples were taken at 1 day,3 days,5 days,1 week,2 weeks,3 weeks,and 4 weeks.The Ph value of the soaking solution,the amount of GM released,and the degradation rate and strength of the sample after drying were measured.Results The strength of the composite bone cement slowly decreases after soaking.The in vitro degradation rate and GM release of composite bone cement increased with the increase of soaking time and increased with the increase ofβ-TCP content.The pH value of the composite bone cement soaking solution decreased with the increase of the soaking time and decreased with the increase of theβ-TCP content.Conclusion Theβ-TCP content of the composite bone cement has an ideal mixing ratio of 35%.The performance of the two groups of bone cement can be combined to the maximum extent,and the desired strength,degradation rate,and GM release amount can be obtained.