新型可膨胀聚甲基丙烯酸甲酯骨水泥理化性质及生物相容性分析

Physicochemical and biocompatible study on novel expandable bone cement

目的评价一种新型可膨胀聚甲基丙烯酸甲酯(poly methyl methacrylate,PMMA)骨水泥的理化性质、生物力学特征及其生物相容性。方法以聚丙烯酸(ploy acrylic acid,PAA)改性PMMA研发一种新型具有膨胀特性的骨水泥(expandable bone cement,EBC)以改善PMMA骨水泥(PMMA bone cement,PBC)聚合体积收缩现象。通过测定EBC的膨胀倍率、聚合温度、面团时间、凝固时间评价EBC的理化性质;压缩实验测定EBC的压缩强度及弹性模量等生物力学的特征。用含有EBC及PBC浸提液的培养基培养成骨细胞,CCK-8测定EBC的细胞毒性作用,评价EBC的生物相容性。结果 EBC吸模拟体液24 h平衡后体积膨胀约8.80%。同时EBC的聚合温度为(51.73±3.64)℃,显著低于PBC,差异具有统计学意义(P<0.05),且适宜注射的面团时间为(5.06±0.46)min,较PBC显著延长,差异具有统计学意义(P<0.05),两者的凝固时间差异无统计学意义(P>0.05)。EBC的压缩强度为(36.15±11.19)MPa,明显高于正常椎体松质骨;但弹性模量为(849.26±324.47)MPa,显著低于PBC(2 148.89±176.13)MPa,差异具有统计学意义(P<0.05)。细胞毒性实验显示EBC与PBC相对吸光度分别为1.30±0.11、1.31±0.08,两者之间差异无统计学意义(P>0.05)。可见与PBC相似,EBC具有较好的生物相容性。结论 EBC具有良好的膨胀性能,可有效克服PBC聚合体积收缩的缺陷。EBC聚合温度较低、面团时间较长,弹性模量较低可降低成形术后邻近椎体再骨折风险,且生物相容性较好,有望应用于椎体成形术及关节置换术。

Objective To evaluate the physicochemical, biomechanical properties and biocompatibility of a novel expandable bone cement. Methods A novel poly methyl methacrylate （PMMA） based expandable bone cement （EBC） modified with ploy acrylic acid （PAA） was developed to improve the volumetric shrinkage of PMMA bone cement （PBC） because of polymerization. Expansive rate, polymerization temperature, dough time and setting time were investigated versus PBC to evaluate physicochemical properties of EBC. Compressive test was carried out to determine the mechanical property of EBC. Biocompatibility was accessed by evaluating the cytotoxicity of EBC and PBC to the osteoblast which was cultured with medium containing EBC and PBC extraction. Results PAA modified EBC achieved approximate 8.80% volumetric expansion after soaked in simulated body fluid （SBF） for 24 h. The polymerization temperature of EBC was （51.73 ±3.64） ℃ , which was significantly lower than PBC （ P 〈 0. 05 ）. The dough time of EBC was （ 5.06 ± 0.46） min, and it was longer than PBC （ P 〈 0.05 ） , there was no difference of setting time between EBC and PBC （ P 〉 0. 05 ）. The compressive strength of EBC was （36.15 ±11.19） Mpa, which was higher than the normal cancellous bone （4.77 ± 0. 72 ） MPa. But the elastic modulus of EBC was significant lower than PBC （849.26 ± 324. 47 ） MPa vs. （ 2 148.89 ± 176. 13 ） MPa （ P 〈 0.05 ）. The relative abserbance of CCK-8 test of PBC and EBC were 1.30 ±0.11 and 1.31 ±0.08 respectively, indicated that there was no difference of biocompatibility between EBC and PBC （ P 〉 0. 05 ）. Conclusion The novel EBC can overcome the volumetric shrinkage of PBC effectively by volumetric expansion. EBC with lower polymerization temperature and longer dough time than PBC. In addition, the lower elastic modulus of EBC enable it to reduce the risk of adjacent vertebral failure after vertebroplasty, and the good biocompatibility make it an ideal bone substitute material in future vertebroplasty and joint replacement.