复合型可注射磷酸钙骨水泥在胫骨平台塌陷骨折修复中的生物力学研究

摘要

目的 探讨一种复合聚乳酸-羟基乙酸共聚物的新型可注射磷酸钙骨水泥(CPC)结合双螺钉固定在胫骨平台SchatzkerⅡ型骨折模型修复中的生物力学性能,为临床微创治疗提供力学依据.方法 取10对老年尸体胫骨近端标本制备成胫骨平台SchatzkerⅡ型骨折模型后成对匹配随机分配到实验组和对照组中,分别采用CPC加压注入和自体松质骨充填植骨结合双螺钉横排固定的方法植骨固定胫骨平台骨折.将标本在材料测试机上进行轴向垂直压缩,记录载荷-位移数据,测量2组标本的最大失效载荷和抗压刚度.结果 新型CPC室温下具有良好的可注射性,在胫骨平台塌陷下方骨缺损区充填充分,且材料在骨缺损区周围松质骨中进一步渗透、扩散.实验组胫骨干骺端平均骨密度为(0.639 ±0.081)g·cm-2,对照组为(0.668±0.083)g·cm-2,2组间差异无统计学意义(P＞0.05).实验组最大失效载荷为(4 101-813)N,对照组最大失效载荷为(692±138)N,2组间比较差异有统计学意义(P＜0.05).实验组轴向抗压刚度为(1 363±362)N·mm-1,对照组轴向抗压刚度为(223±54)N·mm-1,2组间比较差异有统计学意义(P＜0.05).结论 在胫骨平台SchatzkerⅡ型骨折中采用新型复合CPC加压充填植骨结合双螺钉固定技术,能有效恢复胫骨平台的抗塌陷力学性能,是一种理想的植骨填充材料.%Objective To investigate the biomechanics of a novel injectable calcium phosphate cement( CPC) composited by polylactic-co-glycolic acid in repairing tibial plateau type Schatzker Ⅱ fracture combined with double-screw fixation, and provide the mechanical basis for the clinical minimally invasive treatment. Methods Ten matched pairs of proximal tibia specimens were taken from 10 elderly cadavers and then were prepared Schatzker Ⅱ tibial plateau fracture model. The matched 10 pairs specimens were randomly divided into experiment group which were fixed by using CPC by means of forcing injection combined with double-screw fixation and control group which were fixed by filling autologous cancellous bone combined with double-screw fixation. All specimens were loaded under axial compression on material testing machine and then recorded the load-offset data. The maximum load to failure and compressive stiffness of specimens in the two groups were measured. Results The novel CPC had a good injectable ability at room temperature and had the characteristic of filling the bone defect fully and permeating furtherly in the surrounding cancellous bone. The average bone mineral density of tibial metaphysis was (0.639 ±0.081 )g ocm-2 in the experiment group and(0.668 ±0.083)g·cm-2 in the control group,the differences between the two groups were not statistically significant (P ＞0.05). The maximum load to failure in the experiment group and control group was (4 101 ±813)N and (692 ± 138)N,respectively,and the differences between the two groups were statistical significance. The axial compressive stiffness of the experiment group was( 1 363 ±362)N·mm-1 and the control group was(223 ±54)N·mm-1 ;the differences between the two groups were statistical significance ( P ＜0.05). Conclusion The novel composite CPC can effectively restore the biomechanical properties of tibial plateau in repairing tibial plateau type Schatzker Ⅱ fracture by means of forcing injection combining with double-screw fixation. It is an ideal bone graft filler material in the clinical application.