geneX~骨水泥强化椎弓根螺钉体内的实验研究

The experiment study of geneX~ bone cement augmentation of pedicle screw in animal model

目的通过动物实验,评估新型带负电荷硫酸钙/β-磷酸三钙复合骨水泥(geneX^(?))用于强化体内椎弓根螺钉的生物力学性质变化及可行性。方法选取6只健康山羊腰椎L_(1-5)双侧共30个椎弓根随机分为3组:geneX^(?)组,聚甲基丙烯酸甲酯骨水泥(Polymethylmethacrylate,PMMA)组,空白对照组,每组10个椎弓根。术后3个月处死动物取材行Mirco-CT检查、组织学检查及生物力学实验。结果轴向拔出力实验:geneX^(?)组(803±155)N,PMMA组为(994±122)N,两者差异无统计学意义(P>0.05)。两组均明显高于对照组的(524±118)N,差异具有统计学意义(p<0.05)。组织学观察及Mirco-CT显示geneX^(?)组中螺钉周围骨水泥已经完全降解、吸收,骨小梁排列致密,成熟骨小梁附近可见大量新生骨组织,明显优于对照组及PMMA组。结论geneX^(?)骨水泥可有效强化椎弓根螺钉内固定的强度,其强化作用随时间推移而增强,对防止骨质疏松症患者内固定的拔出发生率有重要意义。

Objective To evaluate the long-term in vivo biomechanical effects of a newly developed biphasic calcium composite bone cement （geneX？）with a negative surface charge augmentation of pedicle screw. Methods Bilateral pedicles of lumbar vertebrae （L1~5） of 6 female sheep were fi xed with pedicle screws. One pedicle of each vertebral body was treated with a screw augmented with either geneX？（geneX？ group） or PMMA （PMMA group） and the contralateral pedicle was treated with a screw without any augmentation （control group）. Three months later, the sheep were killed and biomechanical tests, micro-CT analysis and histological observation were conducted on the isolated specimen vertebrae. Results Both the axial and vertical stabilities of the pedicle screws in geneX？ group were significantly enhanced compared with those in the control group （P〈0.05）. Micro-CT reconstruction and analysis showed that there were more bone trabeculae around the screws in geneX？ group compared with those in control group and PMMA group （P〈0.05）, and the bone trabeculae were signi fi cantly denser than those in control group （P〈0.05）. Histological observation showed that geneX？ was completely degraded and bone trabeculae around the screws in geneX？ group were more and denser than that in the control group. Bone trabeculae held the screws tightly without any interspaces between screw and bone, which formed strong bonding between bone and screw. Conclusions geneX？ cement augmentation of the pedicle screw increase the strength of screw-bone interface, geneX？ cement augmentation of the pedicle screw may be a viable clinical option for the augmentation of pedicle screw fixation.