骨水泥加固椎弓根螺钉的生物力学特性

Biomechanical properties of bone cement injectable canulated pedicle screw

背景:由于骨质原因及结构特点导致椎弓根螺钉经常出现把持力下降,从而发生松动、拔出,导致内固定失败,因此提高椎弓根螺钉的稳定性显得尤为重要。目的:检测可注射骨水泥空心椎弓根螺钉椎弓根螺钉生物力学稳定性,为优化骨水泥使用量提供参考。方法:选取7具新鲜成人尸体T11-L4椎体标本共40个椎体,随机分为可注射骨水泥空心椎弓根螺钉及DTPS TM椎弓根螺钉组,各20个,置钉后分别注入1,2,3,5 m L骨水泥,通过影像学观察骨水泥弥散分布情况,并测得最大轴向拔出力进行比较。结果与结论:骨水泥用量为1-3 m L时,可注射骨水泥空心椎弓根螺钉组螺钉平均最大轴向拔出力显著高于DTPS TM组(P<0.05)。骨水泥用量为5 m L时,2组平均最大轴向拔出力差异无显著性意义(P>0.05)。可注射骨水泥空心椎弓根螺钉组的直线回归方程为Y=25.269X+133.681(R2=0.837),DTPS TM椎弓根螺钉组的直线回归方程为Y=32.039X+99.251(R2=0.936)。骨水泥用量在1-5 m L时,2组螺钉最大轴向拔出力与骨水泥量高度正相关(|R|>0.8)。说明骨水泥强化椎弓根螺钉可显著提高螺钉稳定性,椎弓根螺钉最大轴向拔出力与骨水泥使用量呈高度正相关,可注射骨水泥空心椎弓根螺钉在达到满意的内固定强化效果同时,减少骨水泥使用量,降低了骨水泥泄漏风险,相比DTPS TM椎弓根螺钉更具有优势。

BACKGROUND： Bony and structural feature often cause pullout strength decrease of pedicle screw, which induces loosening and pullout, and finally results in fixation failure. Thus, it is very important to elevate the stability of pedicle screw. OBJECTIVE： To detect the biomechanical stability of bone cement injectable canulated pedicle screw, and to provide reference for bone cement dosage. METHODS： We selected T11-L4 samples of seven fresh adult corpses, containing 40 vertebral bodies. They were randomly divided into bone cement injectable canulated pedicle screw group and DTPS TM pedicle screw group（n=20）. After screw implantation, 1, 2, 3 and 5 m L bone cement was injected. The diffuse distribution of bone cement was observed by imaging. The maximum axial pullout strength was measured. RESULTS AND CONCLUSION： When the dose of bone cement was 1-3 m L, the average maximum axial pullout strength was significantly greater in the bone cement injectable canulated pedicle screw group than in the DTPS TM pedicle screw group（P〉 0.05）. When the bone cement dosage was 5 m L, no significant difference in the maximum axial pullout strength was detected between the two groups（P 〉0.05）. The regression equation was Y=25.269X＋133.681（R2=0.837） in the bone cement injectable canulated pedicle screw, and Y=32.039X＋99.251（R2=0.936） in the DTPS TM pedicle screw group. When the dosage of bone cement was 1-5 m L, the maximum axial pullout strength was highly positively correlated with bone cement dosage（｜R｜ 0.8）. These results suggested that bone cement augmentation pedicle screw could apparently elevate the stability of the screw. The maximum axial pullout strength of the pedicle screw was positively correlated with bone cement dosage. After reaching the satisfactory fixation effects, the bone cement injectable canulated pedicle screw can reduce bone cement dosage, diminish the risk of bone cement leakage, and have more advantages than DTPS TM pedicle screw.