不同量骨水泥强化新型空心椎弓根螺钉的体外生物力学研究

Influence of the volume of bone cement on the reinforcement of a novel canulated pedicle screw:a biomechanical study in vitro

目的探讨自行设计的可注射骨水泥椎弓根螺钉(bone cement injectable canulated pedicle screw,CICPS)在注入不同量骨水泥时的骨水泥弥散情况及生物力学稳定性。方法按临床置钉标准程序将CICPS、韩国DTPSTM椎弓根螺钉和普通椎弓根螺钉植入骨质疏松松质骨模型(骨密度0.16 g/cm3,n=7)中,分别加压注射不同体积骨水泥(1、2、3、5ml)增强2种空心螺钉,普通螺钉作为对照组。X线、CT观察骨水泥弥散形态;最大轴向拔出力实验分析骨水泥使用量与最大轴向拔出力之间的关系;比较3种螺钉生物力学稳定性的特点。结果 X线观察螺钉均未发生骨水泥向后泄漏。X线、CT三维重建显示骨水泥从CICPS 3个侧孔中流出,分布均匀;而骨水泥主要从韩国DTPSTM椎弓根螺钉的近端侧孔流出,远端侧孔较少。CICPS各组(1、2、3、5 ml)最大轴向拔出力分别为(140.3±15.9)、(197.1±9.8)、(215.4±10.7)、(237.0±23.6)N;DTPSTM各组(1、2、3、5 ml)最大轴向拔出力分别为(114.3±17.7)、(180.5±13.6)、(207.2±30.0)、(291.3±25.1)N。经骨水泥增强的空心椎弓根螺钉最大轴向拔出力显著高于普通螺钉[(28.5±4.0)N,P<0.05]。空心螺钉最大轴向拔出力随骨水泥使用量的增加而增大。骨水泥使用量为1、2、3 ml时,CICPS的生物力学稳定性显著高于DTPSTM(P<0.05)。骨水泥使用量为5 ml时,DTPSTM的生物力学稳定性高于CICPS(P<0.05)。结论在骨质疏松椎体模型中,骨水泥增强可显著增加CICPS的锚定作用;骨水泥使用量在1～3 ml的情况下,其稳定性优于同类产品。

Objective To evaluate the bone cement distribution and signed bone cement injectable canulated pedicle screw （CICPS）. Methods biomechanical stability of self-de- CICPS, DTPS？ and solid pedicle screws were implanted into osteoporotic bone models （density： 0.16 g/cm3, n = 7 ） according to the clinical standard procedure. Four different volumes of bone cement （ 1, 2, 3 and 5 ml） were used to reinforce CICPS and DTPS？, respectively, and the solid pedicle screws were used as control. X-ray and CT were applied to observe the bone cement distribution in different groups. Maximum axial pullout strength test was used to analyze the relationship between the bone cement volume and maximum axial pullout strength, and the biomechanical stabilities of CICPS, DTPS？ and solid pedicle screws were compared. Results X-ray showed that there was no bone cement rear leakage in all screws. Three-dimensional reconstruction of X-ray and CT showed bone cement well and widely distributed through the three side holes of the CICPS in bone models. Bone cement flowed out mainly through the proximal side hole of the DTPS？ but rarely through the distal side hole. The maximum axial pullout strength of each group was as follows ： solid pedicle screws ： （28.5± 4.0） N ; CICPS ： 1 ml （140.3±15.9） N, 2 ml （197.1 ±9.8） N, 3 ml （215.4±10.7） N and5 ml （237.0±23.6） N; and DTPS？ ： 1 ml （114.3±17.7） N, 2 ml （ 180.5 ±13.6） N, 3 ml （207.2±30.0） N and 5 ml （291.3±25.1 ） N. The maximum axial pullout strength of the CICPS and DTPS？ after reinforced by bone cement was significantly greater than that of the control group, and the strength increased along with the increase of bone cement volume. When the volume of bone cement was 1, 2 and 3 ml, the biomechanical stability of the CICPS was higher than that of the DTPS？ （P 〈 0.05 ）. When the volume of bone cement was 5 ml, the biomechanical stability of the DTPS？ was higher than that of the CICPS （P 〈 0. 05）. Conclusion It is effective to enhance the biomechanical stability of CICPS by bone cement reinforcement in osteoporotic bone model. When the volume of bone cement for clinical treatment was 1 -3 ml, the CICPS is proved safer and more stable than otherproducts.