钽涂层椎弓根螺钉的研制与初步动物实验研究

Development and preliminary animal experiment of tantalum coated pedicle screw

目的设计研制一种新型涂层的椎弓根螺钉,并通过涂层检测验证所制备涂层情况,通过动物实验验证其较传统椎弓根螺钉在增强螺钉与骨组织结合强度方面的优势。方法以10 kg体重雄性约克夏猪为实验动物,经CT扫描及三维重建测量腰1-腰5椎体椎弓根高度、宽度及进钉深度,并确定进钉点及进钉角度,以测量所得数据为标准,设计生产椎弓根螺钉。运用气相沉淀法(CVD chemical vapor deposition)进行螺钉表面钽(Ta tantalum)涂层处理,并进行电镜扫描、X射线衍射(XRD x-ray diffraction)检测及涂层结合强度检测。4只10 kg雄性约克夏猪进行动物实验,在全麻下行腰椎1-3椎体后路椎弓根螺钉植入术,左侧为实验螺钉组,右侧为对照螺钉组。3个月后进行动物处死,取手术节段腰椎标本进行螺钉最大轴向拔出力测试并进行统计学分析。结果根据动物CT扫描及三维重建测量所得椎弓根数据,设计的螺钉为直径4 mm,长度为20 mm;涂层处理后XRD检测钽涂层含量99.24%,电镜扫面1000倍下涂层表面呈鳞状,涂层结合强度为45.3 MPa。植入动物体内3个月后,钽涂层椎弓根螺钉组最大轴向拔出力为(616.62±17.72)N,对照组为(556.85±25.72)N,差异存在统计学意义(P<0.001)。结论利用气相沉淀法进行螺钉表面钽涂层处理方便可靠,所得涂层钽含量高、表面均匀但有具有微隙,与螺钉基质结合力强。钽涂层椎弓根螺钉植入动物体内组织相容性良好,与骨组织间结合强度较无涂层螺钉明显增强。

Objective To design and develop a type of pedicle screws with new geometry and coating,and verify its superiority in gripping force compared with uncoated pedicle screws by animal experiment. Methods 10 kg male Yorkshire pigs were chosen as experimental animals. CT scanning and three-dimensional reconstruction were used to measure the pedicle size of first to fifth lumbar. The data obtained was a standard of design and production of pedicle screws. Coat the pedicle screws with tantalum through chemical vapor deposition,and took SEM,XRD and adhesion strength testing. Four 10 kg male Yorkshire pigs for experiment,the surgery was lumbar vertebrae 1-3 pedicle screw implantation by posterior approach,left side for the experiment screw group and the other for the comparison screw group. After three months,put the pigs to death,tested the maximum axial pullout force and took statistical analysis. Results According to the measured data of CT scanning and three-dimensional reconstruction,the diameter ofscrew was 4 mm and the length was 15 mm. The XRD test showed the coating contented 99.24% tantalum,the electron microscope sweep showed the surface as scaly under 1000 times magnification,and adhesion strength testing result was 45.3 MPa. Three months after surgery,took biomechanical test and statistical analysis. The results showed the experiment group was bet-ter than comparison group in maximum axial pullout force（P〈0.001）. Conclusion It is convenient and reliable to coat pedicle screw with tantalum through chemical vapor deposition,the coating is smooth but by the way contains micro-gaps,and its adherence to screw is tight enough. The histocompatibility of new coating screw is excellent,and it can significantly enhance the bonding strength between bone and screw compared with non-coating screw.