不同角度置钉对椎弓根螺钉稳定性的影响

Effect of different angles of implanted screws on the stability of pedicle screw

背景:有研究表明经皮椎弓根螺钉置入的准确性及手术效果要优于开放手术,但既往研究中对置钉角度与螺钉稳定性的关系尚不清楚。目的:观察不同角度置钉对椎弓根螺钉稳定性的影响。方法:选取成年猪椎体标本30个,分别按照不同的冠状面及矢状面角度置钉,通过机器测试各标本螺钉的最大拔出力,并绘制载荷-位移曲线,进行统计分析。结果与结论:10°及15°冠状面及矢状面角度置钉的螺钉最大拔出力及最大能量明显优于0°角组(P<0.05)。当应力超出最大拔出力时,螺钉的拔出力呈现缓降趋势,冠状面及矢状面10°及15°夹角组曲线相似,斜率优于0°角组(P<0.05)。结果证实,置钉角度为经皮椎弓根螺钉稳定性提供有力帮助,螺钉开始松动后,把持力呈现稳步下降趋势。

BACKGROUND：Some studies have showed that the accuracy and surgery outcome of the percutaneous pedicle screw implantation was superior to open surgery, but the relationship between the angle of pedicle screws and screw stability is stil unclear in previous studies. OBJECTIVE：To investigate the effect of different angles of implanted screws on the stability of pedicle screw. METHODS：A total of 30 vertebral specimens of adult pigs were selected and screws were implanted respectively according to different coronal and sagittal angles. The maximum pul-out strength of screws from each specimen was tested by machine. Load-displacement curves were drew and statistical y analyzed. RESULTS AND CONCLUSION：The maximum pul-out strength and maximum energy of screw with 10° and 15° coronal and sagittal angles implantation were significantly better than those of 0° angle group （P〈0.05）. When the stress exceeded the maximum pul-out strength, the pul-out strength of screw decreased gradual y. The curves in coronal and sagittal 10° and 15° angle groups was similar, and the slope was better than 0° angle group （P〈0.05）. These results confirm that the angle of the implanted screw provides effective assistance to the stability of percutaneous pedicle screw. After the looseness of the screws, the pul out strength shows a steady downward trend.