【摘要】 目的初步探讨常用的椎弓根螺钉置入方法对骨质疏松椎体中螺钉稳定性的影响。方法从尸体中获取6节腰椎椎体经DEXA和QCT检测骨密度值,证实为骨质疏松后在计算机导航下按随机分组的方法向12个椎弓根中置入不同方向的椎弓根螺钉,使用MTS-858生物力学仪脊柱力学测试平台进行±250 N的循环负荷疲劳测试,记录负荷循环中的螺钉位移,计算系统的刚度系数并进行对比分析。结果M agerl法在负荷循环中的位移明显高于Krag法和尾向法(P<0.01);M agerl法的松动程度也明显大于Krag法和尾向法(P<0.01)。结论对于骨质疏松患者的腰椎后路椎弓根螺钉内固定手术,常用的螺钉平行上终板的技术不能提供最好的生物力学稳定性。更多还原

【Abstract】 Objective To study the effect of various directions on insertion of lumbar pedicle screws in osteoporotic lumbar vertebrae.Methods Six cadaveric lumbar vertebrae were harvested and evaluated with dual-energy x-ray absorptiometry(DEXA) and quantitative computed tomography(QCT) to assess bone mineral density.Matched,polyaxial pedicle screws were then randomly assigned by side and placed using the Magerl,Krag or caudad trajectory technique assisted by Iso-C 3D scan and 3D navigation system.Cyclic loading tests were performed with a maximum 250 N load at 3 Hz up to 30 000 cycles while recording load and displacement.Stiffness quotients were calculated for comparison.Results As shown in the cycle-displacement curve,the displacements of the pedicle screw inserted with Magerl trajectory were higher than those inserted with Krag or caudad trajectory(P<0.01).As shown in the cycle-stiffness curve,the stiffness was significantly higher for Krag and caudad method than for Magerl method(P<0.01).Conclusion In osteoporotic lumbar vertebrae,the placement of pedicle screws should not parallel superior endplate and polyaxial pedicle screws should be chosen.更多还原