【摘要】 目的:比较三种设计的颈椎椎弓根螺钉的最大拔出力,为临床选择颈椎椎弓根螺钉类型提供生物力学依据。方法:设计制作三种颈椎椎弓根螺钉,根据螺纹部分分为内径锥形螺钉(A型)、松质骨螺钉(B型)、皮质骨螺钉(C型),利用6具C3～C6节段的21节新鲜颈椎骨标本,置入三种类型的椎弓根螺钉,进行拔出试验,测定每种螺钉的最大拔出力,进行统计学分析比较。结果:三种螺钉平均拔出力存在差异,平均拔出力从大到小的顺序为:松质骨螺钉、内径锥形螺钉、皮质骨螺钉,前两者间无显著差异,但与皮质骨螺钉的平均拔出力存在显著差异。结论:内径锥形螺钉抗拔力高,同时螺钉根部强度好,抗弯曲、断裂性能好,是颈椎椎弓根固定的理想螺钉类型。更多还原

【Abstract】 Objective:To compare the axial pullout force of three types of screws for cervical pedicle fixation, and to provide biomechanical data for clinical selection of proper screw type. Methods: Three types of screws, with 3.5 mm in outside diamerter and 20 mm in length of their thread parts, were designed. They have different characteristics in their thread parts: type A screw is cylindrical-shape in outside-diameter with conical-shaped core diameter, that is, it has an increased core diameter at the thread-shaft junction, and has an minimum core diameter and deepest thread at the screw tip. Type B is cancellous screw, with smaller core diameter and deeper thread. Type C is cortical screw, with lager core diameter and shallower thread. The C₃ to C₆ vertebrae from six cadaveric specimens were fixed with screws inserted into the bilateral pedicle at a depth of 20 mm. Coaxial pullout force was recorded for each type of screw. The mean pullout data of three type screws were compared with a two- independent samples test. Results:The mean pullout force of type A, B, and C screws were 650, 670, and 585 N respectively. There were no significant difference in pullout force between type A and B, but type A and B screws were significantly stronger than type C screws （P<0.05）. Conclusion:Type A screw is recommended for clinical selection because of its greater pullout strength and its ability of being more resistant to screw bending failure or fracture than the cancellous screw of the same outside diameter.更多还原