一种新型经椎弓根螺钉动力内固定系统的设计和力学测试

摘要]目的设计一种新型经椎弓根螺钉动力内固定系统，并测试其对失稳腰椎的稳定性效果及对相邻节段的作用。方法 1采用6具人新鲜尸体腰椎标本，测试各个节段的活动度，为新型动力内固定系统的设计提供参数支持。2以钛合金棒、钛缆和钛合金碟片弹簧为主要结构，根据正常腰椎各节段的活动度，参照文献报道的相关测试结果，设定动态连接棒屈曲范围0~10°，旋转范围0~5°，并对其进行了相关力学测试。3制作腰椎失稳模型，测试新型动力内固定系统固定后失稳腰椎固定节段及相邻节段的运动范围（ROM）和中性区（NZ），并与坚强固定对比，同时测定其上邻节段软骨终板下压力，探讨其稳定性及对相邻节段的作用。结果 与完整脊柱相比，新型动力内固定系统固定后屈伸和侧屈方向的ROM和NZ较完整脊柱减小（P<0.05），但旋转方向的ROM和NZ与完整脊柱无显著性差异（P>0.05）。与坚强固定组相比，新型动力内固定组三个主方向的ROM和NZ均显著增加，差异有显著性意义（P<0.01）。疲劳试验后的结果表明，固定节段在三个主方向上的ROM和NZ均较疲劳前显著增加（P <0.05），但与失稳脊柱相比，差异仍具有显著性意义，与完整脊柱相比，动力内固定屈伸方向的ROM和NZ仍较小，两组相比差异显著（P <0.05），侧屈与旋转方向的ROM和NZ与完整脊柱无显著性差异（P >0.05）。结论 新型动力内固定系统可控性强、可靠性好、能够提供足够的活动度。新型动力内固定系统能对失稳腰椎提供各方向上的稳定性，尤其对前屈后伸的稳定效果最好，疲劳试验后也能提供足够的稳定性。相邻节段的ROM和上邻节段终板下压力与固定方式无显著相关。

Prospective design and stability evaluation of a new dynamic stabilization system for lumbar spine

Abstract] Objective To design and determine the magnitude of stabilization and the effect on the adjacent segment of a new dynamic stabilization system. Methods 1. Six lumbar cadaver spines were tested for ROM of each segment. 2. New dynamic system consists of titanium-alloy rods, cables and springs. The system was designed for 10º motion in flextion-extension and lateral bending, 5º for rotation. 3. Six lumbar cadaver spines were used for testing. A controlled defect was created in the L3/4 segment. The ROM for the bridged and the adjacent segments were determined. The end plate stress of both stabilization methods on the superior adjacent segments were measured at the same time. Results Both the dynamic system and rigid fixator reduced the ROM and NZ below the magnitude of the intact spine for lateral bending, flexion and extension. In axial rotation the ROM for the dynamic system was in the range of the intact spine, while the rigid fixator showed a decreased ROM. For adjacent segments, no significant differences of ROM were found among intact, dynamic and rigid fixation systems. Conclusion In the lumbar cadaver spines after defect was created in the L3-4 segment, restoration of stability with the new dynamic system is possible in flexion, extension, right and left lateral bending, and in axial rotation. The ROM and NZ of the adjacent segments were not affected by the instrumentation of the bridged segment.