Stephens G C, Devito D P, McNamara M J, Spengler D M
Department of Orthopaedics and Rehabilitation, Vanderbilt University Medical Center, Nashville, Tennessee 37232-2550.
J Spinal Disord. 1993 Jun;6(3):252-5. doi: 10.1097/00002517-199306030-00012.
This study examines changes in stiffness in a three-level spinal construct utilizing transpedicular Cotrel-Dubousset instrumentation. In addition, we evaluated the effect of adding offset laminar hooks at the same level as the superior transpedicular fixation. Porcine lumbar spines (L-1 to L-5) were tested as: (a) intact spine, (b) intact spine with instrumentation, and (c) instrumented spine after L-3 corpectomy. Instrumented constructs were tested with and without laminar hooks placed at the level of superior transpedicular fixation. Constructs were tested in modes of axial compression and torsion in a MTS materials testing machine. The fully instrumented intact spines demonstrated a 28.0% stiffness increase over the intact spines in torsion (p < 0.005) and a 23.1% increase in the mode of axial compression (p < 0.0002). There was no statistically significant difference in axial or torsional stiffness in the instrumented intact spine constructs when hooks were added. In the corpectomy model, addition of the laminar hooks increased stiffness in axial compression an average of 26.9% (p < 0.002) and in torsion an average of 28.1% (p < 0.0005). This increase in stiffness may aid in preventing the postoperative progression of kyphosis noted in studies utilizing similar constructs in clinical application for the treatment of lumbar burst fractures.
本研究考察了采用椎弓根Cotrel-Dubousset器械的三级脊柱结构的刚度变化。此外，我们评估了在与上位椎弓根固定同一水平添加偏置椎板钩的效果。对猪腰椎（L1至L5）进行如下测试：（a）完整脊柱，（b）带器械的完整脊柱，以及（c）L3椎体切除术后的器械固定脊柱。对器械固定结构在有和没有在上位椎弓根固定水平放置椎板钩的情况下进行测试。在MTS材料试验机上对结构进行轴向压缩和扭转模式测试。完全器械固定的完整脊柱在扭转时刚度比完整脊柱增加了28.0%（p < 0.005），在轴向压缩模式下增加了23.1%（p < 0.0002）。添加钩后，器械固定的完整脊柱结构在轴向或扭转刚度方面无统计学显著差异。在椎体切除模型中，添加椎板钩使轴向压缩刚度平均增加26.9%（p < 0.002），扭转刚度平均增加28.1%（p < 0.0005）。这种刚度增加可能有助于防止在临床应用中使用类似结构治疗腰椎爆裂骨折的研究中所指出的术后后凸畸形进展。
