Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013, USA.
Neurosurgery. 2010 Mar;66(3 Suppl Operative):178-82; discussion 182. doi: 10.1227/01.NEU.0000350869.35779.05.
To compare the biomechanics of costotransverse process screw fixation with those of pedicle screw fixation in a cadaveric model of the upper thoracic spine.
Ten human thoracic spines were instrumented across the T3-T4 segment with costotransverse and pedicle screws. Nonconstraining pure moments (maximum, 6.0 Nm) were applied to induce flexion, extension, lateral bending, and axial rotation. The range of motion, lax zone, and stiff zone were determined in each specimen in the normal state, after 3-column destabilization, and after instrumentation. After flexibility testing was completed, axial screw pull-out strength was assessed.
In all directions of loading, both fixation techniques significantly decreased lax zone and range of motion at T3-T4 compared with the destabilized state (P < .001). During all loading modes except lateral bending, pedicle screw fixation allowed significantly less range of motion than costotransverse screw fixation. Pedicle screws provided 62% greater resistance to axial pull-out than costotransverse screws.
The costotransverse screw technique seems to provide only moderately stiff fixation of the destabilized thoracic spine. Pedicle screw fixation seems to have more favorable biomechanical properties. These data suggest that the costotransverse process construct is better used as a salvage procedure rather than as a primary fixation strategy.
比较经肋横突关节螺钉固定与经椎弓根螺钉固定在上胸段脊柱尸体模型中的生物力学。
10 个人胸椎标本在 T3-T4 节段行肋横突和椎弓根螺钉固定。在无约束的纯力矩（最大 6.0 Nm）下，使标本产生屈伸、侧屈和轴向旋转运动。在正常状态、三柱失稳后和固定后，每个标本的活动范围、松弛区和僵硬区均被确定。柔韧性测试完成后，评估轴向螺钉拔出强度。
在所有加载方向上，与失稳状态相比，两种固定技术均显著减少 T3-T4 的松弛区和活动范围（P <.001）。在除侧屈以外的所有加载模式下，椎弓根螺钉固定的活动范围均显著小于肋横突螺钉固定。与肋横突螺钉相比，椎弓根螺钉提供了 62%更大的轴向拔出阻力。
肋横突关节螺钉技术似乎仅为失稳胸段脊柱提供了中等刚度的固定。椎弓根螺钉固定具有更有利的生物力学特性。这些数据表明，肋横突关节结构更适合作为挽救性手术，而不是主要的固定策略。
