Segmental motion adjacent to an instrumented lumbar fusion - The effect of extension of fusion to the sacrum
Segmental motion adjacent to an instrumented lumbar fusion - The effect of extension of fusion to the sacrum
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DOI：
10.1097/01.brs.0000143667.55696.bd
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发表时间：
2004-11-01
期刊：
影响因子：
3
通讯作者：
Hart, R
中科院分区：
文献类型：
--
作者：
Untch, C;Liu, Q;Hart, R
研究设计。我们使用尸体腰骶棘对 L4-L5 与 L4-S1 融合模型的颅段 (L3-L4) 相邻节段运动进行体外生物力学比较。 目的。目的是确定将短腰椎融合延伸至骶骨与停止在 L5 之间对未融合颅骨段的生物力学影响。背景数据摘要。腰椎和腰骶椎融合术后患者的晚期后遗症可能会出现邻近节段退变的放射影像证据。据信，与融合结构相邻的生物力学的改变导致了这些退行性变化。与结束 L5 融合相比，对于因包含骶骨而导致的颅骨相邻节段力学变化知之甚少。方法。七个人体尸体腰骶椎在 L4、L5 和 S1 处安装了椎弓根螺钉。从L4-L5和L4-S1放置杆来模拟相应的融合模型。使用材料测试系统在屈曲伸展、侧向弯曲和轴向旋转时向脊柱施加负载控制力矩。电磁传感器用于记录 L3-L4、L4-L5 和 L5-S1 运动段的 6 df 运动。记录角位移并计算每个脊柱和结构的系统刚度。使用配对样本 t 检验来确定记录差异的显着性。结果。在屈曲-伸展载荷下，L4-S1 模型的 L3-L4 矢状面角位移为 9.0，而 L4-L5 模型为 7.8（+15%；P = 0.002）。在横向弯曲载荷下，L4-S1 模型在冠状面中的 L3-L4 运动为 12.8，L4-L5 模型为 14.5（-12%；P = 0.002）。在轴向旋转测试中，L4-S1模型的L3-L4扭转运动与L4-L5模型相当。与 L4-L5 模型相比，L4-S1 模型的整体系统刚度有所增加。结论。在此负载控制模型中，跨 L5-S1 延伸融合并不能持续增加 L3-L4 的运动。虽然可能很难将这一发现转化为临床环境，但从避免邻近节段疾病的角度来看，避免在下腰椎融合中与骶骨融合可能不会提供显着的益处。
Study Design. We present an in vitro biomechanical comparison of adjacent segment motion at the cranial segment (L3-L4) for an L4-L5 versus an L4-S1 fusion model using cadaveric lumbosacral spines.Objectives. The purpose is to determine the biomechanical effect on the unfused cranial segment of extending a short lumbar fusion to the sacrum versus stopping at L5.Summary of Background Data. Radiographic evidence of adjacent segment degeneration can occur as a late sequela in patients following lumbar and lumbosacral spinal fusions. It is believed that altered biomechanics adjacent to the fusion construct contribute to these degenerative changes. Little is known regarding changes in cranial adjacent segment mechanics resulting from inclusion of the sacrum compared to ending a fusion at L5.Methods. Seven human cadaveric lumbosacral spines were instrumented with pedicle screws at L4, L5, and S1. Rods were placed from L4-L5 and from L4-S1 to simulate the corresponding fusion models. A material testing system was used to apply load-controlled moments to the spines in flexion-extension, lateral bending, and axial rotation. Electromagnetic sensors were used to record 6 df motion across the L3-L4, L4-L5, and L5-S1 motion segments. Angular displacements were recorded and system stiffness was calculated for each spine and construct. A paired sample t test was used to determine significance of recorded differences.Results. Under flexion-extension loading, the angular displacement in the sagittal plane at L3-L4 for the L4-S1 model was 9.0 compared to 7.8 for the L4-L5 model (+15%; P = 0.002). Under lateral bending loading, L3-L4 motion in the coronal plane for the L4-S1 model was 12.8 and was 14.5 for the L4-L5 model (-12%; P = 0.002). In axial rotation testing, L3-L4 torsional motion for the L4-S1 model was equivalent to the L4-L5 model. Overall system stiffness increased for the L4-S1 model compared with the L4-L5 model.Conclusions. In this load-controlled model, extending fusion across L5-S1 did not consistently increase motion at L3-L4. While it may be difficult to translate this finding to a clinical setting, avoiding fusion to the sacrum in a lower lumbar fusion may not provide significant benefit from the standpoint of avoiding adjacent segment disease.