Compressive Preload Reduces Segmental Flexion Instability After Progressive Destabilization of the Lumbar Spine
Compressive Preload Reduces Segmental Flexion Instability After Progressive Destabilization of the Lumbar Spine
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DOI：
10.1097/brs.0000000000000093
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发表时间：
2014-01-15
期刊：
影响因子：
3
通讯作者：
Patwardhan, Avinash G.
中科院分区：
文献类型：
--
作者：
Fry, Robert W.;Alamin, Todd F.;Patwardhan, Avinash G.
研究设计.生物力学人体尸体研究。我们假设，增加压力预负荷将减少髓核切除术、后韧带切除术和减压手术后的节段性不稳定。由于脊柱肌肉组织和重力，人体脊柱在体内经历显著的压缩预载荷。虽然已经研究了失稳过程对脊柱运动的影响，但压缩预载荷对失稳的多节段腰椎运动反应的影响尚未得到证实。在L4-L5髓核切除术后、棘间和棘上韧带横断后以及中线减压（双侧椎板切开术、部分内侧关节面切除术和椎间孔切开术）后，对8具人体尸体脊柱（L1-骶骨，51.4 +/- 14.1岁）进行了完整测试。在0 N、200 N和400 N压缩随动件预载荷下，对样本施加屈曲（8 Nm）和伸展（6 Nm）载荷。采用重复测量方差分析和Bonferroni校正的多重比较分析高柔韧性区L4-L5活动度（ROM）和屈曲刚度。在一组固定的载荷条件下，观察到节段ROM随着高柔韧性区的扩张（屈曲刚度降低）沿着逐渐增加，并伴有系列不稳定。施加增加的压缩预载荷并没有显著改变节段ROM，但确实显著增加了高柔韧性区域的节段刚度。在最不稳定的情况下，400 N的预载荷不能使节段刚度恢复到完整水平。代表退行性和医源性不稳定的解剖结构改变与节段ROM显著增加和节段刚度降低相关。尽管施加压缩预载荷，模拟增加轴向肌肉活动的效果，显著增加了节段刚度，但并未恢复至完整水平;因此表明单独的核心加强可能无法补偿与中线手术减压相关的结构稳定性损失。这表明，外科植入物或干预措施可能会专门增加屈曲刚度并限制屈曲ROM，以抵消手术减压导致的医源性不稳定。
Study Design. Biomechanical human cadaveric study.Objective. We hypothesized that increasing compressive preload will reduce the segmental instability after nucleotomy, posterior ligament resection, and decompressive surgery.Summary of Background Data. The human spine experiences significant compressive preloads in vivo due to spinal musculature and gravity. Although the effect of destabilization procedures on spinal motion has been studied, the effect of compressive preload on the motion response of destabilized, multisegment lumbar spines has not been reported.Methods. Eight human cadaveric spines (L1-sacrum, 51.4 +/- 14.1 yr) were tested intact, after L4-L5 nucleotomy, after interspinous and supraspinous ligaments transection, and after midline decompression (bilateral laminotomy, partial medial facetectomy, and foraminotomy). Specimens were loaded in flexion (8 Nm) and extension (6 Nm) under 0-N, 200-N, and 400-N compressive follower preload. L4-L5 range of motion (ROM) and flexion stiffness in the high-flexibility zone were analyzed using repeated-measures analysis of variance and multiple comparisons with the Bonferroni correction.Results. With a fixed set of loading conditions, a progressive increase in segmental ROM along with expansion of the high-flexibility zone (decrease of flexion stiffness) was noted with serial destabilizations. Application of increasing compressive preload did not substantially change segmental ROM, but did significantly increase the segmental stiffness in the high-flexibility zone. In the most destabilized condition, 400-N preload did not return the segmental stiffness to intact levels.Conclusion. Anatomical alterations representing degenerative and iatrogenic instabilities are associated with significant increases in segmental ROM and decreased segmental stiffness. Although application of compressive preload, mimicking the effect of increased axial muscular activity, significantly increased the segmental stiffness, it was not restored to intact levels; thereby suggesting that core strengthening alone may not compensate for the loss of structural stability associated with midline surgical decompression. This suggests that there may be a role for surgical implants or interventions that specifically increase flexion stiffness and limit flexion ROM to counteract the iatrogenic instability resulting from surgical decompression.