Porter Randall W, Crawford Neil R, Chamberlain Robert H, Park Sung Chan, Detwiler Paul W, Apostolides Paul J, Sonntag Volker K H
Division of Neurological Surgery, Spinal Biomechanics Research Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013-4496, USA.
J Neurosurg. 2003 Jul;99(1 Suppl):98-103. doi: 10.3171/spi.2003.99.1.0098.
The authors compared the biomechanical stability of two multilevel cervical constructs involving the placement of equal size anterior cervical plates (ACPs) after decompressive surgery: the first is placed after three-level corpectomy with strut graft and the second after two-level corpectomy and aggressive discectomy with strut graft. In addition, both constructs were evaluated with and without the application of a screw attaching the ACP to the strut graft to determine whether the additional screw enhanced stability in any mode of loading.
Nondestructive repeated-measures in vitro flexibility tests were performed in human cadaveric cervical spines. Nonconstraining pure moments of up to 1.5 Nm were applied while recording three-dimensional angular motion stereophotogrammetrically at each level from C4-5 to C7-T1. Nine specimens underwent the three-level corpectomy/strut graft procedure and eight specimens the two-level corpectomy/discectomy strut graft procedure. Failures during testing eliminated two of the former specimens and three of the latter specimens from analysis. The construct applied after the two-level procedure allowed a significantly smaller normalized neutral zone during flexion-extension than the three-level construct (p = 0.04). Normalized elastic zone and range of motion were consistently smaller in the two- than in the three-level construct, but the differences were not significant. Addition of a screw to the strut graft significantly reduced motion in the three-level procedure-treated specimens during flexion and lateral bending but had no effect on two-level corpectomy-treated specimens.
The construct associated with the two-level corpectomy/discectomy provided better immediate postoperative stability than that associated with the three-level corpectomy. The addition of a screw to the strut graft conferred stability on the three-level construct but not the two-level construct.
作者比较了减压手术后两种多级颈椎固定结构的生物力学稳定性，这两种结构均使用了尺寸相同的前路颈椎钢板（ACP）：第一种是在三级椎体次全切除并植入支撑骨块后放置，第二种是在二级椎体次全切除并积极切除椎间盘后植入支撑骨块。此外，对这两种固定结构分别在使用和不使用将ACP与支撑骨块连接的螺钉的情况下进行评估，以确定额外的螺钉是否能在任何加载模式下增强稳定性。
在人类尸体颈椎上进行非破坏性重复测量体外柔韧性测试。施加高达1.5 Nm的非约束纯力矩，同时从C4-5至C7-T1的每个节段通过立体摄影测量法记录三维角运动。九个标本接受了三级椎体次全切除/支撑骨块植入手术，八个标本接受了二级椎体次全切除/椎间盘切除支撑骨块植入手术。测试过程中的失败使前一组的两个标本和后一组的三个标本被排除在分析之外。二级手术应用的固定结构在屈伸过程中的标准化中立区明显小于三级固定结构（p = 0.04）。二级固定结构的标准化弹性区和活动范围始终小于三级固定结构，但差异不显著。在支撑骨块上添加螺钉显著降低了三级手术治疗标本在屈曲和侧方弯曲时的运动，但对二级椎体次全切除治疗的标本没有影响。
与二级椎体次全切除/椎间盘切除相关的固定结构比与三级椎体次全切除相关的固定结构在术后立即提供了更好的稳定性。在支撑骨块上添加螺钉使三级固定结构获得了稳定性，但二级固定结构未获得。
