Wilke H-J, Drumm J, Häussler K, Mack C, Kettler A
Institut für Unfallchirurgische Forschung und Biomechanik, Zentrum für muskuloskelettale Forschung, Universitätsklinikum Ulm, Helmholtzstrasse 14, 89081, Ulm, Deutschland.
Orthopade. 2010 Jun;39(6):565-72. doi: 10.1007/s00132-009-1587-3.
Interspinous spacers are commonly used to treat lumbar spinal stenosis or facet joint arthritis. The aims of implanting interspinous devices are to unload the facet joints, restore foraminal height, and provide stability especially in extension but still allow motion. This paper summarizes several in vitro studies, which compared four different interspinous implants - Coflex, Wallis, DIAM, and X-STOP - in terms of their three-dimensional primary stability, the intradiscal pressure, and stability after cyclic loading. 24 human lumbar spine specimens were divided into four equal groups and tested with pure moments in flexion/extension, lateral bending, and axial rotation: intact, after decompression with hemifacetectomy, and after implantation. Implantation had similar biomechanical effects with all four implants. In extension, they overcompensated the instability caused by the defect and restricted extension to about 50% compared to the intact state. In contrast, in flexion, lateral bending, and axial rotation the values of the range of motion stayed similar compared to the defective state. Intradiscal pressure after implantation was similar to that of the intact specimens in flexion, lateral bending, and axial rotation but much smaller during extension; 50,000 load cycles increased the range of motion in all motion planes by no more than 20%, but in extension motion this was still less than in the intact state.
棘突间撑开器常用于治疗腰椎管狭窄症或小关节关节炎。植入棘突间装置的目的是减轻小关节负荷、恢复椎间孔高度，并在伸展时提供稳定性，同时仍允许活动。本文总结了几项体外研究，这些研究比较了四种不同的棘突间植入物——Coflex、Wallis、DIAM和X-STOP——在三维初始稳定性、椎间盘内压力以及循环加载后的稳定性方面的差异。将24个人类腰椎标本分成四组，分别在屈曲/伸展、侧方弯曲和轴向旋转时施加纯力矩进行测试：完整状态、半椎板切除减压后状态以及植入后状态。所有四种植入物的植入都产生了相似的生物力学效应。在伸展时，它们过度补偿了由缺损引起的不稳定性，与完整状态相比，将伸展限制在约50%。相比之下，在屈曲、侧方弯曲和轴向旋转时，与缺损状态相比，活动范围值保持相似。植入后的椎间盘内压力在屈曲、侧方弯曲和轴向旋转时与完整标本相似，但在伸展时要小得多；50000次加载循环使所有运动平面的活动范围增加不超过20%，但在伸展运动中仍小于完整状态。
