Motion path of the instant center of rotation in the cervical spine during in vivo dynamic flexion-extension: implications for artificial disc design and evaluation of motion quality after arthrodesis.
Motion path of the instant center of rotation in the cervical spine during in vivo dynamic flexion-extension: implications for artificial disc design and evaluation of motion quality after arthrodesis.
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DOI：
10.1097/brs.0b013e31828ca5c7
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发表时间：
2013-05-01
期刊：
影响因子：
3
通讯作者：
Kang J
中科院分区：
文献类型：
--
作者：
Anderst W;Baillargeon E;Donaldson W;Lee J;Kang J
病例对照描述无症状受试者动态屈伸过程中C2-C7各颈椎运动节段瞬时旋转中心（ICR）的运动路径。比较无症状和单节段关节融合术患者的ICR路径。ICR已被提议作为活动度（ROM）的替代方法，用于评估脊柱运动质量和识别异常的中端运动学。尚未报告ICR在动态运动期间的运动路径。20名无症状对照、12名C5/C6和5名C6/C7关节融合术患者进行了全ROM屈伸，同时在30 Hz下收集了双平面X线片。先前确认的跟踪过程确定了三维椎骨位置，精度为亚毫米。采用有限螺旋轴法计算相邻椎体间的ICR。线性混合模型分析确定了运动节段之间以及对照组和关节融合患者之间ICR路径的差异。从C2/C3到C6/C7，每个连续运动节段的平均ICR位置均向上移动上级（p < .001）。从C2/C3运动节段到C6/C7运动节段，每度屈曲-伸展的ICR位置的AP变化降低（p <0.001）。在所有运动节段和屈曲-伸展角度上，ICR位置的无症状受试者变异性（95% CI）在SI方向上平均为±1.2 mm，在AP方向上平均为±1.9 mm。无症状组和关节融合术组在平均ICR位置（所有p ≥ .091）或每个屈曲-伸展度的ICR位置变化（所有p ≥ .249）方面无显著差异。为了复制无症状的体内颈椎运动，椎间盘置换术应考虑到ICR位置和运动路径的节段特异性差异。单节段前路关节融合术似乎不会影响颈椎屈伸运动质量。
Case-control. To characterize the motion path of the instant center of rotation (ICR) at each cervical motion segment from C2 to C7 during dynamic flexion-extension in asymptomatic subjects. To compare asymptomatic and single-level arthrodesis patient ICR paths. The ICR has been proposed as an alternative to range of motion (ROM) for evaluating the quality of spine movement and for identifying abnormal midrange kinematics. The motion path of the ICR during dynamic motion has not been reported. 20 asymptomatic controls, 12 C5/C6 and 5 C6/C7 arthrodesis patients performed full ROM flexion-extension while biplane radiographs were collected at 30 Hz. A previously validated tracking process determined three-dimensional vertebral position with sub-millimeter accuracy. The finite helical axis method was used to calculate the ICR between adjacent vertebrae. A linear mixed-model analysis identified differences in the ICR path among motion segments and between controls and arthrodesis patients. From C2/C3 to C6/C7, the mean ICR location moved superior for each successive motion segment (p < .001). The AP change in ICR location per degree of flexion-extension decreased from the C2/C3 motion segment to the C6/C7 motion segment (p < .001). Asymptomatic subject variability (95% CI) in the ICR location averaged ±1.2 mm in the SI direction and ±1.9 mm in the AP direction over all motion segments and flexion-extension angles. Asymptomatic and arthrodesis groups were not significantly different in terms of average ICR position (all p ≥ .091) or in terms of the change in ICR location per degree of flexion-extension (all p ≥ .249). To replicate asymptomatic in vivo cervical motion, disc replacements should account for level-specific differences in the location and motion path of ICR. Single-level anterior arthrodesis does not appear to affect cervical motion quality during flexion-extension.