Functional neck motion is achieved by the cervical segments with each composed of an intervertebral disc (IVD) and two facet joints (FJs). Using biplane fluoroscopic imaging, we investigated the ranges of motion (ROMs) of the three joints in the cervical spines (from C3 to C7) of eighteen asymptomatic subjects. Three functional neck motions were examined, including flexion–extension (FE), lateral bending (LB) and axial twisting (AT). Our measurements showed that the translations of both IVD and FJs primarily occurred in the sagittal plane during all neck motions, and the anteroposterior translations of IVDs were significantly smaller than those of the corresponding FJs (p < 0.05) at all segments. For example, the ranges of IVD and FJ anteroposterior translations at C3/4 were 2.7 ± 0.7 mm vs. 3.5 ± 1.1 mm in FE, 0.9 ± 0.5 mm vs. 4.6 ± 1.1 mm in LB, and 1.0 ± 0.5 mm vs. 3.1 ± 1.0 mm in AT. Furthermore, we introduced an IVD-FJ translation ratio, which represents the ratio of the IVD to FJ translational ROMs. In FE neck motion, the IVD-FJ anteroposterior translation ratios decreased from 0.81 ± 0.18 at C3 to 0.52 ± 0.19 at C3, indicating gradually increasing resistances of IVDs compared to FJs from the proximal to distal levels. In LB neck motion, the smallest IVD-FJ translation ratios (0.14 ± 0.09 and 0.43 ± 0.30) occurred at C4/5 for both anteroposterior and left–right translations. In AT neck motion, the largest IVD-FJ anteroposterior translation ratio (0.42 ± 0.21) occurred at C3/4, and was significantly different from those at C4/5 and C5/6 (p < 0.05). These data could be used as references for improving motion-preserving cervical treatment methods that aimed to achieve the normal ranges of translational motions of both IVD and FJs.

通过颈部节段实现功能性颈部运动，每个颈部节段由一个椎间盘（IVD）和两个小关节（FJs）组成。使用双平面荧光成像，我们调查了18名无症状受试者的颈椎（从C3到C7）中三个关节的运动范围（ROM）。检查了三个功能性颈部运动，包括屈伸（FE），横向弯曲（LB）和轴向扭曲（AT）。我们的测量结果显示，IVD和FJ的平移主要发生在所有颈部运动的矢状面，并且IVD的前后平移明显小于相应FJ的平移（p <0.05）。例如，IVD和FJ前后平移范围在C3 / 4分别为2.7±0.7 mm vs.3.5±1.1 mm（FE），0.9±0.5 mm vs.LB（4.6±1.1 mm）和1.0±0.5 mm vs. 3.1在AT时为±1.0毫米 此外，我们介绍了IVD-FJ翻译比率，它表示IVD与FJ翻译ROM的比率。在FE颈部运动中，IVD-FJ前后翻译比从C3处的0.81±0.18降低到C3处的0.52±0.19，这表明与FJ相比，IVD的阻力从近端到远端逐渐增加。在LB颈部运动中，前后平移和左右平移均在C4 / 5处发生最小的IVD-FJ平移比（0.14±0.09和0.43±0.30）。在AT颈部运动中，最大的IVD-FJ前后翻译比（0.42±0.21）发生在C3 / 4，p  ＜0.05）。这些数据可以用作改进旨在保持IVD和FJ的平移运动正常范围的保持运动宫颈治疗方法的参考。