Elsevier

Journal of Biomechanics

Volume 112, 9 November 2020, 110023
Journal of Biomechanics

Quantifying the ranges of relative motions of the intervertebral discs and facet joints in the normal cervical spine

https://doi.org/10.1016/j.jbiomech.2020.110023Get rights and content

Abstract

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.

Introduction

The cervical spine is prone to injuries and degenerative changes, that can eventually lead to pain, malfunction, and/or neurological complications (Nouri et al., 2015). While the mechanisms of cervical pathology are unclear and assumed to be multifactorial (Akter and Kotter, 2018), biomechanical/iatrogenic changes of the spine are widely considered as a factor causing spinal load changes and initiating disc degeneration (Dai, 1999). Surgical therapies, such as spinal fusion and total disc arthroplasty (TDA), are widely performed to treat severe cervical disc diseases. While TDA is associated with several complications including heterotopic ossification and implant failures (Leven et al., 2017, Nunley et al., 2018), spinal fusion is associated with a higher risk of adjacent segment degeneration (ASD) due to altered segment biomechanics at adjacent levels (Dmitriev et al., 2007, Laratta et al., 2018, Luo et al., 2015, Schwab et al., 2006). An accurate quantification of cervical spine motion could enhance our understanding of the normal, pathological, and surgically treated spines, and help improve surgical techniques and rehabilitation regimens.

Functional cervical motion is achieved by the intervertebral cervical segments with each being composed of an intervertebral disc (IVD) and two facet joints (FJs). Numerous in vitro and in vivo studies have investigated the biomechanical responses of the cervical spine using load transducers (Moroney et al., 1988, Panjabi et al., 2001, Wen et al., 1993, White et al., 1975), motion capture (Black et al., 1996, Henmi et al., 2006), X-ray imaging (Reitman et al., 2004, Wu et al., 2007), computed tomography (CT) (Penning and Wilmink, 1987, Watanabe et al., 2012), and magnetic resonance imaging (MRI) (Ishii et al., 2006, Ishii et al., 2004, Nagamoto et al., 2011). Recently, model based tracking techniques that combined subject-specific vertebral models and bi-plane radiography have been employed to evaluate six-degree-of-freedom (6DOF) intervertebral motions under dynamic physiological loading conditions (Anderst et al., 2013b; Lin et al., 2014, McDonald et al., 2014, Yu et al., 2019). However, most previous studies focused on the kinematics of the intervertebral segments. Fewer in vitro and computational studies have reported on the morphology of FJs (Milne, 1991, Rong et al., 2017) and uncovertebral joints (Panjabi et al., 1991), and on how intact or TDA-treated segment kinematics and load-sharing were affected by FJs (Bauman et al., 2012, Chang et al., 2007, Kang et al., 2010, Patel et al., 2017, Stieber et al., 2011) or uncovertebral joints (Kang et al., 2010, Snyder et al., 2007, Wachowski et al., 2017, Wachowski et al., 2007, Wang et al., 2016). However, little is known on the in vivo kinematics and synergistic function of the IVD and the FJs in the normal human cervical spine. This information is critical for evaluation of the effect of spine pathologies on changes of cervical biomechanics and for improvement of spinal surgeries that can maximally restore the normal spine function.

Previously, we have investigated the intervertebral motion and IVD deformation of the subaxial cervical spine using a dual fluoroscopic imaging system (DFIS) (Yu et al., 2017). In this study, we further investigated the ranges of motion (ROMs) of the IVD joint and FJs of the human cervical spine during functional activities of the neck, including maximal flexion–extension (FE), lateral bending (IB) and axial twisting (AT) motions using the DFIS. Due to the fundamentally different structures of the IVD and FJs, the FJs are commonly recognized to be more mobile than the IVD joints, whereas quantitative comparisons were less reported. The objective of this study is to quantify the differences in the ROMs of both joints in the cervical spines of asymptomatic subjects during various in vivo neck motions. We hypothesized that the segment rotational ROMs and the ratios of IVD to FJ translational ROMs (shortened by the IVD-FJ translation ratio hereafter) are level-dependent, i.e., they vary at different segments.

Section snippets

Subject recruitment

The experiments were performed at two medical centers and approved by their internal review boards (see Supplementary Material). All recruited subjects signed informed consent prior to participation. Each subject was first evaluated in terms of neck pain and other spinal disorders. Then, using magnetic resonance imaging (MRI) or computerized tomography (CT) images of the subjects, the presence of any anatomic abnormalities or early disc degeneration was used as a criterion for exclusion from

The rotational ROMs of cervical segments during three neck motions

During the FE motion of the neck, the ROMs of the primary rotation and coupled LB and AT of the cervical segments were shown in Table 1 and Fig. 4a. From C3/4 to C6/7, the ROMs of the primary rotation were 14.8 ± 4.3°, 17.6 ± 4.5°, 15.9 ± 5.2° and 11.3 ± 4.0°, respectively, with the ROM of C6/7 significantly smaller than those of C4/5 (p < 0.001) and C5/6 (p = 0.016). The mean ROMs of the coupled rotations were between 2.1° to 3.3°.

During neck LB (Table 1 and Fig. 4b), the ROMs of the primary

Discussion

This study investigated the 6DOF (rotational and translational) ROMs of both the intervertebral disc joint and FJs at each subaxial cervical segment during in vivo functional neck motions. During FE of the neck, the dominant segmental rotation was in the sagittal plane (FE rotation) coupled with small out-of-plane rotations (Fig. 4). During both LB and AT of the neck, regardless of primary or coupled rotations, the LB rotation was always larger than the AT and FE rotations at each segment (Fig.

Conclusion

This study quantified the ranges of relative motions of the IVD and FJs in the subaxial cervical spine during various neck motions, and showed that the FJs experienced greater in-plane translations than the IVDs, especially in the AP direction during each neck motion. These data could help understand the normal neck function, and provide valuable references for evaluation of the biomechanical efficacy of cervical surgical treatments. Furthermore, they could be also used to define optimal design

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

We are thankful for the funding supports from National Institutes of Health (1R03AG056897), Shanghai Pujiang Program (17PJ1405000), National Natural Science Foundation of China (31771017), and Shanghai Jiao Tong University (YG2017MS09, ZH2018QNA06, ZXGF082101/050).

References (54)

  • W.E. Anderst et al.

    Kang Motion Path of the Instant Center of Rotation in the Cervical Spine During In Vivo Dynamic Flexion-Extension

    Spine (Phila Pa. 1976)

    (2013)
  • W.J. Anderst et al.

    In vivo cervical facet joint capsule deformation during flexion-extension

    Spine (Phila. Pa. 1976)

    (2014)
  • W.J. Anderst et al.

    Six-Degrees-of-Freedom Cervical Spine Range of Motion During Dynamic Flexion-Extension After Single-Level Anterior Arthrodesis

    J. Bone Jt. Surg.

    (2013)
  • K.M. Black et al.

    The influence of different sitting positions on cervical and lumbar posture

    Spine (Phila. Pa. 1976)

    (1996)
  • U.-K. Chang et al.

    Changes in adjacent-level disc pressure and facet joint force after cervical arthroplasty compared with cervical discectomy and fusion

    J. Neurosurg. Spine

    (2007)
  • L. Dai

    Disc degeneration and cervical instability

    Zhonghua Wai Ke Za Zhi

    (1999)
  • A.E. Dmitriev et al.

    Stabilizing Potential of Anterior, Posterior, and Circumferential Fixation for Multilevel Cervical Arthrodesis

    Spine (Phila Pa.1976)

    (2007)
  • J. Goffin et al.

    Intermediate Follow-up after Treatment of Degenerative Disc Disease with the Bryan Cervical Disc Prosthesis: Single-Level and Bi-Level

    Spine (Phila Pa. 1976)

    (2003)
  • S. Henmi et al.

    A biomechanical study of activities of daily living using neck and upper limbs with an optical three-dimensional motion analysis system

    Mod. Rheumatol.

    (2006)
  • T.Y. Ishii et al.

    Sugamoto Kinematics of the cervical spine in lateral bending: in vivo three-dimensional analysis

    Spine (Phila Pa. 1976)

    (1976)
  • T. Ishii et al.

    Kinematics of the subaxial cervical spine in rotation in vivo three-dimensional analysis

    Spine (Phila. Pa. 1976)

    (2004)
  • H. Kang et al.

    Analysis of load sharing on uncovertebral and facet joints at the C5–6 level with implantation of the Bryan, Prestige LP, or ProDisc-C cervical disc prosthesis: An in vivo image-based finite element study

    Neurosurg. Focus

    (2010)
  • J.L. Laratta et al.

    Outcomes and revision rates following multilevel anterior cervical discectomy and fusion

    J. Spine Surg.

    (2018)
  • D. Leven et al.

    Cervical disc replacement surgery: indications, technique, and technical pearls

    Curr. Rev. Musculoskelet. Med.

    (2017)
  • J. Luo et al.

    Incidence of adjacent segment degeneration in cervical disc arthroplasty versus anterior cervical decompression and fusion meta-analysis of prospective studies

    Arch. Orthop. Trauma Surg.

    (2015)
  • C.P. McDonald et al.

    Three-dimensional motion analysis of the cervical spine for comparison of anterior cervical decompression and fusion versus artificial disc replacement in 17 patients: clinical article

    J. Neurosurg. Spine

    (2014)
  • N. Milne

    The role of zygapophysial joint orientation and uncinate processes in controlling motion in the cervical spine

    J. Anat.

    (1991)
  • Cited by (14)

    • Intervertebral kinematics during neck motion 6.5 years after fusion and artificial disc replacement

      2022, Clinical Biomechanics
      Citation Excerpt :

      Model based tracking using biplane dynamic x-ray radiography combined with computed tomography (CT) or magnetic resonance imaging (MRI) is arguably the most effective approach currently to obtain accurate 3D motion of cervical vertebrae during physiological motion tasks of the neck representing normal activities (Anderst et al., 2011; McDonald et al., 2010; Yu et al., 2017). Using this technique, intervertebral kinematics and dynamic changes in neuroforaminal geometry during neck motion have been investigated in normal (asymptomatic) participants (Chang et al., 2017; Lin et al., 2014; Wang et al., 2020; Yu et al., 2017). The effect of surgery on neck motion has been investigated using model based tracking predominantly for ACDF and motion analyses have been limited to short post-operative time periods (up to 28 months) (Anderst et al., 2016; LeVasseur et al., 2021).

    • In vivo primary and coupled segmental motions of the healthy female head-neck complex during dynamic head axial rotation

      2021, Journal of Biomechanics
      Citation Excerpt :

      The global coordinate system was set at the centroid of T1 for measurement of head movements with respect to T1 (Fig. 1B). To analyze the intervertebral kinematics, two local coordinate systems were established between each cervical segment, conforming to previous definitions for upper cervical segments (Zhou et al., 2020) and lower cervical segments (Wang et al., 2020) (Fig. 1C). For the C0-1 and C1-2 intervertebral articulations, the origins of the C0, C1, and C2 coordinate systems were set at the middle point of the line connecting the centroids of the left and right articular surfaces.

    • In vivo intervertebral kinematics and disc deformations of the human cervical spine during walking

      2021, Medical Engineering and Physics
      Citation Excerpt :

      Recent studies have demonstrated that the motion tracking technique based on dual fluoroscopic imaging is a reliable method to determine intervertebral motion in various functional neck motions [2,4,16]. Therefore, in this study, we used a dual fluoroscopic imaging system (DFIS) combined with a validated 3D-to-2D registration technique [2,16] to quantify in vivo intervertebral kinematics and disc deformations of the cervical spines in asymptomatic subjects during a gait cycle on a treadmill. The measurements of ground reaction forces and an optical motion capture system were also performed to synchronize the DFIS measurements of cervical kinematics to a gait cycle.

    View all citing articles on Scopus
    View full text