Longitudinal Study of the Six Degrees of Freedom Cervical Spine Range of Motion During Dynamic Flexion, Extension, and Rotation After Single-level Anterior Arthrodesis

Abstract

Study Design A longitudinal study using biplane radiography to measure in vivo intervertebral range of motion (ROM) during dynamic flexion/extension and rotation. Objective To longitudinally compare intervertebral maximal ROM and midrange motion in asymptomatic control subjects and single-level arthrodesis patients. Summary of Background Data In vitro studies consistently report that adjacent segment maximal ROM increases superior and inferior to cervical arthrodesis. Previous in vivo results have been conflicting, indicating that maximal ROM may or may not increase superior and/or inferior to the arthrodesis. There are no previous reports of midrange motion in arthrodesis patients and similar-aged controls. Methods Eight single-level (C5/C6) anterior arthrodesis patients (tested 7±1 months and 28±6 months post-surgery) and six asymptomatic control subjects (tested twice, 58±6 months apart) performed dynamic full ROM flexion/extension and axial rotation while biplane radiographs were collected at 30 images/s. A previously validated tracking process determined three-dimensional vertebral position from each pair of radiographs with sub-millimeter accuracy. The intervertebral maximal ROM and midrange motion in flexion/extension, rotation, lateral bending, and anterior-posterior translation were compared between test dates and between groups. Results Adjacent segment maximal ROM did not increase over time during flexion/extension or rotation movements. Adjacent segment maximal rotational ROM was not significantly greater in arthrodesis patients than in corresponding motion segments of similar-aged controls. C4/C5 adjacent segment rotation during the midrange of head motion and maximal anterior-posterior translation were significantly greater in arthrodesis patients than in the corresponding motion segment in controls on the second test date. Conclusions C5/C6 arthrodesis appears to significantly affect midrange, but not end-range, adjacent segment motions. The effects of arthrodesis on adjacent segment motion may be best evaluated by longitudinal studies that compare maximal and midrange adjacent segment motion to corresponding motion segments of similar-aged controls to determine if the adjacent segment motion is truly excessive.

Analysis of Correlation Between Age and Cervical Facet Joint Degeneration and Modic Changes in Patients with Cervical Spondylotic Myelopathy

“…Axial, sagittal, and coronal orientation of the subaxial cervical spine was reported to change from level to level [24]. The present study shows that the variation of facet orientation is associated with MCs dimensions at different cervical levels.…”

“…Independent of age, we revealed that the subaxial cervical facet at each level showed the most vertical orientation. It is generally accepted that the rotation movements are dominated by the axial cervical spine, whereas the flexion-extension is dominated by the subaxial spine [24]. The shallowness of C3 facet joints determines mobility between 2 vertebral bodies, and vertical facets restrain the translation of the axial spine over C3.…”

Estimation of Cervical Spinal Loading and Internal Motion at Adjacent Segments after C5–C6 Fusion Using a Musculoskeletal Multi-Body Dynamics Model during the Head Flexion–Extension Movement

“…After cervical spinal fusion, motion in the treated level is eliminated. In contrast, ranges of motion at adjacent segments generally increase in daily activities, due to the compensatory effect [7]. On the other hand, joint biomechanics is known to affect intervertebral disc degeneration [8][9][10].…”

The impact of bilateral facetectomy on the instantaneous helical axis of the functional thoracic spinal unit T4-5 during axial rotation

“…In contrast to parameters such as range of motion or stiffness, the IHA and its migration enable the comprehension of the complex motion properties of an FSU. Although the IHA has been analyzed by different approaches, including sequential radiography, optical systems, and finite element studies (Rousseau et al 2006 , 2008 ; Dugailly et al 2010 ; Park et al 2011 ; Crawford et al 2012 ; Anderst et al 2013 , 2016 ), the 6D apparatus used in this study offers a comparably very high spatial-temporal resolution. The authors hypothesized that: (1) the location of the IHA is placed somewhere near the posterior part or even at the border of the vertebral body in the horizontal plane and (2) the resection of both FJs leads to an instability of the FSUs and a ventral shift in the locations of the IHA.…”