Kinematic characteristics of patients with cervical imbalance: a weight-bearing dynamic MRI study

Kinematic characteristics of patients with cervical imbalance: a weight-bearing dynamic MRI study

Koji Tamai, Phillip Grisdela Jr., Joshua Romanu, Permsak Paholpak, Zorica Buser, Jeffrey C. Wang

January 2019, pp 1 - 9
First Online: 08 January 2019

Study design

It is a retrospective analysis of 1806 consecutive cervical magnetic resonance images taken in weight-bearing flexion, neutral, and extension positions.


The aim was to identify the kinematic characteristics of patients with cervical imbalance. Additionally, factors were analysed in the neutral position that could predict the characteristics.

Summary of background data

Little is known about the kinematic characteristics during cervical flexion and extension positions of the patient with cervical imbalance (cervical sagittal vertical axis (cSVA) in neutral position ≥ 40 mm).


After evaluating the whole images, cervical imbalance group (cSVA ≥ 40 mm, n = 43) and matched control group (


There were no significant differences in range of motion and the change in bulged discs. There was significant difference in the presence of LF bulge from flexion to extension (p = 0.023); the incidence of LF bulge increased sharply from neutral to extension in imbalance group, while there was linear increase in control group. The canal diameter (odds ratio = 0.61, p = 0.002) and disc height (odds ratio = 1.60, p = 0.041) showed significant relationship with the segments with LF bulge observed in extension but not in neutral position in the imbalance group; the cut-off values were 10.7 mm for canal diameter (sensitivity 82.5%, specificity 66.7%) and 7.1 mm for disc height (70.8%, 58.5%).


Patients with cervical imbalance had a stark increase in LF bulge from the neutral to extension position. Canal diameter  7.1 mm on neutral images may predict the segments with LF bulge observed in extension, but not in the neutral position.

Level of evidence

II (Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding).

Graphical abstract

These slides can be retrieved from Electronic Supplementary Material.[Figure not available: see fulltext.]