Article

We theorized that active cervical extension should influence the
position of the nucleus pulposus (NP) within the intervertebral disk (IVD) in the
sagittal plane. Although several studies on the lumbar IVD have been conducted,
there are no quantitative data for in vivo positional changes of the NP in the cervical IVD. OBJECTIVE: To evaluate the influence and mechanism of cervical
extension on the deformation and migration of IVD and NP in the sagittal plane
and understand underlying mechanisms of the extension maneuver. DESIGN:
Asymptomatic subjects underwent magnetic resonance imaging while supine with
their cervical spines in neutral and extended positions. SETTING: Academic
medical center. PARTICIPANTS: Ten young, healthy male participants (age range
19-30 years; mean 22.4 +/- 1.64 years). METHODS: T2-weighted sagittal images from
C3-C4 to C6-C7 of subjects in both neutral and extension positions were analyzed.
MAIN OUTCOME MEASUREMENTS: Deformation of IVD and positional change of NP were
quantified and compared between neutral and extension positions. Intersegmental
angles between vertebrae, horizontal positions of anterior and posterior IVD and
NP margins, IVD outer and inner heights, and sagittal morphology of NP were
quantified and compared between the neutral and extension positions. Correlations
between the measured parameters and segmental extension angle were also
investigated. RESULTS: Anterior and posterior IVD margins moved posteriorly with
respect to the vertebral body in extension. Both NP margins remained unchanged
relative to the vertebral body but moved anteriorly with respect to the IVD. IVD
outer and inner heights in the anterior region increased in extension, and
morphological changes of the NP were less noticeable when compared with its
relative migration within the IVD. Most of the intradiskal changes were linearly
correlated with the segmental extension angle. CONCLUSIONS: Cervical extension
induces anterior migration of the NP away from the posterior disk margin and may
have a clinical effect on diskogenic neck pain resulting from internal disk disruption. LEVEL OF EVIDENCE: Not applicable.
CI - Copyright (c) 2017 American Academy of Physical Medicine and Rehabilitation.
Published by Elsevier Inc. All rights reserved.

Langue : ANGLAIS