Displacement of the spinal segments

In which direction does
the spinal segment displace?

Last Updated; 1996.10.06
Generally, the decision for the displacement of vertebra is based on the bone just below it. And from the 2nd cervical to fifth lumbar, these bones could displace by rotation, tilt, or posterior.

Rotation=Left or right shift of spinous process viewed from posterior to anterior(P-A).
Tilt=The difference of the height of bilateral transverse process of vertebra viewed from P-A.
Posterior or Anterior=Viewed from lateral

There are rules for representing these displacements, but the explanation for these is cut off because of its complication.

1. Rotation

2. Tilt : based on the bone just below it

3. Posterior: based on the bone just below it

George's Line

is a line drawn down the posterior margins of vertebral bodies. (It should drawn from body pedicle junction to body pedicle junction without following any pathological or hyperplastic changes on the body margins.)

Normal George's Line

should form a smooth gentle, convex anteriorly, unbroken curve, which is the anterior boundary of the neural canal and gives indication of the integrity of the spinal canal (below center figure).

Abnormal George's Line

is a break in the continuity of this line which is indicative of loosening of the motor unit and may result in a anterior displacement or posterior displacement.

With anterior as well as posterior segmental displacement, a steplike kinking of the tubelike neural canal occurs.
Consequently, the spinal cord, cauda equina, and/or membranes are slightly too markedly encroached upon, resulting in neurological insult and distress.

Posterior Displacement

According to the spinal facet structure, the spinal vertebral bone tends to displace toward to posterior (except first cervical bone).

See above figure, right side.

In my clinical experience, about 80% of patients complaining of low back pain, have this posteriority somewhere in lumbar area of the spine.

This malposition is named
RETROLISTHESIS or RETROSPONDYLOLISTHESIS,
REVERSE SPONDYLOLISTHESIS,
VERTEBRAL RETROPOSITION,
SPONDYLOLISTHESIS POSTERIOR,
RETRODISPLACEMENT
in the Roentgenographic Diagnostics.

The following literature refers to this posteriority.

*ANATOMICO-ROENTGENOGRAPHIC STUDIES OF THE SPINE
Lee A. Hadley, M.D.
Cherles C Thomas Publisher
Springfield, 1964
ISBN 0-398-02818-4, pp.390-395

*THE RADIOLOGY OF VERTEBRAL TRAUMA
Gehweiler・Osborne・Becker
W. B .Saunders Company
Philadelphia , 1980
ISBN 0-7216-4065-6 pp.445-452

This phenomenon was firstly reported in 1929 by Brailsford, Hibbs, Swift. Accordingly, the honor of first discovery of this phenomenon should be given to them.

However, Dr. Gonstead D.C. asserted first that these posterior displacements can be corrected manually.

Anterior Displacement

Incidence of the anterior displacement is much lower than the posterior displacement because of the spinal facet structure.

This is called SPONDYLOLISTHESIS or PSEUDOSPONDYLOLISTHESIS by medical orthopedics. See above figure.

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In which direction does the spinal segment displace?