The lumbosacral region in man is exposed to special static and dynamic load. In a supine position, the disc size increases because of the absence of axial load. In a standing position, with physiological posture of the spine, strain discomfort occurs which is increased even more in the sitting position due to the curvature of the lumbar region of the spine and the irregular distribution of pressure in the discs as a result of this. This special problem of sitting posture can be confirmed by examinations

Rosemeyer, B.

English

NASA Technical Reports Server

NASA TECHNICAL MEMORANDUM NASA TM-75579
THE LUMBOSACRAL SEGMENT AS A VULNERABLE REGION
IN 'VARIOUS POSTURES
B. Rosemeyer
(NASA-TM-75579) THE LOMBOSACRAL SEGMENT AS N78-33713
A VULNERABLE,REGION IN VABIOUS POSTURES
(National Aeronautics and Space
Administration) 6 p HC A02/MF A01 CSCL 06P ^ Unclas
'^  33790
Translation of "Das lumbosaRrale Bewegungssegment als
Locus minoris resistentiae bei verschiedenen Karperhaltungen*,"
Orthopaedjishche Praxis, Vol. 13, No?.. 8, f
/ 1 9 7 7 , PP. 537-539.
NATIONAL AERONAUTICS- AND SPACE ADMINISTRATION
WASHINGTON, D.C. 205^6 OCTOBER 1978
https://ntrs.nasa.gov/search.jsp?R=19780025770 2020-03-22T01:46:38+00:00Z
STANDARD TITLE PAGE
1. Reporl.No. NASA TM-75579 2. Government Ace. s. ion No.
" ' • - . - • ' ".—fc\
4. Tide and Subtitle
THE LUMBOSACRAL SEGMENT AS A VULNERABLE
REGION IN VARIOUS POSTURES
7. Author(i)
B. Rosemeyer
9. Performing Organization Name and Address
Leo Kanner Associates
Redwood City, 9^061
12. Sponsoring Agency Nome ond Address
National Aeronautics and Space Adminis-
tration, Washington, D.C. 20546
3. Recipient's Catalog No.
5
- <5cTob0e'r 1978
6. Performing Organization Code
8. Performing Organization Report No.
10. Work Unit No.
IV. Contract of Grant No.
NASw=3199
13. Type of Report and Period Covered
Translation
14. Sponsoring Agency Code
15. Supplementary Notes
Translation of "Das lumbosakrale'-Bewegungssegment als Locus
mi'nor.is reslstentiae bei,verschiedenen Korperhaltungen*,'j
Orthopaedishche Praxis, Vol. 13, No. 8-, 1977, pp. 53-7-539.
16. Abstroct
The Lumbosacral region in man is exposed to special static
and dynamic load. In a supine position, the disc size in-
creases because of the absence of axial load. In a standing
position, with physiological posture of the spine, strain
discomfort occurs which is increased even more in the sitting
.position due to the curvature of the lumbar region of the
spine and the irregular- distribution of pressure in the discs
as a result of this. This special problem of sitting posture
can be confirmed by examinations.
17. Key Words (Selected by Author(s)) 18. Distribution Statement
Unlimited-Unclassified
19. Security Cloisif. (of this report)
Unclassified
20. Security Classif. (of this page)
Unclassified
21. No. of Pages 22. Price
NASA-HQ
THE LUMBOSACRAL SEGMENT AS A VULNERABLE REGION
IN' VARIOUS POSTURES
B. Roseroeyer
Orthopedic Clinic and Orthopedic Polyclinic,
University of Munich
The human spine has two functions to perform, one static /537*
and one dynamic. For the most part, they are interconnected.
With regard to the first, its function is to be loaded in the
longitudinal axis by the weight of the body. The load line
does not run through the center of each vertebral body, but
is displaced as a result of the sagittal curvature in the shape
of a double S. However, because of the shape of the individual
segments, the load on the discs is nevertheless uniform. Secondly,
the spine must cushion changing loads, such as are produced while
walking or during a change of posture. During a change of pos-
ture the bending movements of the spine.are physiological, these
occur rapidly and thus improve the metabolism-in the bradytrophic
tissues of the movement segments. ;
The necessity of having to perform two different functions
explains the fact that the spinal column is not optimally equipped
for one of the two load functions alone. The exclusively static 7538
load adversely affects the metabolism in the discs, especially
during a forced change in the. shape <3f the spinal column.- The
exclusively dynamic function, suchaas occurs during weightlessness,
causes a slow change in the spongiose structures in the vertebral
bodies.
The weak point in this system is the transition region be-
tween the mobile lumbar area of the spine and the sacrum fixed
in the .pelvis... . .This, ±.S: the, .site of. 7-0-.p.ej?. .cent. ,o.f. .the.
' * —A. ' "~
'Numbers in the margin indicate pagination in the foreign text.
flexion/extension movement, of the entire lumbar region of the
spine,, contributing to the greatest static lo.ad,. since the
erection of the spine in humans takes place primarily in this
region (Pig. 1). A special load of the lumbosacral transition
region is therefore typical for man and manifests itself in
degenerative changes here with an early onset,(Fig. 2),
These in turn upset the harmony of the path of movement and
shift the load into the adjacent regions.
The different postures of man have their problems es-
pecially in the lumbosacral region. After a long period of
lying in a fixed position—for example, in a plaster cast—
there develops a greater amount of fluid uptake in the discs,,
in spite of physiological spinal configuration, due to the
lack of axial spinal load and the lack of movement. The discs
increase in size and an expansion pain occurs in the posterior
longitudinal ligament. In addition, the spine becomes slow to
react. In the extreme case, a slipped disc may occur as a re-
sult of a sudden change in posture.
In the standing position, the physiological curves of the
spine are maintained (.Fig. 3a), The pressure is uniformly
distributed in the lumbosacral disc. Discomfort arises due to
the static load and should stimulate movement. They are the
result of ligamentous strain and not the expression of an
irregular distribution of pressure in the hydroelastic system.
Degenerative changes develop exclusively as a result of the
unavoidable load on this region caused by holding the body
erect.
In the sitting position, the shape of the spine is in-
fluenced by the position of the hip joint. During severe
berlding at the hip the lumbar region of the spine is stretched
or is even made kyphotic. Seventy per cent of this bending
occurs.in the lumbosacral segment (Fig. 3b). The result is
uneven disc strain with an increase in intradiscal pressure.
As in the lying and standing positions, load peaks can be
reduced only by a change in posture. For the unfavorable
static sitting position with kyphosis of the lumbar region,
there is thus the compound problem of the axial spinal load 7539
and the load due to an uneven distribution of pressure in
the intervertebral disc. Nine out of 10 test subjects had
a poor sitting posture with ^ respect to the way they held the
lumbar region of the spine. And yet they had the feeling of
sitting comfortably. Therefore, it is not surprising that
85 per cent of a group of patients being treated for per-
sistent lumbago stated that their discomfort occurred especi-
ally while in a sitting position.
Static body postures are problematic for the human spine.
If, in the standing position, the lumbosacral segment is strained
in its normal position, then in the sitting position there is
also a forced and uneven distribution of pressure in the disc
due to kyphosis of the lumbar region of the.spine. If the
axial load on the spine due to holding the trunk erect is
unavoidable, then by correcting a long-term sitting posture
it must be attempted to avoid fehe additional bending of the
lumbar region of the spine (Fig. 3c). The adaptability of man
should not unnecessarily be taken advantage of, especially in
the choice of static sitting postures. For the lumbosacral
segment, an adverse, long-term body posture may easily be a
factor which causes early troubles and late injuries as a
result of degenerative changes wh'&eh have-not yet become
manifest.
FiguresCaptions.,
Fig. 1. Model of the lumbar region of the spine in lordosis
(left) and kyphosis Cright). Seventy per cent of the total
flexion/extension movement takes place in the lumbosacral seg-
ment, 20 per cent in the segment immediately above this and
10 per cent distributed over the remaining segments. This, in
conjunction with the static conditions, gives rise to the special
load on the lumbosacral transition segment.
Pi'g. 2. Thirty-seven=year-old male. Pronounced arthrosis
which is especially localized on the lumbosacral transition
segment with a decrease in disc size, changes in the upper
plate of SI and the bottom plate of E5 and in the small verte-
bral joints.
Fig. 3a»to 3c. Sketeches of the lumbosacral transition
segment in standing position with lardosis of the lumbar region
of the spine, in the sitting position with kyphosis of the
lumbar region and in the sitting position with lordosis of
the lumbar region. In the case of lordosis, physiological,
i.e. uniform disc compression in the lumbosacral region, in
the sitting position with kyphosis, irregular pressure distri-
bution in the disc with ventral load peaks.


The lumbosacral segment as a vulnerable region in various postures

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server