Effects of unisegmental disc compression on adjacent segments: an in vivo animal model
Frank Unglaub, Thorsten Guehring, Helga Lorenz, Claus Carstens & Markus Kroeber
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abstract
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It is controversial whether fusion of discs in the spine leads to
increased degeneration on the remaining discs or whether the
degenerative changes are merely a part of the inevitable natural
history process. To determine the effects of unisegmental
compression and subsequent recovery on adjacent segments, we studied
histology, radiology and intradiscal pressure using an in vivo
rabbit model. Fifteen New Zealand rabbits were divided in to three
groups of five. In the first group, the intervertebral disc L4-L5 of
the lumbar spine was axially loaded for 28 days with an external
loading device. In the second group, the intervertebral disc was
compressed for 28 days and allowed to recover for an equal amount of
time, with the loading device removed. Five animals underwent a sham
operation, in which the external loading device was situated, but
their discs remained unloaded for 28 days. The intradiscal pressure
was determined in the loaded discs as well as in the cranial and
caudal adjacent discs. Lateral radiographs were taken from each
subjected intervertebral disc with adjacent vertebral bodies and the
cranial and caudal adjacent segments. The compressed discs showed
lower intradiscal pressure in comparison with the control group,
which remained unloaded. In the cranial and caudal discs adjacent to
the loaded discs the average intradiscal pressure was similar to the
unloaded controls. The loaded discs demonstrated a significant
decrease in disc space. No discs adjacent to the loaded discs
changed in height. The lamellar architecture of the inner, middle,
and outer annulus became more disorganized in the loaded discs. The
nucleus pulposus showed increase of mucoid degeneration and
increased cell death. Intervertebral discs from the control group
and the adjacent discs to the compressed discs maintained their
normal morphology. This study shows that mechanical loading of discs
in the spine can cause rapid degeneration. Adjacent discs, however,
did not change in terms of radiology, intradiscal pressure, or
histology.
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citation
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Unglaub F, Guehring T, Lorenz H, Carstens C, kroeber m. Effects of
unisegmental disc compression on adjacent segments: an in vivo
animal model. European spine journal : official publication of the
European Spine Society, the European Spinal Deformity Society, and
the European Section of the Cervical Spine Research Society 2005;
14:949-55.
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type
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journal paper/review (English)
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date of publishing
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12-2005
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journal title
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European spine journal : official publication of the European Spine
Society, the European Spinal Deformity Society, and the European
Section of the Cervical Spine Research Society (14/10)
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ISSN print
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0940-6719
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pages
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949-55
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PubMed
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15717190
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DOI
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10.1007/s00586-004-0800-7
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