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KMID : 0350519950480030801
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Journal of Catholic Medical College
1995 Volume.48 No. 3 p.801 ~ p.812
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The Changes of Adjacent Intervertebral Discs after Lumbar Spinal Immobiliation in Rabbit
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Abstract
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In has been known that the mechanical force loaded on spinal segments is changed after lumbar spinal immobilization. The abnormally high stress concentrated on the adjacent segments to the fused site results in degenerative changes of the
intervertebral
discs. In the present study, we investigated the changes following lumbar spinal immobilization in the spinal segment including intervertebral disc located just above the fused segment to relate the radiological findings of the spinal segment
with
the
histopathological findings of the intervertebral disc using 20 adult rabbits, 4 control and 16 experimental group. Bilateral pedicular screw and plate were fixed at L6-7 spinal segment of experimental group.
The experimental group were sacrificed 4, 8, 12 and 16 weeks after the operation.
@ES The results were as follows :
@EN 1. On the radiological examination of the L5-6 segment, the end plate sclerosis has been observed since 8th week after operation. At 12th week, the evidence of angular difference was seen. The more prominent findmgs for degenerative change
such
as
anterior traction spur and angular difference were scen at 16th week.
2. Grossly, the mild discoloration of the intervertebral disc was ween at 4th week after operation. From 8th week, the degenerative changes such as discoloration, dehydration, and fibrosis were detected and were more prominent at 12th and 16th
week.
3. Histologically, amorphous debris was seen from 4th after operation in the nucleus pulposus. At 8th week, increased fibre bundles and chondroid cells were observed. The juncion between the annulus fibrosus and nucleus pulposus were
progressively
distorted. From 12th week, the cluster of chondroid cells and chondroid metaplasia were formed. No definite demarcation between nucleus plposus and annulus fibrosus was observed. These changes were more definite at 16th week. In the end-plate
cartiage,
spindle shape of chondrocyte and loss of columnar arrangement were detected from 8th week. At 12th wee, the microfracture of end-plate cartilage and osteoid forma tion were observed. At 16th week, it was unable to notice the borderline of the
end-plate
cartilage and more osteoid formations were observed. On the stain for the mucopolysaccharides, the evidence of neutral mucopolysaccharides were observed. After 12th weeks, the neutral mucopolysaccharide and chondroid metaplasia were more
prominent.
4. In intervertebral disc, more severe degenerative changes were noticed at the posterior parts of nucleus pulposus and annulus fibrosus.
Above results suggest that the posterior spinal immobiliztion seems to accelerate the degenerative changes in the adjacent intervertebral disc above the immobilization. And these changes were more prominent at the posterior part of the
intervertebral
disc.
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