The Journal of Bone and Joint Surgery, Vol 68, Issue 7 1066-1072, Copyright © 1986 by Journal of Bone and Joint Surgery, Inc
Histological development of intervertebral disc herniation
T Yasuma, E Makino, S Saito and M Inui
Sagittal and horizontal sections of 257 intervertebral discs obtained at
autopsy and material obtained from 441 operations for herniation of a disc
were examined histologically. In the material that was taken at autopsy,
myxomatous degeneration of the annulus fibrosus increased in proportion to
the age of the subject. The bundles in the internal layer of the annulus
fibrosus reversed their usual direction and showed myxomatous degeneration,
sometimes resulting in posterior and anterior convex bulging in the
internal layer of the anterior and posterior parts of the annulus fibrosus,
respectively. When material from a disc was surgically removed as a single
free fragment (as in a complete extrusion or a sequestration type of
herniation), annulus fibrosus with myxomatous degeneration was found in
most material, while the nucleus pulposus rarely was. These results suggest
that, from the standpoint of pathomechanism, a protrusion type of
herniation of the annulus fibrosus exists in which only the annulus
fibrosus is protruded due to reversal of the bundles of the annulus
fibrosus, without involvement of the nucleus pulposus. This type of
herniation would be a separate entity from the protrusion type of
herniation of the nucleus pulposus that occurs when the nucleus pulposus is
protruded through a fissure in the annulus fibrosus.
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