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Degenerated lumbar intervertebral disc. A morphological study
Wojciech J Łebkowski1, Janusz Dziecioł
1Department of Neurosurgery, Medical Academy, Białystok. wleb@amb.ac.bialystok.pl
Summary
Lumbar disc herniation may not always involve nucleus pulposus displacement. Some herniations are solely prolapses of the annulus fibrosus, necessitating revised classification based on histological findings.
Area of Science:
- Orthopedics
- Spinal Surgery
- Pathology
Background:
- Lumbar disc herniation is commonly attributed to nucleus pulposus displacement through annulus fibrosus defects.
- Disc degeneration is considered the primary cause of these displacements.
Purpose of the Study:
- To investigate the morphological nature of lumbar disc herniations, particularly protrusion and prolapse.
- To evaluate the involvement of annulus fibrosus and nucleus pulposus in herniated discs.
- To propose a revised classification for lumbar disc herniation based on histological findings.
Main Methods:
- Surgical specimens from 187 lumbar disc herniation surgeries were analyzed.
- Autopsy specimens from 308 individuals were examined macroscopically and microscopically.
- Morphological and histological examinations were performed to identify the herniated components.
Main Results:
- Annulus fibrosus was the herniated part in 29% of surgical cases and seriously involved in 21.5%.
- Macroscopic degeneration was advanced in 82 and pronounced in 42 autopsy specimens.
- Microscopic examination revealed myxomatous degeneration in the annulus fibrosus, with some cases showing annulus fibrosus bulge without nucleus pulposus involvement.
Conclusions:
- The common understanding of lumbar disc herniation requires verification as annulus fibrosus prolapse can occur independently.
- A histological classification differentiating between nucleus pulposus herniation, annulus fibrosus herniation, and mixed-type herniation is proposed.