Abstract
Introduction
Changes in vertebral endplate sclerosis and permeability seem to be a crucial aspect in the course of disk degeneration. Detailed information on microstructural changes of the subchondral bone of the endplates and the trabecular vertebral bone is missing, especially when bony remodeling runs parallel with disk remodeling or not. Therefore, the goal of this study was to analyze this in an established disk degeneration model on minipigs.
Materials and Methods
Animals were divided into three groups. Group 1 and 2 received partial nucleotomy with a 16G-biopsy-cannula to induce moderate disk degeneration and were followed for 13 and 24 weeks, respectively. Group 3 did not receive surgery and served as controls. A total of 24 disks and 48 endplates with subchondral bone and trabecular vertebral bone were analyzed histologically and by quantitative micro-CT. Standardized elliptical volumes of interest were analyzed by Skyscan-micro-CT-software.
Results
Both group 1 and 2 showed disk degeneration with significant loss of disk height, higher disk- and endplate-degeneration-scores, fibrous scarring, and loss of notochordal cells (p < 0.05 compared to controls). Micro-CT revealed less sclerosis (BV/TV) and reduced trabecular thickness of subchondral bone underneath the endplates 13 weeks after nucleotomy compared to untreated controls (p < 0.05 group 1 vs. group 2 and 3); after 24 weeks, however, values turned back to those of controls again. The same correlation was found in more distant trabecular vertebral bone, though BV/TV values were lower. Separate analysis of changes above and below the operated disk did not show differences.
Conclusion
Contrary to the concept of simultaneous bony endplate sclerosis and disk degeneration, we found reduced BV/TV and trabecular thickness early after nucleotomy induced disk degeneration. At later stages of disk degeneration, sclerosis was not higher than in healthy controls, indicating that disk degeneration can proceed independently from endplate sclerosis. The vertebral bone is highly reactive to disk disturbances but does not automatically react with increased sclerosis.
Yes
None declared