Development and Histopathological Validation of a Novel Unilateral Three-Level Lumbar Artery Ligation Model of Progressive Intervertebral Disc Degeneration.

Background: Intervertebral disc degeneration (IVDD) is a major contributor to low back pain and disability worldwide. Increasing evidence suggests that vascular insufficiency plays a critical role in its pathogenesis; however, existing experimental models inadequately reproduce vascular-driven disc degeneration. To develop and histopathologically validate a novel unilateral three-level lumbar artery ligation model capable of inducing progressive vascular insufficiency-related IVDD in rats. Methods: Fifty-two Sprague-Dawley rats (26 males and 26 females) were randomly assigned to a sham-operated control group or to three experimental groups representing the acute (day 3), subacute (day 15), and chronic (week 8) stages following unilateral ligation of three consecutive lumbar arteries. Intervertebral discs (L4-L5) were analyzed using histopathological staining (Hematoxylin-Eosin and Safranin O/Fast Green). Disc morphology, nucleus pulposus (NP) and annulus fibrosus (AF) integrity, extracellular matrix composition, and disc height parameters were evaluated using a standardized histological scoring system and comprehensive morphometric analyses. Radiological disc height measurements were performed at the chronic stage. Results: Unilateral three-level lumbar artery ligation induced a clear, progressive, and time-dependent pattern of IVDD. Histopathological scores increased significantly from the acute to the chronic phase (p < 0.001), demonstrating gradual disruption of NP and AF architecture, marked loss of proteoglycan content, and progressive structural deterioration. Sex-based analysis revealed no statistically significant differences across time points, although a trend toward higher degeneration scores in females was observed at Week 8. Morphometric evaluation demonstrated region-specific (midline, right, and left) and time-dependent alterations in NP and AF heights (all p < 0.05). Although no significant side-to-side differences were observed during the acute and subacute stages (Day 3 and Week 2; all p > 0.05), NP height showed a trend toward reduction on the ligated side at Week 8 without reaching statistical significance (p = 0.076), whereas AF height was significantly reduced compared with the contralateral side (p = 0.001). Radiological assessments failed to detect significant bilateral differences, emphasizing the superior sensitivity of histopathological and morphometric analyses in identifying early and progressive degenerative changes. Conclusion: The proposed unilateral three-level lumbar artery ligation model successfully reproduces the acute, subacute, and chronic stages of IVDD through controlled vascular insufficiency. By avoiding direct mechanical damage to the intervertebral disc, this approach more closely reflects the stepwise pathophysiological evolution of vascular-related IVDD than conventional mechanistically induced models. This model demonstrates consistent and progressive degeneration at histopathological and morphometric levels, providing a robust, reproducible, and clinically relevant platform for investigating vascular contributions to IVDD and for the preclinical evaluation of regenerative and therapeutic strategies.