Disc degeneration promotes regional inhomogeneity in the trabecular morphology of loaded rat tail vertebrae

Abstract

Summary: Background: There is a close relationship between the vertebral trabecular morphology and the condition of the associated disc. Objective: The relationship between disc degeneration and vertebral trabecular inhomogeneity is unclear. This study aimed to analyse the regional changes of vertebral trabecular morphology after disc degeneration. Methods: Thirty male Sprague–Dawley rats were randomly assigned to five groups. Group 1 served as an experimental group for the assessment of disc degeneration induced by needle puncture. Group 2 served as a sham group for trabecular morphology analysis. In Group 3, rats had their tail bent between the eighth and tenth coccygeal vertebrae. In Group 4, the tail of rats was bent with a compression load of 4.5 N. In Group 5, rats first underwent disc degeneration induced by a needle puncture before their tail was bent with a compressive load of 4.5 N. Magnetic resonance imaging was performed on all groups, and histological examination was performed on rodents from Group 1. The ninth coccygeal vertebrae of rats from Groups 2–5 were scanned by Micro-computed tomography. Trabecular morphologic changes were assessed in the concave and convex regions by bone volume fraction, trabecular number, trabecular thickness and trabecular separation. Results: Vertebral trabecular morphology in the concave region improved significantly, whereas the convex region was of significantly lower trabecular morphologic parameters with disc degeneration. The difference in trabecular morphologic parameters between the convex and concave regions increased significantly after disc degeneration. Conclusion: Disc degeneration promotes regional inhomogeneity in the vertebral trabecular morphology, with the convex region of the vertebrae having the worse trabecular bone morphology than the concave region. The translational potential of this article: Our study indicates that disc degeneration promotes regional inhomogeneity in the vertebral trabecular morphology. Regional variations in trabecular microarchitecture are helpful to predict vertebral fragility. This may help to elucidate the mechanisms by which disc degeneration contributes to vertebral fracture. Keywords: Animal model, Disc degeneration, Regional inhomogeneity, Trabecular morphology