Oral Posters: Thoraco-lumbar Degenerative

Presented by: Z-P Luo - View Audio/Video Presentation (Members Only)

Author(s):

T. Liang(1), L.-L. Zhang(1), W. Xia(1), H.-L. Yang(1), Z.-P. Luo(1)

(1) Orthopaedic Institute, Department of Orthopaedics, The First Affiliated Hospital, Soochow University, Suzhou, China

Abstract

The precise mechanism of intervertebral disc degeneration remains unrevealed, especially at the nanoscale. The purpose of this study was to determine the alternation of collagen fibrils in annulus fibrosus after degeneration and to discuss the intervertebral disc degeneration pathogenesis at the nanoscale. An intervertebral disc degeneration model was induced by combining bending moment of 0.01Nžm and compressive loading of 1.8, 4.5 and 7.2N, respectively, on rat tails using an external fixation device. The structure and the elastic modulus of individual collagen fibril at nanoscale was examined two weeks after loading by the use of atomic force microscopy. The collagen fibrils altered from diameter of 170±18nm and elastic modulus of 0.86±0.12GPa in the intact annulus fibrosus, to diameter of 310±24nm (P<0.001) and elastic modulus of 1.27±0.30GPa (P=0.003) on the concave side after bearing 7.2N. The collagen fibrils thickened and stiffened to various degrees in degeneration process, and displayed distinctions between the concave and the convex from the inner layer to the outer layer. In comparison, significant disorder and decrease of cell numbers in the annulus fibrosus after bearing loading were observed at the microscale from the hematoxylin/eosin staining, suggesting the induction of the structural rupture and functional depression of intervertebral disc. The results of this study indicated that the degeneration was not only associated with the disorder at microscale, but also the collagen fibrils alteration at nanoscale, leading possibly to changes in the mechanical and physiological environment around the annulus fibrosus cells.