Cross-species structure-mechanics prediction in the intervertebral disc

Lower Structure Index (SI) predicts elevated deformation in rat and mini-pig intervertebral discs, with structure–strain inverse correlations tightening to Spearman p values of about -0.5 to -0.7 across higher-strain domains.

• Why it matters: Animal IVD models are uncertain for human pathophysiology, and few studies link hierarchical collagen structure to mechanical function across species in a unified framework.
• What they did: Rat, mini-pig, and human IVDs (n = 3/species) were imaged by synchrotron CT, with rat and mini-pig discs also compressed in situ and analyzed by DVC; SI combined local anisotropy and fibre orientation, then was tested using finite-element modelling and synthetic fibre phantoms.
• The result: SI mapped mechanically vulnerable regions, showed scale-dependent structural conservation across species, and in human degenerated discs revealed heterogeneous redistribution; fibril-informed homogenisation enabled anisotropic organ-scale modelling that independently supported SI-based predictions.

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