An Examination of the Mechanical Properties of the Annulus Fibrosus: The Effect of Vibration on the Intra-Lamellar Matrix Strength

This study examined how whole-body vibration exposure affects the mechanical integrity of the intra-lamellar matrix of the intervertebral disc’s annulus fibrosus. Porcine cervical FSUs were subjected to static compression or sinusoidal vibration prior to testing individual annular lamellae under tension perpendicular to collagen fibers. Vibrated lamellae exhibited significantly larger toe regions in stress–stretch curves without changes in linear modulus or ultimate strength, suggesting sub-failure matrix damage (likely elastin or proteoglycan crosslinks) rather than fiber rupture. Regional analysis showed interaction effects between anterior/posterior and superficial/deep tissue layers. The authors conclude that vibration induces early-stage damage in the annular intra-lamellar matrix, compromising load transfer between collagen bundles and potentially facilitating delamination.