Effect of shear force on intervertebral disc (IVD) degeneration: an in vivo rat study.

Abstract

Mechanical stress on the intervertebral disc (IVD) may contribute significantly to IVD degeneration, although its pathomechanism has not been fully understood. The purpose of this study was to test the hypothesis that sustained application of static shear force would result in IVD degeneration with minimum injury. We applied shear force on the rat lumbar spine (L5-L6) using a custom-designed loading device for 1 or 2 weeks. Degenerative changes such as nucleus pulposus cavity loss and border disruption were observed from the histology sections, indicating that the application of sustained dorsoventral shear force on the L6 vertebra induced degeneration of the IVDs in L5-L6 and adjacent levels of motion segment in 1 and 2 weeks. The findings of the present study could be useful for gaining a more relevant understanding of the biomechanical load factors of IVD degeneration not only for enabling better therapeutic interventions but also reducing the risk of low back injury.