Effect of intervertebral disc degeneration on biomechanical behaviors of a lumbar motion segment under physiological loading conditions

The consideration of biomechanical alterations due to intervertebral disc (IVD) degeneration is crucial for the accurate analysis of spine biomechanics. In this study, finite element (FE) models of the L4-L5 motion segment with full coverage of the degeneration grades from healthy IVD to severe degeneration were developed. The effects of IVD degeneration on spine biomechanics were analyzed under physiological loading conditions using compressive forces and bending moments. The FE models of all degeneration grades were consistent with published data in terms of the ranges of motion. Severe IVD degeneration showed lower inter-segmental rotations in flexion-extension and lateral bending, lower intradiscal pressure in all motions, higher facet joint forces in lateral bending and axial rotation, and higher von-Mises stress in annulus ground substance in all motions versus the healthy IVD. These findings could provide fundamental information for understanding the characteristics of the biomechanical behaviors of degenerated lumbar motion segments.