Numerical study of lateral bending influence on lumbar intervertebral disc

The objective of this study is to investigate the influence of in the frontal plane constrained and free lateral bending moves on lumbar spine intervertebral disc and to decide whether lateral bending could be beneficial for lumbar spine rehabilitation. A three dimensional poroelastic finite element model of L4-L5 intervertebral disc was used to investigate the influence of lateral bending moves on healthy and degenerated lumbar intervertebral discs. Results of finite element modeling show that stress values in moderately degenerated annulus fibrosus increase more when lateral bending is combined with flexion and extension, also, additional flexion, extension and axial rotation movements reduce fluid velocity in nucleus pulposus compared with pure (in the frontal plane constrained) lateral bending. These results suggest that pure lateral bending exercise could be more beneficial than other moves in order to achieve better nutrition of intervertebral disc, and that degeneration of intervertebral discs should be evaluated before defining an intensity of lateral bending exercise.