The effect of degenerative morphological changes of the intervertebral disc on the lumbar spine biomechanics: a poroelastic finite element investigation

Abstract

Intervertebral disc degeneration involves changes in the spinal anatomical structures. The mechanical relevance of the following changes was investigated: disc height, endplate sclerosis, disc water content, permeability and depressurisation. A poroelastic nonlinear finite element model of the L4–L5 human spine segments was employed. Loads represented a daily cycle (500 N compression combined with flexion–extension motion for 16 h followed by 200 N compression for 8 h). In non-degenerative conditions, the model predicted a diurnal axial displacement of 1.32 mm and a peak intradiscal pressure of 0.47 MPa. Axial displacement, facet force and range of motion in flexion–extension are decreased by decreasing disc height. By decreasing the initial water content, axial displacement, facet force and fluid loss were all reduced. Endplate sclerosis did not have a significant influence on the calculated results. Depressurisation determined an increase of the disc effective stress, possibly inducing failure. Degenerative instability was not calculated in any simulations.

Keywords:

• lumbar spine
• spine biomechanics
• disc degeneration
• finite element
• poroelastic
• intradiscal pressure

Acknowledgement

This project is funded by the EU project GENODISC (HEALTH-F2-2008-201626).

Notes

1. Fabio Galbusera is a Ph.D. student at the University of Ulm, Germany, and has an exclusive research collaboration with IRCCS Istituto Ortopedico Galeazzi, Milan, Italy

2. Email: [email protected]

3. Email: [email protected]

4. Email: [email protected]

Additional information

Notes on contributors

Fabio Galbusera

1

Hendrik Schmidt

2

Cornelia Neidlinger-Wilke

3

Hans-Joachim Wilke

4