Role of disc injury in inducing disc degeneration: A layered composite finite element approach

B. T. Monroe*, V. K. Goel, L. G. Gilbertson, James Neil Weinstein

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The contributions of `mechanical' factors in producing the separation of the laminae in a degenerated disc are not well understood. We believe it is due to the increase in interlaminar shear stresses at the layer interfaces following `injury' to the disc. A three-dimensional nonlinear finite element model of an intact L3-4 lumbar motion segment was created to predict the interlaminar shear stresses within the intervertebral disc as a function of disc injury to test our hypothesis. Injury was modeled as element removal in the postero-lateral portion of the disc. The degree of injury was increased from slight injury to complete discectomy with the nucleus removed. Axial compression, lateral bending, flexion-extension, and pure torsional loads were analyzed. Disc bulge, as well as displacements and coupled motions were predicted. Unlike other models, the model created for this study included a `true' fiber reinforced composite element for the annulus fibrosus. This element provided a method of obtaining the interlaminar shear stresses in the disc. It was predicted in all load cases, except torsion, that the interlaminar shear stresses increase with injury as do the coupled motions. For torsional loading the interlaminar shear stresses decreased 35% from the intact model to the complete discectomy model. For axial compression, there was a 102% increase in the interlaminar shear stresses from the intact model to the model with complete discectomy. Similarly, the increases were 35%, 57%, and 57% for extension, flexion, and lateral bending respectively. These large shear stresses, caused by asymmetry in the disc structure due to injury, are believed to be a primary cause of further degeneration through laminae separation.

Original languageEnglish (US)
Title of host publication1992 Advances in Bioengineering
PublisherPubl by ASME
Number of pages4
ISBN (Print)0791811166
StatePublished - Dec 1 1992
EventWinter Annual Meeting of the American Society of Mechanical Engineers - Anaheim, CA, USA
Duration: Nov 8 1992Nov 13 1992


OtherWinter Annual Meeting of the American Society of Mechanical Engineers
CityAnaheim, CA, USA

ASJC Scopus subject areas

  • Engineering(all)

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