Alterations in the mechanical behavior of the human lumbar nucleus pulposus with degeneration and aging.

Journal Academic Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.

This study tested the hypothesis that changes in the morphology and composition of the nucleus pulposus with age and degeneration have associated changes in its mechanical properties. A torsional shear experiment was used to determine viscoelastic shear properties of cylindrical samples of human nucleus pulposus with large ranges of grades of morphological degeneration (normal to severely degenerated) and ages (range: 16-88 years; average: 57 +/- 21.5 years). Viscoelastic shear properties were determined from stress-relaxation and dynamic sinusoidal tests. A linear viscoelastic law with a variable-amplitude relaxation spectrum was used to model experimental behaviors of nucleus pulposus specimens. A statistically significant increase in the instantaneous and dynamic shear moduli was found with increasing age and grade of degeneration; the values for moduli ranged from 5.0 to 60 kPa. A significant decrease in tan delta was also detected; the values ranged from 0.43 to 0.33, indicating a decreased capacity for the nucleus pulposus to dissipate energy. The dynamic modulus and tan delta were also significantly affected by frequency. It was generally concluded that the nucleus pulposus undergoes a transition from "fluid-like" behavior to more "solid-like" behavior with aging and degeneration.

Full Text

Duke Authors

Cited Authors

  • Iatridis, JC; Setton, LA; Weidenbaum, M; Mow, VC

Published Date

  • March 1997

Published In

Volume / Issue

  • 15 / 2

Start / End Page

  • 318 - 322

PubMed ID

  • 9167638

International Standard Serial Number (ISSN)

  • 0736-0266

Digital Object Identifier (DOI)

  • 10.1002/jor.1100150224


  • eng

Citation Source

  • PubMed