Document Detail

Influence of osmotic pressure changes on the opening of existing cracks in 2 intervertebral disc models.
MedLine Citation:
PMID:  16845351     Owner:  NLM     Status:  MEDLINE    
STUDY DESIGN: An experimental hydrogel model and a numerical mixture model were used to investigate why the disc herniates while osmotic pressure is decreasing. OBJECTIVE: To investigate the influence of decreasing osmotic pressure on the opening of cracks in the disc. SUMMARY OF BACKGROUND DATA: In the degeneration process, the disc changes structure (i.e., cracks occur, and osmotic pressure decreases). Disc herniation typically develops when hydration declines, but, on the other hand, it is said that the anulus of a highly hydrated disc has a high risk of rupture. We hypothesized that disc herniation is preceded by the opening of cracks as a result of decreasing osmotic pressure. METHODS: The osmotic pressure was changed in hydrogel samples with a crack, which was visualized with a confocal laser scanning microscope (Zeiss, Göttingen, Germany). A 2-dimensional finite element mixture model simulated a decrease in osmotic pressure around a crack in a swelling material. RESULTS: Experiments and simulations show that a decrease in osmotic pressure results in the opening of cracks. The simulations show high effective stress concentrations around the crack tip, while the overall stress level decreases, indicating an increased risk of crack growth. CONCLUSIONS: Decreasing osmotic pressure in a degenerating intervertebral disc enhances the opening of existing cracks, despite the concomitant decrease in anular stresses.
Silvia Wognum; Jacques M Huyghe; Frank P T Baaijens
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Spine     Volume:  31     ISSN:  1528-1159     ISO Abbreviation:  Spine     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-07-17     Completed Date:  2006-08-09     Revised Date:  2009-07-09    
Medline Journal Info:
Nlm Unique ID:  7610646     Medline TA:  Spine (Phila Pa 1976)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1783-8     Citation Subset:  IM    
Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
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MeSH Terms
Edema / complications*
Intervertebral Disk / injuries*
Osmotic Pressure
Spinal Diseases / complications*
Spinal Fractures / etiology*
Comment In:
Spine (Phila Pa 1976). 2006 Jul 15;31(16):E525-6; discussion E527   [PMID:  16845336 ]

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