Document Detail

Replacing the nucleus pulposus of the intervertebral disk: prediction of suitable properties of a replacement material using finite element analysis.
MedLine Citation:
PMID:  15348304     Owner:  NLM     Status:  PubMed-not-MEDLINE    
An axisymmetric finite element model of a human lumbar disk was developed to investigate the properties required of an implant to replace the nucleus pulposus. In the intact disk, the nucleus was modeled as a fluid, and the annulus as an elastic solid. The Young's modulus of the annulus was determined empirically by matching model predictions to experimental results. The model was checked for sensitivity to the input parameter values and found to give reasonable behavior. The model predicted that removal of the nucleus would change the response of the annulus to compression. This prediction was consistent with experimental results, thus validating the model. Implants to fill the cavity produced by nucleus removal were modeled as elastic solids. The Poisson's ratio was fixed at 0.49, and the Young's modulus was varied from 0.5 to 100 MPa. Two sizes of implant were considered: full size (filling the cavity) and small size (smaller than the cavity). The model predicted that a full size implant would reverse the changes to annulus behavior, but a smaller implant would not. By comparing the stress distribution in the annulus, the ideal Young's modulus was predicted to be approximately 3 MPa. These predictions have implications for current nucleus implant designs.
J R Meakin
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of materials science. Materials in medicine     Volume:  12     ISSN:  0957-4530     ISO Abbreviation:  J Mater Sci Mater Med     Publication Date:  2001 Mar 
Date Detail:
Created Date:  2004-09-06     Completed Date:  2005-03-07     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9013087     Medline TA:  J Mater Sci Mater Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  207-13     Citation Subset:  -    
Copyright Information:
Copyright 2001 Kluwer Academic Publishers
Department of Biomedical Physics and Bioengineering, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK.
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