Document Detail

The effect of cyclic compression on the mechanical properties of the inter-vertebral disc: an in vivo study in a rat tail model.
MedLine Citation:
PMID:  12620780     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To assess the changes in the mechanical properties of inter-vertebral discs in vivo following static and cyclic compressive loading of different frequencies. DESIGN: An in vivo biomechanical study using a rat-tail model of the inter-vertebral disc.Background. Mechanical loading has been suggested as playing a major role in the etiology of disc degeneration, but the relationship is still not fully understood. METHODS: Sixty Sprague-Dawley rats were subject to daily compressive stress via pins inserted in the 6th and 7th caudal vertebrae over a two-week loading period. Animals were randomly divided into a sham group (pin insertion, no loading), a static loading group, or cyclic loading groups of 0.5, 1.5, or 2.5 Hz. Loading was applied for 1 h each day from the 3rd to 17th day following pin insertion, and the angular compliance, angular laxity, and inter-pin distance were measured in vivo at days 0, 3, 10 and 17. RESULTS: Changes in the inter-vertebral disc height depended on the frequency of loading, with the decrease in disc height in the static compression group significantly greater than that in all other groups, whereas the decrease in the 1.5 Hz cyclic compression group was significantly smaller than that in all other compression groups. CONCLUSIONS: Changes in disc properties depend on both the total load exposure and the frequency of loading. Cyclic loading in general produced less marked changes than static loading, but loading at particular frequencies may result in more severe changes. RELEVANCE: Previous studies have shown the in vivo changes in the mechanical properties of inter-vertebral discs to depend on the magnitude and duration of loading. In this study, a frequency dependent response to cyclic loading is also demonstrated.
Congo T S Ching; Daniel H K Chow; Fiona Y D Yao; Andrew D Holmes
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Clinical biomechanics (Bristol, Avon)     Volume:  18     ISSN:  0268-0033     ISO Abbreviation:  Clin Biomech (Bristol, Avon)     Publication Date:  2003 Mar 
Date Detail:
Created Date:  2003-03-06     Completed Date:  2003-05-09     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8611877     Medline TA:  Clin Biomech (Bristol, Avon)     Country:  England    
Other Details:
Languages:  eng     Pagination:  182-9     Citation Subset:  IM    
Jockey Club Rehabilitation Engineering Centre, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR, PR China.
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MeSH Terms
Compressive Strength
Intervertebral Disk / physiology*,  radiography
Rats, Sprague-Dawley
Reference Values
Reproducibility of Results
Sensitivity and Specificity
Tail / physiology*,  radiography
Weight-Bearing / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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