Document Detail

In vivo dynamic stiffness of the porcine lumbar spine exposed to cyclic loading: influence of load and degeneration.
MedLine Citation:
PMID:  9493772     Owner:  NLM     Status:  MEDLINE    
The dynamic axial stiffness of the L2-3 motion segment subjected to vibratory loading under intact and injured states of the intervertebral disc was studied using an in vivo porcine model. Three groups of animals with the following states of the intervertebral discs were studied: intact disc, acutely injured disc, and degenerated disc. A miniaturized servo-hydraulic exciter was used to sinusoidally vibrate the motion segment from 0.05 to 25 Hz under a compressive load with a peak value of either 100 or 200 N. The dynamic axial stiffness of the intervertebral disc was calculated at 1-Hz intervals over the frequency range. The results showed that the dynamic axial stiffness was frequency dependent. A positive relationship was found between an increase in mean dynamic stiffness and load magnitude. An increase in mean stiffness with successive exposures at the same load magnitude was observed, despite the allowance of a recovery period between loading. The greatest difference was noted between the first and second load sets. No significant change in stiffness was found due to an acute disc injury, whereas a significant increase in mean stiffness was found for the degenerated disc group as compared with the intact group. The form of the frequency response curve, however, remained relatively unaltered regardless of the degenerated state of the disc. With heavier loads, repeated loading, and/or disc degeneration, the stiffness of the intervertebral disc increases. An increase in stiffness can mean a reduction in the amount of allowable motion within the motion segment or a potentially harmful increase in force to obtain the desired motion. This may locally result in greater stresses due to an altered ability of the disc to distribute loads.
A Kaigle; L Ekström; S Holm; M Rostedt; T Hansson
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of spinal disorders     Volume:  11     ISSN:  0895-0385     ISO Abbreviation:  J Spinal Disord     Publication Date:  1998 Feb 
Date Detail:
Created Date:  1998-04-13     Completed Date:  1998-04-13     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8904842     Medline TA:  J Spinal Disord     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  65-70     Citation Subset:  IM    
Department of Orthopaedics, Göteborg University, Sahlgrenska University Hospital, Sweden.
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MeSH Terms
Compressive Strength
Disease Models, Animal
Intervertebral Disk* / injuries,  pathology,  physiopathology
Lumbar Vertebrae

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