Document Detail

Shock absorption in lumbar disc prosthesis: a preliminary mechanical study.
MedLine Citation:
PMID:  12902950     Owner:  NLM     Status:  MEDLINE    
Lumbar disc prostheses have been used in treating symptomatic degenerative disc diseases. A few prostheses of the ball-socket design are currently available for clinical use, the joint mechanism being materialized either with a hard polymer core or a metal-to-metal couple. Other prostheses of "shock absorber" design were not available at the time of the study. The objective of this work was to establish whether there was a difference in the shock absorption capacity between a device having an ultra-high-molecular-weight polyethylene center core and a device having a metal-on-metal bearing. Vibration and shock loading were applied to two lumbar total disc prostheses: PRODISC, manufactured by Spine Solutions, and MAVERICK Total Disc Replacement, manufactured by Medtronic Sofamor Danek. The shock absorption capacity of the device was evaluated by comparing the input and the output force measurements. The disc prosthesis was mounted onto a test apparatus. Each side of the device was equipped with a force sensor. The input shock load and the output resulting forces were simultaneously measured and recorded. The loading force pattern included 1). a static preload of 350 N plus an oscillating vibration of 100 N with frequency sweeping from 0 to 100 Hz and 2). a sudden shock load of 250 N applied over a 0.1-second interval. Both input and output signal data were processed and were transformed into their frequency spectrums. The vibration and shock transmissibility of the device, defined as the ratio of the output spectrum over the input spectrum, were calculated in sweeping the frequency from 0 to 100 Hz. The phase deviation was calculated to characterize the shock absorber effects. For both tested devices under vibration and shock loading, the phase angle displacement between the input and the output signals was 10 degrees. Under oscillating vibration loading, both tested devices had a transmission ratio higher than 99.8%. Over the frequency interval 1-100 Hz, the difference in transmission ratio between the two devices was <0.3%. Under sudden shock loading, both tested devices had a transmission ratio higher than 98%. The difference between the two devices was <0.8%. Both tested devices have identical vibration and shock transmissibility.
J C LeHuec; T Kiaer; T Friesem; H Mathews; M Liu; L Eisermann
Publication Detail:
Type:  Comparative Study; Evaluation Studies; Journal Article    
Journal Detail:
Title:  Journal of spinal disorders & techniques     Volume:  16     ISSN:  1536-0652     ISO Abbreviation:  J Spinal Disord Tech     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-08-06     Completed Date:  2003-10-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  101140323     Medline TA:  J Spinal Disord Tech     Country:  United States    
Other Details:
Languages:  eng     Pagination:  346-51     Citation Subset:  IM    
Department of Orthopedics, CHU Pellegrin Tripode, Bordeaux, France.
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MeSH Terms
Arthroplasty, Replacement / instrumentation*,  methods
Compressive Strength
Energy Transfer
Equipment Failure Analysis / instrumentation,  methods*
Intervertebral Disk Displacement / surgery*
Joint Prosthesis*
Lumbar Vertebrae / surgery*
Oscillometry / methods
Stress, Mechanical

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

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