Document Detail

Simplified motion and loading compared to physiological motion and loading in a hip joint simulator.
MedLine Citation:
PMID:  10902437     Owner:  NLM     Status:  MEDLINE    
Two wear tests were conducted using the Durham Hip Joint Wear Simulator to investigate the effects of simplified motion and loading on ultra-high molecular weight polyethylene (UHMWPE) acetabular cup wear rates. Bovine serum was used as a lubricant and a gravimetric technique was used to measure wear. The first wear test duration was 7.1 x 10(6) cycles and investigated the effect of simplified loading. This was achieved by using full physiological motion and loading for the first 5 x 10(6) cycles of the test, then physiological motion with simplified loading for the final 2.1 x 10(6) cycles of the wear test. The UHMWPE acetabular cup wear rates using full physiological motion and loading were 32.2 and 51.7 mm3/10(6) cycles against zirconia and CoCrMo femoral heads respectively. Using simplified loading the cup wear rates were 30.1 and 49.2 mm3/10(6) cycles against zirconia and CoCrMo respectively which was not significantly different from wear rates with physiological loading. The effect of simplified motion was investigated in a second wear test of 5.0 x 10(6) cycles duration. Physiological loading was applied across the prosthesis with physiological motion in the flexion/extension plane only. Mean wear of the acetabular component dropped to 0.197 mm3/10(6) cycles. The surfaces of all the acetabular cups were subject to gross examination, optical microscopy and scanning electron microscopy. No notable difference was observed between the cups subjected to physiological motion and loading and those subjected to simplified loading. The cups worn with a single plane of motion had a much smaller worn area and a notable difference in surface features to the other cups. Simplifed loading is therefore an acceptable simplification in simulator testing but simplifying motion to the flexion/extension plane axis only is unacceptable.
S L Smith; A Unsworth
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine     Volume:  214     ISSN:  0954-4119     ISO Abbreviation:  Proc Inst Mech Eng H     Publication Date:  2000  
Date Detail:
Created Date:  2000-08-24     Completed Date:  2000-08-24     Revised Date:  2009-06-08    
Medline Journal Info:
Nlm Unique ID:  8908934     Medline TA:  Proc Inst Mech Eng H     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  233-8     Citation Subset:  IM    
Centre for Biomedical Engineering, University of Durham, UK.
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MeSH Terms
Equipment Failure Analysis / methods*
Hip Joint / physiology*
Hip Prosthesis*
Materials Testing
Prosthesis Design
Reg. No./Substance:

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

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