Document Detail


An in vitro comparison of the motion behavior of different bipolar endoprostheses.
MedLine Citation:
PMID:  10537257     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The relative motion of 3 different bipolar endoprostheses was evaluated in vitro. A paired fresh acetabulum was frozen at 0 degrees C and defrosted 12 hours before the experiment. Three bipolar endoprostheses were evaluated: UNIQHIP system (United Orthopedics), UHR system (Osteonics), and AML system (Depuy). The surface roughness and spherical roundness of outer shells and inner heads of the bipolar prostheses were measured before the experiments. The acetabulum and outer shell of the bipolar prostheses were fixed on a Bionix 858 material testing system axially by separate fixation tools. The axial load of 1,400 N and 2,800 N was than applied on the specimen. The axis was rotated from 0 degrees to 90 degrees at the speed of 1 degree/s. All 3 outer shells were tested to this paired acetabulum randomly and separately. The frictional torque on the outer bearing surface of the different prostheses was recorded by the material testing system. The frictional torque on the inner bearing surface was also measured by the same procedure as was done for the outer bearing. The final results were statistically compared by the 1-way analysis of variance test method. Bipolar prostheses of the UHR system showed the largest frictional torque on outer bearing when it was loaded with 1,400 N and 2,800 N. The final results showed that all the bipolar prostheses had ideal motion behavior when functioning under the loading of 1,400 N. The frictional torque on the inner bearing was found to be larger than the frictional torque on the outer bearing in some prostheses when the loading was increased to 2,800 N. Thus, the bipolar endoprostheses functioned as unipolar prostheses. The only relative motion remained between the outer bearing surface and the acetabulum. This effect causes complications, such as implant protrusion in the acetabulum.
Authors:
C Y Lung; T H Chen; C K Cheng; K S Lee; W H Lo
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Randomized Controlled Trial    
Journal Detail:
Title:  The Journal of arthroplasty     Volume:  14     ISSN:  0883-5403     ISO Abbreviation:  J Arthroplasty     Publication Date:  1999 Oct 
Date Detail:
Created Date:  1999-11-17     Completed Date:  1999-11-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8703515     Medline TA:  J Arthroplasty     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  822-6     Citation Subset:  IM    
Affiliation:
Orthopaedic Biomechanics Laboratory, Institute of Biomedical Engineering, National Yang Ming University, Taipei, Taiwan, ROC.
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MeSH Terms
Descriptor/Qualifier:
Hip Prosthesis*
Humans
Prosthesis Design
Torque

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


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