Document Detail


Insufficient acetabular version increases blood metal ion levels after metal-on-metal hip resurfacing.
MedLine Citation:
PMID:  21656317     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Many factors affect the blood metal ion levels after metal-on-metal (MOM) hip arthroplasty. The main surgically adjustable variable is the amount of coverage of the head provided by the cup which is a function of the inclination and version angles. However, most studies have used plain radiographs which have questionable precision and accuracy, particularly for version and large diameter metal heads; further, these studies do not simultaneously assess version and inclination. Thus the relationship between version and blood metal ions levels has not been resolved.
QUESTIONS/PURPOSES: We determined whether cup inclination and version influence blood metal ion levels while adjusting for age at assessment, gender, body mass index, horizontal femoral offset, head size, manufacturer hip type, and Oxford hip score.
PATIENTS AND METHODS: We prospectively followed 100 individuals (51 females, 49 males) with unilateral MOM hip resurfacing who underwent clinical assessment, CT scanning, and blood metal ion measurement. Multiple regression analysis was used to determine which variables were predictors of blood metal ion levels and to model the effect of these variables.
RESULTS: Only cup inclination, version angles, and gender influenced blood cobalt or chromium levels. Cobalt and chromium levels positively correlated with inclination angle and negatively correlated with version angle. The effect of changes in version angle was less than for inclination angle. Based on our observations, we developed a formula to predict the effect of these parameters on metal ion levels.
CONCLUSIONS: Our data suggest insufficient cup version can cause high blood metal ions after MOM hip arthroplasty. We were unable to show that excessive version caused high levels.
LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
Authors:
Alister J Hart; John A Skinner; Johann Henckel; Barry Sampson; Fabiana Gordon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-06-09
Journal Detail:
Title:  Clinical orthopaedics and related research     Volume:  469     ISSN:  1528-1132     ISO Abbreviation:  Clin. Orthop. Relat. Res.     Publication Date:  2011 Sep 
Date Detail:
Created Date:  2011-08-02     Completed Date:  2011-09-30     Revised Date:  2011-09-30    
Medline Journal Info:
Nlm Unique ID:  0075674     Medline TA:  Clin Orthop Relat Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2590-7     Citation Subset:  AIM; IM    
Affiliation:
Department of Orthopaedic Surgery, Imperial College, Charing Cross Hospital Campus, London SW7 2AZ, UK. a.hart@imperial.ac.uk
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MeSH Terms
Descriptor/Qualifier:
Acetabulum / physiopathology,  radiography,  surgery*
Adult
Aged
Analysis of Variance
Arthroplasty, Replacement, Hip / adverse effects,  instrumentation*
Chromium / blood
Cobalt / blood*
Female
Hip Joint / physiopathology,  radiography,  surgery*
Hip Prosthesis*
Humans
Linear Models
London
Male
Middle Aged
Prospective Studies
Prosthesis Design
Risk Assessment
Risk Factors
Sex Factors
Surface Properties
Time Factors
Tomography, X-Ray Computed
Chemical
Reg. No./Substance:
7440-47-3/Chromium; 7440-48-4/Cobalt

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


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