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document
Metal release and metal allergy after total hip replacement with resurfacing versus conventional hybrid prosthesis . BACKGROUND Metal-on-metal ( MOM ) total hip arthroplasties were reintroduced because of the problems with osteolysis and aseptic loosening related to polyethylene wear of early metal-on-polyethylene ( MOP ) arthroplasties . The volumetric wear rate has been greatly reduced with MOM arthroplasties ; however , because of nano-size wear particles , the absolute number has been greatly increased . Thus , a source of metal ion exposure with the potential to sensitize patients is present . We hypothesized that higher amounts of wear particles result in increased release of metal ions and ultimately lead to an increased incidence of metal allergy . METHODS 52 hips in 52 patients ( median age 60 ( 51-64 ) years , 30 women ) were randomized to either a MOM hip resurfacing system ( ReCap ) or a standard MOP total hip arthoplasty ( Mallory Head/Exeter ) . Spot urine samples were collected preoperatively , postoperatively , after 3 months , and after 1 , 2 , and 5 years and tested with inductively coupled plasma-sector field mass spectrometry . After 5 years , hypersensitivity to metals was evaluated by patch testing and lymphocyte transformation assay . In addition , the patients answered a questionnaire about hypersensitivity . RESULTS A statistically significant 10- to 20-fold increase in urinary levels of cobalt and chromium was observed throughout the entire follow-up in the MOM group . The prevalence of metal allergy was similar between groups . INTERPRETATION While we observed significantly increased levels of metal ions in the urine during the entire follow-up period , no difference in prevalence of metal allergy was observed in the MOM group . However , the effect of long-term metal exposure remains uncertain .
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Intervention_Physical
total hip replacement with resurfacing
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Intervention_Physical
conventional
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Intervention_Surgical
hybrid prosthesis
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Intervention_Physical
Metal-on-metal ( MOM ) total
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Intervention_Surgical
hip arthroplasties
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Intervention_Physical
MOM hip resurfacing system ( ReCap )
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Intervention_Physical
standard MOP total hip arthoplasty ( Mallory Head/Exeter )
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Intervention_Physical
MOM
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Intervention_Physical
MOM
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Outcome_Physical
Metal release
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Outcome_Physical
metal allergy
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Outcome_Adverse-effects
release of metal ions
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Outcome_Adverse-effects
incidence of metal allergy
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Outcome_Adverse-effects
hypersensitivity to metals
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Outcome_Physical
hypersensitivity
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Outcome_Physical
urinary levels of cobalt and chromium
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Outcome_Adverse-effects
metal allergy
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Outcome_Physical
levels of metal ions in the urine
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Outcome_Physical
prevalence of metal allergy
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Participant_Condition
total hip replacement with resurfacing
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Participant_Condition
Metal-on-metal ( MOM )
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Participant_Sample-size
52
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Participant_Age
60
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Participant_Age
51-64
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Participant_Age
30 women