Increased Mortality in Metal-on-Metal versus Non-Metal-on-Metal Primary Total Hip Arthroplasty at 10 Years and Longer Follow-Up: A Systematic Review and Meta-Analysis.
OBJECTIVE
There are concerns about increased mortality in patients with metal-on-metal bearings in total hip arthroplasty (THA).


OBJECTIVE
To determine the mortality and the morbidity in patients with metal-on-metal articulations (MOM THA) compared to patients with non-metal-on-metal articulations (non-MOM THA) after primary total hip arthroplasty.


METHODS
Search of PubMed, MEDLINE, EMBASE, Web of Science, Cochrane, CINAHL, AcademicSearchPremier, ScienceDirect, Wiley and clinical trial registers through March 2015, augmented by a hand search of references from the included articles. No language restrictions were applied.


METHODS
Two reviewers screened and identified randomised controlled trials and observational studies of primary total hip arthroplasty comparing MOM THA with non-MOM THA.


METHODS
Two reviewers independently extracted study data and assessed risk of bias. Risk differences (RD) were calculated with random effect models. Meta-regression was used to explore modifying factors.


METHODS
Difference in mortality and difference in morbidity expressed as revisions and medical complications between patients with MOM THA and non-MOM THA.


RESULTS
Forty-seven studies were included, comprising 4,000 THA in randomised trials and over 500,000 THA in observational studies. For mortality, random effects analysis revealed a higher pooled RD of 0.7%, 95%, confidence interval (CI) [0.0%, 2.3%], I-square 42%; the heterogeneity was explained by differences in follow-up. When restricted to studies with long term follow-up (i.e. 10 years or more), the RD for mortality was 8.5%, 95%, CI [5.8%, 11.2%]; number needed to treat was 12. Further subgroup analyses and meta-regression random effects models revealed no evidence for other moderator variables (study level covariates, e.g. resurfacing vs. non-resurfacing MOM) than follow-up duration. The quality of the evidence presented in this meta-analysis was characterized as moderate according to the CLEAR-NPT (for non-pharmacological trials) and Cochrane risk of bias Table.


CONCLUSIONS
Meta-analysis suggests there may be an increased long-term risk of mortality and revision surgery for patients with MOM THA compared to patients with non-MOM THA.


BACKGROUND
PROSPERO 2014:CRD42014007417.
Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
B G
http://orcid.org/0000-0001-5351-5057
BG
Pijls
Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
J M T A
JM
Meessen
Walaeus Library, Leiden University Medical Centre, Leiden, The Netherlands.
J W
http://orcid.org/0000-0003-1120-4781
JW
Schoones
Department of Medical Statistics, Leiden University Medical Center, Leiden, The Netherlands.|Mathematical Institute, Leiden University, Leiden, The Netherlands.
M
M
Fiocco
Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
H J L
HJ
van der Heide
FDA Medical Device Epidemiology (MDEpiNet) Science and Infrastructure Center, U.S. Food and Drug Administration, Silver Spring, MD, United States of America.|Department of Healthcare Policy and Research, Weill Cornell Medical College, New York, NY, United States of America.
A
A
Sedrakyan
Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands.
R G H H
RG
Nelissen
D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods* / Q000401:mortality*; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects / Q000706:statistics & numerical data*; D006801:Humans; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects / Q000706:statistics & numerical data*; D009026:Mortality / Q000639:trends; D011475:Prosthesis Failure / Q000639:trends; D012086:Reoperation / Q000401:mortality / Q000706:statistics & numerical data