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
Thoracic Surgery, Video-Assisted
Objective To determine the mortality and the morbidity in patients with metalonmetal articulations (MOM THA) when compared to patients with nonmetalonmetal articulations (nonMOM THA) after primary total hip arthroplasty. Design Systematic review, metaanalyses and metaregression (registration: PROSPERO 2014:CRD42014007417). Method Search of PubMed, MEDLINE, EMBASE, Web of Science, Cochrane, CINAHL, AcademicSearchPremier, ScienceDirect, Wiley and clinical trial registers. We included randomised controlled trials and observational studies of primary total hip arthroplasty comparing MOM THA with nonMOM THA. We used metaregression to identify and evaluate potential modifying variables such as followup duration. Results Fortyseven studies were included, comprising over 4,000 THA in randomised trials and over 500,000 THA in observational studies. For mortality, random effects analysis revealed a higher pooled risk difference (RD) of 0.7% (95%CI: 0.02.3% ; Isquare 42%); the heterogeneity was explained by differences in followup. When restricted to studies with long term followup (i.e. 10 years or more), the RD for mortality was 8,5% (95%CI: 5,811,2). Further subgroup analyses and metaregression random effects models revealed no evidence for other modifying variables (study level covariates, e.g. resurfacing vs. nonresurfacing MOM) than followup duration. Conclusion Metaanalysis suggests there may be an increased longterm risk of mortality associated with MOM THA compared to patients with nonMOM THA. Conflict of interest and financial support: R. Nelissen is a member of the International Medical Device Regulators Forum, a board member of LROI and the chairman of the European Network Orthopaedic Registries. ICMJE forms provided by the authors are available online along with the full text of this article.