Three National Joint Registries Indicate Metal-on-Metal Hip Implants Associated with Higher Revision Rates than Traditional Metal-on-Polyethylene Hip Replacements
NEW YORK — A recent comprehensive assessment of available data, authored by, among others, the director of epidemiology at the United States Food and Drug Administration, and the director of the Australian National Joint Registry, concluded that the data do not indicate any advantage for metal-on-metal hip implants compared with traditional metal on polyethylene bearings.
The study, Sedrakyan A., et al., Comparative Assessment of Implantable Hip Devices with Different Bearing Surfaces: Systematic Appraisal of Evidence. BMJ 2011;343:d7434, is thought to be the first systematic appraisal of clinical outcomes after hip replacement with various bearing surfaces.
The authors also found that metal-on-metal hip implants were associated with higher occurrence of revision compared with traditional metal-on-polyethylene hip replacements in the adjusted analyses of three national joint registries: Australian, New Zealand, and England and Wales National Registries (including over 720,000 patients). The authors further noted that their findings related to clinical outcomes of metal-on-metal implants were augmented by reports that show severe metallosis associated with such implants.
In the view of the authors, “[A] large and high quality randomized controlled trial of bearing surfaces in total hip replacements need to be conducted before any claims of benefit are made.” This view is in contrast to the marketing campaigns of some of the manufacturers of metal-on-metal hip replacements that suggest that the metal-on-metal system offers benefits such as greater durability and longer useful life, less wear and lesser probability of dislocation than traditional hip replacements.