Researchers Find Evidence of Genotoxicity in Nanoparticles Released by Metal-on-Metal Hip Implants


Researchers Find Evidence of Genotoxicity in Nanoparticles Released by Metal-on-Metal Hip ImplantsOverview: For some time, medical professionals have been aware that metal-on-metal hips can shed tiny pieces of metal in the body and suspected that these nanoparticles cause damage to a cell’s genetic material. But up until now, few have looked into how these debris interact with tissues in the body. The latest study has linked inflammation in failed metal-on-metal hip implants to cobalt ions (Co2+), which studies have shown to be genotoxic.



  • A study published in Chemical Communications has linked the inflammation in failed metal-on-metal implants to the release of Co2+ , which is known to caused damage to a cell’s genetic material
  • Researchers used high resolution X-rays in combination with electron spectroscopy to analyze the electronic structure of particles
  • All-metal hips are associated with high failure rates and other complications; researchers have long suspected the release of metal ions as a major risk factor

Manufacturer & Product

Johnson & Johnson/ DePuy Orthopaedics Biomet Smith & Nephew Zimmer Wright Medical Technology
ASR (recalled) M2a Magnum Oxinium Durom CONSERVE Hip Systems
Pinnacle   Birmingham BHR   Profemur

Side Effects & Complications

  • High failure rate
  • Necrosis (tissue death)
  • Increased levels of cobalt and chromium ions
  • Pain at the implant, sometimes spreading to the groin and back
  • Osteolysis (bone loss)
  • Fluid collections/solid masses around the hip joint

The Study

The study was published online on June 13th in Chemical Communications journal. Researchers combined two different methods to conduct their study; X-ray absorption spectroscopy (XAS) and electron energy-loss spectroscopy (EELS) were used analyze tissue samples taken from patients with a failed all-metal implant. Using this new approach, researchers found that Co2+ ions are released, and residual chromium is oxidized. According to the authors, this “overt release” of cobalt ions “is probably responsible for the inflammatory response”. In the past, Co2+ ions have been linked to genotoxicity, meaning that they cause damage to a cell’s genetic material.

“We were able to meet patients who had these failing implants and we could see first-hand the chronic inflammation, pain and loss of mobility they experienced.” said co-author Mary Ryan. “Our work is one of the first to study these nanoparticles and the effects that they have on damaged cells and tissue. This has enabled us to understand in much more detail the side effects that these materials may have in patients.”

Concerns Over Metal Ions

Metal ions have been one of the major health concerns with regards to metal-on-metal hips. Since the devices uses a metal head rubbing against a metal cup, the implant can shed tiny particles of chromium and cobalt. Previous research has linked metal hips to a host of complications leading to revision surgery to correct the problem. In May, the Journal of Arthroplasty published a study showing that metal implants corrode faster than metal-on-plastic.