Corrosion Expert Witness Opines on Defective Hip Implant Component


Corrosion Expert WitnessThis case involves a claim against the medical device manufacturer of Wright Conserve Hip Replacement, a metal-on-metal total hip prosthesis. Numerous patients in the state of Georgia who have received this implant have suffered complications following total hip arthroplasty, including metallosis, due to corrosion of the head-neck taper. These patients have suffered a range of complications from metallosis, and thus have required revision surgery. It was alleged that the hip implant  system was designed and / or manufactured negligently, and that corrosion caused by mechanical stress on the devices was causing metal to enter the patients’ bloodstreams.

Question(s) For Expert Witness

  • 1. Have you ever done research on the head-neck taper as it pertains to metallosis? If so, please explain the wear and potential failure of its design.
  • 2. Have you previously designed such devices?

Expert Witness Response E-007593

The research group I lead at my university works at the leading edge of artificial hip implant design and analysis. I have done research on the head-neck taper as it pertains to metallosis. The critical aspect of the head-neck taper is failure due to fretting corrosion, which is a combination of fretting wear and a corrosive medium (such as joint fluid). Fretting corrosion generates wear particles that may get absorbed into soft tissue and the blood flow, causing inflammation, high Co and/or Cr levels (in case of a metal femoral head), and ultimately tissue necrosis. This failure mode stems from the modular design of present day hip implants, which allows micro-motion to occur between the different components. I understand the application of artificial hip implants, and the science and engineering that is involved. In addition, I have the track record through my tenure-track academic position, publication, and funding record to be considered an expert in this field.

Expert Witness Response E-007633

I am an ex-FDA medical device reviewer and I have worked on multiple hip implant cases previously as a Forensic Expert. I am very familiar with metallosis or the inflammation reaction to metallic particles released during wear of the hip implants. The previous hip implant cases I have worked on as a Forensic Expert involved evaluation of the design and failure of the implant and/or medical device. I am highly qualified due to my previous forensic experience in similar devices, my regulatory and engineering experiences at the FDA and my educational background.

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