Home Forums Other Specialities Orthopaedics Failure of Metal on Metal (MOM )Total Hip Joints

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    Many of us have stated in the past that we will be hesitant to use a metal on metal (MOM) Total Hip Joint because of the metal particles that are released through friction between the ball and socket component of the joint and subsequent reaction and loosening of the prosthesis after a few years. Many papers have indicated this and we have seen and revised such joints after they had become loose. However MOM joints are still being used by some surgeons. Now a particular joint manufactured by DePuy has come to the attention of patients who have suffered from pain and loosening of that joint.

    DePuy’s Pinnacle implant was first used in the UK in 2002, with the ASR, another metal-on-metal device, released two years later. They were promoted as offering better mobility than devices that used a metal ball and plastic socket. Many British patients were fitted with the controversial implants despite De Puy being warned by experts that the type of device was unsafe.

    Dr Graham Isaac, a senior engineer based in DePuy’s Yorkshire factory, warned in a 1995 report that testing showed metal implants were “working well for a period of time” before wearing down, prompting the “release of a large volume” of debris and prone to “catastrophic breakdown. This was five years before they started implanting these joints on British patients.

    More than 20,000 patients were later fitted with the implants, which experts say can deposit toxic ions into the bloodstream as they wear. Thousands were left in agony and required revision surgery with safer joints.

    A Daily Telegraph investigation has now exposed a series of previously unseen memos, reports and emails, obtained from DePuy, that raised questions about the safety of metal-on-metal devices.
    Mark Lanier, a lawyer, said: “These documents show that DePuy knew this hip would fail.”

    Now more than two decades later, the firm faces thousands of legal claims by patients who say they have suffered as a result of the metal-on-metal joint subsequently produced by DePuy wearing away in their bodies.

    The papers, filed in a US court, include an email from John Irving, a US orthopaedic surgeon, in 2010, forwarded internally to the company’s president, insisting that “it borders on unethical to continue to market” the Pinnacle type of metal-on-metal hips” until the issues are elucidated”.

    In his 1995 memo, Dr Isaac, now “distinguished engineering fellow” at the firm, examined data on metal-on-metal hips produced by rival companies. He wrote: “It is clear from the literature the survivorship of cobalt chromium [the materials used in metal implants], metal-on-metal prostheses in the past have been far from satisfactory. “Manufacturing methods have improved. However, simulator testing of such components suggests their performance is as unpredictable as ever, working well for a period of time before suffering a sudden catastrophic breakdown of the bearing surface accompanied by a release of a large volume of wear debris.”

    He quoted an expert warning that the combination of metal with metal was “likely to give rise to toxic levels of metal under clinical conditions”.

    Boz Michalowska Howells, representing more than 300 UK claims, said it “appeared to be commonly known in the 90s that metal-on-metal hips cause could adverse reactions and it should have rung alarm bells”.

    Extracted from a report by Edward Malnick, Claire Newell and Lexi Finnigan.

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