A lawsuit filed in the United Kingdom alleges that faulty measuring may have caused complications in patients receiving the DePuy Pinnacle metal-on-metal hip implant, Tech Times reports. The case, which was filed at the High Court, showed that DePuy Synthes identified an “error in measuring technique” at a plant reportedly based in Leeds. According to the lawsuit, certain parts of the implant were measured while hot; these measurements are not representative of the implant at room temperature. All-metal hip replacements have become controversial in recent years due to safety concerns and worldwide litigation. In Britain, 23,430 metal-on-metal hip devices have been implanted since 2003.
In Britain, as well as elsewhere in the world, patients have filed lawsuits alleging the implants caused inflammation, crippling pain and other adverse effects. In metal-on-metal hip implants, both the ball and socket components are made of metal, as opposed to plastic or ceramic. A major concern with these all-metal hip devices is that they can release metal particles into the bloodstream and surrounding tissue when the surfaces of the implant rub together. If the implant sizes are not completely accurate, this condition is exacerbated.
DePuy says their Pinnacle hip implant is accurate within 32 microns. The findings of a 2008 investigation suggest that being slight off will not impair the implant liners’ function or raise the risk of safety issues. According to surgeons, however, even a tiny difference in measurement can have significant implications for patients. British Orthopaedic Association’s former president Tim Briggs said “When the components are implanted they are matched. If there is a difference in the size it doesn’t have to be very much at all, you will change the wear characteristics,” according to Tech Times. Similarly, orthopedic professor Edward Davis said patients may suffer severe consequences if the ball component is measured at 80 degrees Celsius while the socket is measured at 30 degrees Celsius.
Stephen Cannon, vice president of Royal College of Surgeons and honorary consultant for the Royal National Orthopaedic Hospital, says mismatched components can lead to problems regardless of whether a hip implant is a metal-on-metal or not. If the ball and socket do not fit well together, the wear rate increases. According to the National Health Service (NHS), patients who have a metal-on-metal hip implant should lookout for symptoms such as: pain in the hip, leg or groin, limping, inflammation near the hip, grinding, chest pain, difficulty breathing, numbness, weakness, changes in hearing or vision, feeling cold and weight gain. Experiencing these symptoms does not necessarily mean that the implant has failed, but NHS does advise a checkup.