A report in the British Medical Journal (BMJ) that raised serious concerns about the safety metal-on-metal hip implants contained some very interesting information about an all-metal version of DePuy Orthopaedic’s Pinnacle implant system. It seems there was evidence that the metal-on-metal Pinnacle hip replacement device was exposing patients to unhealthy levels of metal ions as early as 2008, even as DePuy Orthopaedics was promoting it as an alternative to its recalled ASR hip implant devices.
According to the BMJ report, British health regulators advised patients and doctors in 2010 that recipients of metal-on-metal hip implants should undergo screening if blood tests reveal cobalt levels higher than 7 μg/L. However, metal ion levels above this threshold have been recorded in around 20% of patients (range 5-22%) with some metal-on-metal prostheses, including the Pinnacle. The authors of the report also asserted that data showing raised metal ions in people with the Pinnacle device have been available in the medical literature since 2008.
According to the BMJ article, despite mounting evidence that the all-metal version might harm patients, the Pinnacle device formed a key part of the DePuy’s main hip strategy in 2009. According to an internal company email cited by the report, the company had been contacted that same year by Japanese surgeons with concerns about the Pinnacle metal hip system. The surgeons reported seeing “generated metal debris between stem taper and head, and final necrosed tissue” and blamed it on the poor connection between the two, the report said.
In August 2010, DePuy recalled the ASR Hip Resurfacing System and the ASR Acetabular Hip Implant System – both all-metal devices – because of an unusually high premature failure rate. DePuy then promoted the Pinnacle as “an alternative for the majority of patients” when the ASR implants were recalled.
In 2011, Tony Nargol, a consultant surgeon at the University Hospital of North Tees, warned British health regulators about potential problems with the DePuy Pinnacle all-metal system. According to a report from the BBC, Dr. Nargol’s hospital tested the nearly 1,000 patients who had been fitted with the all-metal Pinnacle there.
“The trust has brought back all the patients with Pinnacle cups – nearly 1,000 – tested them all, screened them, scanned them, and we know exactly what’s happening,” Dr. Nargol said. “And we found out that of about 970 patients, 75 failures related to metal debris, which is really quite high.”
According to the BBC, Dr Nargol said he first told DePuy about damaged tissue in metal-on-metal Pinnacle patients in 2008.
In 2010, a senior DePuy executive said in an internal document that he was “concerned” about problems with the metal-on-metal Pinnacle and similar implants. “I feel the problem is emerging as more serious than first thought,” he wrote.