Engineer warned of hip risks five years before use in patients

today exposes a series of previously unseen memos, reports and emails, obtained from DePuy, that raised questions about the safety of metal-on-metal devices.

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.

In the same year, a surgeon advising DePuy told the firm that “we need to be cautious of the legal/litigation issues, lawyers etc ... perception of metal debris and metal ion release.”

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 Telegraph also reveals how: Senior company figures were told in 2003 that one surgeon had already collected “a lot of bad data about metal-onmetal debris” in patients who had received DePuy implants;

A 2005 report warned that risks to patients of metal-on-metal were “as yet undetermined” but “the risk to DePuy may be major in terms of product liability or business impact”;

An internal email in 2008 acknowledged “growing concerns over metalon-metal hips”. Surgeons needed “a high stability non-metal option”;

Tony Nargol, a surgeon based in North Tees, repeatedly told DePuy from around 2008 about problems with its implants but was labelled an “outlier” and told his patients may simply have high volumes of metal in their blood because of a local “water supply problem”;

A report commissioned by the company in 2008 about the use of one of DePuy’s first metal-on-metal implants found that tiny particles released from the devices “have killed the bone” and soft tissues around the hip and “resulted in the tendons ripping away”.

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”.

He accused the firm of a “head-in- the-sand response to this problem” and warned that “the products are harming patients” – three years before the implant was eventually discontinued.

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.

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 has 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”.

The document was part of papers read out in a Texas court, where patients are suing DePuy over the Pinnacle implant. They were passed to the Telegraph by their lawyers.

DePuy’s lawyers have said in court that the company had “always warned about the potential for a tissue reaction in a metal-on-metal device”.

A spokesman said patient safety was its “first priority” and it “acted appropriately and responsibly in the design and testing” of the Pinnacle.

The implant was cleared for sale by national regulators and “is backed by a strong track record of clinical data showing reduced pain and restored mobility for patients suffering from chronic hip pain”.

The spokesman added that the plastic and ceramic alternatives also “wear and produce debris”, and that “the body reacts to any foreign material”.

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