Jury in DePuy ASR Case Told: Metal-on-Metal Device Constructed with Many Design DefectsFeb 7, 2013
The controversial metal-on-metal hips recalled by DePuy Orthopaedics are at the center of the first trial of some 10,000 cases brought against the device maker, a unit of Johnson & Johnson. Some 93,000 ASRs were involved in the global recall.
In the most recent testimony, McGill University professor, Dennis Bobyn—expert witness on behalf of Loren Kransky—said of the device, “Because it has the geometry that it does, it is susceptible to changing shape as it is forced into a patient’s pelvis…. If I have a larger object that has to go into a smaller hole, something has to move.” Bloomberg News pointed out that at that the time the DePuy ASR was recalled in 2010, Johnson & Johnson said that 12 percent of the implants failed within five years.
Such failure typically results in the need for so-called “revision” surgery, a painful, complex process in which the faulty device is surgically removed and a different device is implanted in its place.
Bobyn, a biomedical engineering expert, said the device had a number of design defects that led to their failing at a much greater rate than other devices, said Bloomberg News. Bobyn testified in state court in Los Angeles. Kransky, from Montana, is a retired prison guard who filed the lawsuit over his failed ASR hip, one of 10,000 similar complaints.
“Is it your opinion that the ASR hip implant has multiple design defects that alone or together cause it to fail at a much greater rate than other hip implants?” Kransky’s attorney asked Bobyn. Bobyn said it was, according to Bloomberg News. When asked if “any claimed benefits of the ASR were greatly outweighed by the risks of the implant” and if Kransky’s ASR implant was defective, “causing it to fail, generating excessive amount of cobalt and chromium wear debris,” Bobyn said, yes, those were his opinions, wrote Bloomberg News.
The device is constructed in such a way that a metal ball rests atop the femur and rotates in a cup that is placed in the hip, explained Bloomberg News. Because of the device’s allegedly defective design, the metal components rub against one another during normal use, shedding dangerous cobalt and chromium into patients’ bodies, which can lead to serious health reactions. According to Bobyn’s testimony, said Bloomberg News, the metal cup’s shape, which is smaller than a half-circle; the cup’s thin wall; and that the cup is one, not two, pieces, all contributed to the device’s defective design and subsequent failures.
For many years, testified Bobyn, the ASR was inferior to other hip devices, citing failure rates in other devices of 3.8 percent after 32 years, or 2 percent after five years, Bloomberg News said in its report of the testimony. An Australian national joint registry found that ASR’s failure rate exceeded 40 percent in the last year alone, according to Kransky’s attorney.
The day prior to Bobyn’s testimony, jurors were shown videotaped testimony from Paul Voorhost, a statistician at DePuy, who said the company reviewed data revealing that 28 percent of ASR hips failed at a Finland hospital, said Bloomberg News. Voorhost also said that, based on data from a United Kingdom national joint registry in 2011, more than 27 percent of ASR hips failed just after seven years.
Kransky’s lawsuit, like the thousands of other similar cases pending in the litigation, alleges that the DePuy ASR generated a toxic amount of chromium and cobalt ions. This metal debris buildup allegedly led to complications such as blackened tissue and the need for early revision surgery.
Meanwhile, in an unprecedented move last month, the U.S. Food and Drug Administration (FDA) announced that metal ion testing be conducted for all-metal hip replacement patients experiencing symptoms such as pain, swelling, or difficulty walking. In issuing these new guidelines, the agency also recommended diagnostic imaging and regular physical examinations be conducted, as well.