The 93,000 metal hip implants that Johnson & Johnson’s DePuy unit recalled in 2010 had multiple design defects that caused them to fail at a much greater rate than other devices, a biomedical engineering expert told a jury.
Dennis Bobyn, a McGill University professor, testified today at the first trial among 10,000 lawsuits over claims J&J defectively designed ASR hips. At the time of the recall, J&J said 12 percent of the devices failed within five years, requiring follow-up surgeries known as revisions.
Bobyn testified in state court in Los Angeles as an expert witness on behalf of Loren Kransky, a retired prison guard who sued over his failed ASR hip. Michael Kelly, a lawyer for Kransky, asked Bobyn his opinion of the device, in which a metal ball that sits atop the femur rotates in a cup placed in the hip. Thousands of plaintiffs claim that patients are harmed by cobalt and chromium that fleck into surrounding tissue.
“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?” Kelly asked Bobyn, who said it was.
Kelly also 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 those were his opinions.
Analysts have said J&J may have to pay billions of dollars to resolve the lawsuits.
Bobyn testified that the shape of the metal cup, which is less than a half-circle, and the thin wall of the cup contributed to its defective design. He said that the one-piece cup, rather than two pieces, also contributed to failures.
“Because it has the geometry that it does, it is susceptible to changing shape as it is forced into a patient’s pelvis,” Bobyn said. “If I have a larger object that has to go into a smaller hole, something has to move.”
He said the ASR was inferior to other hips on the market for many years. He said a hip devised by John Charnley in the U.K. in 1958 failed at a 3.8 percent rate after 32 years. He said a ceramic DePuy hip known as the Duraloc failed at a 2 percent rate after five years.
Kelly has told jurors that an Australian national registry showed that the ASR failure rate last year exceeded 40 percent.
Bobyn appeared a day after jurors saw videotaped testimony from Paul Voorhorst, a DePuy statistician. He said that the company reviewed statistics showing that 28 percent of ASR hips had failed at a hospital in Finland. He also discussed data from the U.K. national joint registry in 2011 showing that more than 27 percent of ASR hips failed after seven years.
The Kransky case is Kransky v. DePuy, BC456086, California Superior Court, Los Angeles County (Los Angeles). The consolidated federal case is In re DePuy Orthopedics Inc., ASR Hip Implant Products Liability Litigation, 10-MD-2197, U.S. District Court, Northern District of Ohio (Toledo).