3M Bair Hugger Litigation Reinstated By Appeals Court, Returning Thousands of Joint Infection Lawsuits to MDL

More than 6,000 Bair Hugger infection lawsuits filed against 3M Company have been reinstated by a federal appeals court, after finding that plaintiffs’ expert witness testimony about problems with the surgical warming blankets was sufficient to allow the cases to proceed.

In 2019, following several years of litigation, a U.S. District Judge dismissed the federal Bair Hugger litigation, after excluding plaintiffs’ expert witnesses, who would have testified that the forced air warming blankets caused thousands of infections following hip and knee replacement procedures in recent years. However, the U.S. Court of Appeals for the Eighth Circuit has now overturned that decision, returning the cases to the lower court for further proceedings.

The 3M Bair Hugger was widely used in operating rooms nationwide, to control body temperature during orthopedic joint replacement surgery, by forcing warm air into a blanket placed over the patient. However, plaintiffs alleged that the product was unreasonably dangerous and defective, causing contaminants from the floor to entire the sterile surgical site. In most cases, plaintiffs suffered devastating infections that resulted in the need for multiple surgical procedures to remove the infected joint, temporarily insert an antibiotic spacer and then ultimately go through another joint replacement.

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Bair Hugger Lawsuits

Bair Hugger warming blankets may be the cause of knee or hip surgery infections.


Given similar questions of fact and law raised in lawsuits filed through the federal court system, the U.S. Judicial Panel on Multidistrict Litigation (JPML) centralized the cases before U.S. District Judge Joan Ericksen in the District of Minnesota for coordinated discovery and pretrial proceedings in 2015. Following coordinated discovery and pretrial proceedings, Judge Ericksen ultimately dismissed the 3M Bair Hugger litigation after deciding that plaintiffs’ expert witness testimony was not sufficiently reliable and based on sound science to allow the cases to reach a jury.

In an opinion (PDF) issued on August 16, a panel of judges on the Court of Appeals determined that Erickson erred in this decision, and they have reinstated the cases.

According to the 35 page ruling, “there is significant support for the proposition that the Bair Hugger independently is capable of disrupting airflow so as to transmit bacteria to the surgical site when other airflow-disruptive variables are controlled for, and there also is empirical support for the proposition that those other variables can facilitate the Bair Hugger’s airflow-disruptive effect in a real-world operating room.”

While reinstating the cases and some of plaintiffs’ expert testimony, the appellate court did exclude some parts of their testimony, and refused a plaintiffs’ request to unseal some filings in the appeals process.

The decision means 3M once again face thousands of hip infection lawsuits and knee infection lawsuits filed in the federal court system, which may now be scheduled for a series of early bellwether trials to help gauge how juries may respond to certain evidence and testimony that will be repeated throughout the litigation if Bair Hugger infection settlements are not reached.


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