“I want people to know what they did to me.” Those were the words of Cincinnati businessman Tim Hopkins, who lost his right leg to an infection he says was caused by 3M’s Bair Hugger, a surgical warming blanket used in 80 percent of U.S. hospitals. Currently, this device is the cause of action in approximately 4,700 lawsuits against 3M, which obtained manufacturing and distribution rights when it took over the company Arizant Healthcare in 2010.

Last month, the first bellwether trial, held in a federal court in Minneapolis, Minnesota, ended in a verdict for the defendant. Counsel for plaintiff Louis Gareis of South Carolina attributed the loss to rulings by Judge Joan Ericksen that prevented the introduction of evidence, which included email communications dating back to 2006.

In one of the messages, the clinical affairs director at Arizant advised against a study of the Bair Hugger’s infection risks because of potentially detrimental effects on his own career. Another email from 2012 came from an outside researcher who expressed concern over 3M’s failure to conduct a “bacterial sampling study” in response to a paper from the previous year that had not adequately addressed safety concerns of forced air warming.

Lawyers for 3M successfully argued that the emails were irrelevant since the trial was centered on the Bair Hugger’s design, which the plaintiff claimed to be defective. This early court victory for 3M has implications for the thousands of cases yet to be heard. Nonetheless, Gareis’ lawyers plan to appeal the verdict.

Meanwhile, Tim Hopkins, a former athlete who has filed suit against the health care providers that performed the knee surgery during which he contracted the infection that cost him his leg, is speaking out. Hopkins had knee replacements in 2009 and 2010. However, in 2015, the prosthesis in his right knee failed, and he underwent revision surgery at Beacon Orthopaedics, a clinic specializing in sports-related injuries.

Two months afterward, Hopkins experienced a mishap that damaged the knee yet again. Over the next several months, he underwent additional surgeries and treatments, but the leg would not heal. Between May and October, Hopkins repeatedly raised concerns about possible infections, but his surgeon assured him that all was well and normal.

By mid-October, Hopkins’ leg had swelled considerably. His surgeon drained fluid from the leg and again assured him there was no infection. A few hours later, Hopkins was admitted to an emergency room where a trauma surgeon spent five hours removing infected tissue. Hopkins recalls the surgeon telling him, “It’s like cancer, you can’t even see the knee replacement.”

He later learned that his infection was caused by a strain of bacteria known as Propionibacterium Acnes, the same one that causes acne on the skin surface. According to research published in Nature, this strain often finds its way into the sites of joint implants. The exact reason is not known, but many believe that forced-air warming blankets, such as the Bair Hugger, play a major role.

The other problem is that artificial joints, unlike their natural counterparts, lack blood vessels – so it is difficult for antibodies to get to the site of a bacterial infection. Meanwhile, the infection can grow slowly, over a period of years – as was the case for Tim Hopkins. By the time such an infection becomes apparent, it is usually too late.

Attorneys for the defendants have asked Judge Lisa Allen to place a gag order on Hopkins. She has not yet granted their request. Their clients, Beacon Orthopaedics and Christ Hospital Health Network, have not commented except to say they dispute Hopkins’ account. At the same time, 3M continues to defend its product.

Last year, the company started an Internet campaign, featuring an FDA review of the product (which has since been removed from the FDA website) stating that they were unable to find a single “consistently reported association” between the Bair Hugger and surgery-related infections. On its own website, 3M points out that “More than 200 million patients have been warmed using the Bair Hugger system,” claiming “There are NO verified cases of infection caused by the Bair Hugger system.”

Hopkins, who has incurred personal medical bills of $100,000 and business losses of over $250,000 as a result of his infection, has sued the two health care providers for medical malpractice and has joined the litigation against 3M. His case is scheduled to go to trial next summer.