Patricia Caplinger says a Medtronic representative was in the operating room when her doctor inserted its Infuse device into her spine in a way not approved by the U.S. Food and Drug Administration. After her surgery, Caplinger developed constant pain, weakness and a condition called foot drop that led to a torn ligament in her right knee. Barely a year after her first surgery, she needed another operation to remove excess bone growth in her spine. That growth, she says, was caused by an off-label use of Infuse that Medtronic improperly promoted.

Caplinger anticipates further corrective surgeries and a possible cancer risk. But if a new U.S. Appeals Court decision stands, Caplinger will not get to sue Medtronic. By a 2-1 vote, a three-judge panel in the 10th ­Circuit ruled on April 21 that Caplinger's suit was not allowed by federal law.

So the Oklahoma woman, like hundreds of other people injured by Infuse, had her lawsuit thrown out before she could question Medtronic.

The judges' call — the first federal appellate decision on Infuse — could influence trial court judges in other device malfunction cases, said William Mitchell College of Law Prof. J. David Prince, a national authority on product liability. It could also discourage injured people who have not yet filed suit from doing so and make lawyers reluctant to take their cases even if they try.

There are no federal product ­liability laws, Prince added, and federal enforcement efforts surrounding device malfunctions are lacking.

"Pretty clearly," Prince said, "there is a systemic failure here."

In a statement to the Star Tribune, Medtronic PLC said if Caplinger's case had been allowed, "we would stand behind our product and vigorously defend it in court." But the company declined to comment on Caplinger's charges that a Medtronic representative was present at her ­surgery and that the company improperly promoted the unapproved implantation.

Federal laws narrowly limit who gets to sue in such cases as Caplinger's. People hurt by medical devices must offer explanations about how a device maker's actions specifically contributed to their individual injuries. Even then, if they cannot show exactly how the device maker's actions violated federal law or how those actions can be pursued by state personal injury laws that do not usurp federal power, they cannot sue.

The restrictions are founded in the concept that federal laws take precedence over state laws, a concept known as pre-emption. This makes FDA-approved devices generally off-limits to suits except in very specific circumstances. But federal rules on the right to sue device makers are so voluminous and complex that they are at times contradictory, as are the court decisions interpreting them.

In fact, some Infuse cases have gotten through Medtronic's technical objections and ended in settlements. In May 2014, Medtronic settled 950 Infuse cases for $22 million and set aside $120 million to $140 million to deal with what it said were 3,800 other Infuse damage claims, some filed as suits and some not.

The judges who threw out Caplinger's suit said her lawyers might have culled thousands of pages of laws and regulations to find a way through pre-emption. But in what has become a Catch-22, specifics needed to make a case often depend on access to information that can only be obtained in questioning the device maker. That can't take place if you are not allowed to sue.

"Much of the critical information about device specifications is kept confidential as a matter of federal law," DePaul law Prof. Max Helveston explained in a 2013 Georgia Law Review article that concluded that a judge's "expansive" interpretation of pre-emption has left those injured by medical devices without "recourse against the manufacturers."

Critics say this legal conundrum lets device makers dodge responsibility for injuries their products cause.

At this point, said Allison Zieve, one of Caplinger's lawyers, Medtronic has "succeeded in getting immunity from a regulatory scheme it circumvented."

Device makers, including Medtronic, say that the federal device approval process provides adequate protection and that personal injury lawsuits stifle new treatments and hurt those who benefit from their current products.

"Without pre-emption, there would be no central standard for device safety, effectiveness, testing, labeling, and marketing, which would ultimately be detrimental to patients, their safety, and their access to medical innovation," Medtronic said in a statement to the Star Tribune.

The issue has enormous scope. Medtronic acknowledges 3,800 possible actions involving Infuse. Personal injury lawyers suggest that number could grow if they can ever get an Infuse case to trial. Across the entire medical device industry, the number of injury suits forestalled by federal restrictions is incalculable. But it is likely massive.

"Do corporations hide behind pre-emption?" Prince asked. "Yeah, they do. … I find this whole drama very frustrating. I don't think there's a simple solution."

No specifics on risks

The simplest solution often proves the hardest. Judges want technical and factual details that those who are hurt cannot or do not provide. Zieve contends Medtronic "pushed to have the device used" in the unapproved way it was implanted in Caplinger. The FDA never blessed that use. So the government has not determined if it is safe and effective.

"It was not just that Medtronic sold [Infuse] for use A and it was used for use B," Zieve, the director of Public Citizen Litigation Group, maintained. Rather, Medtronic mounted an aggressive marketing campaign for unapproved uses, said Zieve, who is still deciding whether to appeal the three-judge panel's ­decision to the entire 10th Circuit.

The law lets doctors use devices off-label if they think it will help patients. But Infuse, which at one point grew to about $900 million in annual sales, is used off-label 85 to 90 percent of the time, critics charge.

The FDA does not require listing specific risks of off-label Infuse use on the product's label. Instead, the "warnings" section includes the following disclaimer: "[t]he safety and effectiveness of the Infuse Bone Graft component with other spinal implants, implanted at locations other than anterior open or anterior laparoscopic approaches have not been established."

In a written response to a Star Tribune question about how patients and doctors are supposed to get information about specific risks from off-label uses of Infuse, the FDA pointed to two public notices it has issued since it approved the product in 2002. The first, a "Public Health Notification" sent to health care providers in July 2008, warned of "Life-threatening Complications Associated With Recombinant Human Bone Morphogenetic Protein in Cervical Spine Fusion." The letter recommended that doctors use alternative treatments or become clinical investigators. The second notice, a "Safety Alert for Human Medical Products" came out in January 2015. It noted "reports of serious injuries, such as excess bone growth, fluid accumulation, inhibited bone healing, and swelling" when the recombinant protein was used in surgeries on children under 18.

Recombinant human bone morphogenetic protein is the active ingredient in Infuse. But neither the product name nor its manufacturer are in the FDA notices. Nor are any of the other crippling side effects referenced in hundreds of Infuse lawsuits and thousands of complaints.

Meanwhile, the alleged presence of a Medtronic representative in Caplinger's operating room, Medtronic's 2006 payments of $40 million to settle what the U.S. Justice Department called "kickbacks to doctors to induce them to use [Medtronic] spinal products," and 2012 Senate Finance Committee revelations that some multimillion-dollar company-sponsored Infuse research downplayed risks of off-label uses made no difference to the judges who tossed the Caplinger case.

Caplinger's was one of the first Infuse cases brought in the U.S., said Stuart Goldenberg, the Minneapolis lawyer who co-chairs the national Infuse Litigation Group. "The complaint never talked about misbranding" in violation of U.S. law nor about any specific state law actions that run parallel to federal authority, Goldenberg said.

Goldenberg has used both ­tactics to survive pre-emption in other Infuse cases, including several filed in Minnesota state courts. Coincidentally, within days of the federal Caplinger ruling, the Minnesota appeals court overturned parts of a trial judge's pre-emption of some of Goldenberg's Minnesota Infuse cases and ordered them heard.

But, typically, the judges warned that the charges would require much more proof than was originally offered in order to prevail.

Like Caplinger, that is all Goldenberg's clients wanted: a day in court to make their case.