In the

United States Court of Appeals

For the Seventh Circuit ____________________

No. 16-3957

IN RE: ZIMMER, NEXGEN KNEE IMPLANT 

 PRODUCTS LIABILITY LITIGATION

APPEAL OF: THEODORE F. JOAS and DARLENE A. JOAS

____________________

Appeal from the United States District Court 

for the Northern District of Illinois, Eastern Division.

No. 13 C 9216 — Rebecca R. Pallmeyer, Judge.

____________________

ARGUED MAY 22, 2017 — DECIDED MARCH 8, 2018

____________________

Before FLAUM, EASTERBROOK, and SYKES, Circuit Judges.

SYKES, Circuit Judge. Theodore Joas underwent a total

knee replacement at a Wisconsin hospital and received a 

Zimmer NexGen Flex knee implant. Within a few years, he

began experiencing pain in his new knee. X-rays confirmed 

that the implant had loosened and required a surgical fix. 

Joas brought a panoply of claims against Zimmer, Inc., the

implant manufacturer. His case was transferred to a multidistrict litigation in the Northern District of Illinois, where it 

was eventually treated as a bellwether case. Applying 

Wisconsin law, the presiding judge entered summary judgment for Zimmer.
2 No. 16-3957

Joas asks us to reinstate a single claim based on a theory 

of inadequate warning. His appeal raises some unresolved 

issues in Wisconsin product-liability law—most notably, the 

application of the “learned intermediary” doctrine, which 

the Wisconsin Supreme Court has not yet had an opportunity to address. We predict that the state high court would 

follow the lead of other states and adopt this doctrine. We 

affirm the judgment.

I. Background

Joas’s suit is the second bellwether case in a multidistrict 

litigation concerning Zimmer NexGen Flex knee implants. 

Plaintiffs in the litigation allege that they have suffered pain 

and loss of movement because the NexGen Flex is prone to 

premature loosening.1

In 2008 Joas had knee-replacement surgery at a hospital 

in Eau Claire, Wisconsin. His surgeon used a Zimmer 

NexGen Flex implant. At the time Joas worked for Pepsi 

Bottling Group, and his job required him to lift and carry 

heavy loads and to squat repeatedly throughout the day. 

Soon after the surgery he was able to engage in physical 

therapy, return to work, and participate in recreational

activities like hunting and canoeing. By 2011, however, Joas

began to feel pain in his new knee. An x-ray and bone scan 

revealed aseptic loosening of the tibial component of the 

implant. Translation: the bond between the implant and the 

shinbone had weakened. He had revision surgery in October 

2012. 

 

1 The first case resulted in a jury verdict for Zimmer. See Batty v. Zimmer 

Inc., No. 12-cv-6279, 2015 WL 11142538 (N.D. Ill. Nov. 6, 2015).
No. 16-3957 3

In 2013 Joas sued Zimmer alleging that the NexGen Flex 

design causes premature loosening for total-kneereplacement patients who engage in activities that require a 

high degree of knee flexibility. He filed his suit in federal 

court in New Jersey and raised product-liability claims 

premised on allegations of defective design, manufacture, 

and warning.2 (He also alleged misrepresentation and 

statutory consumer-protection claims, but he abandoned 

them at summary judgment.) The New Jersey court transferred the case to a multidistrict proceeding then underway 

in the Northern District of Illinois addressing lawsuits 

against Zimmer based on its NexGen Flex implant.

The judge designated Joas’s case as a bellwether and 

scheduled a trial. In the meantime Zimmer moved for 

summary judgment on all claims. Among other things, the 

manufacturer sought to exclude the testimony of Dr. Joseph 

Fetto, Joas’s expert witness. Dr. Fetto’s report indicated that

his opinion testimony would be based on a differential 

etiology methodology, which entailed identifying and ruling 

out potential causes of the tibial loosening to arrive at the 

likeliest cause of Joas’s injury. Applying Rule 702 of the 

Federal Rules of Civil Procedure and Daubert v. Merrell Dow 

Pharmaceuticals, Inc., 509 U.S. 579 (1993), the judge excluded 

Dr. Fetto’s testimony as unreliable because he did not have

any discernible basis for determining which potential causes 

of the loosening were reasonable and which were not. 

 

2 Joas’s wife is also a plaintiff, but her claims are entirely derivative. The 

New Jersey venue choice was curious. Joas and his wife are citizens of 

Wisconsin; the surgery was performed there; and Zimmer is a Delaware 

corporation with its principal place of business in Indiana.
4 No. 16-3957

Dr. Fetto was Joas’s only expert who would testify that a 

defect in the knee implant caused his injury. With his expert’s testimony excluded, Joas could not prevail on his 

claims based on defective design or manufacture. The exclusion of Dr. Fetto’s testimony also left a causation gap in 

Joas’s claim based on inadequate warning. To the extent that 

this claim could survive without Dr. Fetto’s testimony, the 

judge rejected it as deficient in other respects and entered 

summary judgment for Zimmer on all claims.

II. Discussion

Joas limits his appeal to his claim based on defective

warning. The claim rests on two theories. Joas argues that 

Zimmer (1) failed to issue proper warnings directly to him as 

the recipient of the knee replacement; and (2) failed to issue 

proper warnings to his surgeon, who implanted the device.

Importantly, Joas does not quarrel with the exclusion of 

Dr. Fetto’s testimony. Rather, he urges us to allow this claim

to go forward based on the testimony of Dr. John Dearborn, 

Zimmer’s expert witness. Dr. Dearborn testified in deposition that he would have used two bags of cement to properly 

bond a knee implant to the patient’s shinbone. Joas’s surgeon, Dr. Bryan Larson, used only one bag of cement, consistent with his normal practice. Joas maintains that Zimmer 

had a duty to warn that two bags of cement are needed to 

achieve a proper bond. 

The judge disallowed the claim for two reasons. First, she 

applied the learned-intermediary doctrine, which (as relevant here) holds that the manufacturer of a medical device 

has no duty to warn the patient as long as the manufacturer

provides adequate warnings to the physician. Second, the 

judge held that even if Zimmer had a duty to warn the 
No. 16-3957 5

surgeon, Joas has no evidence of causation because 

Dr. Larson testified in deposition that he did not read the 

packaging material Zimmer sent with the NexGen Flex 

implant. Rather, he testified that he based his surgical technique entirely on his general medical training and his surgical fellowship. So an improved warning, the judge held,

would not have made any difference.

To overcome this factual deficit, Joas asked the judge to 

recognize and apply a legal presumption that the surgeon 

would have heeded an improved warning had Zimmer 

provided one. The judge declined to do so, holding that the

proposed “heeding presumption” has no support in 

Wisconsin law.

Both aspects of the failure-to-warn claim raise novel 

questions under Wisconsin law. We turn first to Joas’s claim 

that Zimmer breached a duty to directly warn him. That 

inquiry requires us to predict whether the Wisconsin 

Supreme Court would recognize the learned-intermediary 

doctrine for use in defective-warning cases involving medical devices. We then turn our attention to Joas’s argument 

that Zimmer failed to adequately warn the surgeon.

A. Alleged Failure to Warn the Patient

We begin with the learned-intermediary doctrine, which 

if applicable defeats Joas’s claim that Zimmer had a duty to 

directly warn him. The doctrine holds that the manufacturer 

of a prescription drug or medical device fulfills its duty to 

warn of the product’s risks by informing the prescribing 

physician of those risks. Neither the Wisconsin Supreme 

Court nor the state’s intermediate appellate courts have 

addressed the doctrine.
6 No. 16-3957

“When interpreting state law, a federal court’s task is to 

determine how the state’s highest court would rule.” Rodas 

v. Seidlin, 656 F.3d 610, 626 (7th Cir. 2011). If the state’s 

supreme court has not yet addressed the issue, the federal 

court should “consult and follow the decisions of intermediate appellate courts” to predict how the supreme court 

would act given the chance, unless “there is a convincing 

reason to predict the state’s highest court would disagree.”

ADT Sec. Servs., Inc. v. Lisle-Woodridge Fire Prot. Dist., 

672 F.3d 492, 498 (7th Cir. 2012). And absent “any authority 

from the relevant state courts, [the federal court] ... shall 

examine the reasoning of courts in other jurisdictions addressing the same issue and applying their own law for 

whatever guidance about the probable direction of state law 

they may provide.” Pisciotta v. Old Nat’l Bancorp, 499 F.3d 

629, 635 (7th Cir. 2007).

As we’ve noted, no Wisconsin appellate court has yet 

addressed this topic. As best we can tell, just one Wisconsin 

trial-court decision addresses the learned-intermediary 

doctrine. In Straub v. Berg, the judge applied the doctrine, 

noting that “courts of numerous other jurisdictions almost 

universally hold that in the case of prescription drugs, a 

manufacturer’s provision of proper warnings to a prescribing physician will satisfy the manufacturer’s duty to warn 

since the patient cannot obtain the drug except through the 

physician.” No. 00-cv-0117, 2003 WL 26468454, at *6 (Wis. 

Cir. Ct. Jan. 6, 2003). 

A few federal district courts applying Wisconsin law 

have also invoked the learned-intermediary doctrine. See 

Menges v. Depuy Motech, Inc., 61 F. Supp. 2d 817, 830 (N.D. 

Ind. 1999) (holding that since the medical device at issue is 

“available only upon prescription of a duly licensed physi-
No. 16-3957 7

cian, the warning required is not to the general public or to 

the patient, but to the prescribing doctor”) (quotation marks 

omitted); Monson v. Acromed Corp., No. 96-C-1336, 1999 WL 

1133273, at *20 (E.D. Wis. May 12, 1999) (holding in a 

medical-devices failure-to-warn case that the manufacturer’s 

duty to warn ran only to the treating doctor because he “is in 

the best position to understand the patient’s needs and 

assess the risks and benefits of a particular course of treatment”) (quotation marks omitted); Lukaszewicz v. Ortho 

Pharm. Corp., 510 F. Supp. 961, 963 (E.D. Wis. 1981) (noting 

that “the provision of proper warnings to a physician will 

satisfy the manufacturer’s duty to warn since the patient 

cannot obtain the drug except through the physician”).

One district judge has said in passing that “Wisconsin 

does not apply the learned intermediary doctrine.” Maynard 

v. Abbott Labs., No. 12-C-0939, 2013 WL 695817 (E.D. Wis. 

Feb. 26, 2013). That statement is incorrect—the Wisconsin 

Supreme Court has never weighed in on the topic. Maynard 

itself is bereft of any analysis on the point.

The doctrine enjoys broad support in other jurisdictions. 

As the Texas Supreme Court has recently explained, “[t]he 

highest courts of at least thirty-five states have adopted 

some form of the learned intermediary doctrine within the 

prescription drug products-liability context or cited favorably to its application within this context.” Centocor, Inc. v. 

Hamilton, 372 S.W.3d 140, 158 n.17 (Tex. 2012) (collecting 

cases). And the intermediate appellate courts in another 

13 states have applied the learned-intermediary doctrine or 

have predicted that their supreme courts would do so. See 

Tyree v. Boston Sci. Corp., 56 F. Supp. 3d 826, 828 n.3 (S.D. W. 

Va. 2014) (confirming Centocor’s count and collecting other 

appellate-court decisions). 
8 No. 16-3957

The justification for adopting the learned-intermediary 

doctrine in cases involving prescription drugs applies even 

more forcefully in cases involving surgical implants. As one 

district judge has explained, patients “could conceivably 

gain access to prescription drugs without their doctor’s 

assistance, [but] it is not reasonably conceivable that an 

individual could obtain and implant a device that requires a 

trained surgeon without the intervention of a physician.”

Beale v. Biomet, Inc., 492 F. Supp. 2d 1360, 1368 (S.D. Fla. 

2007).

In short, there is good reason to think that given the opportunity, the Wisconsin Supreme Court would join the vast 

majority of state supreme courts and adopt the learnedintermediary doctrine for use in defective-warning cases like 

this one involving a surgical implant. We predict that the 

state high court would do so. Accordingly, to the extent that 

Joas’s defective-warning claim is based on Zimmer’s duty to 

warn him, it is foreclosed by the learned-intermediary doctrine.

That point aside, summary judgment for Zimmer was 

proper on this aspect of the claim for a number of additional 

reasons. To start, although as a general matter a manufacturer owes a duty to warn consumers of dangers associated 

with the proper use of its product, Joas has not identified 

any danger that Zimmer should have warned him about. 

Strasser v. Transtech Mobile Fleet Serv., Inc., 613 N.W.2d 142, 

154 (Wis. 2000). He claims in his brief that he thought the 

implant would last at least 20 years based on some Zimmer 

marketing materials he read.3 But as we’ve noted, he aban-

 

3 The marketing material Joas points to is a pamphlet provided to him by 

his doctor that he assumed “was probably from Zimmer” but which the 
No. 16-3957 9

doned his misrepresentation and consumer-protection 

claims on summary judgment. He cannot resurrect them on 

appeal by repackaging them as a new iteration of his defective-warning claim.

Summary judgment for Zimmer was also proper on this 

claim because Joas has no evidence to support causation. “A 

plaintiff who has established both a duty and a failure to 

warn must also establish causation by showing that, if 

properly warned, he or she would have altered behavior and 

avoided injury.” Kurer v. Parke, Davis & Co., 679 N.W.2d 867, 

876 (Wis. Ct. App. 2004). Joas argues that if Zimmer had 

warned him of a risk of early failure, he would have “heeded the warning and been inclined to choose an implant with 

a known greater longevity.”

But Joas didn’t select the NexGen Flex implant. 

Dr. Larson did, and he made his decision based on his own 

past experience, not on any marketing materials or information provided by Zimmer.

Q. In the case of Mr. Joas, is it true that you 

chose the products that you thought would 

best treat his medical condition? 

A. Yes. 

Q. And, again, what did you base your selection of the LPS-Flex and the stemmed tibial 

component for Mr. Joas on?

 

doctor testified was not actually produced by Zimmer but, rather, by the 

“general academy source down in Eau Claire.”
10 No. 16-3957

A. On my experience with it and what it’s provided for patients that I’ve done previous to 

that particular individual.

Moreover, Joas has not identified another implant that is 

known to have greater longevity that he would have selected if he had made the choice himself. “Even in the event that 

a warning is inadequate, proximate cause is not presumed.” 

Id. “Absent proof that a more complete or explicit warning 

would have prevented” his acceptance of the NexGen Flex

implant, Joas “cannot establish that [Zimmer’s] alleged 

failure to warn was the proximate cause of [his] injuries.” Id.

Indeed, Joas testified in deposition that even if he had been 

warned that a certain percentage of these implants might 

loosen or fail, he still would have gone through with the 

surgery. The judge was right to award summary judgment 

to Zimmer on this aspect of Joas’s defective-warning claim.

B. Alleged Failure to Warn the Surgeon

Joas also claims that Zimmer failed to issue an adequate 

warning to his surgeon about the amount of cement needed 

to properly bond the knee implant. This theory is based 

entirely on Dr. Dearborn’s testimony that he would have 

used two cement bags during the surgery instead of just one, 

as Dr. Larson did.4

That’s not enough to support a defective-warning claim

in this context. No evidence supports Joas’s contention that 

it was Zimmer’s responsibility to instruct surgeons about the 

amount of cement they should use in implant surgery. In 

 4 As noted above, Dr. Dearborn was Zimmer’s expert witness. Joas’s own 

expert witness testified that there was nothing deficient in the surgeon’s 

technique.
No. 16-3957 11

fact, all the record evidence is to the contrary. Dr. Dearborn 

explained in his expert report that “surgeons are primarily 

guided in their [implant] technique by the basic medical 

training received during residency and/or fellowship training.” Dr. Larson confirmed as much in his own deposition:

Q. The technique that you used to implant [the 

NexGen Flex] products in Mr. Joas in 2008, 

how’d you learn that technique?

A. From my fellowship training and residency.

Q. And with respect to how to position the 

components or cement the components, 

how did you learn that?

A. Again, from the residency and my fellowship training.

Q. Is there any printed material or written material from Zimmer that you relied upon in 

knowing how to position or implant 

Mr. Joas’s products?

A. No, there is not.

Q. Were you relying exclusively on training 

and education during your residency and 

fellowship?

A. That’s correct.

In addition, in his expert report, Dr. Dearborn explained 

that the warnings and instructions Zimmer included with its 

implant were “reasonable and adequately inform[ed] the 

relevant healthcare providers” of the foreseeable risks. 

Surgical cementing techniques and the adequacy of warnings from implant manufacturers are specialized medical 
12 No. 16-3957

issues and not “within the realm of the ordinary experience 

of mankind”; expert testimony is required to support a 

defective-warning claim premised on this theory. State v. 

Kandutsch, 799 N.W.2d 865, 872 (Wis. 2011) (quotation marks 

omitted). Joas has none.

Beyond the lack of expert support for this theory, no evidence suggests that Dr. Larson would have followed an 

improved instruction on cementing techniques had Zimmer 

provided one. Joas argued at the summary-judgment hearing that the judge should allow this claim to go forward 

based on a “heeding presumption,” which permits the 

factfinder to presume, in the absence of proof, that a proper 

warning would have been read and heeded. Here again, the 

state appellate courts have not addressed this doctrine. We 

seriously doubt that they would adopt it in this context.

To the contrary, as we’ve already noted, the state court of 

appeals has recently held that “[a] plaintiff who has established both a duty and a failure to warn must also establish 

causation by showing that, if properly warned, he or she 

would have altered behavior and avoided injury.” Kurer,

679 N.W.2d at 876. The plaintiff in that case failed to show 

that the relevant actor “would have heeded a different 

warning,” so the court upheld a summary judgment for the 

defendant. Id. at 880.

Joas relies on Tanner v. Shoupe, an earlier failure-to-warn

case about an exploding car battery. 596 N.W.2d 805 (Wis. 

Ct. App. 1999). There the defendant argued that additional 

warnings would have been useless because Tanner, the 

plaintiff, testified that he did not read any warnings on the 

battery. But the case turned on whether an improved warning would have been read and heeded by an earlier user. The 

court determined that “[i]f the battery had contained a 
No. 16-3957 13

warning against pounding on the vent caps, a fact-finder 

could ‘reasonably assume that it [would have been] read and 

heeded’ by the users prior to Tanner.” Id. at 818 (emphasis 

added) (quoting RESTATEMENT (SECOND) OF TORTS § 492A 

cmt. j (AM. LAW INST. 1965)).

By its own terms, then, Tanner does not apply to an actor 

who has “admitted he did not read the warnings” himself. 

Id.; see also Forst v. SmithKline Beecham Corp., 602 F. Supp. 2d 

960, 970 & n.4 (E.D. Wis. 2009) (applying Kurer instead of 

Tanner in a case involving prescription-drug warnings

because of its “analogous facts”). Kurer, not Tanner, controls

here.

Dr. Larson testified that he did not read the instructions 

that accompanied the knee implant. So even if Joas could 

establish that Zimmer breached a duty to warn the surgeon, 

summary judgment was appropriate because no evidence 

shows that “if properly warned, [Dr. Larson] would have 

altered [his] behavior and avoided injury.” Kurer, 

679 N.W.2d at 876.

As a fallback position, Joas asks us to certify the questions of the learned-intermediary doctrine and the heeding 

presumption to the Wisconsin Supreme Court. We have no 

need to take that step. Certification is appropriate if we are 

“genuinely uncertain about a question of state law that is 

vital to a correct disposition of the case.” Cleary v. Philip 

Morris Inc., 656 F.3d 511, 520 (7th Cir. 2011) (quotation marks 

omitted). No genuine uncertainty exists here.

AFFIRMED.