                        RECOMMENDED FOR FULL-TEXT PUBLICATION
                             Pursuant to Sixth Circuit Rule 206
                                    File Name: 12a0145p.06

                UNITED STATES COURT OF APPEALS
                                FOR THE SIXTH CIRCUIT
                                  _________________


                                                X
                                                 -
 ANDREW RODRIGUEZ,
                                                 -
                               Plaintiff-Appellant,
                                                 -
                                                 -
                                                     No. 11-5335
           v.
                                                 ,
                                                  >
                                                 -
 Corporation; STRYKER SALES CORPORATION, -
 STRYKER CORPORATION, a Michigan
                                                 -
                                                 -
 a Michigan Corporation,
                        Defendants-Appellees. -
                                                N
                   Appeal from the United States District Court
                for the Middle District of Tennessee at Cookeville.
              No. 2:08-cv-124—Aleta Arthur Trauger, District Judge.
                                  Argued: April 18, 2012
                            Decided and Filed: May 21, 2012
    Before: GIBBONS and SUTTON, Circuit Judges; DUGGAN, District Judge.*

                                    _________________

                                         COUNSEL
ARGUED: James T. Blanch, PARSONS BEHLE & LATIMER, Salt Lake City, Utah,
for Appellant. Hall R. Marston, SEDGWICK, Los Angeles, California, for Appellees.
ON BRIEF: James T. Blanch, Richard E. Mrazik, Alan S. Mouritsen, PARSONS
BEHLE & LATIMER, Salt Lake City, Utah, for Appellant. Robert M. Connolly,
STITES & HARBISON, Louisville, Kentucky, for Appellees.




        *
        The Honorable Patrick J. Duggan, United States District Judge for the Eastern District of
Michigan, sitting by designation.


                                               1
No. 11-5335        Rodriguez v. Stryker Corp. et al.                               Page 2


                                 _________________

                                       OPINION
                                 _________________

       SUTTON, Circuit Judge. Stryker Corporation and its sales affiliate, Stryker
Sales Corporation (together, “Stryker”), make and sell a pain pump, which a doctor
prescribed for Andrew Rodriguez after his shoulder surgery. When the pump allegedly
damaged the cartilage in Rodriguez’s shoulder, he sued the companies, seeking recovery
for the injury. The district court granted summary judgment to Stryker. We affirm.

                                            I.

       In November 2004, Rodriguez had arthroscopic surgery to treat pain and
instability in his shoulder joint. Dr. John Kuhn performed the operation, and at the end
of the procedure he implanted a pain-pump catheter in Rodriguez’s shoulder. Over the
next two days, a Stryker pain pump delivered a regular dose of a local anesthetic,
bupivicaine, to the shoulder joint. Rodriguez’s condition improved after surgery but
worsened over time, and in 2008 he learned he no longer had any cartilage remaining in
his shoulder, a condition called chondrolysis.

       Rodriguez sued Stryker in 2008, alleging strict liability, negligence and breach
of warranty. Stryker moved for summary judgment and to exclude or limit the testimony
of Rodriguez’s experts on Daubert grounds. Even accepting the admissibility of the
expert testimony for the sake of argument, the district court concluded that Stryker could
not reasonably have known about the risk of chondrolysis in 2004 and thus had no duty
to warn of the risk. The court also held that Rodriguez failed as a matter of law to prove
causation.

                                           II.

       Under Tennessee law, a manufacturer must warn users about non-obvious
dangers caused by its product. Pittman v. Upjohn Co., 890 S.W.2d 425, 428–29 (Tenn.
1994); Evridge v. Am. Honda Motor Co., 685 S.W.2d 632, 636 (Tenn. 1985). The duty
No. 11-5335          Rodriguez v. Stryker Corp. et al.                              Page 3


to warn extends to known dangers or dangers that a manufacturer “could [have]
discover[ed] through the exercise of reasonable care.” Allen v. Upjohn Co., No. 833,
1981 WL 649508, at *4 (Tenn. Ct. App. Dec. 30, 1981).

          Rodriguez does not claim that Stryker knew its pumps could cause chondrolysis.
That would not be possible. Even though doctors, including Rodriguez’s doctors, had
been using pain pumps to provide anesthetics to post-operative joints for years, no
reported case of chondrolysis linked to anesthetics appears until 2005—after
Rodriguez’s November 2004 surgery. Rodriguez claims instead that Stryker should have
known about the risk. But “the state of scientific and technological knowledge available
to the manufacturer . . . at the time the product was placed on the market,” Tenn. Code
Ann. § 29-28-105(b), see Allen, 1981 WL 649508, at *5, defeats this claim as a matter
of law.

          The articles. Rodriguez submits thirteen articles published at various times
during the seventy years before the surgery, which allegedly put Stryker on notice about
the danger of using its pain pumps inside a joint. Yet none of the articles draws a
connection between pain pumps and chondrolysis, leaving Rodriguez to argue something
more inferential: that the studies “document[ ] significant damage to articular cartilage
after prolonged exposure to foreign solutions, including bupivicaine.” Rodriguez Br. at
32. Even that is a stretch, however, given what the articles say.

          A 1933 article shows that injecting rabbit joints with various water and saline
solutions produces chronic arthritis. J. Albert Key, The Production of Chronic Arthritis
by the Injection of Weak Acids, Alkalies, Distilled Water, and Salt Solution in Joints,
15 J. Bone & Joint Surgery 67, 84 (1933). The injections in this study, however, took
place over a period of weeks, far longer than the two-day pain pump used here, not to
mention that the study did not use bupicivaine (or for that matter humans). Id. at 67–68.

          Three other articles compare solutions typically used in arthroscopic surgery and
recommend the best solution for cartilage. Brian F. Reagan et al., Irrigating Solutions
for Arthroscopy, 65 J. Bone & Joint Surgery 629–31 (1983); S.K. Bulstra et al., The
Effect In Vitro of Irrigating Solutions on Intact Rat Articular Cartilage, 76 J. Bone &
No. 11-5335         Rodriguez v. Stryker Corp. et al.                                 Page 4


Joint Surgery 468–70 (1994); J.S. Jurvelin et al., Effects of Different Irrigation Liquids
and Times on Articular Cartilage, 10 Arthroscopy 667–72 (1994). But they do not warn
against using solutions in the joint space; they recommend only which solution should
be used.

        Four other articles address the risk of chondrolysis. But they tie the risk to
gentian violet (a dye) and chlorhexidine (an antiseptic), not bupivicaine (an anesthetic).
Kazuya Tamai et al., Chondrolysis of the Shoulder Following a “Color Test”-Assisted
Rotator Cuff Repair—A Report of 2 Cases, 68 Acta Orthopaedica Scandinavica 401–02
(1997); Y. Shibata et al., Chondrolysis of the Glenohumeral Joint Following a Color
Test Using Gentian Violet, 25 International Orthopaedics 401–03 (2001); C.M. Douw
et al., Clinical and Pathological Changes in the Knee After Accidental Chlorhexidine
Irrigation During Arthroscopy, 80 J. Bone & Joint Surgery 437–40 (1997); A.L. van
Huyssteen & D.J. Bracey, Chlorhexidine and Chondrolysis in the Knee, 81 J. Bone &
Joint Surgery 995–96 (1999).

        Three other articles address the use of bupivicaine within a joint. But they fail
to say that such use is unsafe. John P. Fulkerson & Thomas F. Winters, Jr., Articular
Cartilage Response to Arthroscopic Surgery, 2 Arthroscopy 184, 186 (1986)
(bupivicaine can inhibit cartilage but “it appears that this effect on cartilage is
transient”); John W. Jaureguito et al., The Effects of Morphine on Human Articular
Cartilage of the Knee, 18 Arthroscopy 631, 635 (2002) (combination of morphine and
bupivicaine “does not have a deleterious effect on human articular cartilage”); Roberta
Nole et al., Bupivicaine and Saline Effects on Articular Cartilage, 1 Arthroscopy 123,
126 (1985) (“[b]upivicaine itself seems to be fairly well tolerated by articular cartilage”).

        Another article describes a patient who developed chondrolysis and says the
patient used a pain pump with bupivicaine after surgery.                Damon H. Petty,
Glenohumeral Chondrolysis After Shoulder Arthroscopy, 32 Am. J. Sports Med. 509,
511 (2004). But the article is a series of three case studies, each listing an outcome the
authors cannot explain (chondrolysis) and all of the factors that might have played a role
in the outcome. Id. at 511, 514. It makes no claim that chondrolysis and pain pumps are
No. 11-5335          Rodriguez v. Stryker Corp. et al.                                  Page 5


linked, and in two of the case studies the patients developed chondrolysis even though
no pain-pump use is mentioned. Id. at 514.

        A final article says that single intra-articular injections “probably do[ ] not cause
permanent alterations in . . . articular cartilage” but that “[r]epeated injections . . . should
be approached with caution.” J. Neidel et al., Intra-Articular Injections and Articular
Cartilage Metabolism, 111 Archives of Orthopaedic and Trauma Surgery 237, 240
(1992). The article concludes that “the microtrauma caused by [an] injection,” when
repeated, plays a role in the permanent damage along with the foreign solution. Id. Yet
pain pumps do not present that risk—they are designed, indeed, to eliminate it—as they
are “[p]lace[d] . . . at the desired location” once in order to deliver continuous doses of
anesthetic. R.162-10 at 3. When all is said and done, not one of Rodriguez’s thirteen
articles shows that medical experts understood in 2004 that infusing a joint with
bupivicaine for two days could cause irreversible cartilage damage. Stryker had no duty
to understand what the relevant medical literature did not.

        Expert report. Rodriguez’s expert does not fill this gap. Dr. Stephen Trippel
submitted an expert report, claiming that general medical knowledge about articular
cartilage, combined with the then-extant scientific literature, should have put Stryker on
notice that this pain pump would harm cartilage. “[C]ourts have a duty to inspect the
reasoning of qualified scientific experts” in determining whether a case should go to a
jury, Kalamazoo River Study Group v. Rockwell Int’l Corp., 171 F.3d 1065, 1072 (6th
Cir. 1999); cf. Tamraz v. Lincoln Elec. Co., 620 F.3d 665, 670 (6th Cir. 2010), including
whether an expert’s sources support his conclusions, see Conde v. Velsicol Chem. Corp.,
24 F.3d 809, 813 (6th Cir. 1994). This last requirement undermines Trippel’s report.
He relies on several articles published after Rodriguez’s surgery, which do not speak to
what Stryker should have known months or years earlier based on expert knowledge at
the time. He also relies on articles published before Rodriguez’s surgery, but they are
the same thirteen articles discussed above, and none of them supports the conclusion that
Stryker reasonably should have known about the risk that its pumps could cause
chondrolysis. The thirteen articles, indeed, undermine the expert report because they
No. 11-5335          Rodriguez v. Stryker Corp. et al.                                  Page 6


show that medical experts did not understand the risks posed to cartilage by pain pumps
in 2004, when Rodriguez had his surgery. That presumably is why Dr. Trippel testified
in another case that, consistent with these articles, no studies linked chondrolysis to a
patient’s pain pump prior to 2005:

         Q: And can you identify, Dr. Trippel, in one article where the author has
         concluded—let’s talk about through . . . June 23, 2005—where the author
         wrote that some patient had experienced an outcome that affected their
         cartilage and they attributed it to any local anesthetic administered to the
         patient in any way or manner?
         A: Well, . . . the answer to the question is no.

R.116-9 at 3.

         Rodriguez submits that the pre-2004 articles, as interpreted by Dr. Trippel, show
some knowledge that cartilage could be weakened by lengthy exposure to foreign
solutions. Judge Trauger asked and aptly answered the same question in her opinion
below:

         While the pre-2004 medical articles raise the general notion that health
         of (usually animal) cartilage could be weakened by prolonged exposure
         to certain “foreign elements,” it is a bridge way too far to say that
         Stryker—in the context in which infusion pumps were broadly used and
         medically accepted without reservation— should have, prior to
         marketing the pain pump, culled through seven decades of literature,
         found the sporadic articles raising this concern, ignored all the
         authority/evidence to the contrary, and then independently concluded that
         its pain pump could cause chondrolysis, particularly where no one in the
         medical community connected the destruction of cartilage to the use of
         pain pumps until after the plaintiff’s surgery.

R.183 at 12–13; see Krumpelbeck v. Breg, Inc., 759 F. Supp. 2d 958, 974 (S.D. Ohio
2010) (same).

         Rodriguez insists that determining how many inferences to draw based on an
expert’s opinion “is the jury’s prerogative, not the court’s.” Br. at 33. Yes and no. Yes,
it is the jury’s prerogative to draw reasonable inferences from the competing evidence
presented at trial. But no, juries do not determine whether and when a party presents
No. 11-5335        Rodriguez v. Stryker Corp. et al.                              Page 7


sufficient evidence to create a triable issue of fact. Trial and appellate courts must
decide whether the inferences a party asks the jury to draw are too speculative to be
reasonable. See Tamraz, 620 F.3d at 672. “Courts need not submit to the jury
negligence cases containing only a spark or glimmer of evidence that requires the finder-
of-fact to make a leap of faith to find the defendant liable for the plaintiff’s injury.”
Morris v. Wal-Mart Stores, Inc., 330 F.3d 854, 865 (6th Cir. 2003).

       That is just the problem here. Rodriguez asks a jury to find that because there
were isolated instances over seventy years when evidence showed that a few foreign
solutions caused temporary harm to joint cartilage, Stryker should have known (and
warned) that using its pain pump in a joint with bupivicaine would cause permanent
damage. On this record, the theory requires two speculative leaps. It requires the
inference that evidence of harm resulting from other solutions meant that anesthetics
would cause the same harm. And it requires the inference that evidence of transient
harm to joints meant that irreversible cartilage damage was likely. Both are far too
conjectural and too many steps removed from the problem that developed. Just because
ingesting one type of liquid over a period of time may cause a problem does not mean
that ingesting another liquid will cause the same problem. And just because cleaning a
wound with rubbing alcohol causes temporary discomfort does not permit the inference
that cleaning a wound more than once will produce permanent discomfort. To conclude
otherwise would establish a claim for hindsight negligence, not common law negligence.

       The 510(k) notification process. Rodriguez claims that Stryker should have
known that its pain pump was not safe to use in a joint because the Food and Drug
Administration had twice denied permission to market the pump for that use. Yet the
FDA’s denials say nothing about the safety (or danger) of using Stryker’s pump. The
FDA gave Stryker permission to market its pump through the 510(k) notification
procedure, a streamlined process that determines only whether a medical device is
“substantially equivalent” to another approved device already on the market. 21 U.S.C.
§ 360c(f)(1)(A); id. § 360(k); 21 C.F.R. § 807.100. Stryker received permission through
the 510(k) process to market its pump with a single indication for use: “to provide
No. 11-5335        Rodriguez v. Stryker Corp. et al.                               Page 8


continuous infusion of a local anesthetic directly into the intra-operative site for
postoperative pain management.” R.162-10 at 2. The FDA twice denied requests,
however, to add a specific indication for using the pump in a joint. Rodriguez claims
this should have put Stryker on notice that using the pump in a joint was not safe.

       Two considerations undo this argument. First, “the 510(k) process is focused on
equivalence, not safety.” Medtronic, Inc. v. Lohr, 518 U.S. 470, 493 (1996). The FDA’s
action means only that no other device on the market carried that indication for use. It
does not mean that the pump was (or might potentially be) dangerous to use in the joint
space. The 510(k) process does not comment on safety. Id. Second, the indication for
use that the FDA did approve—using the pump at the “intra-operative site”—covers the
use of the pump in a joint. The pain-pump package echoed those instructions, without
saying anything more about where to place the pain pump, whether in the joint space or
elsewhere. The most Stryker could have concluded from the FDA’s actions was that no
other pain pump on the market was indicated for use in a joint, and that other pain pumps
instead carried a broader indication for use at the site of an operation. None of this
information would have given Stryker a hint that its device was unsafe for use in a joint
or that it should warn users of that danger.

       Duty to test. Rodriguez argues that Stryker breached its duty to test its pain
pump by not conducting a study about the effects of using the pump in a joint. This
argument collapses into the failure-to-warn claim. A manufacturer has a duty to exercise
“ordinary and reasonable care not to expose the public to an unreasonable risk of harm”
from its product. Pittman, 890 S.W.2d at 428. As it applies to testing, that means the
manufacturer must exercise ordinary and reasonable care in testing a product for
potential danger. See Allen, 1981 WL 649508, at *4. Rodriguez’s evidence shows only
that in 2004 the medical community knew that some foreign solutions could have a
harmful effect on joints, and that the damage could be permanent in the case of gentian
violet and chlorhexidine. The articles do not show that local anesthetics like bupivicaine
could cause permanent cartilage damage. At most they indicate that bupivicaine might
cause temporary, not lasting, cartilage damage, which does not suffice to inform Stryker
No. 11-5335        Rodriguez v. Stryker Corp. et al.                                 Page 9


it needed to conduct a study determining the long-term effects of using bupivicaine in
a joint. The law does not require a company to test for hidden risks that neither it nor
the medical community had a reasonable basis to suspect. “A manufacturer is not an
insurer of a product that is . . . incapable of causing injury.” Fulton v. Pfizer Hosp.
Prods. Group, Inc., 872 S.W.2d 908, 912 (Tenn Ct. App. 1993).

       Pain-pump marketing. Rodriguez claims that Stryker negligently marketed its
pain pump because it knew surgeons were using the pump in joints, and it encouraged
them to do so. The first problem with this argument is that Rodriguez overstates it. He
points to a guide Stryker published for its sales representatives that encourages
“coach[ing] the surgeon on catheter placement.” Rodriguez Br. at 47. But the guide also
tells salespeople to use the examples of placement listed in the guide, none of which
includes the glenohumeral joint space, which is the placement used in Rodriguez’s
surgery and the one now linked to chondrolysis. The only other evidence of coaching
is the deposition of another doctor in another case, who says Stryker representatives told
him pain pumps could be used in a joint space. That testimony does not do the trick,
however, due to a second problem: it makes no difference that Stryker knew surgeons
would use its pump in the joint space or even encouraged them to do so since Rodriguez
has failed to show that Stryker knew or should have known that the use was dangerous.
The FDA approved Stryker’s pain pump for use at the intra-operative site, and none of
Rodriguez’s evidence indicates that Stryker marketed its pump beyond that approved
use.

       Strict liability. In rejecting Rodriguez’s strict liability claim, the district court
invoked comment k to the Restatement (Second) of Torts, which insulates from liability
manufacturers of unavoidably unsafe products that are properly prepared and
accompanied by an adequate warning.          Restatement (Second) of Torts § 402A.
Rodriguez does not argue that the district court erred in applying comment k to his
claim. His only argument is that comment k does not protect Stryker because, based on
his other arguments, the company did not adequately warn about the risks of using its
No. 11-5335         Rodriguez v. Stryker Corp. et al.                             Page 10


pain pump in a joint. Because Rodriguez’s duty-to-warn arguments fail, this argument
necessarily fails as well.

                                            III.

        The district court also found causation wanting. Even if Stryker had a duty to
warn, it added, Rodriguez failed to show that any breach proximately caused his injury.
See Nye v. Bayer Cropscience, Inc., 347 S.W.3d 686, 704–05 (Tenn. 2011). We agree.

        In his complaint, Rodriguez alleged that Stryker “failed to provide adequate post-
marketing warnings and instructions to physicians and medical providers using the
pump.” R.1 at 9. To prevail on his failure-to-warn claim, Rodriguez bore the burden of
showing that, “had [Stryker given] additional warnings . . . , [he] would not have
sustained [his] injur[y].” King v. Danek Med., Inc., 37 S.W.3d 429, 453 (Tenn Ct. App.
2000). In attempting to establish causation, he has provided only the deposition of his
surgeon, Dr. Kuhn, and it does not help.

        By the time of Rodriguez’s surgery, Dr. Kuhn had used pain pumps in shoulder
joints after surgeries with many patients—more than one hundred times per year since
1994. He learned to use the pumps early in his career and continued using them in the
same way. He could not recall how he learned to use the pumps but agreed that,
“however [he] got trained in the use of pain pumps, [he] w[as]n’t relying on a sales rep
for that training.” R.116-14 at 7. Dr. Kuhn does not recall ever speaking to a Stryker
sales representative. He knew that other brands of pain pumps existed, but he did not
participate in decisions about which brands to buy for the hospital. A nurse would
deliver the pump to him in the operating room without any packaging or the instructions
for use. Dr. Kuhn could not remember ever reviewing Stryker’s pump instructions:

        Q: [A]s you sit here today, do you recall reviewing Stryker’s instructions
        for use?
        A: I don’t recall it.

Id. at 20. And during his more than ten years using the pumps, he knew of no other
patients who had the kind of complications Rodriguez developed:
No. 11-5335         Rodriguez v. Stryker Corp. et al.                              Page 11


        Q: And based on the information you gave me, that you have been in
        practice since 1994, performing shoulder surgeries, approximately 300
        to 350 a year, and of those at least up through 2006, about a third to half
        the time, placing a [pain-pump] catheter in the joint; is that correct?
        A: Yes.
        Q: And Mr. Rodriguez is the only patient you are aware of that has made
        a claim of chondrolysis; is that correct?
        A: Yes.

Id. at 9. On this record, Rodriguez faces a causation problem: He has no evidence that,
even if Stryker had placed the proposed warning in the instructions or given it through
a sales representative, the warning would have reached Dr. Kuhn or would have
prevented the injury.

        Trying to sidestep this problem, Rodriguez adds that Stryker should have warned
physicians in two other ways: a “Dear Doctor” letter or a label on the pain pump. The
first impediment to these arguments is that Rodriguez’s complaint claims only that
Stryker should have provided “adequate” warnings, not warnings in these forms tailored
to reach the practices of Rodriguez’s physician. If these warnings were the only
“adequate” ones in this setting, it was Rodriguez’s burden to argue that and provide
evidence showing it.

        The second impediment is that Rodriguez raises the option of a “Dear Doctor”
letter or direct label in connection with his FDA arguments, not as a way of establishing
causation for the duty-to-warn claim. Rodriguez argues that Stryker should have known
that it needed to “revise its instructions or at least circulate a Dear Doctor Letter” when
the FDA rejected its requests to approve the pump specifically for use in a joint. Reply
Br. at 15. As shown, however, the FDA position did not obligate Stryker to send any
such letter. At oral argument, Rodriguez suggested that Stryker could have placed a
warning directly onto its pain pump. That argument does not appear in Rodriguez’s
appellate briefs or his complaint. It does receive a short mention in his trial court briefs
to the effect that the pump “lacked a warning—placed on the device itself, so that it
would be seen by surgeons in the sterile field—that the FDA had not approved use of
No. 11-5335        Rodriguez v. Stryker Corp. et al.                             Page 12


Stryker’s pain pump in the intra-articular space.” R.152 at 15–16. But once again, even
if a party could preserve an argument in this way, the FDA position did not require this
type of warning.

       The third impediment is that these warnings do not establish causation even on
their own terms given the evidence at hand as to both the tort and FDA theories. As to
the “Dear Doctor” letters, Rodriguez points only to this exchange with Dr. Kuhn:

       Q: A Dear Doctor letter is when a company . . . learn[s] . . . they are now
       getting adverse reports on a particular, either machine, or the drug, [and]
       they send out a letter called a Dear Doctor letter to warn the doctors or
       instruct the doctors of what’s happened?
       A: Yes
       Q: You have had that over the years, have you not?
       A: I have seen that for medications, yes.

R.162-3 at 12. This exchange conveys only the unsurprising reality that Dr. Kuhn knew
what “Dear Doctor” letters were, not that he received and reviewed them, and most
importantly not what he would have done with a “Dear Doctor” letter in this case and
not what such a letter would have looked like in this instance.

       The same problem applies to Rodriguez’s direct-label argument. Rodriguez still
must show that a direct label would have caused Dr. Kuhn to change his long-standing
pain-pump use, King, 37 S.W.3d at 429, and Rodriguez makes no attempt at any such
showing. He never asked Dr. Kuhn about the possibility of a warning printed on
Stryker’s pain pump, what that warning might have said, or whether it would have
influenced his decisions about using the pump. The only comment of Dr. Kuhn’s that
comes remotely close is this:

       Q: If there had ever been any black-box warnings about the dose [of
       bupivicaine] that you ultimately chose for [Rodriguez], if there had been
       a warning that it destroy[s] cartilage, it stands to reason you wouldn’t
       have used it, correct?
       A: That’s correct.
No. 11-5335        Rodriguez v. Stryker Corp. et al.                             Page 13


R.162-3 at 68. That comment speaks to bupivicaine, not pain pumps, and says nothing
about what kind of pain-pump warning would have influenced Dr. Kuhn. Rodriguez
has shown only that “it stands to reason” that a warning about bupivicaine would have
prevented Dr. Kuhn from using bupivicaine. Rodriguez has not presented any evidence
that a warning on Stryker’s pain pump would have caused Dr. Kuhn not to use the device
in Rodriguez’s joint space, thus preventing his injury. Rodriguez has failed as a matter
of law to establish a triable issue of fact over causation on his failure-to-warn claim.

                                           IV.

       For these reasons, we affirm.
