In the
 United States Court of Appeals
                For the Seventh Circuit
                       ____________

No. 04-2158
ARTHUR W. FUESTING,
                                           Plaintiff-Appellee,
                             v.

ZIMMER, INC.,
                                       Defendant-Appellant.
                       ____________
         Appeal from the United States District Court
                for the Central District of Illinois.
         No. 2:02-CV-02251—Harold A. Baker, Judge.
                       ____________
   ARGUED JANUARY 4, 2005—DECIDED AUGUST 30, 2005
                     ____________


  Before FLAUM, Chief Judge, and EVANS and WILLIAMS,
Circuit Judges.
  WILLIAMS, Circuit Judge. In this strict liability and
negligence case, plaintiff Arthur W. Fuesting sued defen-
dant Zimmer, Inc., an orthopaedic implant manufacturer,
for damages resulting from the failure of his prosthetic
knee. After a jury trial, where Fuesting was awarded
$650,000, Zimmer appeals, arguing that the district
court erroneously applied Federal Rule of Civil Procedure
702 and Daubert v. Merrell Dow Pharmaceuticals, Inc., 

(1993) in admitting unreliable expert testimony.
Because we find that the district court did err in admit-
ting unreliable expert testimony, we reverse. We further
find that Fuesting cannot prevail on his claims as a mat-
2                                               No. 04-2158

ter of law without this improperly admitted testimony.
Finally, we remand the case to the district court with
instructions to direct a verdict in defendant’s favor.


                   I. BACKGROUND
  Zimmer is a manufacturer of orthopaedic implants and in
1991 manufactured an implant known as the I/B Knee,
which was designed to increase the mobility of knee joints
and to restrict involuntary knee motion. It is used in a
medical procedure called total knee anthroplasty, which is
a procedure that involves the replacement of three bone
surfaces with artificial components: the lower end of the
femur (thigh bone); the top surface of the tibia (shin bone);
and the back surface of the patella (knee cap). The I/B Knee
has a metal femoral component, a dome-shaped patellar
component, and a metal tibial bone plate with an ultra-high
molecular weight polyethylene surface molded on top. In
1991, Zimmer sterilized all of its I/B Knee implants through
a process known as gamma irradiation in an air environ-
ment—a sterilization method almost universally employed
by knee prosthesis manufacturers at that time.
  Fuesting, who suffers from arthritis in both knees, had
his right knee replaced with one of Zimmer’s I/B Knee
implants on February 5, 1992.1 The procedure was per-
formed by Fuesting’s treating orthopaedic surgeon, Dr.
James McKechnie. The tibial component of this particular
implant had been manufactured and sterilized seven
months before the procedure—a period of “time on the shelf
                                                         ”
considered short by industry standards. By May of 2001,
Fuesting began experiencing pain and swelling in the right



1
  In 1985, Fuesting had his left knee replaced with one of
Zimmer’s I/B Knee implants. To date, this implant continues
to function well.
No. 04-2158                                                  3

knee. Accordingly, on November 14, 2001, Dr. McKechnie
replaced the Zimmer knee implant with a Johnson &
Johnson model.2 Due to grinding and crunching in the new
model, the knee was replaced yet again on April 23, 2003.
  In October 2002, Fuesting brought two claims against
Zimmer related to its I/B Knee based on theories of strict
liability and negligence related to design defect. The de-
fect in the design of the I/B Knee, according to Fuesting,
was the method in which it was sterilized at the time of
its manufacture (gamma irradiation in air). In support
of his claim, the plaintiff proffered two witnesses: his
treating orthopaedic surgeon (Dr. McKechnie) and an
expert witness by the name of James Pugh.
  Pugh, a litigation consultant, was vital to both Fuesting’s
theories of liability, opining as to both causation and defect.
With respect to causation, Pugh opined that Zimmer’s
chosen method of sterilization, as well as the implant’s time
on the shelf, caused the implant’s polyethylene to oxidate,
and ultimately delaminate and prematurely fail. As to
defect (and negligence for that matter), it was Pugh’s
opinion that alternative sterilization methods (such as
ethylene oxide and gamma irradiation in an inert environ-
ment) were available to Zimmer in 1991; that these meth-
ods were better than gamma irradiation in air; and that
Zimmer should have known of them at the time of the I/B
Knee’s manufacture.
  In a pre-trial motion in limine, Zimmer moved to ex-
clude Pugh’s opinions on causation and defect as unreliable
under Federal Rule of Evidence 702. The district court
denied the motion, allowing Pugh to testify at trial. At trial,
Pugh—attributing his opinions to “basic polymer sci-
ence”—testified that the cause of Fuesting’s right I/B Knee’s


2
  The orthopaedic community refers to the replacement of a
knee implant as a “revision.”
4                                                No. 04-2158

premature failure was its sterilization through gamma
irradiation in air, and concluded that any knee implant
(with a polyethylene tibial component) sterilized in such a
manner would be defective. Dr. McKechnie concurred, based
solely on his “major in chemistry.”
  To debunk the plaintiff’s theory on causation, Zimmer
offered its own expert testimony at trial. Dr. William
Maloney—an orthopaedic surgeon and leading researcher
in the field of joint replacement and osteolysis—testified
that the delamination in Fuesting’s implant was likely
attributable not to oxidation of its polyethylene component,
but rather to physical abrasions and wear and tear of the
implant’s components due to peculiarities in Fuesting’s gait
and bone growth. Maloney further testified that
the plaintiff’s post-implant weight gain—in contravention of
his doctor’s advice—exacerbated this wear and tear. In
addition, Dr. Albert Burstein, the implant co-inventor,
testified that the gamma sterilization process probably
did not cause oxidation, that wear and tear caused the
failure, and that the implant was a tremendous clinical
success. Burstein further testified that Pugh’s proffered,
alternative sterilization process was more dangerous
and more likely to cause wear.
  In response to Fuesting’s theory on design defect, Zimmer
sought to introduce evidence on the state of the art of
implant sterilization in 1991 through Dr. Albert Burstein.
In contrast to Pugh’s opinion on defect, Dr. Burstein would
testify as the I/B Knee’s co-inventor that in 1991 it was
virtually universal industry practice to sterilize implants by
gamma irradiation in air. Fuesting objected to this testi-
mony, arguing that the data and other information that
Burstein considered in forming his opinion on state of the
art had not been disclosed to the plaintiff as required of
Rule 702 witnesses by Federal Rules of Civil Procedure
26(a)(2)(A) & (B). The district court agreed, and, despite
having allowed Fuesting to introduce evidence that Zimmer
No. 04-2158                                                   5

and other manufacturers today sterilize implants in inert
(as opposed to open air) environments, barred Dr.
Burstein’s state of the art testimony.
  The jury found in favor of Fuesting, awarding him
$650,000. On appeal, Zimmer challenges, among other
things, the denial of its motion to exclude Pugh’s testi-
mony on causation and defect.


                       II. ANALYSIS
  In both strict liability and negligence actions regard-
ing design, Illinois law (under which Fuesting’s claims
proceed) requires plaintiffs to establish “the existence of
a defective condition in the product at the time it left
the manufacturer’s control,” Carrizales v. Rheem Mfg.
Co., 

, 580 (Ill. App. Ct. 1991), and “a causal
link between the alleged design defect . . . and [the plaintiff
                                                             ’s]
injury,” Baltus v. Weaver Division of Kidde & Co., 

, 586 (Ill. App. Ct. 1990). Toward both
these ends, Fuesting proffered the expert testimony of
Pugh—the propriety of which rests at the center of this
appeal. Before reaching the merits of Zimmer’s appeal,
however, we must first address its motion to strike a
portion of Fuesting’s appellate response brief.


A. Zimmer’s Motion to Strike Portions of Fuesting’s
   Brief on Appeal Granted
  In the first five pages of his Response brief—a portion of
his statement of facts entitled “Published Litera-
ture”—Fuesting cites several medical journal articles that
suggest that implant sterilization by gamma irradiation
in air causes ultra high molecular weight polyethylene
components to oxidize. He marshals these articles here in
an apparent effort to bolster his expert’s testimony on
causation and defect. Indeed, these works may suggest that
6                                                No. 04-2158

Pugh’s challenged conclusions have received some modicum
of acceptance from the scientific community. The problem
is, these articles cannot be found in the record.
  Accordingly, Zimmer argues that this portion of
Fuesting’s statement of facts must be stricken as viola-
tive of Seventh Circuit Rule 28(c). Rule 28(c) requires
that an appellate brief’s statement of facts “be a fair
summary without argument or comment. No fact shall be
stated as part of the brief unless it is supported by reference
to the page or pages of the record or appendix where that
fact appears.” The articles cited in the first five pages of
Fuesting’s Response were neither before the district court
during its Daubert briefing on the admissibility of Pugh’s
testimony, nor referenced by Pugh in his expert report, nor
authenticated, moved, or admitted into evidence. And while
the quotes from these articles can be found on the trial
transcript, they appear there only by virtue of Fuesting’s
counsel having read sentences from each article to Zimmer’s
expert witness (Dr. Burstein) during cross-examination.
What’s more, once read to him, the quotes almost invariably
met with Dr. Burstein’s disapproval. Cf. Fed. R. Evid.
803(18) (excepting “statements contained in published
treatises, periodicals, or pamphlets on a subject of . . .
medicine, or other science” from the rule excluding hearsay
provided that such treatises have been “called to the
attention of an expert witness upon cross-examination” and
“established as a reliable authority by the testimony or
admission of the witness or by other expert testimony or by
judicial notice”) (emphasis added).
  This is not the first time that the propriety of this portion
of Fuesting’s brief has been challenged. In a previous
motion to strike pursuant to Rule 28(c), which we granted
on October 4, 2004, Zimmer noted these very same deficien-
cies, as well as one more—a failure to provide cites to the
record or an appendix where the contested articles could be
No. 04-2158                                                  7

found. Fuesting has since revised his brief to include
requisite cites to the record, arguing now that such amend-
ments have cured any previously found deficiencies.
  But Rule 28(c) requires more of litigants than mere
support citations and record references. It also requires that
appellate brief fact statements be a fair summary of the
facts. See Day v. N. Ind. Pub. Serv. Corp., 

,
384-85 (7th Cir. 1999) (granting motion to strike pursuant
to Rule 28(c) where portion of fact statement was argumen-
tative and unsupported by citation). The reasons for
requiring a fair summary are patent and aplenty, and chief
among them is the efficient administration of the appellate
process. See 

is vital to efficient performance
of the appellate task.”). Citations to the record designed to
convince the court of a fact devoid of basis in the record
impede that administration. They are in effect designed to
mislead the court, and for that reason are, to put it mildly,
not fair. Thus, misleading factual assertions and citations
violate Rule 28(c) too. See McDonald v. Village of Winnetka,

, 1009 n.11 (7th Cir. 2004) (noting that mis-
leading cites to the record violate Rule 28(c)). Set forth
without context or qualification, Fuesting’s quotations from
articles neither before the court nor in evidence as “facts”
are misleading, and thus violate Rule 28(c). Therefore,
Zimmer’s renewed motion to strike is granted, and this
court will not consider the first five pages of Fuesting’s
amended response.
8                                                 No. 04-2158

B. Inadequate Daubert Inquiry
  Proceeding to the merits of the appeal, Zimmer challenges
the district court’s denial of its pre-trial motion to exclude
Pugh’s expert testimony on causation and defect. The
admissibility of scientific expert testimony is governed by
Federal Rule of Evidence 702, and in particular Daubert v.
Merrell Dow Pharmaceuticals, Inc., 

(1993).
“We first undertake a de novo review of whether the district
court properly followed the framework set forth in Daubert.”
Bradley v. Brown, 

, 436 (7th Cir. 1994). “Pro-
vided the district court adhered to Daubert’s parameters, we
will not disturb the district court’s findings unless they are
manifestly erroneous.” 

    Rule 702 provides:
     If scientific, technical, or other specialized knowl-
     edge will assist the trier of fact to understand the
     evidence or to determine a fact in issue, a witness
     qualified as an expert by knowledge, skill, experi-
     ence, training, or education[ ] may testify thereto[,]
     in the form of an opinion or otherwise, if (1) the
     testimony is based upon sufficient facts or data, (2)
     the testimony is the product of reliable principles
     and methods, and (3) the witness has applied the
     principles and methods reliably to the facts of the
     case.
Daubert has construed Rule 702 as requiring the district
court to perform a “gate-keeping function” before admitting
expert scientific testimony. Daubert v. Merrell Dow
Pharmaceuticals, 

, 589 (1993). This function is
to “ensure that any and all scientific testimony or evidence
admitted is not only relevant, but reliable.” 

considering whether the testimony “will assist the trier of
fact to understand or determine a fact in issue,” a district
court must make “a preliminary assessment of whether the
reasoning or methodology underlying the testimony is
No. 04-2158                                                 9

scientifically valid.” 

  To aid courts in assessing the reliability of scientific
expert testimony, the Daubert Court set forth the following,
non-exhaustive list of “guideposts” for consideration: (1)
whether the scientific theory can be and has been tested; (2)
whether the theory has been subjected to peer review and
publication; (3) the theory’s known or potential rate of error
when applied; and (4) whether the theory has been “gener-
ally accepted” in the scientific community. 

see
also Chapman v. Maytag Corp., 

, 687 (7th Cir.
2002). In addition to these factors, the 2000 Advisory
Committee’s Notes to Rule 702 suggest other benchmarks
for gauging expert reliability, including: (5) whether
“maintenance standards and controls” exist; (6) whether the
testimony relates to “matters growing naturally and directly
out of research they have conducted independent of the lit-
igation,” or developed “expressly for purposes of testifying”;
(7) “[w]hether the expert has unjustifiably extrapolated
from an accepted premise to an unfounded conclusion”; (8)
“[w]hether the expert has adequately accounted for obvious
alternative explanations”; (9) “[w]hether the expert is being
as careful as he would be in his regular professional work
outside his paid litigation consulting”; and (10) “[w]hether
the field of expertise claimed by the expert is known to
reach reliable results for the type of opinion the expert
would give.” Fed. R. Evid. 702 advisory committee’s note
(2000 amends.).
  While the particular factors identified in Daubert may not
always be pertinent in assessing the reliability of expert
testimony, Kumho Tire Co. v. Carmichael, 

, 150
(1999), they are precisely apt for analysis here, see 

(concerning the admissibility of expert testimony
regarding the deleterious medical effects of introducing a
foreign substance—the antinausea drug, Bendectin—into
the human body). And while we again must emphasize that
the Daubert inquiry is a flexible one, and that an expert’s
10                                               No. 04-2158

testimony need not satisfy each of the above factors to be
admissible, it is nonetheless crucial that a Daubert analysis
of some form in fact be performed. 

.
  Although the district court offered a relatively lengthy
discussion of Pugh’s credentials, the court’s Daubert fac-
tor analysis was not sufficient. As the court noted in
assessing whether the expert had the requisite “knowledge,
skill, experience, training, or education,” Pugh obtained an
undergraduate degree from the Massachusetts Institute of
Technology (MIT) in Metullurgy and Materials, and a
doctorate from MIT in Biomedical Engineering; he has
extensive experience in the fields of biomedical engineering,
metullurgy, and materials science, including professorships
at colleges of engineering and medicine; and he has long
studied polyethylene failure (the chemical that allegedly
delaminated, causing Fuesting’s implant to fail). Accord-
ingly, the court rightly concluded that “Dr. Pugh possesses
the requisite knowledge, skill, experience, training, and
education pursuant to Fed. R. Evid. 702.”
  But possessing requisite credentials alone is not enough
to render expert testimony admissible. Clark v. Takata
Corp., 

, 759 n.5 (7th Cir. 1999) (“A supremely
qualified expert cannot waltz into the courtroom and render
opinions unless those opinions are reliable and relevant
under the test set forth by the Supreme Court in Daubert.”).
The district court must also, in keeping with its
gatekeeper’s duty, assess the reliability of the methodology
the expert has employed in arriving at his opinion. This the
district court did not do. Instead, the court made reference
to Pugh’s deposition, satisfying itself that “his analysis was
discussed at length throughout the deposition [where] he
articulated a scientific reason for the failure of the polyeth-
ylene in Fuesting’s knee” without “rely[ing] on generalized
analogies or inapplicable scientific principles.” But nothing
is said as to what exactly that articulated scientific reason
No. 04-2158                                                11

is, or how it measures up to Daubert’s indicia of reliability.
The court, invoking again Pugh’s deposition as well as
his expert report, further found that the expert had suffi-
ciently ruled out Fuesting’s weight and activity level as
potential causes of polyethylene failure in the plain-
tiff’s implant. But the court made no mention of how
Pugh ruled those alternative causes out, let alone whether
and why it found that method reliable. To satisfy its
essential role, the gatekeeper must do more than just make
conclusory statements. A more searching Daubert analysis
is required, and we find the district court’s examination of
Pugh’s testimony inadequate.
  Indeed, when subjected to a more thorough Daubert
analysis, Pugh’s testimony proves unreliable, as its juxtapo-
sition against the Daubert guideposts plainly reveal.
Turning first to his testimony on causation, Pugh opined
that Zimmer’s chosen method of sterilization (gamma
irradiation in air), as well as the implant’s time on the shelf
(seven months), caused the implant’s polyethylene to
oxidate, then delaminate, and ultimately fail. “The first and
most significant Daubert factor is whether the scientific
theory has been subjected to the scientific method.” 

. Here, it is undisputed that Pugh did not
conduct any scientific tests or experiments to bolster his
theory relating polyethylene delamination to gamma
irradiation in air, nor did he produce or rely upon any
studies to verify his conclusions. See 

(finding error in the admission of expert testimony
unsupported by scientific tests, experiments, and studies).
Such insulation of his theory from the dispassionate
crucible deeply, if not fatally, compromises his testimony’s
reliability.
  Another indicator of unreliability is the unjustifiable
extrapolation from an accepted premise to an unfounded
conclusion. See Gen. Elec. Co. v. Joiner, 

, 146
(1997) (“A court may conclude that there is simply too great
12                                              No. 04-2158

an analytical gap between the data and the opinion prof-
fered.”); McMahon v. Bunn-O-Matic Corp., 

,
657-58 (7th Cir. 1998) (holding that a “bare conclusion”
offered without explanation or empirical support fails the
reliability requirement of Rule 702); Fed. R. Evid. 702
advisory committee’s note (2000 amends.) (listing
“[w]hether the expert has unjustifiably extrapolated from
an accepted premise to an unfounded conclusion” as a
relevant factor in determining reliability of expert testi-
mony). Rather than relying upon tests, experiments or
studies, Pugh attributed his opinion to “basic polymer
science,” which, even Zimmer concedes, reveals that gamma
irradiation of polyethylene can create free radicals that
bond with oxygen, thereby decreasing its molecular weight
by keeping molecular chains from re-forming, increasing its
density, and making the polyethylene susceptible to
delamination. The problem here is that Pugh did not bridge
the analytical gap between these basic principles and his
complex conclusions. For example, he did not specify, with
respect to Fuesting’s implant in particular, what quantum
of each variable is required to set this agreed upon chain
reaction in motion. How much radiation does it take to
cause oxidation, and to what degree? How much oxidation
must occur to render polyethylene more susceptible to
delamination? And once polyethylene becomes more
susceptible to delamination, how then does oxidation affect
delamination? Are all forms of polyethylene, including that
used by Zimmer (which the company claims to be oxidation-
resistant), susceptible to delamination? What effect, if any,
does implantation into the human body have on the rate of
oxidation? Basic polymer science alone cannot answer these
questions. Some greater methodology is required to bridge
the analytical gap between general principles and particu-
lar conclusions, and to vest thereby the opinion with
requisite reliability.
  Furthermore, Pugh’s delamination theory has not
No. 04-2158                                                 13

been published or otherwise subjected to peer review, and
there is no evidence that his theory has gained general
acceptance in the scientific community. See Cummins v.
Lyle Indus., 

, 369 (7th Cir. 1996) (“Rule 702 is
designed to ensure that, when expert witnesses testify in
court, they adhere to the same standards of intellectual
rigor that are demanded in their professional work. This
objective can be accomplished in a number of different
ways, including through the review of experimental,
statistical, or other scientific data generated by others in
the field.”). In particular, his untested and unpublished
theory that polyethylene delamination from oxidation
triggered by gamma irradiation results in an appearance
distinctive from delamination from other causes—leaving a
readily identifiable “signature” or “hallmark”—has not
received any, let alone general, scientific acceptance. To the
contrary, the record suggests that the I/B Knee at issue is
one of the most successful knee implants ever studied, has
the longest and highest survivorship rate published for any
knee prothesis, and has even been called the “gold stan-
dard” of its kind.
   Finally, while there is some genuine disagreement as
to whether Pugh has adequately accounted for alterna-
tive causes of the implant’s failure, Fuesting does not
dispute that Pugh developed his opinion expressly for this
litigation. All told, Pugh’s testimony on causation stacks up
quite poorly against most all indicia of reliability, rendering
the district court’s decision to admit the opinion error.
  Nor does Pugh’s testimony on defect pass Rule 702
muster. As to defect, Pugh testified that alternative steril-
ization methods (such as ethylene oxide and gamma
irradiation in an inert environment) were available to
Zimmer in 1991; that these methods were better than
gamma irradiation in air; and that Zimmer should have
known of them at the time of the I/B Knee’s manufacture.
But here again Pugh failed to perform a reliable comparison
14                                             No. 04-2158

of the chosen sterilization technique with the proffered
alternatives. Instead, he relied solely on the fact that the
gamma irradiation in air causes more oxidation than other
methods, while neglecting to consider other factors that
may have counseled the use of that chosen method (such as
effectiveness in sterilization, or minimizing implant wear
and tear).
  Furthermore, Pugh’s testimony that Zimmer should
have sterilized the subject implant through gamma irradia-
tion in an inert environment is wholly unfounded. The
record reveals that, at the time of the subject I/B
Knee implant’s manufacture (1991), it was virtually
universal industry practice to sterilize such implants by
gamma irradiation in air. Indeed, no manufacturer at
that time employed any of Pugh’s proffered methods, and
Pugh has cited no contemporary articles counseling the
use of such methods. Accordingly, the district court’s
decision to admit Pugh’s opinion on defect was also error.
  Without Pugh’s testimony, Fuesting cannot establish
either defect or negligence, as he proffered absolutely no
other evidence in support of those elements. And, save for
Dr. McKechnie’s sparse testimony on the subject—based
merely on his “major in chemistry,” presenting another
untested extrapolation susceptible to Rule 702 chal-
lenge—Fuesting has offered no other evidence as to causa-
tion. In the absence of such evidence, Fuesting cannot
establish the requisite elements of his claim, and thus
cannot prevail on his claims as a matter of law. Therefore,
we see no reason to remand for a new trial, nor to reach the
other issues raised on this appeal. Instead, we reverse this
case and remand the matter to the district court with
instructions to direct a verdict in favor of defendant.


                   III. CONCLUSION
  For the reasons stated above, we REVERSE the district
No. 04-2158                                            15

court’s decision to admit Pugh’s expert testimony on
causation and defect, and REMAND this case to the district
court with instructions to direct a verdict in defendant’s
favor.

A true Copy:
      Teste:

                       ________________________________
                       Clerk of the United States Court of
                         Appeals for the Seventh Circuit




                  USCA-02-C-0072—8-30-05