United States Court of Appeals
                             For the Eighth Circuit
                         ___________________________

                                 No. 16-3428
                         ___________________________

                                    Judith A. Redd

                        lllllllllllllllllllll Plaintiff - Appellant

                                            v.

                              DePuy Orthopaedics, Inc.

                        lllllllllllllllllllll Defendant - Appellee
                                       ____________

                     Appeal from United States District Court
                   for the Eastern District of Missouri - St. Louis
                                   ____________

                               Submitted: June 6, 2017
                                 Filed: July 5, 2017
                                   [Unpublished]
                                   ____________

Before LOKEN, MURPHY, and MELLOY, Circuit Judges.
                          ____________

PER CURIAM.

       After the stem fractured in Judith Redd's hip implant, she filed this diversity
action against the hip manufacturer, DePuy Orthopaedics, Inc, alleging product defect
and failure to warn under Missouri law. She hired metallurgist Shankar Sastry as an
expert witness to testify about the allegedly defective product. The district court1
excluded Dr. Sastry's testimony on defect and causation and granted DePuy summary
judgment on all of Redd's claims. Redd appeals, arguing that the district court abused
its discretion by excluding parts of Dr. Sastry's testimony. We affirm.

                                           I.

        In 2008 Judith Redd received a total hip replacement. At that time she was a
little over five feet tall, weighed 302 pounds, and took immunosuppressant drugs.
These factors placed her at a higher risk for failure of the hip replacement, and in
2012 the implanted hip stem fractured. When the hip stem was removed, doctors
learned that it had not properly grown into the bone at the top of Redd's hip (a
possibility they had been aware of given her risk factors). She received a second hip
stem implant which similarly fractured less than two years after it was inserted.

        Redd filed this diversity action against DePuy Orthopaedics, the supplier of the
initial hip stem implant, asserting negligence and strict liability claims based on
product defect and failure to warn. She hired Shankar Sastry, a professor of
metallurgy and materials science, to analyze the cause of the fracture. Dr. Sastry had
done research in fatigue fracture initiation in metal objects, but not in metal objects
implanted in the human body. His analysis considered metallurgical factors, but not
any biomechanical factors (such as a hip stem's failure to grow into the hip bone like
Redd's). He also did not review any records related to the manufacturing process of
Redd's replacement hip before issuing his expert report. Dr. Sastry's report concluded
that the metal in Redd's hip stem was predominantly in a hexagonal close packed
("HCP" or "non austenitic") phase, rather than in a face centered cubic ("FCC" or
"austenitic") phase which, along with the coarse grain size of the metal alloy, had


      1
       The Honorable Catherine D. Perry, United States District Judge for the
Eastern District of Missouri.

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caused a premature and sudden fatigue fracture. He acknowledged that
environmental factors could have also contributed to the failure of the hip implant,
but said that "any small variation in the biomechanical forces" would have been
"secondary in nature" to the hip stem's non austenitic state "in terms for the failure."

      After the close of discovery, DePuy moved for summary judgment and the
exclusion of Dr. Sastry's testimony under Federal Rule of Evidence 702 and Daubert
v. Merrell Dow Pharmaceuticals, Inc., 

(1993). Redd submitted an
affidavit from Dr. Sastry testifying that DePuy's own specifications required the
material in the hip stem implant to be austenitic and that environmental factors would
be "secondary in the cause of the fracture when the material is inherently defective
to begin with." DePuy responded with a motion to strike Dr. Sastry's affidavit as
impermissibly supplementing or changing his expert opinion after the close of
discovery.

       The district court granted DePuy's motion to exclude parts of Dr. Sastry's
testimony after concluding that he lacked "a scientific or factual basis to conclude that
there was a manufacturing defect or to opine on causation," although he was qualified
to testify about metallurgy (i.e., that the material was in an HCP or non austenitic
phase). The court observed that Dr. Sastry had failed to "consider the necessary
issues of the forces that were exerted on [the] implant as it was placed in Ms. Redd's
hip." It also granted DePuy's motion to strike Dr. Sastry's affidavit since "many of
[his] statements directly contradicted things he said in his deposition" and a party
cannot "change testimony just to avoid summary judgment or a Daubert motion."
Redd then lacked any expert testimony on defect or causation, and DePuy's motion
for summary judgment on her manufacturing defect claim was granted, as well as on
her remaining claims. Redd appeals the grant of summary judgment as to her
manufacturing defect claim, challenging the exclusion of Dr. Sastry's affidavit and
expert testimony.



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                                          II.

      Redd argues that the district court erred by excluding Dr. Sastry's affidavit
which had been submitted after DePuy moved for summary judgment. We review
such an exclusion of evidence for abuse of discretion. Yates v. Rexton, Inc., 

, 802 (8th Cir. 2001).

       A party may not avoid summary judgment by submitting an affidavit that
contradicts rather than clarifies previous sworn testimony. Cole v. Homier Distrib.
Co., 

, 867 (8th Cir. 2010). Here, Dr. Sastry's affidavit arguably crossed
the line between clarifying prior testimony and changing prior testimony. First, his
affidavit discussed DePuy's material specifications for the hip stem implant. At his
deposition, however, Dr. Sastry said that he had not been provided with and therefore
had not relied on the specific manufacturing, testing, and regulatory records for the
hip stem which had been implanted in Redd. Second, the affidavit said that any
environmental factor would have been a secondary cause of the fracture if the
material were inherently defective to begin with. At his deposition, however, Dr.
Sastry said that environmental factors would have been secondary causes of the
fracture to the defective material only if there had been "small variations in [the]
biomechanical forces" operating on the implanted metal. He further said that he had
not considered any biomechanical forces in Redd's case and thus did not discuss
whether any variations in those forces had been small or large. Given such
differences between the testimony Dr. Sastry provided during discovery and his
affidavit, we conclude that the district court did not abuse its discretion by excluding
the affidavit from consideration at summary judgment.

                                          III.

      Redd also argues that the district court erred by excluding Dr. Sastry's
testimony that (1) her hip stem implant had a manufacturing defect and (2) that defect

                                          -4-
caused the hip stem to fracture. We review a district court's "decision to exclude
expert evidence for an abuse of discretion." Kuhn v. Wyeth, Inc., 

, 624
(8th Cir. 2012). This same deferential standard of review applies even when the
exclusion of the testimony will result in summary judgment in favor of one party. See
Gen. Elec. Co. v. Joiner, 

, 142–43 (1997).

        District court judges "must ensure that any and all scientific testimony or
evidence admitted is not only relevant, but reliable." 

.
Under Federal Rule of Evidence 702, the opinion of an expert witness is reliable if
"(1) it is based on sufficient facts or data, (2) it is the product of reliable principles
and methods, and (3) the expert has reliably applied the principles and methods to the
facts of the case." 

. An expert opinion is relevant if "[t]he
expert's scientific, technical, or specialized knowledge . . . [will] 'assist the trier of
fact to understand the evidence or determine a fact in issue.'" 

R.
Evid. 702). "The proponent of the expert testimony must prove its admissibility by
a preponderance of the evidence." Lauzon v. Senco Prods., Inc., 

, 686
(8th Cir. 2001).

       We first consider Dr. Sastry's testimony that the non austenitic phase of the
metal caused Redd's hip stem to fracture. The district court excluded this testimony
because Dr. Sastry had not considered "the forces that were applied to the hip stem"
or "any biomechanical forces." Redd argues that the district court erred by requiring
Dr. Sastry to exclude other potential causes of the fracture. Although Redd is correct
that an expert need not rule out all possible causes of an injury, an expert nonetheless
should "adequately account[] for obvious alternative explanations." Fed. R. Evid.
702 advisory committees note to 2000 amendment; see 

–94
("After discounting obvious alternatives through scientific testing, . . . [the expert]
need only be able to explain why other conceivable causes are excludable."). Here,
Dr. Sastry did not consider the obvious alternative explanation for the fracture
recognized by Redd's own doctors: the failure of the hip stem to grow into Redd's

                                           -5-
upper hip bone and properly distribute her weight. Although Dr. Sastry testified
during his deposition that environmental factors would have been secondary causes
of the fracture to the defective material if there had been "small variations in
biomechanical forces," he nonetheless did not consider whether the biomechanical
forces applied to Redd's hip stem had amounted to such small variations (indeed, he
did not at all consider the biomechanical forces applied to the hip stem). The district
court therefore acted within its discretion by excluding Dr. Sastry's opinion on
causation under Rule 702.

       Redd argues that the district court's causation analysis should have taken
account of Missouri's causation standard, but it is clearly established that Rule 702
rather than state law governs "the propriety of the district court's exclusion of . . .
expert[] reports." Johnson v. Mead Johnson & Co., 

, 561 (8th Cir.
2014). Although Missouri law would govern any merits determination of causation,
it does not impact the district court's preliminary analysis under Rule 702 of the
reliability of an expert's testimony. See 

therefore did not abuse its
discretion by excluding Dr. Sastry's expert testimony that the alleged non austenitic
phase of the metal caused Redd's hip stem implant to fracture.

       We need not determine whether the district court abused its discretion by
excluding Dr. Sastry's testimony on manufacturing defect because the exclusion of
his causation testimony alone supports its summary judgment order. Under Missouri
law, a "plaintiff in a strict products liability . . . claim must show," among other
things, "that the alleged defect caused the claimed damages." Pro Serv. Auto., LLC
v. Lenan Corp., 

, 1214 (8th Cir. 2006). Further, the cause of
sophisticated injuries "requiring surgical intervention or other highly scientific
technique for diagnosis . . . is not within the realm of lay understanding and must be
established through expert testimony." Turner v. Iowa Fire Equip. Co., 

, 1210 (8th Cir. 2000). Since the fracture of Redd's hip stem implant was a
sophisticated injury, and Redd lacked any admissible expert testimony on the cause

                                         -6-
of that fracture, the district court did not err by granting DePuy summary judgment
on her manufacturing defect claim.

                                       IV.

      Accordingly, we affirm the judgment of the district court.
                            ____________________




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