Patricia J. Marquardt,

1
STATE OF MINNESOTA

IN SUPREME COURT

A18-0968

Court of Appeals Gildea, C.J.

Patricia J. Marquardt,

Appellant,

vs. Filed: April 8, 2020
Office of Appellate Courts
James M. Schaffhausen, et al.,

Respondents,

Steven M. Dittes, et al.,

Defendants,

Steven W. Sonnesyn, et al.,

Defendants.

________________________

Eric J. Magnuson, Patrick Stoneking, Robins Kaplan LLP, Minneapolis, Minnesota; and

Douglas E. Schmidt, Schmidt & Salita, Minnetonka, Minnesota, for appellant.

Richard J. Thomas, Chad J. Hintz, Burke & Thomas, PLLP, Arden Hills, Minnesota, for
respondents.

Jennifer E. Olson, Schwebel, Goetz & Sieben, P.A., Minneapolis, Minnesota, for amicus
curiae Minnesota Association for Justice.

________________________

2
S Y L L A B U S
The district court did not abuse its discretion when it admitted testimony from two
medical doctors on the issue of causation.
Reversed and remanded.
O P I N I O N
GILDEA, Chief Justice.
The question presented in this medical malpractice case is whether the district court
abused its discretion when it admitted expert testimony from two medical doctors on the
issue of causation. The district court admitted testimony about causation from Dr. John
Stark, an orthopedic surgeon, and Dr. Kevin Stephan, an infectious-disease specialist. The
court affirmed its decision when it denied respondents’ post-trial motions. A divided panel
of the court of appeals reversed and remanded for a new trial. Marquardt v. Schaffhausen,
No. A18-0968, 2019 WL 2167475, at *5 (Minn. App. May 20, 2019). The court of appeals
concluded that the district court abused its discretion because the doctors lacked the
requisite occupational experience to opine about causation. Id. Because we conclude that
the district court did not abuse its discretion in admitting the doctors’ causation testimony,
we reverse and remand to the court of appeals to consider the remaining issues raised on
appeal.

3
FACTS
This malpractice action arises from the right-knee arthroplasty 1 respondents
Dr. James Schaffhausen and Twin Cities Orthopedics, Inc. (together Dr. Schaffhausen)
performed on appellant Patricia J. Marquardt on January 31, 2012. Marquardt contends
that as a result of the surgery, she suffered permanent neurologic damage. During the
surgery, when Dr. Schaffhausen opened the joint, he observed “a dark cloudy fluid” and
necrotic (dead) tissue. Dr. Schaffhausen ordered a Gram stain test2 and cultures to check
for infection. The Gram stain test results were negative, suggesting “that the likelihood of
infection [wa]s very low.” Accordingly, Dr. Schaffhausen elected to proceed with the total
knee replacement. The remainder of the su rgery went as expected, and Marquardt’s
recovery seemed to go smoothly, at least initially . Two days after the surgery,
Dr. Schaffhausen recorded his discharge notes, explaining that Marquardt “underwent total
knee replacement without complication” and that she should be discharged.
But the next day (February 3), while Marquardt was still in the hospital, the results
of the cultures became available. One of the four cultures showed that the knee had an
infection called methicillin -resistant Staphylococcus a ureus (MRSA). In response,
Dr. Schaffhausen, after receiving advice from a medical -management doctor and an

1 Arthroplasty is the medical term for surgery to “reduce pain and/or restore mobility
to” a dysfunctional joint. Thomas L. Stedman, Stedman’s Medical Dictionary for the
Health Professions & Nursing 144 (7th ed. 2012). In common terms, knee arthroplasty is
knee-replacement surgery.

2 A Gram stain test is used because it “gives relatively quick res ults” about whether
any bacteria are present and if so what type . Gram Stain , Lab Tests Online ,
https://labtestsonline.org/tests/gram-stain (last visited Apr. 3, 2020) [opinion attachment].

4
infectious-disease doctor, ordered 6 weeks of IV vancomycin (antibiotic) therapy to treat
the MRSA.
After several days of this trea tment, Marquardt suffered renal failure, which the
treating physician concluded may be due to vancomycin toxicity. The vancomycin
treatment was then canceled. Over the next several weeks, Marquardt suffered seizures
and was in and out of the hospital. An MRI showed signs that are “concerning for a process
such as ADEM [acute disseminated encephalom yelitis], encephalitis.” 3 ADEM became
the work ing diagnosis for the doctors. By this time , Marquardt had also developed
symptoms of brain damage, which caused deficits including vision changes and confusion.4
Although Marquardt made cognitive improvements, her knee pain continued and
so, on March 20, doctors removed the knee -replacement component, replacing it with an
antibiotic-impregnated spacer. Marquardt was discharged from the hospital on March 27.

3 ADEM is an inflammation of the central nervous system, specifically the brain and
spinal cord, that can result in brain damage. Stedman’s Medical Dictionary, supra at 28–
29. At trial, Marquardt’s theory focused on ADEM. She argued that Dr. Schaffhausen
caused her brain damage by performing the knee-replacement surgery because the surgery
allowed the MRSA infection to enter her bloodstream, causing inflammation in the bra in
(ADEM), which resulted in brain damage.

4 A different doctor later determined that “ADEM . . . [wa]s less likely,” and that
Marquardt could have reversible posterior leukoencephalopathy syndrome, which is also
known as posterior reversible encephalopa thy syndrome (PRES). PRES is a condition
characterized by confusion, headaches, seizures, and “visual abnormalities.” Stedman’s
Medical Dictionary, supra at 1346. At trial, Dr. Schaffhausen’s theory focused on PRES.
Under that theory, Dr. Schaffhausen’s decision to perform the surgery did not cause
Marquardt’s brain injury because her MRSA infection would have been treated with
vancomycin even if he had not performed the surgery. Accordingly, because Marquardt’s
kidneys could not properly process the vancomycin, she would have developed PRES due
to the buildup of vancomycin in her system, and thus she would have suffered brain damage
regardless of whether Dr. Schaffhausen performed the surgery.

5
Then, after three months of treatment, Marquardt had another surgery, inserting a n ew
knee-replacement component. She suffered one unrelated complication and was
discharged on June 29. The lasting impact of Marquardt’s brain injury includes significant
spatial deficits, loss of depth perception, and short-term memory loss.
On August 25 , 2016, Marquardt filed a medical malpractice suit against
Dr. Schaffhausen. The case proceeded to trial and Marquardt offered video depositions of
Dr. Stark and Dr. Stephan. Before introduction of the video depositions, the district court
ruled on admissibility, determining that Marquardt could introduce the video testimony as
to causation. At the close of Marquardt’ s case-in-chief, Dr. Schaffhausen moved for a
directed verdict, arguing that Marquardt had not established causation. The district court
denied that motion.
The jury found for Marquardt, and pursuant to Minn. R. Civ. P. 50 and Minn. R.
Civ. P. 59, Dr. Schaffhausen moved for judgment as a matter of l aw or a new trial . As
relevant here, Dr. Schaffhausen argued that it was error for Dr. Stark and Dr. Stephan to
testify as to causation. The district court denied both motions. The district court explained
that Dr. Stark and Dr. Stephan did not need to be neurologists to give opinion s on the
causation of Marquardt’s injuries. The district court explained that Dr. Schaffhausen’s
objection went to the weight of the opinions rather than to admissibility. Dr. Schaffhausen
appealed.
A divided panel of the court of appeals reversed, remanding to the district court for
a new trial. Marquardt, 2019 WL 2167475, at *5. The court of appeals determined that
Dr. Stark and Dr. Stephan were not qualified to testify as to causation because they lacked

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the requisite occupational experience in neurology, ADEM, and PRES. Id. at *3.
Specifically, the court of appeals explained that Dr. Stark admitted to never treating a
patient with ADEM nor seeing a case of ADEM following a MRSA infection, id., and he
affirmed that he was not an expert in PRES nor had he ever treated or diagnosed PRES, id.
at *4. Moreover, the court of appeals explained that there is no record evidence that
Dr. Stark “consulted with a neurologist about ADEM, PRES, or their causes.” Id.
Regarding Dr. Stephan, the court of appeals explained that he could testify as to the
spread of infections, but that he could not testify as to ADEM or PRES . Id. The court of
appeals observed, “[g]iven Dr. Stephan’s lack of occupational experience in diagnosing
ADEM and lack of experience in treating ADEM, he is not qualified to independently opine
about the neurological conditions or their cause s.” Id. The court also stated that
Dr. Stephan “lacks the prior occupation experience in treating a patient with PRES.” Id.
The court of appeals concluded that neither Dr. Stark nor Dr. Stephan should have
testified about causation. Id. Without expert testimony, the court held that Marquardt had
failed to establish causation a nd thus remanded for a new trial. Id. at *5. The dissent
disagreed and concluded that Dr. Stark and Dr. Stephan were qualified to testify. Id. at *9–
10 (Jesson, J., dissenting).
We granted Marquardt’s petition for review.

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ANALYSIS
On appeal, Marquardt argues that the district court properly admitted the causation
testimony of Drs. Stark and Steph an5 and urges that we reverse the court of appeals’
decision to the contrary. We review the district court’s decision to admit expert testimony
for an abuse o f discretion. Reinhardt v. Colton , 337 N.W.2d 88, 9 3 (Minn. 1983).
Generally, “the exclusion of expert medical testimony lies within the sound discretion of
the trial court, and its ruling will not be reversed unless it is based on an erroneous view of
the law or it constitutes an abuse of discretion.” Id. When exercising its discretion, the
district court has “wide latitude in determining whether there is sufficient foundation upon
which an expert may state an opinion.” Benson v. N. Gopher Enters ., Inc., 455 N.W.2d
444, 446 (Minn. 1990). And we “ apply ‘a very def erential standard’ to the district court
when reviewing a determination as to expert qualification ,” Teffeteller v. Univ. of Minn .,
645 N.W.2d 420, 427 (Minn. 2002) (quoting Gross v. Victoria Station Farms, Inc. ,
578 N.W.2d 757, 761 (Minn. 1998)) , refusing to reverse even if we “would reach a
different conclusion with respect to the sufficiency of the foundation,” Williams v.
Wadsworth, 503 N.W.2d 120, 123 (Minn. 1993). These determinations “demand a case by
case analysis” that is “best left to the trial judge familiar with the setting of the case.”
Benson, 455 N.W.2d at 446 (internal quotation marks omitted).

5 Dr. Schaffhausen spends several pages of his brief arguing that Marquardt did not
establish causation. But causation is not before our court ; the issue before us is whether
the expert testimony of Dr. Stark and Dr. Stephan was admissible. Whether Marquardt
produced sufficient evidence of causation is an issue that the court of appeals will consider
on remand. See Marquardt, 2019 WL 2167475, at *2.

8
The court of appeals held that the expert testimony was ina dmissible because
“neither Dr. Stark nor Dr. Stephan has the requisite occupational experience in neurology,
much less in ADEM or PRES.” Marquardt, 2019 WL 2167475, at *3. The conclusions
of the court of appeals about the doctors’ experiences are accurat e, but th e absence of
experience in neurology does not equate to a determination that the district court abused
its discretion in admitting the testimony.
Expert opinion testimony “must have foundational reliability.” Minn. R. Evid. 702.
To have the requisite foundation to testify, “the witness must have both the necessary
schooling and training in the subject matter involved, plus practical or occupational
experience with the subject.” Lundgren v. Eustermann , 3 70 N.W.2d 877, 880 (Minn.
1985); see al so Gross, 578 N.W.2d at 761 (“The competency of an expert witness to
provide a medical opinion depends upon both the degree of the witness’s scientific
knowledge and the extent of the witness’s practical experience with the subject of the
offered opinion.” ). It was not an abuse of discretion for the district court to hold that
Drs. Stark and Stephan meet that standard.
Dr. Stark is an orthopedic surgeon , and he has practical experience performing
general orthopedics , including knee -replacement surgery. He was also an assistant
professor of orthopedic surgery at the University of Minnesota for eight years , where he
taught residents and medical students how to do knee-replacement surgery and about septic
arthritis (infection inside the joint). Dr. Stark also has practical experience with surgery -
related infections and extensive training “in the recognition and response to infections” that
arise during surgery.

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Dr. Stephan is a specialist in infectious-disease medicine, a subspecialty of internal
medicine. He practiced infectious-disease medicine while on active duty in the military
for 13 years and then became an instructor at a military medical school. He then moved to
Duluth to work as a staff physician. In February 2012, Dr. Stephan became the treating
infectious-disease doctor for Marquardt. Dr. Stephan has experience with MRSA,
explaining that he has “experience in treating patients that have an artificial or prosthetic
knee joint like Ms. Marquardt that are infected with MRSA.” And he has e xperience
treating patients with vancomycin toxicity. He explained that he has had dozens of cases
dealing with vanco mycin toxicity. He testified that, in his experience, most of those
patients “recover without any lasting problems[,]” but that some have balance and hearing
issues.
In short, both experts Marquardt proffered have sufficient training and experience
for the district court to conclude, within its broad discretion, that they were qualified to
opine on causation. As the dissent in the court of appeals noted, the causation issue in this
case was not simply whether Marquardt had ADEM or PRES. Broadly defined, the
causation issue was whether the knee-replacement surgery caused the spread of MRSA and
whether the spread of MRSA ultimately led to Ma rquardt’s injuries. It was not an abuse
of discretion for the district court to conclude that these doctors could opine on that broad
causation question, even if they may not be qualified to testify as to the narrower question
of ADEM versus PRES.

10
In urging us to reach the opposite conclusion, Dr. Schaffhausen cites several cases,
including Cornfeldt v. Tongen, 262 N.W.2d 684 (Minn. 1977). But our precedent does not
compel us to conclude that the district court abused its discretion here.
In Cornfeldt, we analyzed whether it was an abuse of discretion for the district court
to exclude the medical testimony from an internal -medicine specialist, Dr. Belsito. Id. at
693–94. The district court had excluded Dr. Belsito from opining as to the applicable
standard of care required by (1) a surgeon in proceeding with an operation, and (2) an
anesthesiologist in administering a specific type of general anesthetic. Id. at 693. We
evaluated each decision independently.
Regarding the surgeon, we explained that, although “Dr. Belsito [an internist] had
never practiced general surgery nor did he purport to possess expertise in the field of
surgery[,]” the district court erred in requiring “that Dr. Belsito have such a background.”
Id. We noted that “Dr. Belsito had gained sufficient experience from his consultations
regarding the suitability of patients for surgery .” Id. Based on that experience, we said
that his opinion should not have been excluded simply because he was not a surgeon. Id.
at 694.
Regarding the standard of care for an anesthesiologist, we reached a different
conclusion. We concluded that the district court did not abuse its discretion by excluding
Dr. Belsito’s testimony on this point. Id. We explained that, although Dr. Belsito had hired
anesthesiologists and “knew of the effect of anesthetics on the liver,” no evidence
established that “he had sufficient knowledge to differentiate general anesthetics or that he

11
had ever consulted with an anesthesiologist regarding the use of a general anesthetic.” Id.
Under those circumstances, we concluded that the district court did not err. Id.
The experience of Dr. Stark and Dr. Stephan more closely resemble s that of
Dr. Belsito with respect to the surgeon than the anesthesiologist. Specifically, Dr. Stark is
an orthopedic surgeon and has many years of practical experience performing general
surgery, including knee -replacement surgery , the type of surgery at issue here . And
Dr. Stephan has extensive experience dealing with MRSA infec tions and MRSA-infected
prostheses. In Cornfeldt, we stated that “ ‘any person whose profession or vocation deals
with the subject at hand is entitled to be heard as an expert[.]’ ” Id. at 693 (quoting Christy
v. Saliterman, 179 N.W.2d 288, 303 (Minn. 1970)). Dr. Stark and Dr. Stephan have that
requisite professional experience. Accordingly, Cornfeldt does not suggest that the district
court abused its discretion here.
Dr. Schaffhausen also cites Swanson v. Chatterton, 160 N.W.2d 662 (Minn. 1968),
to support an affirmance. In Swanson, we concluded that the district court did not abuse
its discretion by excluding an internal -medicine specialist from testifying about the
applicable standard of care of an orthopedic surgeon. Id. at 666–67. Because the district
court excluded the expert’s testimony, and because “sufficiency of the foundation” to
testify as an expert “is primarily a question for the determination of the trial court,” id. at
667, Swanson provides no guidance for determining whether a dist rict court err ed in
admitting expert testimony.
But even if Swanson did have some bearing on our decision here, it does not support
Dr. Schaffhausen’s argument. In affirming the district court’s decision, w e reviewed the

12
credentials of the proffered exp ert and noted the following factors: (1) he had never
engaged in private practice; (2 ) he had never dealt with the “reduction” of the type of
fracture involved in the case; (3 ) he admitted in his deposition that he did not know any
authorities discussing, nor could he cite any learned articles or orthopedic books about, the
treatment of those fractures; and ( 4) he relied on knowledge that was mainly based upon
what he learned in medical school more than 15 years previously. Id. at 666 –67. We
concluded that, “on this record,” we could not hold that the trial court abused its discretion.
Id. at 667.
Some of the factors raised in Swanson overlap with factors in this case. For
example, Dr. Stark admitted that he has never treated, nor could he diagnose, ADEM or
PRES. He also admitted that he has not treated a knee infection with MRSA and that he
does not know whether there is any published literature suggesting that MRSA can trigger
ADEM. Lastly, he stated that he has never seen a situation similar to Marquardt’s case.
But Dr. Stark has experience that is different than the doctor in Swanson. To begin,
Dr. Stark has experience treating MRSA infections and other types of MRSA -infected
artificial body parts. Also, unlike the excluded internal -medicine doctor in Swanson,
Dr. Stark is an orthopedic surgeon —the same type of doctor as Dr. Schaffhausen.
Moreover, Dr. Stark is not relying only on his medical school education; he is also relying
on at least 17 years of performing, and teaching students how to perform, surgeries ,
including knee -replacement surgery. He also has over 10 years of performing, and
responding to infections asso ciated with, spinal surgeries. In conclusion , Dr. Stark has
more relevant experience than did the doctor in Swanson.

13
Similarly, although Dr. Stephan also admitted that he had never observed dark,
cloudy spinal fluid in a knee joint during surgery , he has much experience with MRSA
infections. In particula r, he has experience treating patients with MRSA -infected
prosthetic knee joints like Marquardt had in this case. As in Swanson, we cannot conclude
that the record as a whole demonstrates that the district court abused its discretion.6

6 None of the other cases Dr. Schaffhausen relies on suggest that the district court
abused its discretion here. See Teffeteller, 645 N.W.2d at 427–28 (clarifying that we apply
“ ‘a very deferential standard’ to the district court” on whether a medical expert has
foundational reliability (quoting Gross, 578 N.W.2d at 761)); Williams, 503 N.W.2d at
124–25 (holding that the district court did not abuse its discretion by excluding a medical
expert who effectively claimed that he lacked knowledge to testify about the applicable
standard of care); Lundgren, 370 N.W.2d at 880–81 (holding that the district court did not
err by excluding a ps ychologist from testifying about the standard of care required by a
family physician in prescribing a drug when the psychologist had never been a family
physician nor prescribed the drug); Kinning v. Nelson , 281 N.W.2d 849, 854 –55 (Minn.
1979) (holding that the district court did not abuse its discretion by determining that the
proposed expert was not qualified to testify about the applicable standard of care because
he was a first -year college student at the time of the malpractice ); see also Adolphson v.
United States , 545 F. Supp. 2d 925, 930 –31 (D. Minn. 2008) (excluding causation
testimony from two proffered medical experts in part because one expert did not actually
opine about causation and the other testified that no known cause for the complication
existed within the medical community).
Dr. Stark and Dr. Stephan are different from the doctors in those cases. Unlike the
doctor in Williams, neither Dr. Stark nor Dr. Stephan claim lack of knowledge; instead,
they state that, based upon their professio nal experience, Dr. Schaffhausen’s negligence
caused Marquardt’s brain damage. Dissimilar from the psychologist in Lundgren,
Dr. Stark practices in the same specialty as Dr. Schaffhausen, and, although Dr. Stephan
practices in a different specialty than Dr. Schaffhausen, he has experience treating MRSA
and MRSA-infected prosthetic components. And distinguishable from the proffered expert
in Kinning, Dr. Stark and Dr. Stephan were practicing medicine at the time of Marquardt’s
surgery. In fact, at the time of the surgery, Dr. Stark had been practicing medicine for
almost 40 years, while Dr. Stephan had been practicing medicine for more than 20 years.
Finally, unlike the proffered expert in Adolphson, neither Dr. Stark nor Dr. Stephan opine
that the medical profession has not recognized causes for ADEM and PRES.

14
In sum, the cases c ited by Dr. Schaffhausen do not show that the district court
abused its discretion in this case. If this case was only about the diagnosis of ADEM versus
the diagnosis of PRES, the argument for excluding testimony from the doctors might be
stronger. But Marquardt’s c laim is not limited to the diagnosis of ADEM or PRES.
Instead, the basic causation question is whether, as Dr. Schaffhausen argued in his opening
statement at trial , the knee -replacement surgery “is a cause of the damage that we all
recognize occurred in this case.”7
The district court has an important gate -keeper role when determining whe ther to
admit expert testimony. See Minn. R. Evid. 702 comm. cmt.—1977. The district court
properly performed that role here, carefully weighing the qualifications of the experts
before deciding to admit their testimony. The district court acknowledged that the question
of admissibility was “close.” And the fact that othe r district courts might have made a
different decision on that question does not make the district court’s decision an abuse of
discretion. See Williams, 503 N.W.2d at 123. On this record, we cannot conclude that the
district court abused its discretion when it determined that Dr. Stark and Dr. Stephan were
competent to testify as to causation.

7 Essentially, the defense’s theory was that Dr. Schaffhausen was not responsible
because he did not cause the underlying infection. Marquardt’s basic theory was that the
knee-replacement surgery caused the MRSA to spread into her bloodstream and that it was
the spread of the infection that caused her brain damage.

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CONCLUSION
For the foregoing reasons, we reverse the decision of the court of appeals and remand
to that court for consideration of the other issues respondents raised on appeal.

Reversed and remanded.

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