United States Court of Appeals
                        For the Eighth Circuit
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                            No. 17-2870
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                     D. Christian Wise; Cheryl Wise

                                 Plaintiffs - Appellants

                                    v.

                         Mayo Clinic Rochester

                                 Defendant - Appellee

                              ____________

                 Appeal from United States District Court
                for the District of Minnesota - Minneapolis
                               ____________

                       Submitted: October 17, 2018
                        Filed: December 19, 2018
                              [Unpublished]
                              ____________

Before SHEPHERD, KELLY, and STRAS, Circuit Judges.
                           ____________

PER CURIAM.
      D. Christian and Cheryl Wise sued Mayo Clinic Rochester for medical
malpractice and lost. On appeal, they challenge the district court’s1 decision to
exclude the testimony of an expert witness at trial. We affirm.

       After months of unexplained joint pain in his hips and shoulders, Christian
sought treatment from Dr. Thomas Osborn, a rheumatologist at Mayo Clinic
Rochester. Dr. Osborn was unable to identify the cause of Christian’s pain and
scheduled him for another visit. In the meantime, Dr. Osborn prescribed prednisone,
a corticosteroid, in increasingly larger doses to treat the pain. Other than telling
Christian to taper his dosage over time if possible, Dr. Osborn did not take any steps
to counteract the potential side effects of prednisone.

       Roughly ten weeks later, Christian again began suffering from pain, this time
in his lower back. Another doctor diagnosed him with four vertebral compression
fractures—possibly caused by steroid-induced osteoporosis, a side effect of
prednisone. He eventually underwent back surgery to fix the damage.

       The Wises filed a lawsuit in federal district court against Mayo Clinic
Rochester for medical malpractice. Their theory was that Dr. Osborn should have
done more to counteract the bone-depleting side effects of prednisone. Their only
expert witness on this point was Dr. Harold Rosen, an endocrinologist who
specializes in treating patients with osteoporosis and has researched the risks of
prednisone. He was prepared to testify that Dr. Osborn failed to exercise reasonable
care when he prescribed prednisone without taking additional precautions to combat
its side effects.




      1
       The Honorable Wilhelmina M. Wright, United States District Judge for the
District of Minnesota.

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      Midway through trial, the defense challenged Dr. Rosen’s ability to provide
expert medical testimony in the case. After both sides had a chance to question Dr.
Rosen, the district court ruled that he was “not qualified to testify regarding the
standard of care for prescribing prednisone under these circumstances” because he
did not have “practical training or experience with the specific treatment at issue.”
Without an expert to testify on the standard of care, the Wises could not prove their
case. See Bigay v. Garvey, 

, 111 n.4 (Minn. 1998) (explaining that
expert testimony on the applicable standard of care is required in a medical-
malpractice case). Accordingly, the district court granted judgment as a matter of law
to Mayo Clinic Rochester.

      The Wises argue that the district court abused its discretion when it excluded
Dr. Rosen’s testimony. See Stowell v. Huddleston, 

, 634 (8th Cir. 2011).
Because this is a diversity action arising under Minnesota law, Minnesota’s expert-
witness rules apply. See 

       To testify about the standard of care, a proposed medical expert must have
“both sufficient scientific knowledge of and some practical experience with the
subject matter of the offered testimony.” Cornfeldt v. Tongen, 

, 692
(Minn. 1977). The dispute here centers on the second requirement, practical
experience, and specifically on whether Dr. Rosen possessed “practical knowledge
of what is usually and customarily done by physicians under circumstances similar
to those which confronted [Dr. Osborn].” 

see also 

(stating that a court should not define the relevant circumstances so
broadly “that it enables an otherwise unqualified witness to offer expert opinion”).
Here, the relevant circumstance was having prescribed prednisone to a patient like
Christian who suffered from unexplained joint pain.

      Dr. Rosen acknowledged that he did “not see patients in [this] setting” and that
he did not have “practical knowledge” of how a doctor would “usually and

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customarily” treat a patient like Christian. And he conceded that he prescribed
prednisone to his patients only “[i]nfrequently.”

       To be sure, Dr. Rosen testified that he had theoretical knowledge about the side
effects of prednisone and how to prevent them. This type of knowledge, however,
was not a substitute for practical experience. See Lundgren v. Eustermann, 

, 880–81 (Minn. 1985) (holding that a proposed witness lacked the
requisite practical experience because he admitted that he had never prescribed the
drug at issue and did “not know how physicians themselves customarily use[d] [the
drug] in treatment of their patients”). The district court accordingly did not abuse its
discretion in excluding Dr. Rosen’s testimony.

      We affirm the judgment of the district court.
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