McDonald v. Zimmer Inc.

                                               Office of the Director   New Mexico
                                                09:35:46 2020.07.10     Compilation
                                                              '00'06-   Commission



          IN THE COURT OF APPEALS OF THE STATE OF NEW MEXICO

Opinion Number: 

Filing Date: December 30, 2019

No. A-1-CA-36565

MICHAEL BRIAN MCDONALD, PH.D,

      Plaintiff-Appellee,

v.

ZIMMER INC., and ZIMMER
HOLDINGS INC.,

      Defendants-Appellants,

and

LAMORRIS RICHARD HERRIN, JR.
and RK ORTHOPEDICS, LLC,

      Defendants.

APPEAL FROM THE DISTRICT COURT OF BERNALILLO COUNTY
Nan G. Nash, District Judge

Released for Publication May 5, 2020.

McGinn, Montoya, Love & Curry P.A.
Randi McGinn
Katie Curry
Albuquerque, NM

Kerry Kiernan, P.C.
Kerry Kiernan
Albuquerque, NM

for Appellee

Rodey, Dickason, Sloan, Akin & Robb, P.A.
Nelson Franse
Krystle A. Thomas
Edward Ricco
Albuquerque, NM

Faegre Baker Daniels LLP
Michael J. Kanute
Chicago, IL
Bruce Jones
Minneapolis, MN

for Appellants

                                                 OPINION

VANZI, Judge.

{1}     Zimmer Inc. and Zimmer Holdings Inc. (collectively, Defendants) appeal the
district court’s finding of strict liability for a design defect in the hip prosthetic implanted
in Brian McDonald (Plaintiff). Following a bench trial, the district court concluded that the
design of the prosthetic was unreasonably dangerous, in that it shed excessive metal
debris, causing poisoning and death of the soft tissue in Plaintiff’s hip joint, requiring
Plaintiff to have additional hip surgeries and ongoing (potentially lifelong) antibiotic
treatment. Defendants argue on appeal that (1) the district court erred in its findings and
conclusions concerning a design defect; and (2) the hip prosthetic is an unavoidably
unsafe product, for which adequate warnings were given, such that Defendants are not
subject to strict liability, pursuant to comment k to the Restatement (Second) of Torts §
402A (1965). Defendants seek judgment as a matter of law, or a new trial. For the
reasons set forth below, we affirm the district court.

BACKGROUND

I.      Procedural History

{2}     Plaintiff filed a lawsuit against Defendants, and co-defendants Lamorris Richard
Herrin, Jr., and RK Orthopedics, LLC, on May 9, 2013. The complaint arose from
Plaintiff’s injuries in connection with the failure of his hip implant, a prosthetic device
designed and manufactured by Defendants. The claims tried before the district court in
December 2016, in a bench trial, sounded in strict liability (design defect and failure to
warn), negligence, breach of express and implied warranties, and punitive damages.
The district court found Defendants strictly liable for a design defect in the prosthetic
device, and dismissed all other claims, including those against co-defendants Herrin
and RK Orthopedics. 1

II.     Facts Presented at Trial


1The co-defendants were dismissed pursuant to a motion under Rule 1-041(B) NMRA, granted by the district court
following the bench trial.
A.      Plaintiff’s Hip Surgeries

{3}     In 2010 Plaintiff was diagnosed with severe osteoarthritis with flattening of the
femoral head, osteophyte formation, and cystic formation. Plaintiff consulted with
orthopedic surgeon Joshua Carothers, M.D., and elected to have total hip replacement
surgery. 2 Dr. Carothers had originally planned to use a single-modular prosthetic device
for Plaintiff’s hip replacement—a Zimmer brand “M/L Taper with VerSys head.” “Single-
modular” describes a device with a fixed or solid neck-stem 3 component (the
component anchored to the femur) coupled with an artificial head (replacing the “ball” of
the natural hip joint). Zimmer’s device, which included a titanium alloy neck-stem
component, and a cobalt-chromium alloy (CoCr) head component, was (at the time)
considered the “gold standard” in total hip replacement. However, during the surgery in
June 2010, Dr. Carothers had to make certain adjustments to accommodate Plaintiff’s
anatomy, and decided to use a dual-modular device instead: the Zimmer brand “M/L
Taper Hip Prosthesis with Kinectiv Technology” (MLTK). 4 The MLTK is a “dual-modular”
device because the neck and stem components of the prosthetic are separate and can
be adjusted, both in relationship to the head and to one another, to account for
variations in joint configuration (e.g., leg length, offset, and version, which refers to the
forward or backward rotation of the hip joint). In Plaintiff’s case, these options allowed
Dr. Carothers to choose an anteverted neck (one with a forward rotation) for Plaintiff’s
implant. Like the traditional M/L Taper, the MLTK’s neck and stem are made of titanium
alloy. The MLTK can be used with either a CoCr head (such as the VerSys) or a
ceramic head. Dr. Carothers used the CoCr head.

{4}     Plaintiff initially recovered well, but by early May 2011, Plaintiff was experiencing
hip pain, groin pain, and loss of flexibility. Dr. Carothers commenced an established
series of tests to determine the cause of Plaintiff’s pain, which showed, inter alia, that
Plaintiff had elevated levels of C-reactive protein (indicating tissue necrosis, or tissue
death), and a pseudotumor5 forming in the hip joint. Plaintiff then saw Christopher
Beauchamp, M.D., at the Mayo Clinic in Phoenix, Arizona, on September 2, 2011,
where Dr. Beauchamp diagnosed Plaintiff with an adverse reaction to metal debris,
associated with the MLTK implant, and scheduled Plaintiff for revision surgery. Dr.
Beauchamp ordered a blood serum test, which revealed slightly elevated chromium
levels, and significantly elevated (tenfold the normal level) cobalt levels. Dr. Beauchamp
performed a revision surgery on Plaintiff’s right hip joint on October 4, 2011, during
which he discovered corrosion 6 and metal debris at the taper junction of Plaintiff’s MLTK

2Also known as “total hip arthroplasty.”
3Also called a “monoblock taper.”
4Dr. Carothers noted in his testimony that, at the time, Presbyterian Hospital (where Plaintiff’s surgery was
performed) had a sole-source contract with Defendants, and therefore Dr. Carothers was restricted to using a
Zimmer product for Plaintiff’s total hip replacement.
5A pseudotumor is metal-related pathology consisting of a large fluid collection in the joint.
6Corrosion is a reduction-oxidation reaction at the surface of a metal. It may occur where two metals with differing
electro-potentials are in contact with one another, and the more active metal (i.e., the metal that more readily
loses electrons) oxidizes, or corrodes. This is known as galvanic corrosion. Corrosion may also occur through micro-
motion or fretting—that is, wear to a metal surface induced by rubbing (on metal or another surface). With
fretting corrosion (also known as tribocorrosion), surface wear removes the metal’s natural oxide coating and
prosthetic, as well as burnishing on the neck component at the second (neck-stem)
junction, necrotic (dead) tissue, and turbid (cloudy) joint fluid. Dr. Beauchamp’s pre-
operative and post-operative diagnoses were failed total hip replacement secondary to
adverse reaction to metal debris caused by the CoCr head on the hip prosthetic
articulating with the titanium trunnion (the top of the neck, where it couples with the
head). Such adverse reaction is also known as metallosis or adverse local tissue
reaction.

{5}     Dr. Beauchamp revised the hip by exchanging the CoCr head for a ceramic
head; he also replaced the Kinectiv neck component and the polyethylene liner (which
rests between the head and the cup). Dr. Beauchamp was unable to remove all of the
necrotic tissue around Plaintiff’s right hip, because removing too much tissue leaves a
patient at risk for joint dislocation; however, retaining necrotic tissue poses a risk of
infection, given the lack of blood circulation to the dead tissue. In fact, Plaintiff
developed an infection following this revision surgery, requiring a second revision
surgery, performed by Dr. Carothers. Dr. Carothers performed an irrigation and
debridement for the infection and replaced the Kinectiv neck and polyethylene liner. He
also replaced the ceramic head from the first revision surgery with a new ceramic
head. 7 Plaintiff has required and may permanently require antibiotic therapy due to his
continued risk for infection. It is probable that Plaintiff will require a third, more
complicated revision surgery in the future to eradicate the infection.

B.      Development of the MLTK

{6}    Single-modular hip prostheses have been widely used since the early 1980s, but
dual-modular prostheses were not developed until approximately twenty years later.
Indeed, when Defendants launched the development of the MLTK in 2001 (through a
project known as “G2”), it was a new design and a “new frontier” for Defendants.
Defendants employed multiple engineers and approximately twenty consulting surgeons
on the design team. The MLTK was intended to be minimally invasive, to offer a wider
range of adjustments to surgeons, and to provide greater flexibility within the joint.
Defendants designed the titanium neck and stem components to be used with either a
CoCr or a ceramic head component. The MLTK offers a total of sixty possible
configurations.

{7}    Hip implants fail for a variety of reasons, including but not limited to dislocation,
fracture, loosening, infection, and metallosis. Some degree of corrosion occurs in all
modular hip implants. Although there is no consensus as to why some patients with a


exposes it to a new chemical environment. In the junction of a modular hip prosthetic, wear is created by the
micro-motion of one component against the other, and small volumes of joint fluid exchanged within the junction
facilitate the corrosive reaction, carrying oxides and metal ions outside of the joint, and generally altering the
electro-chemical environment around and within the joint. This phenomenon has been described as mechanically-
assisted crevice corrosion.
7Dr. Carothers testified that, for Plaintiff’s primary surgery, he believed the benefits of using the MLTK with the
CoCr head outweighed the risks, but at the time, he did not know that the MLTK with CoCr head presented a risk of
metallosis.
corroding implant develop metallosis, while others do not, it is well understood that more
corrosion/metal debris increases the risk of developing metallosis. Defendants were
aware the particular characteristics of the MLTK would increase the risk of micro-
motion, and therefore corrosion and liberated metal debris from junctions of the
prosthetic. Specifically, the MLTK features (1) two modular junctions, and therefore an
additional location where corrosion may occur; (2) a junction between two dissimilar
metals (known to generally pose a higher risk of corrosion than junctions between
similar metals); (3) a neck that is thinner in two planes and more flexible 8 than a
traditional neck (increasing the likelihood of fretting corrosion); and (4) optional
adjustments in length and version that may increase the bending moment 9 in the neck
(further increasing the likelihood of fretting corrosion).

{8}     Accordingly, one of the design goals for the MLTK was to minimize corrosion at
the head-neck and neck-stem junctions, with the goal that the metal debris released by
the device would be within “known acceptable levels.” However, no reasonable level for
wear debris was, in fact, known. Defendants elected to define “known acceptable
level[s]” through a “clinically proven” predicate device: the traditional M/L taper with a
CoCr (VerSys) head, and six-inch tapered titanium neck (a single-modular device). This
device, according to Defendants’ research report on the MLTK, had a “long clinical
history of exhibiting some debris generation without adverse clinical effects.”
Defendants therefore designed a test (known as an accelerated corrosion fatigue test 10)
that would quantify the “worst case” metal debris released by the predicate device,
which was determined to be 5.62 milligrams. Defendants reasoned that, if the debris
generated by the “worst case” orientation of the MLTK in a similar environment was
below 5.62 milligrams, the MLTK would, like the predicate device, avoid adverse clinical
effects. 11

{9}    At trial Defendants explained that they ran corrosion fatigue testing on the two
MLTK junctions “separately,” in order to isolate and measure the worst-case metal
debris generated at the head-neck, and neck-stem junctions, respectively. In effect, the
Defendants tested the entire MLTK device with a ceramic head, but never tested the
entire device with CoCr head. Defendants’ explicit rationale for this was that utilization

8The MLTK neck is in the top third of flexibility among hip prosthetic necks.
9The “moment” is the product of force times distance. In the neck of the MLTK, for instance, the longer the neck,
the greater the moment. A greater moment induces greater bending (and consequently, greater micro-motion in
the junction).
10Accelerated corrosion fatigue testing is calculated to mimic and accelerate the corrosive conditions in the
human body, to measure a prosthetic’s loss of debris under such conditions and to ascertain the fatigue strength
of the components. Fatigue strength refers to resistance to cracking or fracture under corrosion stress. In this case,
such testing entailed immersing the relevant prosthetic components in a solution with a PH slightly more acidic
than the human body, at a temperature somewhat higher than the temperature of the human body, and
subjecting the components to loads analogous to the weight borne by the joint over a period of approximately five
years.
11Defendants initially ran corrosion fatigue testing on a design featuring a CoCr neck, as CoCr is an alloy superior in
strength to titanium. However, this combination generated too much metal debris, and was therefore abandoned
in favor of a design that replaced the CoCr neck with a titanium neck. This change in materials extended the time-
frame of the G-2 project (from three to five years) and resulted in additional costs for Defendants.
of the ceramic head would minimize the debris generated at the head-neck junction,
thus allowing Defendants to isolate the debris generated at the neck-stem junction.
Defendants then separately tested the head-neck junction using a CoCr head and
titanium neck, but did not use the Kinectiv neck, instead using a titanium neck of similar
geometry (a 12/14 Taper) anchored in bone cement. Defendants added together the
metal debris released in each test, 12 which totaled 4.4 milligrams. Because this total
was less than the 5.62 milligrams released by the predicate device, Defendants
determined that the debris generated by the MLTK in vivo would be within “known
acceptable levels.”

{10} Nothing prevented Defendants from performing corrosion fatigue testing on the
entire MLTK device with a CoCr head. Spectrum Accelerated Corrosion Fatigue (SACF)
testing, which would have applied side loads in a variable manner more similar to a
patient’s use of his or her joint, was also considered by the G2 design team in 2006, but
Defendants elected not to pursue it. Although the best evaluation of a device would
include clinical information, in addition to laboratory testing, and one of Defendants’
consulting surgeons, Joshua Jacobs, M.D., proposed clinical studies in 2003 (and 2011,
after the device had been marketed), Defendants never conducted one prior to
launching the MLTK. Again, evidence showed that Defendants deemed a clinical study
unnecessary, reasoning that the clinical predicate device used in the corrosion fatigue
testing provided sufficient information regarding the device’s risk of corrosion in
patients. Ultimately, the MLTK, configured with the CoCr head or the ceramic head,
passed Defendants’ testing for fatigue strength and stability.

C.      Marketing and Use of the MLTK

{11} The MLTK was cleared for marketing by the Food and Drug Administration (FDA)
on January 24, 2007. The MLTK is a “Class III” medical device—meaning one that
either “presents a potential unreasonable risk of illness or injury” or which is “purported
or represented to be for a use in supporting or sustaining human life or for a use which
is of substantial importance in preventing impairment of human health[.]” 21 U.S.C. §
360c(a)(1)(C) (2018). Although such devices are ordinarily required to undergo a
rigorous premarket approval process, the Medical Device Amendments Act of 1976,

 Stat. 539 (the Act), permitted devices that are “substantially
equivalent” to devices already on the market to avoid the premarket approval process.
See 21 U.S.C. § 360e(b)(1)(B) (2018). Courts have observed that this truncated route
(known as the “510k process,” under a prior version of the Act) is “focused on
equivalence, not safety.” Medtronic, Inc. v. Lohr, 

 (1996) (emphasis,
internal quotation marks, and citation omitted). Whereas the premarket review process
(which requires 1,200 hours to complete) is a federal safety review, the on-average 20-
hour review process for devices marketed under 510k “requires little information, rarely
elicits a negative response from the FDA, and gets processed very quickly.” 

(internal quotation marks and citation omitted).



12Defendants actually tested five different constructs for the neck-stem junction and averaged them.
{12} Manufacturers are required to internally track adverse events in connection with
medical devices and to report them to the FDA; these are made public through the
Manufacturer and User Facility Device Experience (MAUDE) database. However,
because such data is primarily controlled by the manufacturers, and because not all
doctors report adverse events to manufacturers, statistical data from MAUDE may not
be used to justify or prove a device’s safety. At trial, evidence was presented that, per
Defendants’ internal reporting, 47 MLTK devices were revised due to metallosis
between July 9, 2009 and June 20, 2016. It is unknown whether, or how many of these
devices were configured in the same manner as Plaintiff’s, because Defendants do not
track reported revisions with sufficient detail to ascertain this information. Dividing this
number by the number of devices sold worldwide through 2016 (148,470), .032 MLTK
devices were revised due to metallosis, for every thousand sold. 13 The traditional M/L
Taper (the predicate device in testing for the MLTK) had a lower metallosis revision rate
(.025 per thousand) during the same period.

{13} At trial, evidence was also presented regarding the MLTK’s performance as
reported through independent registries in Australia and the United Kingdom (UK). 14 It
appears that the MLTK had a significantly higher overall revision rate, 15 and a nine-
times higher rate of revision due to metal-related pathology, compared to all other hip
implant systems being used in Australia as of 2013. In the UK, the revision rate between
2006 and 2016 was 23 for 1,074 MLTK units implanted, for a revision rate of only .021,
but the number of MLTKs sold in the UK has also dropped precipitously since 2012;
zero were sold in 2016. No explanation for this was offered in evidence at trial. 16

{14} In 2010 Dr. Jacobs submitted a research proposal to study fretting corrosion in
the MLTK. The proposal sought to utilize corrosion fatigue and other wear testing of the
entire device (both junctions) with a CoCr head, in multiple configurations. The rationale
for this was that, “presently, the amount of metal released from newer dually modular
head-neck total arthroplasty components is not well characterized and thus the
biological impact of this is not known.” Dr. Jacobs explained that fretting corrosion in
modular junctions “appears to be a major or primary source of metal released in vivo in
total joint arthroplasty patients” and that “[t]he issue of metal release from modular
prosthetic devices is becoming increasingly urgent due to an increasing prevalence of
implant modularity associated with new Kinectiv joint replacement surgery techniques.”
Defendants’ lead engineer in the design of the MLTK, Steven Meulink, met with Dr.
Jacobs, and agreed with his concerns, but Defendants did not fund the proposed
research because they “did not have funding for the project at [the] time.”

13Units sold does not reflect the units actually implanted in a patient, further limiting the usefulness of this data.
14George Kantor, M.D., retained by Plaintiff as an expert in orthopedic surgery, explained that the registry data is
problematic in terms of relying on it to communicate reasons for revision of a given prosthetic device, because the
data is limited in specificity, and the causes of implant failure are complex. For instance, revisions reported as
caused by loosening of the prosthetic, fracture, infection, and osteolysis (bone loss), may have been caused by
metallosis or metal-related pathology, but not reported as such. Dr. Kantor felt that this data’s best function, then,
is as a “canary in the mine-shaft.”
15Dr. Kantor testified that, per National Institutes of Health consensus on hip prosthetic performance, the five-
year revision rate for survival should be 2.0; per the Australian data; the MLTK’s rate was 5.1 at five years.
16It appears that fewer than one-third of the MLTKs implanted in the UK used cobalt-chromium heads.
{15} Dr. Jacobs then reported on ten cases in which head-neck taper corrosion was
“observed at the time of revision[,]” and in which adverse local tissue reactions were
observed in a subset of several patients, leading Defendants to conduct a Quality
Investigation Report (QIR-12014) in 2011. QIR-12014 noted a substantial rise in
“corrosion complaint rates” in the past five years, among which the majority had “in-vivo
times of less than four years.” Moreover, the highest number of complaints were
regarding CoCr heads on MLTK devices or CoCr heads on a fixed CoCr stem (the
VerSys Beaded Full Coat Stem).

{16} Soon thereafter, in 2012, Paul J. Diwelius, M.D., another of Defendants’
consulting surgeons for the MLTK, published a short-term study on a large cohort of
patients, some of whom received a traditional M/L Taper implant, and some of whom
received the MLTK implant, with the aim of understanding whether the advantages of
the MLTK outweigh its disadvantages. He concluded that the advantages of the MLTK’s
modular neck configuration did not translate to better outcomes, and that the benefits of
using the MLTK over the M/L Taper did not outweigh the risks. In a group of three
patients with the MLTK components, he observed corrosion and adverse local tissue
reactions at the junction of the CoCr head and titanium neck. He also noted the risk of
corrosion at the titanium neck-stem junction. Dr. Diwelius “now almost exclusively uses
nonmodular stems and ceramic femoral heads to decrease the possibility of corrosion.”
Dr. Beauchamp, who performed Plaintiff’s first revision surgery, no longer uses the
Zimmer CoCr head in his total hip arthroplasty practice. He has switched to ceramic
heads, to “eliminate cobalt-chromium from the equation,” and reduce the risks to his
patients. Indeed, Dr. Beauchamp testified that the Mayo Clinic in Arizona has largely
shifted to use of ceramic heads, only, to avoid the metal debris generated by CoCr
heads. Dr. Kantor testified that he has performed approximately 5,000 hip surgeries,
and that he never uses dual-modular implants in his primary procedures. Moreover,
although the prevalence of metallosis is not yet well understood, Dr. Kantor sees cases
of metallosis on a monthly basis.

{17} In a 2016 article, Dr. Jacobs recommended, to prevent adverse local tissue
reactions, minimizing the micro-motion of modular junctions, and “optimizing material
selection,” noting that “many surgeons have abandoned CoCr heads entirely” in favor of
ceramic heads. Dr. Jacobs also noted that serum cobalt levels differentially elevated
over chromium levels have become a “hallmark” diagnosis for adverse local tissue
reaction. At trial, Dr. Jacobs testified that he has never seen a case of adverse local
tissue reaction in a patient with a ceramic head component and is only aware of a case
report or two documenting such a reaction in a patient with a ceramic head on a CoCr
stem (not a titanium stem, used in the MLTK). Although Dr. Jacobs testified that ceramic
heads present risks—including a risk of fracture—he felt that these risks are
exceedingly low. Dr. Jacobs was also aware that ceramic head technology was
available in 2010 (when Plaintiff received his primary MLTK implant).

{18} Finally, Jeremy Gilbert, Ph.D., a biomedical engineering expert retained by
Defendants, authored a 2016 study investigating the material loss associated with use
of a ceramic head, versus a CoCr head, on a group of modular hip prosthetics including
the MLTK. Dr. Gilbert found that use of the ceramic head resulted in reduction of
material loss by an order of magnitude (a factor of ten), and that the study’s findings
“support the hypothesis that the use of ceramic heads mitigates metallic material loss
from taper junctions.” At trial, Dr. Gilbert acknowledged that the use of ceramic heads
should eliminate the release of cobalt-chromium entirely. He also testified that a
“constant” in patients who develop adverse local tissue reactions is the presence of
modular junctions, where at least one component in those junctions is fabricated from
cobalt alloy. A 2015 study by Brian J. McGrory, M.D., noted that, while minimal titanium
corrosion still occurs with the use of a ceramic head, it does not seem to cause
metallosis.

{19} In 2010, 90 percent of the femoral heads sold by Zimmer were CoCr, and ten
percent were ceramic. By the time of trial in 2016, 50 percent of the femoral heads sold
by Zimmer were CoCr, and 50 percent were ceramic.

D.      Risk of Injury

{20} Plaintiff’s expert biomechanical engineer, Albert Burstein, Ph.D., testified that
earlier generations of single-modular hip implants did not generate fretting
corrosion/metal debris at toxic levels in meaningful clinical quantities. However, the
MLTK introduced a risk of fretting corrosion well beyond that seen in earlier devices.
According to Dr. Burstein, Defendants did not perform adequate testing with respect to
the risk of corrosion in the MLTK. Specifically, Dr. Burstein opined, Defendants failed to
test the cobalt-chromium head on the full Kinectiv device, even though the Kinectiv
neck-stem is more flexible than a titanium neck anchored in bone cement, and greater
flexibility is known to increase micro-motion, and therefore corrosion. Furthermore,
Defendants’ test of the neck-stem junction did not include a CoCr head, nor the multiple
geometric configurations available to surgeons (such as the anteverted orientation of
Plaintiff’s implant), despite the fact that the version of the neck (in addition to the length)
is known to impact fretting corrosion. Defendants’ failure to adequately test resulted in
the marketing of an unreasonably dangerous and defective device—one that, when
used with a CoCr head, in the configuration seen in Plaintiff’s implant, allowed the
liberation of excessive, toxic quantities of cobalt debris. 17

{21} Dr. Gilbert testified that, in his opinion, the MLTK as configured in Plaintiff is not
unreasonably dangerous. In his view, Defendants effectively tested the worst-case
configurations of the MLTK, and separate testing of each junction was appropriate
under a principle of mechanical engineering known as “Saint Venant’s [p]rinciple,” such
that motion at one of the MLTK junctions should not affect motion at the other. However,
Dr. Gilbert later conceded that corrosion at one location affects other locations of
corrosion, under principles of electrochemistry, as he had previously testified when
presenting to the FDA. Dr. Gilbert stated that the corrosion observed on Plaintiff’s
device was moderate. However, when asked at trial: “If a device is throwing off or

17Dr. Burstein noted that Plaintiff’s configuration was a more “extreme” case within the system of sixty possible
configurations of the MLTK. He explained that, in order to predict performance, an adequate number of
configurations at certain extremes need to be tested (and, in the case of the MLTK, they were not).
creating so much metal debris and corrosion that it causes metallosis or adverse local
tissue reaction, that is not an acceptable risk of harm, is it?” Dr. Gilbert responded, “No,
it’s not.”

III.    Findings and Conclusions on Strict Liability for Design Defect

{22} Based on the evidence presented at trial, the district court found (in relevant part)
that “Plaintiff developed metallosis around his implant and his implant failed due to the
corrosion caused by the cobalt chromium femoral head articulating with the titanium
trunnion.” The district court reasoned that “[a]lthough a small amount of non-toxic
corrosion or metal debris may occur with a hip implant, an implant that causes an
excessive amount of corrosion or metal debris sufficient to cause toxic metal poisoning
creates an unreasonable risk of injury.” It further found that the MLTK device, when
configured with a CoCr head, as in Plaintiff’s case, may generate metal debris sufficient
to cause toxic metal poisoning. Accordingly, the MLTK, as configured in Plaintiff’s case,
was defective.

DISCUSSION

I.      Standard of Review

{23} We review de novo the district court’s application of law to the facts. TPL, Inc. v.
N.M. Taxation & Revenue Dep’t, 

, 

, 

.
Moreover, where a district court enters conclusions of law following a bench trial, those
conclusions must find support in one or more findings of fact. Chavez v. S.E.D. Labs.,

, ¶ 19, 

, 

 (Chavez II). “Findings are sufficient
if, taken together and construed in support of the judgment, they justify that judgment.”

 We review a district court’s factual findings as we would the verdict of a jury—for
substantial evidence. See Bustos v. Hyundai Motor Co., 

, 

, 

; see also Giant Cab, Inc. v. CT Towing, Inc., 

, ___P.3d ___. 18 “Substantial evidence is such relevant evidence as a reasonable
mind might accept as adequate to support a conclusion.” Clovis Nat’l Bank v. Harmon,

, 

, 

 (internal quotation marks and
citation omitted). Moreover, “we resolve all disputed facts in favor of the successful
party, indulge all reasonable inferences in support of a verdict, and disregard all
evidence and inferences to the contrary.” Id. ¶ 7 (noting also that we do not re-weigh the
evidence).

II.     Analysis

{24} Defendants’ first argument on appeal is that the district court effectively held
Defendants “absolutely liable” for Plaintiff’s injuries, both through misapplication of the

18Defendants assert that “[w]hether the evidence presented at trial is sufficient to support the trial court’s
decision” is a question of law subject to de novo review. This is incorrect. The case cited by Defendants for this
proposition, Couch v. Astec Indus., Inc., 

, 

, 

, is addressed to the
standard of review for entry of a directed verdict, not entry of a judgment following trial.
law, and because there were insufficient findings or evidence of a design defect in the
hip prosthetic. Defendants specifically assert that, in its assessment of risk of injury, the
district court failed to make sufficient findings under the seven factors required by
Brooks v. Beech Aircraft Corp., 

, ¶ 32 n.2, 

, 

(citing UJI 13-1407 NMRA, comm. cmt.). Defendants also suggest that the findings,
such as they are, were not supported by sufficient evidence. 19

{25} Defendants’ second argument on appeal is that the district court should have
found strict liability inapplicable to Plaintiff’s claims under comment k to the Restatement
(Second) of Torts Section 402A, pursuant to which “unavoidably unsafe products” are
exempt from strict liability, provided (as here) the product was properly prepared and
marketed and adequate warnings were given. We address each argument in turn.

A.       The District Court Did Not Err in Finding a Design Defect

{26} Defendants first contend that the district court identified no defect in the MLTK,
and instead erroneously “based its conclusion that the MLTK was defective in design on
its finding that the implant was ‘unreasonably dangerous.’ ” However, this is precisely
what is required under New Mexico law. “[A]n unreasonable risk of injury resulting from
a condition of the product or from a manner of its use . . . makes the product defective.”
UJI 13-1406 NMRA; see Rudisaile v. Hawk Aviation, Inc., 

, ¶ 11, 

, 

 (noting that “[c]ourts have generally equated ‘defective’ with
‘unreasonably dangerous’ ”), abrogated on other grounds by Livingston v. Begay, 1982-
NMSC-121, ¶ 24, 

, 

. An unreasonable risk of injury is “a risk
which a reasonably prudent person having full knowledge of the risk would find
unacceptable. This means that a product does not present an unreasonable risk of
injury simply because it is possible to be harmed by it.” UJI 13-1407; see 

 comm.
cmt. (further explaining that “a product is defective if it is unreasonably dangerous as
marketed. It is unreasonably dangerous if a reasonable person would conclude that the
magnitude of the scientifically perceivable danger as it is proved to be at the time of the
trial outweighed the benefit of the way the product was so designed and marketed”
(alteration, internal quotation marks, and citation omitted)). In determining whether a
product design poses an unreasonable risk of injury, the fact-finder conducts a risk-
benefit analysis, and considers “the ability to eliminate the risk without seriously
impairing the usefulness of the product or making it unduly expensive.” UJI 13-1407.

{27} While a “defect” may be considered a separate element of the cause of action in
the sense that an unreasonable danger must result “from a condition of the product or
from a manner of its use,” the concept is broad. See Brooks, 

, ¶ 31
(“Our ‘unreasonable-risk-of-injury’ test [has] allowed for proof and argument under any
rational theory of defect.”); id. ¶ 32 (holding that UJI 13-1406 and 13-1407 “adequately
define ‘defect’ ” by focusing the fact-finder’s attention to evidence of the relative risks
and benefits of a product’s design); see also Rudisaile, 

, ¶ 11 (relying

19Throughout Defendants’ briefs, it is unclear whether they are challenging the district court’s factual findings, or
the evidence in support of those findings, or both. We have endeavored to address both contentions where it
appears they are raised, but the overlapping nature of the arguments has made our review more difficult.
on other state court holdings that “[i]f a product is unreasonably dangerous, it is
necessarily defective[,]” and that separate proof of defectiveness and unreasonable
danger is not required (internal quotation marks and citation omitted)). The cases cited
by Defendants do not offer any meaningful alternative definition of “defect.” For
instance, in Tenney v. Seven-Up Co., 

, ¶ 7, 

, 

, we noted that a defect was an element of proof in a strict liability case, but held
that the product in that case was defective only in the sense that it was unfit for its
intended purpose, and not unreasonably dangerous. We emphasized that strict liability
is only imposed where “the product involves a risk of death or serious personal injury or
substantial damage.” Id. ¶ 6. Similarly, Trujillo v. Berry, 

, ¶ 12, 

, 

, only states that a defective product is an element of a products
liability claim. In Pacific Indemnity Co. v. Therm-O-Disc, Inc., 

 (D.N.M. 2006) (applying New Mexico law), the federal district court held that “the
mere fact that a failure or accident occurred is insufficient to support a strict products
liability claim[,]” and that [t]here must be evidence of a defect[,]” but did not offer any
definition of “defect.”

{28} Here, it was virtually undisputed that significant corrosion and metal debris
generated by the MLTK, as configured with a CoCr head, was a substantial cause of
Plaintiff’s serious injury (i.e., metallosis) and failed implant. The question for the district
court was, then, whether the MLTK so configured posed an unreasonable risk of
metallosis, taking into account the relative risks and benefits of its design. See UJI 13-
1406, -1407. The district court found that the MLTK’s dual modularity and flexible neck,
its multiple possible configurations, and its CoCr-titanium head-neck junction, offers a
number of benefits, but also a risk of corrosion greater than the risk posed by earlier,
single-modular designs. The court further found that, although patients respond
differently to corrosion, greater corrosion increases the associated risks, such as
metallosis. Consistent with the foregoing, the court cited evidence that the MLTK
configured with a CoCr head poses a greater risk of metallosis than other devices.
Defendants’ own consulting expert biomechanical engineer, Dr. Gilbert, testified that it
was not an acceptable risk of harm for a device to generate metal debris sufficient to
cause metallosis. Dr. Beauchamp, who performed Plaintiff’s revision surgery at the
Mayo Clinic, agreed that a safely- designed hip prosthetic should not generate metal
debris sufficient to cause metallosis. The MLTK, including as configured with a ceramic
head, had passed Defendants’ internal product testing/design goals for strength,
corrosion fatigue and junction stability. The court found that Defendants’ own alternative
design—the MLTK with a ceramic head—was being used by Defendants’ own
consulting surgeon and others to avoid the risk of metallosis posed by the CoCr head.
The above findings were sufficient to support the district court’s conclusion that the
MLTK with a CoCr head, as configured in Plaintiff, presented an unreasonable risk of
metallosis, rendering it defective.

{29} Defendants argue that, even if the district court made a broad connection
between the MLTK and an unreasonable risk of injury, it did not adequately connect any
particular feature of the MLTK with the mechanism of injury or the degree of risk, and
therefore erred in finding a design defect. Defendants cite, inter alia, Bustos, 2010-
NMCA-090, ¶ 23, for the proposition that a design defect, and the risk posed thereby,
must be precisely described and quantified. In that case, the “steep rake of [the] support
pillar for the car roof” was identified by expert testimony as the defect that created the
unreasonable risk of injury. That expert based his opinion on the damage to and
measurements of the vehicle at issue, and a calculation that filling the support pillar with
foam would add 10-20 percent structural strength. 

 Here, by contrast, no expert
quantified the amount of corrosion necessary to cause metallosis, and thus no expert
could quantify the “excessive” corrosion allegedly caused by the MLTK in Plaintiff, nor
did any expert describe whether all, or only some of configurations of the MLTK with a
CoCr head were defective.

{30} To the extent Defendants argue that the district court misapplied the law by
failing to require adequate quantification of the risks posed by the MLTK, the defendants
in Bustos, an enhanced injury case, 20 also argued that the plaintiffs were required to
show the unreasonableness of the risk through precise data: namely that, but for the
defective design, the roof would have crushed only to a certain number of inches. Id. ¶
30. We disagreed, as testimony in the record reflected various ways that the strength of
the roof could have been improved without undue cost (including but not limited to
altering the rake of the support pillar), and the expert opined that, as a result of the
failure to undertake any of these improvements, the roof did not provide adequate
survival space in a slow rollover accident. Id. ¶¶ 30-32. Thus, there was evidence from
which a jury could reasonably infer that the roof could and should have been designed
not to crush to a level “way below what would be considered necessary to provide
rollover protection[.]” Id. ¶ 32. Similarly, here, the findings supported the district court’s
reasonable inference that the MLTK could and should have been designed to minimize
corrosion and metal debris to levels that do not cause metallosis.

{31} We further note the following: Defendants elected to market the MLTK without a
precise understanding of what degree of corrosion or volume of metal debris presents a
risk of metallosis. The district court concluded that Defendants’ testing was inadequate
to measure the quantity of corrosion and debris liberated by the MLTK with a CoCr
head. Defendants identify no law that would require Plaintiff to conduct the research and
clinical trials omitted by Defendants in order to establish a precise quantification of the
risks posed by the MLTK. Indeed, we read the district court’s findings regarding the
inadequacies of Defendants’ testing of the MLTK as an explanation for the presence of
an unreasonable risk that could have been better understood and earlier identified, but
was not.

{32} To the extent Defendants argue that there was insufficient evidence to support
the district court’s findings, 21 Defendants’ brief overlooks significant portions of the

20Bustos requires a plaintiff in an enhanced injury case to present evidence as to the degree of enhancement, and
in that sense requires some quantification of the properties affecting risk. 

. We agree
with Plaintiff that this does not equate to a requirement that risks be precisely quantified in every design defect
case.
21In their reply brief, Defendants state that they do not focus “primarily” on the sufficiency of the evidence, which
is of little assistance.
evidentiary record—including key testimony from Dr. Gilbert (Defendants’ own
consulting expert), Dr. Jacobs, Mr. Meulink, Dr. Beauchamp, Dr. Kantor and exhibits
such as research articles and Zimmer’s own internal data. Defendants focus almost
exclusively on Dr. Burstein’s testimony, and the language of the findings themselves,
rather than on the sufficiency of the entire record under the applicable legal standards.
Under our appellate rules, “[a] contention that a verdict, judgment, or finding of fact is
not supported by substantial evidence shall be deemed waived unless the summary of
proceedings includes the substance of the evidence bearing on the proposition[.]” Rule
12-318(A)(3) NMRA. This rule is intended to ensure that we are fully apprised of the
fact-finder’s view of the facts and its disposition of the issues, particularly given that we
“resolve all disputed facts in favor of the successful party, indulge all reasonable
inferences in support of a verdict, and disregard all evidence and inferences to the
contrary.” Harmon, 

; see Martinez v. Sw. Landfills, Inc., 1993-
NMCA-020, ¶ 15, 

, 

 (stating that the purpose of Rule 12-318
is to ensure that the appellate court is fully apprised of the “fact finder’s view of the facts
and it’s disposition of the issues”). The district court’s findings are binding on
Defendants, who failed to set forth the substance of the evidence (favorable or
unfavorable) bearing on those findings. See Maloof v. San Juan Cty. Valuation Protests
Bd., 

, ¶ 19, 

, 

; see also Chavez v. S.E.D.
Labs., 

, 

, 

 (Chavez I), aff’d in part,
rev’d in part on other grounds by Chavez II, 

, ¶ 24.

{33} Defendants’ next argument on appeal is that, in reaching its determination that
the MLTK as configured in Plaintiff posed an unreasonable risk of injury, the district
court failed to consider the seven factors set forth in Brooks, 

, ¶ 32 n.2,
and the committee commentary to UJI 13-1407. But we find no support for the
contention that all seven factors must be considered for every design defect claim.
Rather, UJI 13-1407 states in the committee commentary that “[c]riteria for determining
whether a risk of injury is unreasonable have not been provided in the instruction
because the committee feels this falls within the unique domain of advocacy under the
circumstances of proof in each case.” The commentary then lists the seven risk-benefit
criteria suggested by Professor John W. Wade in his article “The Nature of Strict Tort
Liability for Products,” 44 Miss. L. J. 825, 837-38 (1973):

       (1) the usefulness and desirability of the product . . . ; (2) the availability of
       other and safer products to meet the same need . . . ; (3) the likelihood of
       injury and its probable seriousness, i.e., “risk” . . . ; (4) the obviousness of
       the danger . . . ; (5) common knowledge and normal public expectation of
       the danger (particularly for established products) . . .; (6) the avoidability of
       injury by care in use of the product (including the effect of instructions or
       warnings) . . . [;] and (7) the ability to eliminate the danger without
       seriously impairing the usefulness of the product or making it unduly
       expensive.

We considered these factors in Bustos, where the defendants argued (citing Brooks)
that the jury was improperly instructed on the plaintiffs’ design defect claim because the
jury should have been required to consider whether there was a showing of a
reasonable alternative design. Bustos, 

. This Court held that,
“[w]hile a jury is required to make risk-benefit calculations, consideration of alternative
designs is but one of several risk-benefit considerations that a jury may balance in
determining whether a product created an unreasonable risk of injury.” Id. ¶ 54
(emphasis added). We then referred to the seven risk-benefit considerations set forth in
UJI 13-1407’s committee commentary. See Bustos, 

. This Court
reasoned that only the seventh factor (the ability to eliminate the danger without
seriously impairing the usefulness of the product or making it unduly expensive)
contains language included in the actual jury instruction as something the jury “should”
consider. 

 Defendants conceded this point at oral argument.

{34} Here, the district court’s conclusions of law included consideration of the
manufacturer’s ability to eliminate the danger without seriously impairing the usefulness
of the product or making it unduly expensive. It is unclear from Defendants’ brief
whether they challenge the sufficiency of the findings on this point, or the sufficiency of
the evidence to support those findings. Again, Defendants’ argument flatly ignores the
district court’s findings concerning the use of a ceramic head, Defendants’ own
alternative component part, in order to avoid the risk of metallosis. In other words,
Defendants already market a design that avoids the risk of metallosis without impairing
the product’s functionality. Such findings suffice to demonstrate that the district court
considered the ability to eliminate the danger without impairing the usefulness of the
product or rendering it unduly expensive. See Chavez II, 

, ¶ 19. To the
extent Defendants raise an argument regarding the sufficiency of the evidence to
support these findings, Defendants’ brief again disregards the majority of the evidentiary
record. There was evidence that use of a ceramic head on the MLTK virtually eliminates
the risk of metallosis; evidence that the MLTK with a ceramic head met Defendants’
internal strength and stability requirements; and evidence that sales of the ceramic
head, versus the CoCr head, have gone from ten percent to 50 percent of the market
share since 2010. Defendants presented no evidence that any risk of injury from the use
of their alternative design outweigh the benefits of avoiding metallosis. In any event, we
again hold that the district court’s findings are binding on Defendants, who failed to set
forth the substance of the evidence bearing on those findings. See Rule 12-318(A)(3);
Chavez I, 

; Maloof, 

, ¶ 19.

B.     Defendants’ Argument Under Comment K Was Not Preserved

{35} Defendants’ second argument on appeal is that the district court should have
found the doctrine of strict liability to be inapplicable to Plaintiff’s claims, under comment
k to the Restatement (Second) of Torts, Section 402A. Section 402A provides that a
supplier should not be held strictly liable for the provision of an unavoidably unsafe
product, provided the product was properly prepared and marketed, and adequate
warnings were given.

{36} Specifically, Section 402A comment (1) provides that a seller in the business of
supplying a product “who sells any product in a defective condition unreasonably
dangerous to the user or consumer or to his property is subject to liability for physical
harm thereby caused to the ultimate user or consumer[.]” However, comment k to this
Section provides, in part, as follows:

       Unavoidably unsafe products. There are some products which, in the
       present state of human knowledge, are quite incapable of being made
       safe for their intended and ordinary use. . . . Such a product, properly
       prepared, and accompanied by proper directions and warning, is not
       defective, nor is it unreasonably dangerous. The same is true of many . . .
       drugs, vaccines, and the like, many of which for this very reason cannot
       legally be sold except to physicians, or under the prescription of a
       physician. . . . The seller of such products, again with the qualification that
       they are properly prepared and marketed, and proper warning is given,
       where the situation calls for it, is not to be held to strict liability for
       unfortunate consequences attending their use, merely because he has
       undertaken to supply the public with an apparently useful and desirable
       product, attended with a known but apparently reasonable risk.

{37} New Mexico has incorporated the strict liability standards set forth in the
Restatement (Second) of Torts, Section 402A, with some exceptions and modifications.
See, e.g., UJI 13-1406, use note (providing that the instruction is to be used together
with UJI 13-1407 “in every strict products liability case based upon Restatement
(Second) of Torts § 402A”); UJI 13-1406, comm. cmt. (noting that the language in
Section 402A “has less than the universal application which these instructions are
intended to have for strict products liability relating to production flaw defects, unsafe
design or formulation, warning inadequacies, safety options and products which are
unavoidably unsafe, with a risk of harm not justified by usefulness or desirability of the
product”). New Mexico’s “unavoidably unsafe products” exception is set forth in UJI 13-
1419 NMRA, which provides, in part, as follows:

              There are some products which, even when properly prepared and
       labeled, cannot be made safe for their intended and ordinary use.
       Because of the nature of ingredients or natural characteristics of the
       products, use of these products involves substantial risk of injury, and
       some users will necessarily be harmed. Such products are said to be
       unavoidably unsafe.

              Unless the product unreasonably exposes users to risk of injury,
       there is no liability for supplying an unavoidably unsafe product. Whether
       users are unreasonably exposed to risk of injury turns upon a balancing of
       the dangers and benefits resulting from the product’s use.

The use note of this UJI provide that it “must be given only in cases in which the generic
condition of the product gives rise to the risk of injury, for example, certain chemicals
and drugs. The risk arises from the nature of the product and not from inadequacies of
design, manufacture, or labeling.” UJI 13-1419, use note. The Committee Commentary,
in turn, provides that “[w]hether a risk is reasonable is a question for the jury, balancing
the benefits and hazards of the product.” UJI 13-1419, comm. cmt.

{38} We must first address whether Defendants preserved for our review their
argument that the MLTK is an unavoidably unsafe product under comment k of Section
402A and UJI 13-1419. We hold that they did not.

{39} In general, an issue is not preserved unless the appellant “fairly invoked a ruling
of the trial court on the same grounds argued in the appellate court.” Benz v. Town Ctr.
Land, LLC, 

, 

 (internal quotation marks and citation
omitted). Defendants concede that they did not seek a finding that the MLTK was
“unavoidably unsafe,” nor did they otherwise refer to comment k or UJI 13-1419 in
motion practice, at trial, in written closings, or in their requested findings of fact and
conclusions of law. At oral argument, defense counsel identified only Defendants’
affirmative defenses, set forth in the answer to the complaint, as explicitly raising
comment k of Section 402A or UJI 13-1419. “We require parties to assert the legal
principle upon which their claims are based and to develop the facts in the trial court
primarily for two reasons: (1) to alert the trial court to a claim of error so that it has an
opportunity to correct any mistake, and (2) to give the opposing party a fair opportunity
to respond and show why the court should rule against the objector.” State v. Gomez,

, 

, 

. Thus, an affirmative defense is not
preserved for our review unless it is litigated before the district court and a ruling is
invoked on the issue. See, e.g., Rodriguez ex rel. Rodarte v. Sanchez, 2019-NMCA-
065, ¶¶ 25-26, 

 (holding that the defendant’s statute of limitations
argument, while raised as an affirmative defense in the answer, was not litigated before
the district court; therefore, it was not preserved for appellate review).

{40} Defendants argue, in reply, that their proposed findings and conclusions are
predicates for the application of comment k; therefore, Defendants constructively sought
the trial court’s ruling on the issue, preserving their argument. Specifically, Defendants
sought a conclusion of law that the MLTK did not present an unreasonable risk of harm,
and a conclusion that the MLTK was not defectively designed. Moreover, Defendants
proposed, and the district court adopted the following findings: zero risk of corrosion is
unattainable; some corrosion may occur in any modular implant device; there is no
consensus as to why patients react differently to corrosion; and Defendants’ warnings
for the MLTK were adequate. We hold that, while these points would be relevant to a
Section 402A comment k/UJI 13-1419 analysis, they do not amount to a comment k
analysis.

{41} UJI 13-1419 (New Mexico’s iteration of comment k) is only applicable where a
product “cannot be made safe” for its intended use, and where the nature of a product,
or its “generic condition . . . gives rise to the risk of injury.” UJI 13-1419, use note. It is
inapplicable where the risk arises “from inadequacies of design[.]” 

 Furthermore, New
Mexico’s UJI expressly adopts a case-by-case inquiry, as it contains a caveat that there
may be strict liability even for an unavoidably unsafe product, where the product
“unreasonably exposes users to risk of injury[.]” UJI 13-1419. In other words, even an
unavoidably unsafe product may present dangers so unreasonable that the imposition
of strict liability is appropriate. This risk-benefit determination is a question of fact for the
jury (or in this case, the district court). 

 comm. cmt. Other jurisdictions have adopted
comment k in a similar manner; Oklahoma holds (in a case cited by Defendants) that
the unavoidably unsafe exception does not apply unless the product was incapable of
being made safer at the time of its distribution, and its benefits justify its risks. Tansy v.
Dacomed Corp., 

 (Okla. 1994). On appeal, Defendants cite cases
holding that an FDA-approved medical device is covered by comment k and exempt
from strict liability. See, e.g., Gross v. Stryker Corp., 

 (W.D.
Pa. 2012). However, at least one jurisdiction has addressed the distinction between
drugs/devices approved through the premarket process, and those approved through
the 510k process, holding that the latter are subject to a more rigorous case-by-case
analysis. See, e.g., Burningham v. Wright Med. Tech., Inc., 

, 

 (holding that “when an implanted medical device enters the market through the
510(k) process . . . the manufacturer must prove by a preponderance of the evidence
that (1) when the product was made, it could not be made safe for its intended use even
applying the best available testing and research, and (2) the benefits of the product
justified its risk”).

{42} As the evidence in this case makes clear, a finding that all modular hip implants
present some risk of corrosion is not a finding that all modular hip implants present an
unavoidable risk of metallosis. Indeed, notably, Defendants did not pose this
equivalency to the district court. Defendants proposed no finding that the risk of
metallosis arose from the nature of the MLTK, and not from an inadequacy in design.
Defendants proposed no finding that the MLTK was incapable of being made safe for its
intended use. Defendants ignore the district court’s finding that “[t]he FDA 510(k)
process cannot be used as evidence that the MLTK was safe for use[,]” but their
arguments here suggest that they are entitled to the “blanket” exemption afforded by
some jurisdictions to all prescription drugs and medical devices. In sum, the cited
findings and conclusions would not have alerted the district court, or Plaintiff, that
Defendants were seeking a finding that the MLTK was unavoidably unsafe under
comment k and UJI 13-1419, and accordingly, Defendants have failed to establish that
we can review their comment k argument on appeal. 22

CONCLUSION

{43} For the foregoing reasons, we conclude that the district court properly applied the
law of strict liability for design defect. Moreover, the district court’s findings supported its
conclusion that the MLTK as configured in Plaintiff was defective. Those findings are

22At oral argument, Defendants referred to our holding in Davila v. Bodelson, 

, ¶¶ 25-28, 

, 

, for the proposition that an argument is preserved if there was evidence in the record
supporting a theory, and the theory was tried on implied consent of the parties. But in Davila, the district court
gave an instruction under UJI 13-1419 at trial; the question on appeal was whether the instruction had been given
in error. Davila, 

, ¶ 25. The issue was not, as here, whether the district court’s ruling had been
fairly invoked, such that the court and the plaintiff were able to address the theory presented. See Gomez, 1997-
NMSC-006, ¶ 29. Accordingly, Davila is inapposite.
binding, given that Defendants failed to set forth the substance of the evidence bearing
on them. Defendants also failed to preserve their argument under comment k to the
Restatement (Second) of Torts Section 402A, and we do not address it here.
Accordingly, we affirm.

{44}   IT IS SO ORDERED.

LINDA M. VANZI, Judge

WE CONCUR:

J. MILES HANISEE, Chief Judge

JACQUELINE R. MEDINA, Judge