NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________ 

HOWMEDICA OSTEONICS CORP.,

Appellant

v.

ZIMMER, INC.,

Cross-Appellant

______________________ 

2015-1498, 2015-1503

______________________ 

Appeals from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. 

95/000,428.

______________________ 

Decided: February 26, 2016

______________________ 

 TIMOTHY J. MALLOY, McAndrews, Held & Malloy, 

Ltd., Chicago, IL, argued for appellant. Also represented 

by PATRICIA J. MCGRATH, CHRISTOPHER M. SCHARFF. 

 DAVID K. CALLAHAN, Latham & Watkins LLP, Chicago, IL, argued for cross-appellant. Also represented by 

BRYAN SCOTT HALES, BRYAN RUTSCH, Kirkland & Ellis 

LLP, Chicago, IL.

______________________ 
2 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

Before NEWMAN, LOURIE, and BRYSON, Circuit Judges.

Opinion for the court filed by Circuit Judge LOURIE. 

Opinion concurring in part, dissenting in part filed by 

Circuit Judge NEWMAN. 

LOURIE, Circuit Judge. 

Howmedica Osteonics Corp. (“Howmedica”) appeals 

from an inter partes reexamination decision of the United 

States Patent and Trademark Office (“PTO”) Patent Trial 

and Appeal Board (“the Board”) affirming the examiner’s 

rejection of claims 1–6 of U.S. Patent 6,818,020 (“the ʼ020 

patent”) as anticipated. See Smith & Nephew, Inc. v. 

Howmedica Osteonics Corp., No. 2013-007710, 2014 WL 

1729260, at *12 (P.T.A.B. Apr. 30, 2014) (“Decision”). 

Zimmer, Inc. (“Zimmer”) cross-appeals from the Board’s 

decision reversing the examiner’s rejection of claims 7–12 

of the ʼ020 patent as obvious. Id. at *16. For the reasons 

that follow, we affirm in part and reverse in part. 

BACKGROUND

Howmedica owns by assignment the ʼ020 patent (now 

expired), directed to ultra-high molecular weight polyethylene (“UHMWPE”) with improved properties for use in 

medical implants. UHMWPE is widely used in biomedical applications, and for “articulation surfaces in artificial 

knee and hip replacements” in particular. ʼ020 patent col. 

1 ll. 28–29. The ʼ020 patent explains that all implant 

components go through a sterilization process, most often 

irradiation, before use. Id. col. 1 ll. 42–56. One consequence of that irradiation, however, is the generation of 

free radicals. Id. col. 1 ll. 57–59. 

Free radicals are highly reactive and, when exposed to 

air, can effect “oxidative chain scission reactions.” Id. col. 

2 ll. 35–36. Through those oxidative reactions, the “material properties of the [implant], such as molecular weight, 

tensile, and wear properties, are degraded.” Id. col. 2 ll. 
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 3

36–38. If, however, irradiation occurs in an inert environment, the free radicals react with each other to form 

carbon-carbon cross-links. Id. col. 2 ll. 50–54. Such crosslinking decreases the implant’s overall degradation. 

The ʼ020 patent describes a method for “providing a 

polymeric material, such as UHMWPE, with superior 

oxidative resistance upon irradiation,” and thereby generating UHMWPE implants with improved material properties. Id. col. 3 ll. 35–37. In particular, the ʼ020 patent 

sets forth a two-step process, whereby the polymer is first 

irradiated and then heat treated. Both steps take place in 

an “oxidant-free atmosphere” to improve the cross-linking 

of free radicals. Id. col. 3 l. 65–col. 4 l. 4. The ʼ020 patent 

further provides that “the implant is heated for at least 48 

hours at a temperature of about 37°C to about 70°C and 

preferably for 144 hours at 50°C.” Id. col. 4 ll. 35–37 (the 

preferred embodiment is further described as Method D, 

’020 patent col. 7 ll. 51–58, the method Howmedica states 

generates the claimed properties, Appellant’s Br. 5). 

Claims 1–12 of the ʼ020 patent all recite “[a] medical 

implant comprising an irradiated [UHMWPE] having a 

weight average molecular weight greater than 400,000,” 

and at least one of the following properties:

(1) a solubility of less than 80.9% in trichlorobenzene (claims 1–4, 7–9, and 12), and more particularly in 1,2,4-trichlorobenzene (claim 5); 

(2) the level of free radicals at 1x1017 spins/gram 

or less (claims 2, 6, and 10);

(3) a Fourier Transform Infrared Spectroscopy 

(“FTIR”) oxidation index that does not increase 

during oven aging in air at 80°C for up to 11 

days (claims 3, 7, and 9), 11 days (claims 6, 10, 

11, and 12), or up to 23 days (claims 4 and 8); 

(4) an FTIR oxidation index of 0.01 (claim 11) or 

less (claim 12); and/or
4 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

(5) a weight percent of polyethylene with a molecular weight below 100,000 of less than 18.4% 

(claim 9).

Id. col. 12 ll. 1–54. Claims 7–12 further require the 

UHMWPE to be “annealed at a temperature greater than 

25°C for a sufficient time” to achieve one or more of the 

above properties. Id. col. 12 ll. 24–54. 

In 2005, Howmedica sued Zimmer in the U.S. District 

Court for the District of New Jersey, alleging infringement of claims 1–3, 5–7, and 10–12 of the ʼ020 patent, as 

well as the claims of three related patents.1 Howmedica 

Osteonics Corp. v. Zimmer, Inc., Civ. No 05-897, 2008 WL 

3871733, at *1 (D.N.J. Aug. 19, 2008). In 2007, the district court issued its Markman Order, construing various

disputed terms. Id. Notably, it construed “annealed at a 

temperature greater than 25°C” to mean “annealed at a 

temperature greater than 25°C and less than the melting 

point of the material—approximately 140°C.” Id. at *2. 

In light of that construction, Zimmer moved for partial 

summary judgment of noninfringement of claims 7, 10, 

11, and 12 of the ʼ020 patent. Id. at *1. The court granted the motion, concluding that Zimmer’s accused products 

were annealed above the melting temperature, i.e., at or 

about 150°C, and thus did not satisfy the limitation as 

construed, either literally or under the doctrine of equivalents. Id. at *7 (“Absolutely distilled, Plaintiff’s argument 

is: ignore the specific language and meaning of the claim 

 

1 In 2006, Zimmer moved for summary judgment 

with respect to the three related patents. The district 

court granted the motion in part, concluding that the 

claims of the three related patents were invalid as indefinite. Howmedica Osteonics Corp. v. Zimmer, Inc., Civ. 

No. 05-897, 2007 WL 1741763 (D.N.J. June 13, 2007). We 

affirmed without opinion in 2010. Howmedica Osteonics 

Corp. v. Zimmer, Inc., 397 F. App’x 654 (Fed. Cir. 2010). 
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 5

element. Unmelt is the same as melt. An antonym is a 

synonym. Accordingly, the Court finds that there is no 

genuine issue of material fact . . . .”). 

In 2009, Zimmer requested inter partes reexamination 

of claims 1–12 of the ʼ020 patent. The PTO granted the 

request, and the district court stayed its remaining proceedings pending the outcome of the reexamination. 

The examiner adopted many of Zimmer’s proposed 

rejections, and rejected claims 1–12 over various prior art 

references and combinations thereof. Joint App. (“J.A.”) 

706–21. In particular, the examiner rejected claims 1–6 

as inherently anticipated by Ching-Tai Lue, “Effects of 

Gamma Irradiation and Post Heat Treatments on the 

Structure and Mechanical Properties of Ultra High Molecular Weight Polyethylene (UHMWPE),” Masters Thesis, University of Lowell, 1979 (“Lue”), as evidenced by 

the declaration of Dr. Robert L. Clough (“Clough declaration”). J.A. 710–12. The examiner also rejected claims 7–

12 as obvious over Lue in view of U.S. Patent 3,362,897 

(“Lawton”). J.A. 715–16. Howmedica timely appealed to 

the Board. 

The Board first affirmed the examiner’s rejection of 

claims 1–6 as inherently anticipated by Lue as evidenced 

by the Clough declaration. It noted that “[i]t is undisputed that Lue describes UHMWPE that has been irradiated 

in an inert atmosphere and heat treated at 150°C for one 

hour. Lue does not[, however,] teach all the properties 

recited in the claims.” Decision, 2014 WL 1729260, at *3. 

The Board accordingly examined whether Lue’s material

inherently possesses the claimed properties, and found 

that it does. 

Turning to the Clough declaration, the Board noted 

that Dr. Clough testified to acquiring two different resins 

of UHMWPE and followed a detailed protocol reproducing 

the irradiation and heating procedures in Lue. Id. at *9. 

Dr. Clough then measured the treated UHMWPE for 
6 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

solubility, level of free radicals, and FTIR oxidation index, 

closely following the testing procedures in the ʼ020 patent. 

Id. Dr. Clough testified that the resulting measurements 

fell within the ranges recited in the ʼ020 patent. Id. The 

Board accordingly found that Zimmer had met its burden 

of showing that the properties recited in the claims necessarily were present in the UHMWPE samples treated as 

described in Lue, and shifted the burden to Howmedica to 

show otherwise. Id. at *12. 

The Board rejected each of Howmedica’s arguments in 

response, finding (1) that the preamble language “medical 

implant” did not limit claim scope, and (2) that Howmedica failed to show how any alleged difference between Dr. 

Clough’s reproduction and either the procedure in Lue or 

the solubility testing in the ’020 patent undermined Dr. 

Clough’s demonstration that the claimed properties were 

inherent in Lue. Id. at *10–12. In light of affirming the 

examiner’s rejection of claims 1–6 as inherently anticipated by Lue as evidenced by the Clough declaration, the 

Board declined to address the remaining rejections with 

respect to those claims. Id. at *12. 

The Board then reversed the examiner’s rejections of 

claims 7–12 as obvious in view of several prior art combinations. Addressing the additional limitation in claims 7–

12—“annealed at a temperature greater than 25°C”—the 

Board adopted the district court’s construction from the 

parallel proceeding2 and likewise interpreted the term to 

require annealing “at a temperature greater than 25°C 

 

2 The ʼ020 patent expired during reexamination; the 

Board accordingly reviewed the claims under the framework set forth in Phillips v. AWH Corp., 415 F.3d 1303 

(Fed. Cir. 2005) (en banc), and adopted the district court’s 

interpretation of the “annealed at . . .” limitation. See In 

re Rambus Inc., 694 F.3d 42, 46 (Fed. Cir. 2012). 
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 7

and less than the melting point of the material, approximately 140°C.” Id. at *12–13. 

In light of that determination, the Board reversed the 

examiner’s rejection of claims 7–12 as obvious over Lue in 

view of Lawton. The Board first acknowledged that Lue 

inherently discloses the claimed properties, but only by 

annealing above the temperature range recited in the ’020 

patent. Id. at *14. The Board then turned to Lawton for 

guidance, finding that it indeed teaches annealing within 

the claimed range, but nevertheless fails to suggest that 

lowering the annealing temperature necessarily generates 

the same properties for a given sample of UHMWPE. Id. 

Accordingly, the Board found that “neither the Examiner 

nor the Requester provided a basis in fact and/or technical 

reasoning” to show why a skilled artisan would expect

modifying Lue in light of Lawton to generate UHMWPE 

with the claimed properties. Id.; id. at *15 (“[T]he Examiner and Requester have not shown that, more likely than 

not, the skilled artisan would have recognized that the 

particular required properties could be achieved at temperatures below 140°C by optimizing these parameters.”). 

The Board consequently reversed the examiner’s rejection 

of claims 7–12 as obvious over Lue in view of Lawton. It 

then found the examiner’s remaining rejections similarly

flawed, and reversed on those grounds as well. Id. at *15. 

As a result, the Board declined to address the secondary 

considerations of nonobviousness. Id. at *16. 

Howmedica requested rehearing but the Board rejected the request. Howmedica timely appealed, and Zimmer 

timely cross-appealed. We have jurisdiction pursuant to 

28 U.S.C. § 1295(a)(4)(A). 

DISCUSSION

I. Howmedica’s Appeal

“Determining whether claims are anticipated is a twostep analysis. The first step involves construction of the 
8 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

claims of the patent at issue.” In re Aoyama, 656 F.3d 

1293, 1296 (Fed. Cir. 2011). Whether a preamble limits a 

claim is a question of claim construction. Catalina Mktg. 

Int’l, Inc. v. Coolsavings.com, Inc., 289 F.3d 801, 808 (Fed. 

Cir. 2002). In this case, because the intrinsic record fully 

determines the proper construction, we review the Board’s 

construction de novo. Microsoft Corp. v. Proxyconn Inc., 

789 F.3d 1292, 1297 (Fed. Cir. 2015) (citing Teva Pharm. 

USA, Inc. v. Sandoz, Inc., 135 S. Ct. 831, 840–42 (2015)). 

“The second step involves comparing the claims to the 

prior art.” In re Aoyama, 656 F.3d at 1296. A prior art 

reference anticipates a claim if it discloses each and every 

limitation. Schering Corp. v. Geneva Pharm., 339 F.3d 

1373, 1377 (Fed. Cir. 2003). A single reference may also 

anticipate without expressly disclosing a limitation of the 

claimed invention, if that limitation is necessarily present, 

or inherent, in the reference. See id. Indeed, the inherent 

result must inevitably result from the disclosed steps; it 

cannot be established by probabilities or possibilities. See 

Bettcher Indus., Inc. v. Bunzl USA, Inc., 661 F.3d 629, 639 

(Fed. Cir. 2011). Whether a reference anticipates is a 

question of fact that we review for substantial evidence on 

appeal. In re Morsa, 713 F.3d 104, 109 (Fed. Cir. 2013).

A.

On appeal, Howmedica first faults the Board for finding that the preamble, “medical implant,” does not limit

claim scope.3 According to Howmedica, “medical implant” 

permeates the specification and is an essential feature, 

giving life, meaning, and vitality to the claims. Howmedica argues that this is relevant for two reasons: first, Lue 

does not disclose medical implants, and therefore does not 

 

3 Claims 1–12 all contain the preamble, “medical 

implant.” Howmedica challenges the Board’s determination only with respect to claims 1–6.
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 9

anticipate; and second, Dr. Clough’s reproductions were 

not prepared using medical grade UHMWPE, and thus 

cannot establish inherent anticipation. 

Zimmer responds that the preamble language, “medical implant,” is not limiting. In particular, Zimmer contends that the body of each claim defines a structurally 

complete invention, and that the preamble offers no more 

than a purpose or intended use for UHMWPE with the 

claimed properties. 

“Whether to treat a preamble as a limitation is a determination ‘resolved only on review of the entire[] . . . 

patent to gain an understanding of what the inventors 

actually invented and intended to encompass by the 

claim.’” Catalina, 289 F.3d at 808 (quoting Corning Glass 

Works v. Sumitomo Elec. U.S.A., Inc., 868 F.2d 1251, 1257 

(Fed. Cir. 1989)). “[T]here is no simple test for determining when a preamble limits claim scope, [but] we have set 

forth some general principles to guide that inquiry.” Am. 

Med. Sys., Inc. v. Biolitec, Inc., 618 F.3d 1354, 1358 (Fed. 

Cir. 2010). Generally, a preamble is not limiting. Allen 

Eng’g Corp. v. Bartell Indus., Inc., 299 F.3d 1336, 1346 

(Fed. Cir. 2002). But a preamble may limit the invention

if it recites essential structure or steps, or if it is “necessary to give life, meaning, and vitality” to the claim. See 

Pitney Bowes, Inc. v. Hewlett-Packard Co., 182 F.3d 1298, 

1305 (Fed. Cir. 1999). Conversely, a preamble does not 

limit an invention “where a patentee defines a structurally complete invention in the claim body and uses the 

preamble only to state a purpose or intended use for the 

invention.” Rowe v. Dror, 112 F.3d 473, 478 (Fed. Cir. 

1997). 

In light of those principles, we agree with the Board 

and conclude that the preamble, “medical implant,” does 

not limit claim scope. The applicant did not rely on that

phrase to define the invention, cf. Rowe, 112 F.3d at 479 

(noting that the use of Jepson format “suggests the struc-
10 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

tural importance of the recitations found in the preamble”), or to distinguish prior art during prosecution, J.A. 

5469; see also Am. Med., 618 F.3d at 1359. Nor does any 

term in the bodies of the claims rely on “medical implant” 

for antecedent basis. Cf. Pitney Bowes, 182 F.3d at 1306 

(finding the preamble “necessary to give life, meaning, 

and vitality” to the claim because terms from the body of 

the claim “c[ould] only be understood in the context of the 

preamble statement”). 

On the contrary. The body of each claim describes a 

structurally complete invention, e.g., ’020 patent col. 12 ll.

2–4 (“[A]n irradiated [UHMWPE] having a weight average molecular weight greater than 400,000 and a solubility of less than 80.9% in trichlorobenzene.”), and deletion 

of the preamble language does not affect that structure, 

Catalina, 289 F.3d at 808. The preamble merely describes a use or purpose for irradiated and heat treated

UHMWPE with the claimed properties. Rowe, 112 F.3d 

at 478; Decision, 2014 WL 1729260, at *3 (finding that 

“medical implant” “imports that a UHMWPE is suitable 

as a medical implant if it has the claimed properties”). 

The specification’s regular use of the preamble language, 

“medical implant,” is of no additional import here; it

reiterates that a “medical implant” is one use for 

UHMWPE with the claimed solubility, FTIR oxidation 

index, and level of free radicals. 

Because we agree with the Board, and conclude that 

the preamble language, “medical implant,” does not limit 

the claims, we need not also address whether Lue teaches 

medical implants or whether Dr. Clough’s reproductions 

fail to use medical grade UHMWPE and thereby fail to 

establish inherent anticipation.

B.

Howmedica next challenges two aspects of the Board’s 

finding that claims 1–6 of the ’020 patent are inherently 

anticipated by Lue as evidenced by Clough’s declaration. 
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 11

First, Howmedica argues that Dr. Clough did not faithfully reproduce Lue, either in the UHMWPE resin used or in 

the irradiation procedure. It contends that the deviations 

at best show that the claimed properties might be present 

in Lue, and thereby fail to establish a sound basis for the 

Board to believe that Lue discloses the same product 

claimed by the ’020 patent and to then shift the burden to 

Howmedica to prove otherwise. We find this first challenge unpersuasive. 

Without question, “[i]nherency is a very tricky concept 

in patent law.” In re Montgomery, 677 F.3d 1375, 1383 

(Fed. Cir. 2010) (Lourie, J., dissenting). “An unbounded 

concept of inherency . . . threatens to stymie innovation by 

withdrawing from the realm of patentability that which 

has not been before known, used, or benefited from.” Id.

at 1383–84. As a result, there are strict requirements 

before a finding of inherent anticipation is made. Indeed, 

inevitability is at the heart of inherency; “that a certain 

thing may result from a given set of circumstances is not 

sufficient.” In re Robertson, 169 F.3d 743, 745 (Fed. Cir. 

1999) (citations and quotation marks omitted). 

“[W]hen the PTO shows sound basis for believing that 

the products of the applicant and the prior art are the 

same, the applicant has the burden of showing that they 

are not.” In re Spada, 911 F.2d 705, 708 (Fed. Cir. 1990). 

Such a burden-shifting framework is fair because of “the 

PTO’s inability to manufacture products or to obtain and 

compare prior art products.” In re Best, 562 F.2d 1252, 

1255 (CCPA 1977) (referencing In re Brown, 459 F.2d 531 

(CCPA 1972)). 

The Board implemented that burden-shifting framework in this case, and we find no error in its application. 

With the principles of In re Spada and In re Best in mind, 

the Board first analyzed the disclosure of Lue. See Decision, 2014 WL 1729260, at *3. It found that Lue discloses 

irradiating and heat treating UHMWPE, but at a higher 
12 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

temperature and for a shorter period of time than in the 

’020 patent. Compare ’020 patent col. 4 ll. 35–37 (heating 

preferably for 144 hours at 50°C), with Decision, 2014 WL 

1729260, at *4 (stating Lue teaches heating for 1 hour at 

150°C). According to the Board, the procedures were not, 

on their face, similar enough such that the Board could

presume, without more, that Lue’s product was the same 

as that in the ’020 patent. Decision, 2014 WL 1729260, at 

*5. The Board thus turned to other evidence of record for 

guidance. Id. at *6, *9. 

In particular, the Board turned to the Clough declaration and found that it demonstrated that heat treating by 

the procedures described in both Lue and the ’020 patent 

generated UHMWPE with the same properties. Id. at *9, 

*12. In reaching that determination, the Board analyzed 

how faithfully Dr. Clough reproduced Lue’s procedure. It 

first addressed the resin used by Lue, acknowledged that 

Lue’s resin source no longer exists in its original form, but 

nevertheless found that Dr. Clough “took reasonable steps 

to find similar UHMWPE to that available at the time of 

Lue.” Id. at *10. Indeed, as Dr. Clough testified:

(1) Lue obtained UHMWPE from Dixon Corporation’s (“Dixon”) Bristol, Rhode Island manufacturing facility; 

(2) Dixon became St. Gobain Performance Plastics

(“St. Gobain”); 

(3) Dr. Clough obtained two lots of GUR 4130 material from St. Gobain’s Bristol, Rhode Island 

facility, “which continues to manufacture 

UHMWPE under the trade name Pennlon according to the same process, using the same 

resin-grade, and equipment it has been using 

since the 1970’s”; and

(4) Dr. Clough obtained one lot of GUR 4030, 

which was sent to St. Gobain “to be made into 
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 13

UHMWPE sheets using the same process and 

equipment they use to make Pennlon.” 

J.A. 2049. 

The Board then addressed Dr. Clough’s application of 

the procedures set forth in Lue. According to the Board, 

Dr. Clough “prepared a detailed protocol for reproducing 

the irradiation and heating procedures set forth in Lue on 

GUR 4030 and GUR 4130 UHMWPE samples.” Decision, 

2014 WL 1729260, at *9. Those tests demonstrated a 

level of free radicals, solubility, and FTIR oxidation index

within the ranges recited in the claims of the ’020 patent. 

J.A. 2050. The Board found Dr. Clough’s test results to be 

the “most detailed data presented in the record.” Decision, 2014 WL 1729260, at *9. 

Howmedica argues that the Board accepted too many 

deviations from the strict disclosure of Lue and that, with 

findings clouded by such uncertainty, the Board lacked a 

sound basis for believing that the products of Lue and the 

’020 patent are the same. 

We disagree. A sound basis for believing in identity

does not turn on absolute certainty; rather, a sound basis 

for finding identity requires the Board to make sufficient

factual findings, such that it can reasonably infer that the 

prior art product and that of the patent at issue are the 

same. See In re Spada, 911 F.2d at 708. The Board did 

that here. 

With respect to the starting resin, the Board reasonably found that Dr. Clough used a proper starting material. 

As Howmedica contends, Dixon produced several types of 

UHMWPE during the 1970s, including several blends. It 

produced two resins, GUR 4030 and GUR 4130, J.A. 619–

20; J.A. 637–38, and used GUR 4130 as the base for each 

of its blends, J.A. 641. Howmedica contends that with so 

many types of UHMWPE to choose from, Lue’s disclosure 
14 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

of Dixon products generally offers no guidance to a potential reproducer. We find that contention unpersuasive. 

First, any blend that Dixon produced is irrelevant, for 

Lue suggests that he used unblended UHMWPE, compare 

J.A. 124, with J.A. 126–27; thus, Dr. Clough used unblended UHMWPE. The only remaining concern involves 

the use of GUR 4030 versus GUR 4130, and that distinction is of no moment here because Dr. Clough acquired

and used both. J.A. 2049. Moreover, all of his reproductions with both resins generated UHMWPE with the 

claimed properties. J.A. 2050–51. That Dr. Clough 

acquired his materials from Dixon’s successor certainly 

adds an element of uncertainty. But that should not be 

enough to foreclose the Board’s sound basis for believing

in identity, where, as here, Dr. Clough took reasonable 

steps to acquire an appropriate starting material. We see 

no error in the Board’s finding on this point. 

With respect to the irradiation procedure, we similarly conclude that the Board reasonably found Dr. Clough’s 

reproduction to align with the disclosure of Lue. According to Howmedica, Dr. Clough deviated from Lue’s irradiation procedure in six respects, including using a different 

dose rate and time. Appellant’s Br. 54–55. Importantly, 

however, Howmedica does not assert that Dr. Clough 

deviated in total dose. Indeed, Lue subjected test samples 

to 2.5 Mrad of radiation, J.A. 126, and Dr. Clough complied with that dosage, J.A. 2049. Dr. Clough’s remaining 

deviations are of no consequence here. Minor deviations 

from the strict disclosure of the prior art are accepted, as 

long as one of skill in the art would understand that those 

minor deviations are consistent with the prior art’s teachings. See Glaxo Inc. v. Novopharm Ltd., 52 F.3d 1043, 

1047 n.4 (Fed. Cir. 1995). Here, Lue suggests that total 

radiation dose is the most relevant variable for the irradiation procedure. J.A. 103. Indeed, Lue notes that neither 

dose rate nor irradiation time affects the properties of the 

final material. J.A. 103–104; J.A. 2142–43; J.A. 2159. Dr. 
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 15

Clough complied with that prescription, and only deviated 

in otherwise trivial respects. It was therefore reasonable 

for the Board to find Dr. Clough’s testing to be an accurate reproduction of Lue, and to accordingly place significant weight on the results of those tests.4 We see no error 

in the Board’s finding on this point. 

Ultimately, the Board found Dr. Clough faithfully and 

accurately reproduced Lue. The results of that reproduction demonstrated that UHMWPE treated according to 

Lue has the same properties as those claimed in the ’020 

patent. We conclude that, in view of such findings, the 

Board had a sound basis for believing that the products of 

the prior art and the patent at issue are the same. Thus, 

the Board correctly shifted the burden to Howmedica to 

prove otherwise. 

Howmedica next argues, in the alternative, that the 

Board erred in concluding that Howmedica failed to show 

otherwise. Specifically, Howmedica argues that it sufficiently established that Dr. Clough’s failure to use a hot 

wire mesh during solubility testing discredited his results, 

undermining any finding that Lue’s product necessarily 

has the solubility claimed in the ’020 patent. We find this 

challenge similarly unpersuasive.

 The ’020 patent describes a method of testing solubility in trichlorobenzene as follows: “The samples were then 

hot filtered at approximately 170°C using separate pre-

 

4 Howmedica also argues that Zimmer should have 

conducted additional testing of Dr. Clough’s product by, 

for example, measuring xylene extraction and/or tensile 

properties. Appellant’s Br. 57. While such testing could

have been useful, the Board nevertheless had ample 

evidence before it to find that Dr. Clough accurately 

reproduced Lue, generating UHMWPE with the claimed 

properties. 
16 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

weighed high temperature filters for each sample.” ’020 

patent col. 9 ll. 54–56. It does not specifically require the 

use of a hot wire mesh. In view of that disclosure, the 

Board found that Dr. Clough adequately tested for solubility. In particular, the Board found that Dr. Clough “used 

a high temperature 400-mesh wire filter 0.0001 thick,” 

placed “between two glass funnels, with the upper glass 

funnel preheated to 170°C. The trichlorobenzene solution

(150 mL), which was also at 170°C, was then filtered.” 

Decision, 2014 WL 1729260, at *11. The Board shifted 

the burden accordingly for Howmedica to show that the 

failure to use a hot wire mesh was significant. The Board 

found that Howmedica failed to make such a showing, 

and we conclude that substantial evidence supports that 

finding. 

Howmedica presented expert reports of irradiated and 

heat treated UHMWPE, subjected to solubility testing in 

trichlorobenzene in three scenarios: hot filter/hot filtrate, 

hot filter/cooled filtrate, and cold filter/cooled filtrate. Id. 

The Board found that none of the reports contradicted Dr. 

Clough’s test results. First, the Board found that no 

evidence of record reflected the effects of systematic 

cooling on Dr. Clough’s samples. Id. Indeed, Dr. Clough 

testified to using filtrate at 170°C, and nothing suggested 

that his filtrate dropped below 140°C. Thus, two of 

Howmedica’s testing scenarios, those with a cooled filtrate, were inapposite. The last scenario similarly failed. 

Id. As the Board found, the hot filter/hot filtrate scenario

did not show that filter temperature is a critical factor, 

largely because it failed to replicate and compare the cold 

filter/hot filtrate allegedly used by Dr. Clough. Id. 

Howmedica does not raise any argument on appeal to 

persuade us that the Board’s detailed factual findings 

lack substantial evidence support. We therefore conclude 

that the Board correctly found that Howmedica did not 

meet its burden before the Board. 
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 17

In sum, the Board correctly applied the burdenshifting framework of In re Spada and determined that 

Howmedica failed to satisfy its burden before the Board. 

We accordingly affirm the Board’s finding that claims 1–6 

of the ’020 patent are inherently anticipated by Lue. 

II. Zimmer’s Cross-Appeal

Whether claims would have been obvious is a legal determination based on underlying factual findings. In re 

Baxter, 678 F.3d 1357, 1361 (Fed. Cir. 2012). We review 

the Board’s ultimate conclusion of obviousness de novo, In 

re Elsner, 381 F.3d 1125, 1127 (Fed. Cir. 2004), and we 

review the Board’s underlying factual findings for substantial evidence, In re Gartside, 203 F.3d 1305, 1316 

(Fed. Cir. 2000). Whether there would have been a motivation to combine references and a reasonable expectation 

of success in doing so are such factual findings. See In re 

Hyon, 679 F.3d 1363, 1365–66 (Fed. Cir. 2012); Wyers v. 

Master Lock Co., 616 F.3d 1231, 1237–38 (Fed. Cir. 2010). 

Zimmer challenges the Board’s conclusion that claims 

7–12 of the ’020 patent would not have been obvious over 

the applied prior art. It raises two challenges, and we 

address each in turn. 

A.

Zimmer first faults the Board for assigning patentable 

weight to the additional limitation in claims 7–12, namely, “annealed at a temperature greater than 25°C.” According to Zimmer, it is a process limitation in product-byprocess claims and thus plays no part in the patentability 

analysis under In re Thorpe, 777 F.2d 695 (Fed. Cir. 1985) 

(the “Thorpe issue”). Because claims 7–12 only differ from 

claims 1–6 by the addition of that limitation, Zimmer

argues that claims 7–12 should also be found inherently 

anticipated by Lue as evidenced by the Clough declaration. 

Howmedica responds that Zimmer failed to properly 
18 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

raise the Thorpe issue before the Board and has therefore

waived it. We agree. 

In an appeal from a Board decision, “we have before 

us a comprehensive record that contains the arguments 

and evidence presented by the parties”; our review of that 

decision is limited to the “four corners” of that record. In 

re Gartside, 203 F.3d 1305, 1314 (Fed. Cir. 2000). Without “the benefit of the Board’s informed judgment” in the 

first instance, we decline to consider arguments not raised 

before the Board. In re Watts, 354 F.3d 1362, 1369 (Fed. 

Cir. 2004); In re Berger, 279 F.3d 975, 984 (Fed. Cir. 2002) 

(declining to consider indefiniteness rejection not contested before the Board); In re Schreiber, 128 F.3d 1473, 1479 

(Fed. Cir. 1997) (declining to consider whether prior art 

cited in an obviousness rejection was analogous art when 

that argument was not raised before the Board). 

Zimmer contends that it raised the Thorpe issue in its 

request for reexamination and in its response brief before 

the Board, but we agree with Howmedica that it did not. 

At best, Zimmer suggested that Lue might anticipate

claims 7–12, but only if the limitation was broadly construed to allow annealing at 150°C. Suggesting that Lue 

anticipates in an entirely different context, i.e., where the 

limitation bears patentable weight and warrants a specific construction, J.A. 1081; J.A. 2468 n.10, does not constitute adequately raising the Thorpe issue. Zimmer’s brief 

mention of the Thorpe issue for the first time during an 

oral hearing before the Board, J.A. 2509; J.A. 2526, moreover, does not remedy that shortcoming. Zimmer failed to 

fully raise the Thorpe issue at any point during the proceedings before the PTO. We therefore find the Thorpe 

issue waived and decline to consider it further. 

B.

Zimmer next argues that the Board erred in concluding that claims 7–12 of the ’020 patent would not have 

been obvious over the cited references. Specifically, it
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 19

contends that a skilled artisan, with an understanding of 

the Arrhenius equation, would have reasonably expected 

decreasing the annealing temperature of Lue, according to 

the teaching of Lawton, to still generate the same product, i.e., irradiated UHMWPE with the properties recited 

in the ’020 patent. We agree. 

 Subsumed within an obviousness analysis “is a 

subsidiary requirement” that when “all claim limitations 

are found in a number of prior art references, the burden 

falls on the challenger” to show that “a skilled artisan 

would have been motivated to combine the teachings of 

the prior art,” and that “a skilled artisan would have had 

a reasonable expectation of success in doing so.” Pfizer, 

Inc. v. Apotex, Inc., 480 F.3d 1348, 1361 (Fed. Cir. 2007). 

“The expectation of success must be founded in the prior 

art, not in the applicant’s disclosure.” In re Dow Chem.

Co., 837 F.2d 469, 473 (Fed. Cir. 1988). Absolute predictability is not the standard; “all that is required is a reasonable expectation” derived from the prior art or common 

sense. In re Kubin, 561 F.3d 1351, 1360 (Fed. Cir. 2009) 

(quoting In re O’Farrell, 853 F.2d 894, 903–04 (Fed. Cir. 

1988)); see Amgen v. F. Hoffman La Roche Ltd., 580 F.3d 

1340, 1362 (Fed. Cir. 2009) (“An obviousness determination requires that a skilled artisan would have perceived a 

reasonable expectation of success in making the invention 

in light of the prior art.”). 

Here, the Board only reversed the examiner’s conclusion that claims 7–12 would have been obvious because it 

found that a skilled artisan would not have expected to 

achieve “the particular recited properties without hindsight reliance on the annealing times and temperatures”

in the ’020 patent. Decision, 2014 WL 1729260, at *15. 

That finding is not supported by the record. 

This is a crowded art detailing a well-known problem 

and solution: the annealing of irradiated polyethylene to 

improve oxidation resistance. The ’020 patent has at-
20 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

tempted to fit within that crowd by claiming specific

properties after annealing within a stated temperature 

range. ’020 patent col. 12 ll. 24–54. As the Board found, 

and as we affirmed above, Lue discloses those properties 

when the annealing step occurs just outside of that stated 

temperature range. The Board then assessed the remaining art, finding that Lawton similarly discloses annealing 

irradiated polyethylene, this time within the temperature 

range described in the ’020 patent. Decision, 2014 WL 

1729260, at *14. Indeed, the Board found that Lawton

not only embraces the well-known problem and solution, 

but touts the further benefit that annealing just below the 

melting point will “render [the product] substantially 

amorphous without allowing [it] to lose its shape.” Id.

(citing Lawton col. 7 ll. 63–67). The Board found, however, that a skilled artisan would not have expected modifying Lue according to Lawton, and thereby decreasing the 

annealing step in Lue by at least 10°C, to yield the same 

end product. Id. 

In coming to that conclusion, the Board did not note

the highly predictable nature of the technology. DePuy 

Spine, Inc. v. Medtronic Sofamor Danek, Inc., 567 F.3d 

1314, 1326 (Fed. Cir. 2009) (“[P]redictability is a touchstone of obviousness.”). As we have stated many times, 

“[o]bviousness does not require absolute predictability of 

success . . . all that is required is a reasonable expectation 

of success.” In re Kubin, 561 F.3d at 1350. The record 

here overwhelmingly suggests such a reasonable expectation of success. 

Throughout the proceedings, before the PTO and the 

district court, both parties submitted evidence establishing that polymer chemistry is governed by the well-known 

Arrhenius equation. As even Howmedica’s expert stated: 

“a heating time and a heating temperature are inversely 

related. That is, according to the Arrhenius equation, an 

increase in the heating temperature requires a lower 

heating time to achieve the same or [a] similar reaction 
HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 21

time.” J.A. 2777; see ’020 patent col. 6 ll. 36–48 (even the 

’020 patent embraces the “well-known Arrhenius equation”: “if a higher temperature is used, a short time period 

is required to achieve a [specific] prescribed level of oxidation resistance and cross-linking”). Thus, a skilled artisan, armed with that understanding, would appreciate 

that a specific product can be generated by annealing at

any point along the temperature/time spectrum. Indeed, 

Howmedica’s expert stated: “One of ordinary skill in the 

art further understands that, by applying the Arrhenius 

equation, a level of cross-linking in similarly irradiated 

UHMWPE materials may be obtained by utilizing various 

heating[] times and temperatures.” J.A. 2778. 

The Board avoided this well-known principle in its

analysis of inherent anticipation, see Decision, 2014 WL 

1729260, at *4–5, and avoidance was justified in that 

context. But the Board cannot ignore that longestablished principle here, where it must give due deference to the understanding of those skilled in art, and 

assess whether that skilled artisan would view prior art 

references and expect their combination to successfully 

achieve a particular result. We “cannot [now] deem 

irrelevant the ease and predictability” of decreasing the 

annealing temperature in Lue to achieve the below-themelting-point teaching of Lawton. In re Kubin, 561 F.3d 

at 1360. The record overwhelmingly establishes that a 

skilled artisan would understand that modifying the 

annealing temperature of Lue, as set forth in Lawton, 

would generate the same end-product, as long as the 

annealing time was also modified. And Howmedica failed 

to present any contrary evidence of unpredictability. The 

Board’s brief reliance on the ’020 patent’s discussion of a 

four-hour annealing minimum in the pre-irradiation 

context, Decision, 2014 WL 1729260, at *14, does not 

convince us otherwise. 

The Board’s finding that a skilled artisan would not 

have reasonably expected that modifying Lue according to 
22 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

Lawton would generate UHMWPE with the recited properties lacks substantial evidence support. Furthermore, 

although Howmedica offers minimal indications of commercial success to support the Board’s conclusion, those 

indications fail to outweigh the otherwise clear indication 

of obviousness apparent in the prior art. Ball Aerosol & 

Specialty Container, Inc. v. Ltd. Brands, Inc., 555 F.3d 

984, 994 (Fed. Cir. 2009) (citing Leapfrog Enters., Inc. v. 

Fisher-Price, Inc., 485 F.3d 1157, 1162 (Fed. Cir. 2007)). 

Accordingly, we reverse the Board’s determination, and 

conclude that claims 7–12 would have been obvious over 

Lue in view of Lawton. 

CONCLUSION

We have considered all remaining arguments, but 

conclude that they are without merit. For the reasons set 

forth above, we affirm the Board’s finding that claims 1–6 

are invalid as inherently anticipated, and we reverse the 

Board’s conclusion that claims 7–12 would not have been 

obvious. 

AFFIRMED IN PART, REVERSED IN PART

COSTS

No costs. 
NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________ 

HOWMEDICA OSTEONICS CORP.,

Appellant

v.

ZIMMER, INC.,

Cross-Appellant

______________________ 

2015-1498, 2015-1503

______________________ 

Appeals from the United States Patent and Trademark Office, Patent Trial and Appeal Board in No. 

95/000,428.

______________________ 

NEWMAN, Circuit Judge, concurring in part and dissenting in part.

I concur in the judgment with respect to claims 1–6. 

As to claims 7–12, I would sustain the judgment of the 

PTO Board. Thus I respectfully dissent from the reversal 

of the PTO’s judgment as to claims 7–12.

Claims 1–6: Anticipation 

I agree that the Board correctly applied the law of inherent anticipation, and that the claims were appropriately found to be invalid. I remark however, that the 

Board erred in treating part of the claims’ recitation of the 
2 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

claimed subject matter as a “preamble”. Claims 1–12 all 

commence as follows:

A medical implant comprising an irradiated ultrahigh molecular weight polyethylene [UHMWPE] 

having a weight average molecular weight greater 

than 400,000 and a solubility of less than 80.9% in 

trichlorobenzene. 

The Board held, and the panel majority agrees, that 

the words “medical implant” are not a limitation of the 

claim, but a mere “preamble” of no limitation effect. That 

is incorrect. First, the claim is not written in preamble 

form, but is explicitly directed to a medical implant, not to 

a polymer of varied uses whereby the product identified in 

the “preamble” may not be limiting of either validity or 

infringement. For example, were the accused irradiated 

polyethylene used as a street lamp, it would be ridiculous 

for Howmedica to accuse that product of infringement of 

these claims, even ere all of the listed properties identical. 

The claims are limited to medical implants as much as 

they are limited by the molecular weight and solubility. 

Thus I do not join the court’s ruling that “medical implant” is not a claim limitation and is irrelevant to the 

determination of anticipation. I do not share the court’s 

theory that claims 1–12 apply to any polyethylene having 

the physical and chemical characteristics stated in the 

claim, no matter how remote the product is from being a 

medical implant. 

However, that does not save claims 1–6 here, because 

the Lue thesis mentions medical prosthetic uses of the 

irradiated polyethylene. Lue states:

Recently, UHMW-PE is also being used extensively for prosthetic body implants. The low coefficient of friction, high wear resistance, and 

toughness have brought UHMW-PE’s use in artificial hips, fingers, knees, etc. Extensive evalua-
 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 3

tion by engineering and medical professionals has 

indeed shown that the unique properties of 

UHMW-PE make it the best material available for 

these applications.

Ching-Tai Lue, Effects of Gamma Irradiation and Post 

Heat Treatments on the Structure an Mechanical Properties of Ultra High Molecular Weight Polyethylene 

(UHMW-PE) (June 1979) (M.S. thesis, University of 

Lowell) at 52 (“Purpose of this Study”).

This disclosure, in the same reference that discloses 

the product having all of the claimed properties, explicitly 

or inherently, satisfies the law of anticipation. See In re 

Spada, 911 F.2d 705, 708 (Fed. Cir. 1990) (to anticipate, 

all of the elements and limitations of the claim must be 

found in a single prior art reference). I therefore agree 

that the Board’s finding of anticipation is not in error, and 

join in affirming that claims 1–6 are invalid on this 

ground. 

Claims 7–12: Obviousness

The Board held that none of the several prior art 

combinations showed or suggested the claim limitation 

that requires that the product is “annealed at a temperature greater than 25 oC and less than the melting point of 

the material, approximately 140 oC.” The Board found 

that there was no basis the specification or in the 

knowledge of the stilled artisan to expect that an annealing step should be performed to produce the observed and 

effective properties. The Board found that “the Examiner 

and Requester have not shown that, more likely than not, 

the skilled artisan would have recognized that the desired 

beneficial properties would be achieved at temperatures 

below 140 oC by optimizing these parameters.” 2014 WL 

1729260 at *15. 

Neither have my colleagues on this panel made such a 

showing or identified any source of such a showing. The 
4 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 

Arrhenius equation of the relation between chemical 

reaction rate and temperature says nothing about generation or destruction of free radicals or cross-linking or 

abrasion resistance or any other characteristic of the 

process or the product. Heat-treatment of a polymeric 

product may indeed increase cross-linking, and it may 

also melt the product, which is inimical to cross-linking, 

and may also degrade and destroy the product. The 

premises by which the panel majority selects the patent’s 

temperature and time and reaction sequence are not 

shown or suggested in any reference. 

The Lue reference shows heating the UHMWPE for 1 

hour at 150 oC followed by either slow cooling or shock 

cooling. This heat treatment was performed to investigate its effects on both crystallinity and tensile properties 

of UHMWPE and allow for additional comparison between the irradiated UHMWPE and UHMWPE not 

subjected to irradiation. Lue performs this step above the 

melting point of the UHMWPE, which is inconsistent with 

the annealing process that strengthens the prosthetic 

product. The Howmedica patent illustrates annealing at 

50 oC for 144 hours, well below he melting point of the 

UHMWPE. No application of the Arrhenius equation 

suggests that a prior art heating of a molten polymer at 

150 oC for 1 hour renders obvious the annealing of a solid 

product for 144 hours at 50 oC.

In this crowded field of scientific investigation, another scientist, Lawton, uses prolonged heating below the 

melting point of the UHMWPE to eliminate crystallinity 

and render the product amorphous. However, the Board 

correctly found no suggestion in the prior art to modify 

the Lue process by heating at the Lawton temperature 

range. Only perfect judicial hindsight renders it obvious 

to do so—although not even judicial hindsight can find a 

teaching or suggestion that these procedures should be 

combined to highly beneficial effect.
 HOWMEDICA OSTEONICS CORP. v. ZIMMER, INC. 5

The Board correctly reasoned that a skilled artisan 

would not have expected or predicted to achieve “the 

particular recited properties without hindsight reliance on 

the annealing times and temperatures” taught by 

Howmedica. Id. The Board’s conclusion, reached on 

thorough analysis and sound scientific reasoning, was not 

contradicted by any evidence. Indeed, the panel majority’s holding that “[t]he Board’s finding that a skilled 

artisan would not have reasonably expected that modifying Lue according to Lawton would generate UHMWPE 

with the recited properties lacks substantial evidence 

support” is unjustified. Maj. Op. 21. To the contrary, the 

Board in this Reexamination appears to have been exceedingly through in its treatment of all factual issues 

raised before it. I wish every Board decision was as clean 

and well-reasoned. 

Substantial evidence “means such relevant evidence 

as a reasonable mind might accept as adequate to support 

a conclusion.” Consol. Edison Co. v. NLRB, 305 U.S. 197, 

229 (1938); see In re Morsa, 713 F.3d 104, 109 (Fed. Cir.

2002). Such evidence surely exists in the Board’s 

thoughtful and considered findings. 

I would affirm the Board’s ruling sustaining the validity of claims 7–12. I respectfully dissent from my colleagues’ reversal of the Board’s decision as to these 

claims.