United States Court of Appeals 

for the Federal Circuit ______________________

ARTHREX, INC.,

Appellant

v.

SMITH & NEPHEW, INC., ARTHROCARE CORP.,

Appellees

UNITED STATES,

Intervenor

______________________

2018-1584

______________________

Appeal from the United States Patent and Trademark 

Office, Patent Trial and Appeal Board in No. IPR2016-

00918.

______________________

Decided: August 21, 2019

______________________

ANTHONY P. CHO, Carlson, Gaskey & Olds, PC, Birmingham, MI, argued for appellant. Also represented by 

DAVID J. GASKEY, JESSICA E. ZILBERBERG. 

NATHAN R. SPEED, Wolf, Greenfield & Sacks, PC, Boston, MA, argued for appellees. Also represented by 

RICHARD GIUNTA; MICHAEL N. RADER, New York, NY. 

DENNIS FAN, Appellate Staff, Civil Division, United 
2 ARTHREX, INC. v. SMITH & NEPHEW, INC.

States Department of Justice, Washington, DC, argued for 

intervenor. Also represented by SCOTT R. MCINTOSH,

JOSEPH H. HUNT, KATHERINE TWOMEY ALLEN; THOMAS W.

KRAUSE, JOSEPH MATAL, FARHEENA YASMEEN RASHEED, Office of the Solicitor, United States Patent and Trademark 

Office, Alexandria, VA.

______________________

Before DYK, CHEN, and STOLL, Circuit Judges.

STOLL, Circuit Judge.

In an inter partes review, the Patent Trial and Appeal 

Board ruled claims 10 and 11 of Arthrex, Inc.’s U.S. Patent 

No. 8,821,541 invalid. In doing so, the Board employed different language than Smith & Nephew, Inc.’s petition to 

explain why a person of ordinary skill in the art would have 

been motivated to combine the teachings of the prior art. 

Arthrex asserts that this warrants reversal, but the 

Board’s minor variation in wording does not violate the 

safeguards of the Administrative Procedure Act (APA) and 

did not deprive Arthrex of an opportunity to be heard. Accordingly, we hold that the Board did not violate Arthrex’s 

procedural rights. And because the Board’s findings have 

substantial evidence support, its claim constructions are 

correct, and Arthrex has not articulated a cognizable constitutional challenge to IPR for its patent, we affirm the 

Board. 

BACKGROUND

I

The ’541 patent describes a surgical suture anchor used 

to reattach soft tissue to bone. ’541 patent col. 1 ll. 25–35. 

The disclosed “fully threaded suture anchor” includes “an 

eyelet shield that is molded into the distal part of the biodegradable suture anchor.” Id. at col. 2 ll. 31–35. The eyelet shield acts as a rigid support for the sutures needed to 

hold the soft tissue, “provid[ing] the strength necessary to 
ARTHREX, INC. v. SMITH & NEPHEW, INC. 3

secure the sutures.” Id. at col. 5 ll. 41–42, 51–57. The patent explains that because the support is molded into the 

anchor structure (as opposed to being a separate component), it “provides greater security to prevent pull-out of 

the suture.” Id. at col. 5 ll. 52–56. 

Figure 5 of the ’541 patent illustrates the helical 

threading on body 3 and the integral rigid support (eyelet 

shield 9) of the suture anchor 1:

Independent claims 10 and 11 are at issue here. They 

recite:

10. A suture anchor assembly comprising:

an anchor body including a longitudinal axis, a 

proximal end, a distal end, and a central passage 

extending along the longitudinal axis from an 

opening at the proximal end of the anchor body 

through a portion of a length of the anchor body, 

wherein the opening is a first suture opening, the 

anchor body including a second suture opening disposed distal of the first suture opening, and a third 

suture opening disposed distal of the second suture 

opening, wherein a helical thread defines a perimeter at least around the proximal end of the anchor 

body;
4 ARTHREX, INC. v. SMITH & NEPHEW, INC.

a rigid support extending across the central passage, the rigid support having a first portion and a 

second portion spaced from the first portion, the 

first portion branching from a first wall portion of 

the anchor body and the second portion branching 

from a second wall portion of the anchor body, 

wherein the third suture opening is disposed distal 

of the rigid support;

at least one suture strand having a suture length 

threaded into the central passage, supported by the 

rigid support, and threaded past the proximal end 

of the anchor body, wherein at least a portion of the 

at least one suture strand is disposed in the central 

passage between the rigid support and the opening 

at the proximal end, and the at least one suture 

strand is disposed in the first suture opening, the 

second suture opening, and the third suture opening; and

a driver including a shaft having a shaft length, 

wherein the shaft engages the anchor body, and the 

suture length of the at least one suture strand is 

greater than the shaft length of the shaft.

11. A suture anchor assembly comprising:

an anchor body including a distal end, a proximal 

end having an opening, a central longitudinal axis, 

a first wall portion, a second wall portion spaced 

opposite to the first wall portion, and a suture passage beginning at the proximal end of the anchor 

body, wherein the suture passage extends about 

the central longitudinal axis, and the suture passage extends from the opening located at the proximal end of the anchor body and at least partially 

along a length of the anchor body, wherein the 

opening is a first suture opening that is encircled 

by a perimeter of the anchor body, a second suture 

opening extends through a portion of the anchor 
ARTHREX, INC. v. SMITH & NEPHEW, INC. 5

body, and a third suture opening extends through 

the anchor body, wherein the third suture opening 

is disposed distal of the second suture opening;

a rigid support integral with the anchor body to define a single-piece component, wherein the rigid 

support extends across the suture passage and has 

a first portion and a second portion spaced from the 

first portion, the first portion branching from the 

first wall portion of the anchor body and the second 

portion branching from the second wall portion of 

the anchor body, and the rigid support is spaced axially away from the opening at the proximal end 

along the central longitudinal axis; and

at least one suture strand threaded into the suture 

passage, supported by the rigid support, and having ends that extend past the proximal end of the 

anchor body, and the at least one suture strand is 

disposed in the first suture opening, the second suture opening, and the third suture opening.

Id. at col. 7 l. 58–col. 8 l. 59 (as amended by Certificate of 

Correction) (emphases added to disputed claim terms).

II

Smith & Nephew sought IPR of claims 10 and 11 of the 

’541 patent. It challenged both claims as obvious over U.S. 

Pub. No. 2006/0271060 (“Gordon”) and U.S. Patent 

No. 7,322,978 (“West”). 

Gordon discloses a bone anchor in which a suture loops 

about a pulley 182 positioned within the anchor body. 
6 ARTHREX, INC. v. SMITH & NEPHEW, INC.

J.A. 1758, ¶¶ [0084]–[0086]. Figure 23 illustrates the pulley 182 held in place in holes 184a, b.

J.A. 1747. Smith & Nephew asserted that Gordon disclosed nearly all of the claimed features, including the rigid 

support, which Smith & Nephew identified as pulley 182. 

As relevant here, however, Smith & Nephew acknowledged 

that Gordon did not expressly disclose that the pulley was 

“integral with the anchor body to define a single-piece component,” as required by claim 11. J.A. 228. For that feature, Smith & Nephew relied on West. 

West also describes a bone anchor 10, as shown in Figure 1, reproduced below. 
ARTHREX, INC. v. SMITH & NEPHEW, INC. 7

J.A. 1762. In West’s anchor, “[o]ne or more pins [23a and 

23b] are fixed within the bore of the anchor body [12]. One 

or more sutures can be looped on the pins [23a and 23b].” 

J.A. 1760, Abstract. West explains that to manufacture 

the bone anchor, “anchor body 12 and posts 23 can be cast 

and formed in a die. Alternatively anchor body 12 can be 

cast or formed and posts 23a and 23b inserted later.” 

J.A. 1768 at col. 7 ll. 41–44; see also J.A. 1767 at col. 5 

ll. 58–60. Smith & Nephew argued that this disclosure 

would have motivated one of ordinary skill to manufacture 

the Gordon anchor using a casting process, creating a “rigid 

support integral with the anchor body to define a singlepiece component,” as recited in claim 11. J.A. 217–19. Relying on its expert’s testimony, Smith & Nephew asserted 

that using the West casting process would minimize the 

materials used in the anchor, thus facilitating regulatory 

approval, and would reduce the likelihood of the pulley separating from the anchor body. J.A. 218–19. It also asserted that the casting process was “a well-known and 

accepted technique for creating medical implants” and 

“would have been a simple design choice.” J.A. 218.
8 ARTHREX, INC. v. SMITH & NEPHEW, INC.

Smith & Nephew further argued that claim 11 was anticipated by U.S. Patent No. 5,464,427 (“Curtis”), which describes another bone anchor, and that claim 10 would have 

been obvious over a combination of Curtis and other references. Curtis discloses a threaded anchor that expands to 

lodge into the bone rather than being rotated into the bone. 

J.A. 1776–77 at col. 2 ll. 29–33, col. 3 ll. 12–16. 

Among other things, Arthrex disputed whether a person of ordinary skill would have been motivated to modify 

Gordon in view of West to achieve the invention of claim 11, 

and it asserted that the Curtis ground did not include the 

“helical thread” of claim 10 under the correct construction 

of that term. In its final written decision, the Board disagreed and ruled that Smith & Nephew had shown both 

claims unpatentable on both the Gordon and West and the 

Curtis grounds. Arthrex appeals. 

DISCUSSION

On review of the Board’s final written decisions, we 

evaluate whether the Board’s factual findings are supported by substantial evidence. See Belden Inc. v. Berk-Tek 

LLC, 805 F.3d 1064, 1073 (Fed. Cir. 2015). We review the 

Board’s legal determinations de novo. Id. And we ensure 

the Board complies with statutory and constitutional requirements. Wi-Fi One, LLC v. Broadcom Corp., 878 F.3d 

1364, 1374 (Fed. Cir. 2018) (en banc) (“Enforcing statutory 

limits on an agency’s authority to act is precisely the type 

of issue that courts have historically reviewed.”); Belden, 

805 F.3d at 1080 (reviewing alleged denial of procedural 

due process rights). 

Arthrex challenges the Board’s determination that 

Smith & Nephew proved claims 11 and 10 unpatentable, 

and it attacks the constitutionality of IPRs as applied to its 

patent. We address each argument in turn. 
ARTHREX, INC. v. SMITH & NEPHEW, INC. 9

I

We begin with claim 11. The Board determined that 

one of ordinary skill would have found the claimed invention obvious over Gordon and West, a conclusion Arthrex 

attacks both procedurally and substantively. Because the 

Board did not violate Arthrex’s procedural rights, and because substantial evidence supports the Board’s conclusion 

that a person of ordinary skill would have been motivated 

to combine the teachings of Gordon and West to achieve the 

claimed invention, we affirm. Because we affirm the 

Board’s finding of unpatentability based on Gordon in view 

of West, we do not reach Arthrex’s challenges to the Board’s 

finding that claim 11 is anticipated by Curtis. 

A

Arthrex first contends that the Board impermissibly 

relied on a new theory of motivation to combine in its final 

written decision. As we have often explained, IPR proceedings are formal administrative adjudications subject to the 

procedural requirements of the APA. See, e.g., Dell Inc. v. 

Acceleron, LLC, 818 F.3d 1293, 1298 (Fed. Cir. 

2016); Belden, 805 F.3d at 1080. One of these requirements is that “‘an agency may not change theories in midstream without giving respondents reasonable notice of the 

change’ and ‘the opportunity to present argument under 

the new theory.’” Belden, 805 F.3d at 1080 (quoting Rodale 

Press, Inc. v. FTC, 407 F.2d 1252, 1256–57 (D.C. Cir. 

1968)); see also 5 U.S.C. § 554(b)(3). Nor may the Board 

craft new grounds of unpatentability not advanced by the 

petitioner. See In re NuVasive, Inc., 841 F.3d 966, 971–72 

(Fed. Cir. 2016); In re Magnum Oil Tools Int’l, Ltd., 

829 F.3d 1364, 1381 (Fed. Cir. 2016). 

Arthrex argues that by describing West’s casting 

method as “preferred,” a characterization not found in 

Smith & Nephew’s petition, the Board crafted a new reason 

for combining Gordon and West and violated its procedural 

rights. We disagree. Though the Board used different 
10 ARTHREX, INC. v. SMITH & NEPHEW, INC.

language than the petition in its discussion of whether one 

of ordinary skill would have been motivated to combine 

Gordon and West, it did not introduce new issues or theories into the proceeding. Rather, the Board properly resolved the parties’ dispute about the scope and content of 

West’s disclosure in order to evaluate the theory of obviousness raised in Smith & Nephew’s petition.

West describes that an “anchor body 12 and posts 23 

can be cast and formed in a die. Alternatively anchor 

body 12 can be cast or formed and posts 23a and 23b inserted later.” J.A. 1768 at col. 7 ll. 41–47 (emphasis 

added). Pointing to this statement, the petition proposed 

that a person of ordinary skill would have had “several reasons” to combine West and Gordon, including that the casting process disclosed by West was a “well-known technique 

[whose use] would have been a simple design choice.” 

J.A. 218. Smith & Nephew’s expert relied on the same passage as support for his opinion that a person of ordinary 

skill would have found it obvious to implement Gordon’s 

anchor using West’s casting method. See J.A. 1648–50. 

Throughout the proceeding, the parties disputed how a person of ordinary skill would have understood that specific 

portion of West’s disclosure and whether that disclosure 

would have motivated a person of ordinary skill to combine 

West and Gordon as Smith & Nephew proposed. Arthrex 

had—and took—the opportunity to argue these issues, asserting that West’s casting method would be inherently 

problematic. J.A. 402–05, 421–30. 

In the final written decision, the Board examined the 

parties’ arguments and the portion of West’s disclosure 

cited in the petition. In considering that disclosure, the 

Board noted that West’s presentation of two manufacturing options suggests that the first option, casting, is “primary” and “preferred.” See Smith & Nephew, Inc. v. 

Arthrex, Inc., No. IPR2016-00918, 2017 WL 4677229, 

at *22, *27 (P.T.A.B. Oct. 16, 2017). It concluded that, as 

the petition had argued, one of ordinary skill, reviewing 
ARTHREX, INC. v. SMITH & NEPHEW, INC. 11

West, would have applied West’s casting method to Gordon 

because choosing the “preferred option” presented by West 

“would have been an obvious choice of the designer.” Id. 

at *27.

Arthrex is correct that the Board’s use of “preferred” 

differs from the petition’s characterization of West’s casting as “well-known,” “accepted,” and “simple.” J.A. 218. 

But in finding motivation to combine, the Board relied on 

the same few lines of West as the petition. It considered 

the same proposed combination of West’s casting technique 

and Gordon’s anchor. And it ruled on the same theory of 

obviousness presented in the petition—that one of ordinary 

skill would have recognized that using West’s casting with 

Gordon’s anchor was a “simple design choice.” See id.; 

Smith & Nephew, 2017 WL 4677229, at *27 (determining 

that use of casting “would have been an obvious choice of 

the designer”). 

In these circumstances, the mere fact that the Board 

did not use the exact language of the petition in the final 

written decision does not mean it changed theories in a 

manner inconsistent with the APA and our case law. In 

Sirona Dental Systems GmbH v. Institut Straumann AG, 

for example, we affirmed the Board even though it characterized a reference as providing “geometry data” rather 

than as providing 3-D plaster model data, as the petition 

had. 892 F.3d 1349, 1356 (Fed. Cir. 2018). We explained 

that, as in this case, the Board had cited the same disclosure as the petition and the parties had disputed the meaning of that disclosure throughout the trial. Id. As a result, 

the petition provided the patent owner with notice and an 

opportunity to address the portions of the reference relied 

on by the Board, and we found no APA violation. Id.; see 

also Genzyme Therapeutic Prod. Ltd. P’ship v. Biomarin 

Pharm. Inc., 825 F.3d 1360, 1366 (Fed. Cir. 2016) (finding 

no violation where “[t]he Board’s final written decisions 

were based on the same combinations of references that 
12 ARTHREX, INC. v. SMITH & NEPHEW, INC.

were set forth in its institution decisions”). The same outcome follows here. 

Though Arthrex argues otherwise, this case is unlike 

those in which we have found an APA issue. In Magnum 

Oil Tools, we found an APA violation where the Board 

mixed arguments raised in two different grounds of obviousness in the petition to craft its own new theory of unpatentability. 829 F.3d at 1372–73, 1377. Similarly, in 

SAS Institute v. ComplementSoft, LLC, we faulted the 

Board for announcing a claim construction that “varie[d] 

significantly” from the uncontested construction announced in the institution decision. 825 F.3d 1341, 1351 

(Fed. Cir. 2016) (emphasis added), rev’d and remanded on 

other grounds sub nom. SAS Inst., Inc. v. Iancu, 138 S. Ct. 

1348 (2018). And in NuVasive, we found error where the 

Board relied on portions of the prior art different than 

those presented in the petition as an “essential part of its 

obviousness findings.” 841 F.3d at 971. In all three cases, 

the Board departed markedly from the evidence and theories presented by the petition or institution decision, creating unfair surprise. Here, however, the Board properly 

relied on the same references, the same disclosures, and 

the same obviousness theories advanced by the petition 

and debated by the parties to conclude claim 11 would have 

been obvious. 

Nor is this, as Arthrex elsewhere suggests, a case in 

which the Board’s decision is so divorced from the arguments presented by the petitioner as to impair appellate 

review. See Rovalma, S.A. v. Bohler-Edelstahl GmbH & 

Co. KG, 856 F.3d 1019, 1029 (Fed. Cir. 2017) (vacating and 

remanding where the Board’s decision did not allow “determin[ation of] how the Board reached the conclusion that 

the challenged claims would have been obvious . . . [or] 

whether the Board’s actions complied with the APA’s procedural requirements”). Rather, the Board clearly identified the portion of West it relied on, explained the evidence 

and arguments, and agreed with Smith & Nephew that the 
ARTHREX, INC. v. SMITH & NEPHEW, INC. 13

claims would have been obvious over Gordon in view of 

West. See Outdry Techs. Corp. v. Geox S.p.A., 859 F.3d 

1364, 1369–70 (Fed. Cir. 2017) (finding the Board’s decision sufficient where it “clearly articulated [party’s] arguments,” “engaged in reasoned decisionmaking,” and 

“sufficiently articulated its analysis in its opinion to permit 

our review”). We therefore reject Arthrex’s assertion that 

the Board violated its procedural rights.

B

Arthrex also contends that even if the Board’s decision 

was procedurally proper, the Board erred in finding 

Smith & Nephew had shown a motivation to combine Gordon and West by a preponderance of the evidence. We review this question of fact for substantial evidence. In re 

Kahn, 441 F.3d 977, 985 (Fed. Cir. 2006). When considering whether the teachings of multiple references render a 

claim obvious, courts “determine whether there was an apparent reason to combine the known elements in the fashion claimed by the patent at issue.” KSR Int’l Co. v. Teleflex 

Inc., 550 U.S. 398, 418 (2007). The analysis is a flexible 

one, accounting for “the inferences and creative steps that 

a person of ordinary skill in the art would employ.” Id. 

Substantial evidence supports the Board’s determination that a person of ordinary skill would have been motivated to apply West’s casting method to Gordon’s anchor. 

The Board correctly found that West expressly identifies 

two possible methods for making a rigid support. See 

Smith & Nephew, 2017 WL 4677229, at *26. West states 

that “anchor body 12 and posts 23 can be cast and formed 

in a die. Alternatively anchor body 12 can be cast or formed 

and posts 23a and 23b inserted later.” J.A. 1768 at col. 7

ll. 41–47 (emphasis added). As the Board found, this wording suggests that the default or preferred option disclosed

by West is die casting. See Smith & Nephew, 2017 WL 

4677229, at *27; see also id. at *22 (noting that West describes casting as the “primary” option). Given these two 
14 ARTHREX, INC. v. SMITH & NEPHEW, INC.

options, the Board reasonably determined that forming the 

entire anchor integrally, as a single piece, “would have 

been an obvious choice of the designer.” Id. at *27. 

Additional record evidence supports this result. 

Smith & Nephew’s expert, Mr. Mark Ritchart, offered detailed testimony explaining that using a casting process 

would result in a stronger anchor more likely to receive regulatory approval. J.A. 1649–50. Professor Alexander Slocum testified similarly, stating that the design would also 

“decrease . . . manufacturing costs,” “prevent the suture 

anchor from appearing in and obscuring the bone in xrays,” and “reduce[] . . . stress concentrations” on the anchor. J.A. 2869–70.

Arthrex correctly notes that some evidence arguably 

cuts against the Board’s conclusion. Mr. Ritchart acknowledged potential complexities of casting, J.A. 3839, and Arthrex’s expert, Dr. Kenneth Gall, argued at length that a 

person of ordinary skill would not have applied West to 

Gordon as Smith & Nephew argued, see, e.g., J.A. 3747–49. 

But the presence of evidence supporting the opposite outcome does not preclude substantial evidence from supporting the Board’s fact finding. See, e.g., Falkner v. Inglis, 

448 F.3d 1357, 1364 (Fed. Cir. 2006) (“An agency decision 

can be supported by substantial evidence, even where the 

record will support several reasonable but contradictory 

conclusions.”). And our task on appeal is simply to evaluate whether substantial evidence supports the Board’s fact 

finding; “[w]e may not reweigh . . . evidence.” In re Warsaw 

Orthopedic, Inc., 832 F.3d 1327, 1333 (Fed. Cir. 2016). Because the Board’s finding of motivation to combine is supported by such evidence as “a reasonable mind might 

accept as adequate,” and, as noted above, the Board did not 

err procedurally, we affirm the Board’s conclusion that 

claim 11 would have been obvious over Gordon in view of 

West. Kahn, 441 F.3d at 985.
ARTHREX, INC. v. SMITH & NEPHEW, INC. 15

II

We next address claim 10. Arthrex challenges the 

Board’s construction of “helical thread,” asserting that this 

term should have been construed to require that the helical 

thread “facilitates rotary insertion of the anchor into bone.” 

Appellant’s Br. 55. Because the Board correctly construed 

the term and Arthrex does not otherwise challenge the 

Board’s finding that the Curtis ground renders claim 10 

unpatentable, we affirm without considering whether

claim 10 is also unpatentable based on Gordon and West.

We review the Board’s ultimate claim constructions de 

novo, In re Man Mach. Interface Techs. LLC, 822 F.3d 1282, 

1285 (Fed. Cir. 2016), and we review any subsidiary factual 

findings involving extrinsic evidence for substantial evidence, Teva Pharm. USA, Inc. v. Sandoz, Inc., 135 S. Ct. 

831, 841 (2015). The broadest reasonable interpretation 

standard applies to this IPR.1 Thus, the Board’s construction must be reasonable in light of the record evidence and 

the understanding of one skilled in the art. See Microsoft 

Corp. v. Proxyconn, Inc., 789 F.3d 1292, 1298 (Fed. Cir. 

2015), overruled on other grounds by Aqua Prods., Inc. v. 

Matal, 872 F.3d 1290 (Fed. Cir. 2017) (en banc). 

Here, the Board correctly construed “helical thread” as 

“a helical ridge or raised surface that serves to retain the 

anchor in bone” without limiting the term to threads used 

 

1 Per recent regulation, the Board applies the Phillips claim construction standard to petitions filed on or after November 13, 2018. See Changes to the Claim 

Construction Standard for Interpreting Claims in Trial 

Proceedings Before the Patent Trial and Appeal Board, 

83 Fed. Reg. 51,340 (Oct. 11, 2018) (to be codified at 

37 C.F.R. pt. 42). Because Smith & Nephew filed its petition before November 13, 2018, we apply the broadest reasonable interpretation standard.
16 ARTHREX, INC. v. SMITH & NEPHEW, INC.

to facilitate rotary insertion. Smith & Nephew, 2017 WL 

4677229, at *19. Claim 10 recites “a helical thread defines 

a perimeter at least around the proximal end of the anchor 

body.” This plain claim language suggests that the “helical 

thread” is a structural feature that “defines a perimeter.” 

’541 patent col. 8 ll. 7–8. Consistent with the Board’s construction, the claim does not include any functional limitations. A single sentence in the “detailed description of the 

preferred embodiments” in the specification describes rotating threaded anchors into bone using a driver. Id. 

at col. 6 ll. 4–8. But our case law counsels against incorporating a feature of a preferred embodiment into the claims, 

particularly where, as here, the feature at issue is mentioned only tangentially. See, e.g., In re Van Geuns, 

988 F.2d 1181, 1184 (Fed. Cir. 1993) (“[L]imitations are not 

to be read into the claims from the specification.”). Nowhere does the specification mandate that threaded anchors must be rotated into bone. Rather, the specification 

acknowledges that only “[s]ome threaded suture anchors 

are designed to be inserted into a pre-drilled hole.” ’541 patent col. 1 ll. 36–39 (emphasis added). 

The prosecution history further supports the Board’s 

decision not to limit the claimed “helical thread[s]” to those 

used for rotational insertion. As Arthrex concedes, Appellant’s Br. 60–61 & n.10, three references cited during prosecution describe threaded anchors that are not rotated into 

the bone. As we have explained, art “cited in the prosecution history of the patent constitutes intrinsic evidence.” VFormation, Inc. v. Benetton Grp. SpA, 401 F.3d 1307, 1311 

(Fed. Cir. 2005) (quoting Kumar v. Ovonic Battery Co., 

351 F.3d 1364, 1368 (Fed. Cir. 2003)) (explaining that a 

claim term may be construed based on its “usage in the 

prior art that was cited in the patent”). These references 

confirm that the broadest reasonable construction of the 

term “helical thread” is not limited to threads used for rotatory insertion. Though Arthrex cites dictionaries that 

may support a narrower interpretation, see Appellant’s 
ARTHREX, INC. v. SMITH & NEPHEW, INC. 17

Br. 57, that extrinsic evidence does not outweigh the intrinsic record. See Finisar Corp. v. DirecTV Grp., Inc., 

523 F.3d 1323, 1328 (Fed. Cir. 2008) (“When construing 

claims, the claims and the rest of the patent, along with the 

patent’s prosecution history . . . are the primary resources; 

while helpful, extrinsic sources like dictionaries and expert 

testimony cannot overcome more persuasive intrinsic evidence.”). We thus affirm the Board’s construction. 

III

Finally, we address Arthrex’s challenge to the constitutionality of certain IPRs. Arthrex notes that the Supreme Court has not addressed the constitutionality of IPR 

as applied to patents issued prior to the America Invents 

Act (AIA), which created IPRs. See Oil States Energy 

Servs., LLC v. Greene’s Energy Grp., LLC, 138 S. Ct. 1365, 

1379 (2018) (“Oil States does not challenge the retroactive 

application of inter partes review, even though that procedure was not in place when its patent issued.”). It asks us 

to hold that IPR is unconstitutional when applied retroactively to pre-AIA patents.2 See Appellant’s Br. 62. 

We exercise our discretion and reach Arthrex’s argument rather than finding that Arthrex waived this issue by 

failing to present it to the Board. See e.g., In re DBC, 

545 F.3d 1373, 1378–79 (Fed. Cir. 2008) (noting “discretion 

to reach issues raised for the first time on appeal” but holding party waived constitutional challenge based on Appointments Clause by failing to raise it before the Board); 

Harris Corp. v. Ericsson Inc., 417 F.3d 1241, 1251 

 

2 To the extent Arthrex intends to raise a general 

due process challenge unrelated to retroactivity, the single 

paragraph of conclusory assertions presented in its opening brief is “insufficient to preserve the issue for appeal.” 

See Trading Techs. Int’l, Inc. v. IBG LLC, 921 F.3d 1378, 

1385 (Fed. Cir. 2019). 
18 ARTHREX, INC. v. SMITH & NEPHEW, INC.

(Fed. Cir. 2005) (“An appellate court retains case-by-case 

discretion over whether to apply waiver.”). We need not 

reach the merits of the issue, however, because the ’541 patent issued on September 2, 2014, almost three years after 

passage of the AIA and almost two years after the first IPR 

proceedings began. See Leahy-Smith America Invents Act, 

Pub. L. No. 112-29, § 6(c)(2)(A), 125 Stat. 284, 304 (2011)

(providing that IPR “shall take effect upon the expiration 

of the 1-year period beginning on the date of the enactment 

of this Act [Sept. 16, 2011]”). That Arthrex filed its patent 

applications prior to passage of the AIA is immaterial. As 

the Supreme Court has explained, “the legal regime governing a particular patent ‘depend[s] on the law as it stood 

at the emanation of the patent, together with such changes 

as have since been made.’” Eldred v. Ashcroft, 537 U.S. 

186, 203 (2003) (quoting McClurg v. Kingsland, 42 U.S. 

202, 206 (1843)). Accordingly, application of IPR to Arthrex’s patent cannot be characterized as retroactive. 

In any event, even if Arthrex’s patent had issued prior 

to the passage of the AIA, our court recently rejected arguments similar to Arthrex’s in Celgene Corp. v. Peter. 

No. 18-1167, 2019 WL 3418549, at *12–16 (Fed. Cir. 

July 30, 2019). As we explained, pre-AIA patents issued 

subject to both district court and Patent Office validity proceedings. Though IPR differs from these existing proceedings, we held that the differences between IPRs and the 

district court and Patent Office proceedings that existed 

prior to the AIA are not so significant as to “create a constitutional issue” when IPR is applied to pre-AIA patents. 

Id. at *15; see also id. at *12 & n.13 (affirming that our 

prior decisions ruling that retroactive application of reexamination does not violate the Fifth Amendment, the Seventh Amendment, or Article III “control the outcome” of 

similar challenges to IPR). When Arthrex’s patent issued, 

it is beyond dispute that patent owners expected that “the 

[Patent Office] could reconsider the validity of issued patents on particular grounds, applying a preponderance of 
ARTHREX, INC. v. SMITH & NEPHEW, INC. 19

the evidence standard.” Id. at *16. Consequently, even if 

Arthrex’s patent pre-dated the AIA, application of IPR to 

the ’541 patent would not create a constitutional challenge. 

CONCLUSION

We have reviewed the parties’ remaining arguments 

and find them unpersuasive. We therefore affirm the 

Board.

AFFIRMED