Stryker Corp. v. Intermedics Orthopedics, Inc.

OPINION

FINDINGS OF FACT AND CONCLUSIONS OF LAW

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SPATT, District Judge:

INTRODUCTION

In years past, a person with an arthritic hip was generally relegated to a wheelchair. The advent of modern medical prosthesis technology now permits such a person to walk and resume a normal life through the use of an artificial socket, ball and neck of the hip joint, known as a hip implant prosthesis or femoral prosthesis. Today, the manufacture and supply of prosthetic devices is a growing and profitable industry. The marketing of such devices is estimated to have generated $2.2 billion dollars in revenue to manufacturers in 1990, and has averaged approximately a 15 percent annual dollar growth since 1988. Approximately one quarter of the orthopedic market involves hip implants.

The present case concerns the alleged infringement of a femoral prosthesis patent. The patent in suit is United States Patent No. 4,888,023 (“the 023 patent”), which is entitled “Femoral Prosthesis with Uncoupled Distal Tip.” The 023 patent was filed with the United States Patent Office (“Patent Office”) on January 19,1988 and assigned by its

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inventor to the plaintiff Osteonics Corporation (“Osteonics” or “plaintiff’)- The Patent Office issued the patent on December 19, 1989.

Among the key features of the 023 patent is a metal distal (lower end) tip adapted for engagement with the prosthesis’s stem by means of complementary tapers. The term “distal” means furthest away from the point of attachment. The term “proximal” means nearest the point of attachment. As related to a hip implant or femoral prosthesis and as the terms are used in this opinion, distal means at the lower end of the prosthetic device, and proximal means at the upper end of the device. A diagram of the 023 patent is annexed as Appendix A.

Osteonics is a subsidiary of the Stryker Corporation and is in the business of “researching, developing, designing, manufacturing, marketing and selling hip and knee implants.” (Tr. at 368).

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Since 1988, Os-teonics has manufactured and supplied a femoral prosthesis known as the Omniflex, which is the commercial embodiment of the 023 patent. A diagram of the Omniflex is annexed as Appendix B.

The defendant Intermedies Orthopedics, Inc. (the “defendant” or “Intermedies” or “IOI”) has, since January 1990, manufactured and supplied to the medical and orthopedic industry a femoral prosthesis known as the APR II. A diagram of the APR II is annexed as Appendix C. Each APR II has a metal distal sleeve which engages with the distal portion of the stem by means of a complementary taper. The successor to the APR II is the APR II-T, which was designed in 1991 and introduced in 1992. The three changes embodied in the APR II-T are (1) a tapered neck to fit the ceramic ball, (2) wrapped porous coating all around the proximal portion of the device, and (3) a multi-sized hollowed stem. The APR II-T retained the tapered stem and the distal sleeve which “serves the same purpose as the sleeve made available with the [APR II].” (Tr. at 762).

Both Osteonics and Intermedies supply a full complement of Omniflex and APR II stem sizes and correspondingly sized distal tips or sleeves to the hospital operating room, so that the surgeon is able to assemble and use the stem and the tip or sleeve when medically appropriate. The complete APR II hip system sells for between $3800 and $4000.

This infringement suit was brought by Stryker and Osteonics against Intermedies and Marli Medical Supplies, Inc. (“Mark”), an Intermedies distributor. Osteonics charges Intermedies with literal and willful infringement of claims 8, 10, and 12 of the 023 patent by reason of its manufacture and sale of the APR II and its successor, the APR II-T. (Unless otherwise indicated, references to both the APR II and APR II-T will be to the “APR II”). Osteonics seeks damages, treble damages, injunctive relief and attorneys’ fees pursuant to 35 U.S.C. §§ 284 , 285 (1988). The defendants deny the allegations of literal and willful infringement. Intermedies also asserts that the 023 patent is invalid in light of prior art and because its claims are indefinite, and further asserts that the patent is unenforceable due to inequitable conduct by Osteonics.

This case was tried by the Court over a substantial period of time on all the issues, including liability and damages. This Opinion includes the Court’s findings of fact and conclusions of law on all the issues of liability and damages. Because the parties raise a large number of separate issues, the Court’s findings and conclusions will be integrated and set forth in the discussion of each particular issue.

Although there are two named plaintiffs and two named defendants, the Court will refer to the two plaintiffs as “the plaintiff” or “Osteonics,” and to the two defendants as “the defendant” or “Intermedies” or “IOI.”

I. BACKGROUND

1. The 023 Patent and Claims

In order to recreate the hip joint, a porous stem-type femoral prosthesis consists of (1)

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an artificial acetabulum consisting of a socket or cup, (2) an artificial ball or head of the femur, and (3) a stem, which at the proximal end contains a neck to be attached to the head, and a wedge-shaped affixation surface containing a porous substance that press fits into the softer cancellous bone at the proximal portion of the resected femur.

The socket of the implant is screwed into the acetabulum of the pelvis. The ball is then fitted into the socket. The ball and socket are joined to the femur through the neck on the stem of the prosthesis. The stem itself is inserted longitudinally into the intermedullary canal of the resected femur. In order to prepare the femur, the surgeon must ream out the canal for a length equal to the stem. The distal portion of the canal is reamed until only the harder cortical bone is left. The proximal portion of the canal is reamed by a broach that allows for some of the softer cancellous bone to remain. When the stem is inserted into the canal, the wedge-shaped affixation surface allows the stem to be affixed to the proximal portion of the femur by a tight press fit, with the prosthesis seated on the femoral calcar. The porous surface on the affixation surface is conducive to ingrowth of the softer cancellous bone onto the proximal end of the prosthesis. The stem may also be cemented into the intermedullary canal.

When a person moves, various forces act on the femur. In a normal hip joint, the load (force) on the femur is transmitted through the ball and socket to the proximal portion of the femur, which carries the brunt of the load. In the ease of a stem-type femoral implant, the load on the femur from the joint is transmitted down the metal stem of the implant and is borne by the femur along the entire length of the stem, and not just at the proximal portion of the femur.

Significantly, forces acting on the ball of the prosthesis will tend to cause the prosthesis to swing at the proximal end of the stem, thus causing a bending stress on the stem and creating forces tending to move the distal end of the stem axially (up and down) and transversely (side to side), relative to the femur. This side to side movement of the stem is called “toggling” in the hip implant industry. In addition, and particularly in cases where the stem is cemented to the canal, the stresses acting on the stem tend to concentrate at the distal end of the stem, thus reducing the load stress at the proximal end of the stem. This is called “stress shielding” in the hip implant industry. Stress shielding is undesirable because reducing stress in the proximal end of the stem, where the stress is best accommodated relative to the bone, causes the proximal portion of the femur to atrophy, thereby loosening the affixation of the proximal end of the stem to the femur and requiring replacement of the entire prosthesis. Both toggling and the loosening of the prosthesis resulting from stress shielding cause severe thigh pain to the implant patient.

On January 19,1988, Robert G. Averill and Robert C. Cohen filed the 023 patent application. The patent specifies that it is an improvement of the stem-type femoral prosthesis, because it contains a distal tip which interlocks with the distal end of the stem by means of complementary tapers. The distal tip is made from a fixation resistant metal alloy, which prevents the tip from affixing to the intermedullary canal. According to Os-teonics the 023 patent is a “break-through invention in the field of artificial hips,” because it solves the problems of toggling and stress shielding. Toggling is prevented by placing the distal tip within the harder cortical bone of the femur, such that it fits tightly within the reamed canal. In this way, transverse movements of the distal end of the stem, which is locked onto the tip, are precluded. Proximal stress shielding is prevented by maintaining the tip unaffixed to the wall of the canal, thus allowing axial and rotational movement of the stem relative to the femur. Allowing this movement prevents the concentration of stress at the distal end of the stem.

The patent description summarizes the invention as follows:

The present invention provides an improvement in a stem-type femoral prosthesis, which improvement deals with the problem of stress shielding in a simple, yet effective manner and accomplishes several objects and advantages, some of which

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may be summarized as follows: Provides control over the distribution of loads applied to the prosthesis so as to enable the transmission of axial and transverse forces to the femur at the most appropriate locations for better load distribution; precludes stress shielding and maintains at proximal portions of the femur those stresses which ordinarily are borne by the proximal portions of the femur; ... permits the use of a more flexible stem, and a stem which transmits axial loads to the proximal femur while transferring bending movements to more distal portions of the femur; enables greater versatility in allowing the selection of a prosthesis of appropriate size from an offered range of sizes for increased ease and accuracy of fitting;

The above objects and advantages ... are attained by the present invention [through] the improvement comprising: a distal tip at the distal end of the stem, the distal tip being spaced axially downwardly from the affixation surface a distance sufficient to enable seating of the distal tip within harder portions of the bone in the wall of the femur when the affixation surface is properly seated in the prepared femur and having an external peripheral surface for engaging the harder portions of bone to confine the distal tip against transverse movements within the passage upon completion of the implantation, a fixation-resistant surface finish on the external peripheral surface for maintaining the distal tip unaffixed to the femur and moveable axially relative to the wall of the femur to permit axial displacement of the distal tip and the distal end in response to forces applied to the prosthesis during use of the prosthesis.

Plaintiffs Exh. 2, at Col. 1, line 65 to Col. 2, line 50.

2

The 023 patent lists 14 claims of exclusivity. The relevant claims which are at issue in this suit will be described and discussed below.

Finally, the patent specifies that having complementary tapers between the stem and the distal tip allows for removal and replacement of the distal tip with one of another sized diameter. According to the patent specification, the interchangeability of distal tips allows a wide variety of distal tip diameter sizes to be fitted onto one stem. This interchangeability is called “modularity” in the industry. One of the several benefits of modularity is that the number of stems necessary to accommodate the different sized tips is reduced.

The Omniflex is the preferred embodiment of the 023 patent. It was introduced in 1988, and apparently was a financial success. During the period from 1988 through April 30, 1993, Osteonics sold almost 29,000 of the Omniflex hip implant devices amounting to a sales volume in excess of one hundred million dollars.

The parties agree to the following uncontested facts concerning the Omniflex:

1. The Omniflex hip prosthesis is manufactured and sold by the plaintiff Osteonics and is a preferred commercial embodiment of the prosthetic hip implant device described in the 023 patent and embraced by at least representative claims 8, 10 and 12 of the 023 patent.

2. As of May 31,1992, Osteonics had sold 24,640 Omniflex Hip System hip prostheses embodying the 023 patent claims.

2. The APR II and the Parties’ Contentions

During the time period that the Omniflex was being introduced, the defendant In-termedies was having problems with its own hip implant, called the APR I. In 1988, the defendant marketed the APR I without a distal tip component. This device apparently caused a 24 percent incident of hip pain and, with its sales fading fast, Intermedies would soon find itself out of the hip implant business. Intermedies therefore embarked on the development of the APR II. As ulti

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mately developed, the APR II included a distal sleeve component.

The parties agree to the following uncontested facts concerning the APR II:

1. Each of the APR II and APR II-T hip prostheses includes a femoral stem-type component for implantation in the resected proximal end of a femur. Each of the APR II and APR II-T hip prostheses includes a stem component to be received within the prepared femur (collectively referred to hereinafter as the “APR II and APR II-T stem[s]”).

2. Each APR II and APR II-T stem has a proximal end.

3. Each APR II and APR II-T stem has an affixation surface adjacent to the proximal end for enabling the stem to be affixed in place when seated properly within the prepared femur.

4. Each APR II and APR II-T stem has a distal end spaced axially downwardly from the proximal end for reception within a passage created in the wall of the prepared femur.

5. At all relevant times, Intermedies has manufactured +2mm and +4mm modular distal sleeve components (collectively referred to as “APR II modular distal sleeve[s]”, or “distal sleeve[s]”) for optional use during surgery with each size APR II and APR II-T titanium stem.

6. Each APR II modular distal sleeve component is made from a titanium metal alloy.

7. Each APR II modular distal sleeve is formed with a Morse-type taper on the internal bore thereof which is complementary in design to a Morse-type taper formed on the correspondingly sized APR II or APR II-T titanium stem. The complementary Morse-type tapers formed on the APR II and APR II-T stem/modular distal sleeve components are specially adapted to lockingly engage the modular distal sleeve onto the stem.

8. Each APR II modular distal sleeve component is adapted to be secured to the APR II or APR II-T stem such that, if the sleeve is used, all movements of the stem during use in the body result in corresponding movements of the modular distal sleeve.

9. Each APR II modular distal sleeve has an external peripheral surface so that, if the sleeve is used, it engages the harder cortical bone portions of the femoral canal and confines the distal sleeve against transverse movements within the canal upon completion of the implantation.

10. Each APR II modular distal sleeve is cylindrical.

The plaintiff contends that the APR II infringes the 023 patent. According to the plaintiff, in early February 1988 Intermedies officials attended a conference of the American Association of Orthopedic Surgeons (“AAOS”) in Atlanta, Georgia. At this conference, they obtained a brochure describing the Omniflex. Two weeks later, the plaintiff contends the defendant began designing an APR II distal sleeve modeled on the Omni-flex distal tip. Prior to the conference, the plaintiff claims the APR II did not include a distal sleeve component and Intermedies did not have any plan for developing such a sleeve. The February 1988 AAOS meeting is discussed in more detail later in this Opinion.

Osteonics proceeds with its claim of patent infringement on two theories. First, it contends that there was a literal infringement in that the APR II infringes claims 8,10 and 12 of the 023 patent. Second, the plaintiff also contends that the APR II infringes claims 8, 10 and 12 of the 023 patent under the doctrine of equivalents.

On the other hand, the defendant contends that it devised and created the design of APR II by the ideas of its own personnel and without any reference to the Omniflex. Further, according to the defendant, the APR II functions in a manner “contrary to the design philosophy embodied in the Omniflex implant.” According to the defendant, the Om-niflex was designed to promote flexibility of the stem, while the APR II was designed to eliminate movement in the femur and promote “solid, stable proximal (upper) fit.” Moreover, the defendant contends that its distal sleeve has been used in less than half of the cases in which the APR II was implanted, and that the percentage of cases in

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which the distal sleeve was actually implanted is as low as 5 to 20 percent with most surgeons.

In addition, as a defense, the defendant asserts that prior to the plaintiffs patent, a Dr. Leo Whiteside designed a hip implant with a plastic distal sleeve, which was intended to prevent the prosthesis from moving within the femoral canal. The defendant asserts that because of the non-disclosure of the “prior art” Whiteside distal sleeve to the Patent Office, the plaintiff engaged in inequitable conduct and its patent is unenforceable. With regard to this defense of inequitable conduct, the plaintiff contends that the Whiteside device is not “prior art” to the 023 patent in suit.

The defendant further asserts as defenses that the 023 patent is invalid, because (1) certain of its claims are vague and indefinite, and (2) various prior art render the patent obvious. The plaintiff denies that the patent is invalid on these grounds.

II. AS TO PATENT INFRINGEMENT

1. Literal Infringement

A.

The Legal Standard

Section 271(a) of the Patent Statute, 35 U.S.C. § 271 (a) (1988 & Supp. IV 1992), provides in relevant part that “whoever without authority makes, uses or sells any patented invention, within the United States during the term of the patent therefor, infringes the patent.” In addition, section 271(b) provides that “[w]hoever actively induces infringement of a patent shall be liable as an infringer.” 35 U.S.C. § 271 (b).

See also Joy Technologies, Inc. v. Flakt, Inc.,

6 F.3d 770, 774 (Fed.Cir.1993);

Moleculon Research Corp. v. CBS, Inc.,

793 F.2d 1261, 1272 (Fed.Cir. 1986),

cert. denied,

479 U.S. 1030 , 107 S.Ct. 875 , 93 L.Ed.2d 829 (1987).

In a patent infringement case the burden of proof is on the plaintiff to prove the defendant’s infringement by a preponderance of the evidence.

Conroy v. Reebok Int’l, Ltd.,

14 F.3d 1570, 1573 (Fed.Cir.1994);

Rite-Hite Corp. v. Kelley Co., Inc.,

819 F.2d 1120, 1123 (Fed.Cir.1987).

The determination of infringement is a two-step process. The first step involves determining the meaning and scope of the patent claims asserted to be infringed. The second step entails comparing the properly construed claims to the product accused of infringement.

Markman v. Westview Instruments, Inc.,

52 F.3d 967, 976 (Fed.Cir. 1995) (in banc) (citing

Read Corp. v. Portec, Inc.,

970 F.2d 816, 821 (Fed.Cir.1992)). The first step, referred to as claim construction or interpretation, is a question of law.

Markman,

52 F.3d at 976 ;

Electro Medical Systems, S.A., v. Cooper Life Sciences, Inc.,

34 F.3d 1048, 1053 (Fed.Cir.1994). The second step, application of the construed claim to the accused product, is a question of fact.

Id. Read,

970 F.2d at 822 .

The United States Court of Appeals for the Federal Circuit has analogized the interpretation of patent claims to statutory interpretation.

Markman,

52 F.3d at 987 . To determine the meaning of the patent claims, the Court looks to three sources: the claims, the patent specification, and the patent’s prosecution history.

Id.

at 979 (citing cases);

Electro Medical,

34 F.3d at 1054 . Moreover, expert testimony, including evidence of how those skilled in the art would interpret the claims, may also be used to assist the court in coming to a correct conclusion as to the true meaning of the language claims.

Markman,

52 F.3d at 979-80 (internal quotations and numerous citations omitted).

According to the Federal Circuit, the numerically paragraphed claims of the patent “provide the concise formal definition of the invention,” and “particularly point out and distinctly claim” the subject matter which the applicant regards as his or her invention. It is to “these wordings that one must look to determine whether there has been infringement.” Cor

ning Glass Works v. Sumitomo Elec. U.S.A., Inc., 868

F.2d 1251, 1258 (Fed. Cir.1989) (quoting

Autogiro Co. of America v. United States,

384 F.2d 391, 395-96 , 181 Ct.Cl. 55 (1967)).

Further, the wordings of a claim “describe and point out the invention by a series of limiting words or phrases,” which are called limitations.

Coming Glass,

868 F.2d

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at 1258. In construing the claim, “all the limitations of a claim must be considered meaningful.”

Unique Concepts, Inc. v. Brown,

939 F.2d 1558, 1562 (Fed.Cir.1991);

accord Texas Instruments Inc. v. United States Int’l Trade Comm’n,

988 F.2d 1165 , 1171 (Fed.Cir.1993) (claim cannot be construed so as to render the disputed claim language mere surplusage).

Claims must also be read in view of the specification of which they are a part. “The specification contains a written description of the invention that must enable one of ordinary skill in the art to make and use the invention.”

Markman,

52 F.3d at 979 . However, claims are not to be interpreted by adding limitations appearing only in the specification. Thus, “although the specification may well indicate that certain embodiments are preferred, particular embodiments appearing in the specification will not be read into the claims when the claim language is broader than such embodiments.”

Electro Medical,

34 F.3d at 1054 .

If in evidence, the prosecution history of the patent should also be considered because it is the “undisputed public record” of the patent proceedings, and confirms the construction of the patent by the patentee.

Markman,

52 F.3d at 980 . The prosecution history limits the interpretation of claim terms so as to exclude any interpretation that was disclaimed during prosecution.

Southwall Technologies, Inc. v. Cardinal IG Co.,

34 U.S.P.Q.2d 1673 , 1995 WL 274383 at *4 (Fed.Cir. May 10, 1995) (citing cases).

In addition, extrinsic evidence may be used to help the court understand the claims language. Such evidence consists of all evidence external to the patent and prosecution history, including expert and inventor testimony, dictionaries, and learned treatises. This evidence is helpful to explain scientific principles, the meaning of technical terms, and terms of art that appear in the patent and prosecution history. The extrinsic evidence may be used only for the court’s understanding of the patent, and not for the purpose of varying or contradicting the terms of the claim.

Markman,

52 F.3d at 981 (citing

U.S. Indus. Chems. Inc. v. Carbide & Carbon Chems. Corp.,

315 U.S. 668, 678 , 62 S.Ct. 839, 844 , 86 L.Ed. 1105 (1942)). It should be noted that, by using such extrinsic evidence to assist in its construction of the patent claims, the court is not crediting certain evidence over other evidence or making factual evidentiary findings.

Markman,

52 F.3d at 981 .

Once the claims have been properly construed, they must be applied to the accused product to determine infringement.

Conroy,

14 F.3d at 1573 . As stated in the seminal patent ease of

Graver Tank & Mfg. Co. v. Linde Air Prods. Co.:

In determining whether an accused device or composition infringes a valid patent, resort must be had in the first instance to the words of the claim. If accused matter falls clearly within the claim, infringement is made out and that is the end of it.

Graver Tank,

339 U.S. 605, 607 , 70 S.Ct. 854, 855 , 94 L.Ed. 1097 (1950).

In conducting this second step of the infringement inquiry, the physical similarities between the accused device and the patentee’s commercial embodiment of a patented invention are not to be compared. Rather, the proper comparison is between the patent

claims

and the accused device.

International Visual Corp. v. Crown Metal Mfg. Co.,

991 F.2d 768, 771-72 (Fed.Cir.1993);

Datascope Corp. v. SMEC, Inc.,

879 F.2d 820, 824 (Fed. Cir.1989) (“the district court lost sight of this court’s repeated caution that it is

claims,

not commercial embodiments, that are infringed.”) ce

rt. denied,

493 U.S. 1024 , 110 S.Ct. 729 , 107 L.Ed.2d 747 (1990). As explained by the Federal Circuit, in determining infringement, “the words of the claim must first be interpreted, and, as properly interpreted, they must be ‘read on’ the accused structure to determine whether each of the limitations recited in the claim is present in the accused structure.”

Coming Glass,

868 F.2d at 1258 (citations omitted).

B.

The Infringed Claims

The plaintiff contends that the APR II literally infringes on claims 8, 10 and 12 of the 023 patent. Claim 8 incorporates claims 1, 4 and 5, and is delineated as follows:

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Claim 8:

l.(i) In a stem-type femoral prosthesis for implantation in a resected proximal end of a femur, the prosthesis including a stem to be received within the prepared femur, the stem having a proximal end, an affixation surface adjacent the proximal end for enabling the stem to be affixed in place when seated properly within the prepared femur, and a distal end spaced axially downwardly from the proximal end for reception within a passage created in the wall of the prepared femur, the improvement comprising: (ii) a distal tip integral with the distal end of the stem, the distal tip being spaced axially downwardly from the affixation surface a distance sufficient to enable seating of the distal tip within harder portions of the bone in the wall of the femur when the affixation surface is properly seated in the prepared femur,

(Mi) the stem including a shaft portion located between the affixation surface and the distal tip, the shaft portion having a diameter smaller than the corresponding diameter of the distal tip for enabling flexing in the shaft portion,

(iv) and the distal tip having an external peripheral surface for engaging said harder portions of bone to confine the distal tip against transverse movements within the passage upon completion of the implantation,

(v) and a fixation-resistant surface-finish on the external peripheral surface for maintaining the distal tip unaffixed to the femur and moveable axially relative to the wall of the femur to permit axial displacement of the distal tip and the distal end in response to forces applied to the prosthesis during use of the prosthesis.

4. The improvement of claim 1 including securing means for securing the distal tip to the stem for selective removal and replacement of the distal tip.

5. The improvement of claim 4 wherein the securing means includes a securing mechanism responsive to relative axial movement between the stem and the distal tip for securing and releasing the distal tip and the stem.

8. The improvement of claim 5 wherein the securing mechanism includes an internal bore in the distal tip and complementary tapered surfaces on the stem and on the internal bore of the distal tip.

Claim 10 includes all of the elements of claims 8 and 9, and is delineated as follows:

Claim 10:

Same elements as claim 8.

9. The improvement of claim 8 wherein the external peripheral surface of the distal tip includes means in the form of an axial length long enough to provide an area of contact between the distal tip and the wall of the femur, when the stem is seated properly in the passage for maintaining a relatively low level of stress on the wall of the femur at the location of the distal tip in response to forces applied to the prosthesis which result in transverse forces at the distal tip.

10. The improvement of claim 9 wherein the external peripheral surface is cylindrical such that the distal tip is rotatable about the central axis thereof relative to the wall of the femur.

Claim 12 includes the elements of claims 1 and 11, and is delineated as follows:

Claim 12:

All the elements of claim 1.

11. The improvement of claim 1 wherein the fixation-resistant finish is a smooth finish on the external peripheral surface of the distal tip.

12. The improvement of claim 11 wherein the distal tip is constructed of a metal alloy and the fixation-resistant finish comprises a polished surface.

The defendant contends that the APR II does not infringe claims 8, 10 and 12. According to the defendant, these claims contain the following limitations of claim 1: (1) limitation (iii): “the stem including a shaft portion ... having a diameter smaller than the corresponding diameter of the distal tip for enabling flexing in the shaft portion.”; (2) limitation (ii): “a distal tip integral with the distal end of the stem”; and (3) limitation (v): “a fixation-resistant surface-finish on the external peripheral surface [of the distal tip].” Because each of these limitations is contained

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in independent claim 1, on which claims 8,10 and 12 are dependant, Intermedies contends that the APR II does not infringe these claims.

The Court will construe the claim limitations, and review each of the contentions with respect to the claim alleged to be infringed.

(1)

Limitation (in):

“Enabling Flexing” of the Shaft

(a)

Claims Construction

(i)

Patent Language and Specification

Limitation (iii) of claim 1 states that the 028 patent improvement consists of the stem shaft portion located between the affi-xation surface and the distal tip “having a diameter smaller than the corresponding diameter of the distal tip for enabling flexing in the shaft portion.” Patent at 7:3-7.

Although the term “enabling flexing” is not defined in the patent specification, understanding the problems the patent sought to address and a reading of the patent specification enables the Court to interpret the meaning of the term.

In describing the problems which led to the invention, the patent states in its “Background of the Invention” that certain components of the forces exerted upon the prosthesis during use are transferred to distal portions of the stem, rather than being accommodated by the proximal portion of the prosthesis. This results in concentration of stresses at non-proximal portions of the femur and a corresponding reduction in stresses at the proximal portion of the femur, a condition described above as stress shielding. Moreover, forces on the ball of the prosthesis will tend to swing the prosthesis about the proximal end of the stem, “thereby exerting bending stresses on the stem and establishing forces tending to move the distal end of the stem” in a transverse direction relative to the femur, a condition described above as toggling, and axially relative to the femur. Patent at 1:31-36.

The patent specification explains that the invention’s distal tip is essentially locked onto the distal end of the stem by a system of complementary tapers, so that movement by the distal end of the stem will result in a corresponding movement by the distal tip. By using a distal tip that is the same diameter as the reamed passage inside the femur, the distal tip engages or presses against the harder portion of cortical wall inside the femur. By so pressing against the wall, the tip prevents transverse movements of the stem within the reamed passage, i.e., prevents toggling, while at the same time allowing the transverse force at the distal end to be transmitted to the femur. Significantly, by creating a cylindrically shaped distal tip with a fixation-resistant surface that prevents the tip from affixing to the femur, the distal tip prevents stress shielding by (1) allowing the bending movements of the stem to displace the distal tip, and thus the distal end of the stem, axially upwards, (2) allowing the bending forces to displace the distal tip axially downward in certain cases, and (3) allowing the tip to rotate about its central axis in response to torsional forces. Patent at 4:4-44.

Moreover, in order to reduce the stress in the area of contact of the distal tip’s surface and the cortical bone of the femur, the external surface of the distal tip must be of sufficient length to maintain a relatively low stress in that area. However, the length of the surface of the distal tip must also be short enough “to preserve flexibility in the shaft of the stem.” As described in the specification:

Flexibility in the shaft enables the stem to respond in the manner indicated [bending, and moving axially upward] so that the combination of the prosthesis and the femur can manage the forces to be applied to the prosthesis.

It is desirable that the shaft have sufficient flexibility to preclude excessive stiffening

of the femur by the prosthesis along the implant site. In the preferred configuration, the diameter of the shaft of the stem above the distal tip is made smaller than the diameter of the external peripheral surface of the distal tip itself so as to render the shaft flexible, while still providing a contact area between the distal tip and the wall of the femur great enough to maintain relatively low contact stresses.

Patent at 5:44-57 (emphasis supplied).

Thus, in the Court’s view the specification explains that shaft flexing is the ability of the

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shaft to bend in response to forces transmitted to the stem from loads applied to the femur, resulting in a corresponding axial movement of the distal end of the stem relative to the femur. Significantly, the specification also explains that the patent “enables flexing” by requiring the diameter of the stem shaft above the distal tip to be smaller than the diameter of the distal tip itself. By enabling such flexing, the proximal portion of the femur is kept rejuvenated and alive.

(ii)

The Patent’s Prosecution History

The patent’s prosecution history (Plaintiffs Exh. 568; Defendant’s Exh. AKR) corroborates this interpretation of the term “enabling flexing” found in the third limitation of claim 1. The language of the third limitation was found in claim 14 of initial disclosure of the patent filed with the Patent Office on January 19, 1988. The initial patent disclosure described the bending of the shaft and corresponding axial movement of the distal tip. (Plaintiffs Exh. 568 at 8-10, 24).

After reviewing the disclosure, the Patent Examiner rejected claims 1 and 14, along with other claims, in a letter dated July 14, 1988. The grounds for the rejection of the relevant claims were that claim 1 was anticipated by the Lord patent, and claims 1 and 14 were unpatentable over the Witzel and Freeman patents. (Plaintiffs Exh. 568 at 83, 35).

The Patent Examiner did not discuss the Lord patent. In discussing the Witzel patent, the Patent Examiner concluded that the Witzel device performed the same function as the 023 patent, because the stem of the Wit-zel patent moved axially within a distal tip:

Wherein Witzel’s tip (25 resin) moves axially within the tip in response to axial and bending loads applicant’s device, as claimed, has a tip (metal) fixed to the stem and the stem moves axially in the medul-lary canal in response to axial and bending loads. It is noted that both devices perform the same function: they both transfer and distribute stresses at the tip to the calcar bone ... by permitting the stem of the prosthesis to move axially with respect to the bone thereby transferring and distributing bending stresses from the offset loading on the hip socket ball to the calcar bone through the tip.

(Plaintiffs Exh. 568 at 35).

With regard to the Freeman patent, the Examiner concluded that patent also performs the same function as the 023 patent:

Freeman discloses a typical stem-type femoral prosthesis made of metal with a substantially circular stem. End tip fits onto the tapered end of the stem with a matching taper surface.... It is also clear ... that [the] stem is narrower (at least in portions) than the tip.... It is presumed that the taper surfaces of the tip and stem lock the two together.... It is also noted that Freeman also, as Witzel, uses the tip for stress distribution of the forces at the distal end of the stem due to the loading of the ball.

(Plaintiffs Exh. 568 at 37).

In response to the Patent Examiner’s rejection, the 023 applicant responded by, among other things, amending claim 1 in the initial patent disclosure to include the language of limitation (iii) of the present claim 1. The applicant also distinguished the 023 patent from the Lord, Witzel and Freeman patents, based on stem shaft flexibility.

In distinguishing the 023 patent from the Lord patent, the applicant indicated that the Lord device failed to enable flexibility in the stem shaft, because the diameter of the Lord stem was greater than or equal to the diameter of the distal tip:

[W]hatever the function of the Lord distal tip, the distal tip disclosed in Lord has a diameter which is the same as, or less than, the diameter of the remainder of the femoral stem, and no part of the stem has a diameter less than any diameter of the distal tip.

Accordingly, the reference does not contemplate flexing of the stem and axial movement of the distal tip in the medullary canal in response to loads placed on the implant during service.

The subject matter of the present claims includes structures which enables the femoral stem to flex in response to loads placed on the implant during service, and provides an uncoupled distal tip which is displaced axially within the medullary ca

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nal, relative to the bone of the femur, as the femoral stem is flexed, to accommodate the flexing without deleterious effects. Thus, all of the present claims set forth that the femoral stem includes a shaft portion with a diameter smaller than the corresponding diameter of the distal tip

for enabling the aforesaid flexing of the shaft portion and axial displacement of the distal tip.

(Plaintiffs Exh. 568 at 49-50) (emphasis supplied).

Similarly, in distinguishing the Witzel patent the applicant indicated that the distal sleeve in the Witzel device was fixed to the canal, and thereby did not provide any axial displacement of the sleeve. This results in relatively higher stresses at the distal end of the Witzel device:

In Witzel, a small sleeve of synthetic resin material is first secured in the medullary canal, and then the shaft of the femoral stem is inserted into the sleeve. The shaft can move relative to the sleeve, but there is no displacement of the sleeve relative to the bone of the femur during service. In the construction of the present claims, the distal tip is affixed to the distal end of the stem ... and flexing of the shaft ... during service is accommodated by displacement of the distal tip relative to the surrounding bone of the femur. The difference in structure yields several advantages. Among those advantages is the distribution of stresses during service-Thus, in the Witzel construction, the articulating surfaces between the stem and the sleeve are of limited area, resulting in higher stresses[.]

(Plaintiffs Exh. 568 at 50-51).

With regard to the Freeman patent, the applicant explained that the Freeman device was not similar to the 023 patent, because it used a distal tip affixed to the bone that acted as a “stop” to centralize the stem shaft, and which was not intended to move during use of the stem. (Plaintiffs Exh. 568 at 52).

These claims were ultimately accepted by the Patent Office and the 023 patent was issued.

Thus a review of the patent’s prosecution history corroborates that the term “enabling flexing” is construed as allowing the stem shaft of the prosthesis to flex and move axially upwards, by the use of a distal tip secured to the distal end of the stem which (i) is of a larger diameter than the stem shaft, and (ii) is not affixed to the bone.

(iii)

Evidence from Extrinsic Sources

The scientific principles of shaft flexing were also explained by DR. ALBERT H. BURSTEIN, who is a biomechanical engineer and expert in the field of hip implant devices. Dr. Burstein has “fabricated over 3,000 total joint implants” of which 25 percent were hip implants. Dr. Burstein is a person considered skilled in the art of the subject matter of the 023 patent during the relevant time period involved in this law suit.

During direct examination concerning the 023 patent teachings as compared to the APR II, he explained that the flexing movement of the shaft — which is only on the order of a thousandth of an inch, i.e., less than a hair’s breadth — follows well established bio-mechanical principles:

A Now the way you prevent bending loads from being transmitted distally is to make the stem flexible. Then if it deforms a little bit it doesn’t transmit much bending load. The stiffer the stem, the more bending load it can transmit when the bone deforms.

So the patent teaches that the way you prevent the transmission of bending loads is to make a portion of the stem of diameter smaller than the sleeve so that it is flexible, so that you have enabled flexing of that portion of the stem that’s above the sleeve.

Now when you load it, this portion flexes more freely than if it would have if it were a constant big diameter and transmit proportionately less bending load down here on the bone. It transmits more bending load up on the proximal area, it transmits more, it transmits more proximally. That’s a well-known principle in biome-chanics and taught by the invention and it shows you how to practice that invention by reducing this diameter.

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Q What does the patent teach with respect to the surface characteristics of the sleeve or the tip?

A The patent teaches in order for this to work it must be free to move up and down in the bone in accordance with how much the prosthesis normally wants to move. That is,

under load this prosthesis will move on the order of a thousandth of an inch or two, and it must be free to do so,

and in order to do so, you cannot allow the distal end sleeve or tip to become fixed to the bone. If it becomes fixed to the bone it transects the bone. So by having an affixation resisting surface, that will not allow the bone to grow into or onto the surface, it becomes free to move up and down[.]

Q Dr. Burstein, would you look at Column 5, lines 34-44, and tell the Court in your own words what that means or what that teaching is?

A What the patent is ... teaching ... is it is telling the practitioner of the art [of] how long the sleeve can be made and still function according to this patent. It is saying the sleeve or tip has to be made long enough, that is, it must have some minimum length, so that when it is in the body and you put the load on the prosthesis [the tip] pushes against the side of the bone.... The tip should not create a stress condition on the femur that the femur cannot accept. In plain language it shouldn’t push to hard.

The way you control it is to make the tip long enough so it has enough conduct [sic contact] area on the surface so it shouldn’t push too hard[.]

[The patent] also says there’s another limit. The longer you make it, the less stem there is left over to produce the flexibility you want. So don’t make it so long as to not leave enough stem left over so that you have flexibility, and it tells you essentially the longer you make it, the more reduced the flexibility will be in the leftover portion of the system. (Tr. at 131-135) (emphasis supplied). Dr. Burstein’s elucidation of flexibility is consistent with the Court’s interpretation of the patent limitation.

(b)

Infringement Determination

The defendant makes a sophisticated argument that the claim limitation language at issue requires a stem shaft of lesser diameter than the distal tip

for the purpose of

enabling flexing. According to the defendant, any flexing of the stem shaft that is the natural, inherent result of a smaller diameter shaft relative to the tip is not excluded by the claim. Thus, according to Intermedies, “it would be unfair to extend the patent to cover products that do not have a reduced shaft diameter that exists

for the purpose of enabling flexing.”

Defendant’s Post-Trial Brief at 3. Indeed, Intermedies goes so far as to contend that the language of the claim limitation probably requires that the stem must be significantly narrower over a substantial portion of the shaft length than the diameter of the distal tip.

Based on its interpretation of the claim limitation language, the defendant contends that the APR II does not infringe the first claim of the 023 patent, because the stem geometry of the APR II relative to the distal sleeve does not

purposefully

enable flexing of the stem. According to the defendant, flexibility was not a design criteria of the APR II. Rather, the inventor incorporated the optional distal sleeve to achieve rigid cortical fit and fill against the cortical bone in the dia-physeal (shaft section) area of the femur for patients with a certain bone geometry. Moreover, Intermedies contends that the purpose of having exposed stem shaft above the distal sleeve in the APR II is to prevent impingement by a full-length sleeve covering the entire shaft on the anterior cortical portion of the femur. Any flexing of the APR II stem shaft due to its having a smaller diameter than the distal sleeve is, according to the defendant, the result of natural, inherent physical principles and not intentional in the design of the APR II stem and distal sleeve.

The Court disagrees with the defendant’s contentions. To begin with, neither the claims language nor the specification re

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quires that the stem be significantly narrower over a substantial portion of the shaft length than the diameter of the distal tip. This is an impermissible external limitation grafted onto the claim’s language.

See, e.g., Electro Medical,

34 F.3d at 1054 ;

E.I. duPont de Nemours & Co. v. Phillips Petroleum Co.,

849 F.2d 1430, 1433 (Fed.Cir.),

cert. denied,

488 U.S. 986 , 109 S.Ct. 542 , 102 L.Ed.2d 572 (1988).

More importantly, the Court is not persuaded by Intermedics’s contention that the APR II stem shaft flexing is the result of inherent forces as opposed to purposeful design. Notwithstanding the testimony of DR. LAWRENCE DORR, the chief designer of the APR II prosthesis and a major witness on behalf of Intermedies, and other witnesses on behalf of Intermedies, the record, including admissions and the documentary evidence, shows — and the Court so finds — that the defendant’s contentions concerning shaft flexing are belied by the defendant’s own admissions that the APR II distal sleeve was intended to enable flexibility in the stem shaft above the sleeve, as well as to add bulk or fill to the canal.

In a document prepared by Intermedies entitled “The APR II System — Developed by Larry Dorr, M.D. — Manufactured by In-termedies Orthopedics, Inc.”, Dr. Don-states:

This is Dr. Larry Don. I would like to discuss with you the design rationale of the APR II Hip System.

What we can try to achieve, is the best relationship we can get between the stem and the bone

with the least stiff stem possible in the canal to give the bone it’s best chance to be able to respond optimally when the stem and the bone have to move together.

That is to say, we would like to decrease the differential deflection that occurs between stem and the bone when load is applied to the hip through the stem.

By using a sleeve, we allow some increased flexibility in the stem which will improve this relationship.

(Plaintiffs Exh. 210 at 13) (emphasis supplied).

In a videotape presentation with regard to the APR II, Dr. Don states:

DORR: Now the broach with the sleeve attached there and there’s a screw mechanism that screws on the sleeve here so it cannot disengage in the canal and with the sleeve you can see the difference in the regard to the amount of substrate metal that would be involved if we had to go to an implant that was all that size.

So that we have improved the flexibility of the implant also by using the sleeve

and only having to use this much bulk for the remainder of the implant.

(Plaintiffs Exh. 117 at 13) (emphasis supplied).

Testimony from Intermedies company officials reveals that the reason for designing the APR II was the commercial failure of the APR I, in part because it caused thigh pain resulting from toggling. The development of the APR II was, thus, also geared towards preventing toggling.

NICHOLAS CINDRICH, the President of Intermedies, testified that: “I don’t read patents,” and that in 1989 “APR I sales were fading fast,” and Intermedies required a new hip system:

Q Prior to leaving IOI, did you ever read the 023 patent?

A Huh-uh, I don’t read patents.

Q At the time that IOI began its commercial launch of the APR II, was the APR I still on the market?

A

Yes, whose sales were fading fast.

Q Was it your understanding that the APR II product with the distal sleeve component was important to IOI from the standpoint of rejuvenating the sales that the PAR (sic APR) product was losing? A

For all practical purposes, IOI was finding itself out of the hip business with the APR I. We had to get back into the hip business and I knew that it required a new hip system, and we just happened to call it the APR II.

Q And why was [the APR II] better? A It was better because the APR I was a failed product. It did not perform satisfac

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torily. It was recognized by IOI through this testimony as not performing satisfactorily,

and the APR II, which used the distal sleeve as reported in this testimony, did perform, satisfactorily and was the product that IOI used to get back into the hip business.

(Tr. at 285-286) (emphasis supplied).

WARLONEX JOSE BELEN, the In-termedies Director of Marketing, testified in a deposition as follows:

Q Prior to the use of a distal sleeve component for the APR II, what was the alternative for preventing the toggling problem in connection with a hip prosthesis stem? A We didn’t have one.

(Plaintiff’s Exh. 759, Deposition Transcript at 79). Testifying at the trial, Belen agreed that toggling and thigh pain were problems with the APR I, and that the APR II was designed to prevent toggling at the distal end of the stem:

Q Now, during this entire design process, coming to the APR II Hip System, as part of your review and case studies that you talked about, you also became aware that the APR I system had an extremely high occurrence of thigh pain; is that correct?

A That’s correct.

Q And one of the objectives in designing the APR II was to stop the thigh pain; is that correct?

A Yes.

Q And did you have an understanding at the time you were involved in the design of APR II that toggling motion at the distal end of the stem may have contributed to thigh pain?

A That’s correct. That was my hypothesis.

Q And, the APR II prosthesis, wasn’t that designed so as to prevent toggling of the distal end of the stem?

A Yes.

Q And isn’t it true that a design feature of the option of a distal sling (sic sleeve) were designed to put on the distal stem the prevented (sic) the transverse motion or toggling to occur?

A Yes.

Q And prior to this use of a distal sleeve for the APR II, isn’t it true that IOI had no alternative product for preventing the toggling problem in connection with the distal end of a hip prosthesis?

A True.

Q And isn’t it true prior to the use of the distal sleeve on the APR II device IOI did not have a practical alternative for solving this toggling problem?

A I will say true.

(Tr. at 1018-1020). Belen also testified that an additional product feature of the APR II was to “reduce the stiffness at the distal end of the stem.” (Tr. at 997).

Other documents prepared by Intermedies corroborate that the distal sleeve is designed to permit some flexibility. For example, in an Intermedies document called “An Introduction to the APR II Hip System,” BRIAN OLIND, the Product Manager for the APR II Hip System, discussed the APR II with RONNIE BURCHETT, the group product manager for IOI Hip Systems:

BRIAN OLIND: Well, how does the APR II system address stem/bone ratio?

RON BURCHETT: Stem/bone ratio is addressed by allowing the distal end of the prothesis to be adjusted in diameter with the sleeves. By adding a 2mm or 4mm sleeve you can adjust the distal diameter....

But this stem is not as stiff as a 19mm stem because it still has the 15mm core diameter.

(Plaintiffs Exh. 219 at 3) (emphasis supplied).

Burchett also discussed the flexibility of the APR II in his deposition:

Q Based on that example is it fair to say that the use of the APR II distal sleeve allows IOI to achieve better distal fill, yet, at the same time, use a smaller diameter and, thus, more flexible stem than it otherwise would be able to use to achieve that same fill without a sleeve.

A The design parameters for the II were based on APR I. When we designed the

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II we had the APR I clinical results to compare to.

The stem itself has a different geometry than the APR I; in that, the distal cross-section is circular, not a rectangle.

Because of that, this stem is more flexible than the APR I.

Q Mr. Burchett, please look at Plaintiffs Exhibit 6 for a moment, which is the sample APR II stem and sleeve.

Do you have any reason to doubt that the shaft portion of the APR II stem located above the distal sleeve is capable of flexing in the body in response to bending stresses applied to the prosthesis?

A No. There should be a certain amount of flexibility. Yes.

(Plaintiffs Exh. 760, Deposition Testimony at 91-92, 195) (emphasis supplied).

FREDERICK S. GEORGETTE, the In-termedies Manager of Material, testified in a deposition as follows:

Q During the time you worked at IOI, was it your understanding that the APR II distal sleeve, when implanted in the body would be capable of a small amount of axial motion relative to the femur bone in response to bending stresses applied to the prosthesis?

A Yes.

(Plaintiffs Exh. 772 at 13). Georgette also testified to the following:

Q During the time you worked for IOI was it also your understanding that the APR II distal sleeve when implanted in the body [would] also be capable of a small amount of rotational motion relative to the femur bone in response to rotational or ... torsional motions applied to the prosthesis?

A Yes.

(Tr. at 1244-1245) (Plaintiffs Exh. 772 at 14).

KEVIN DELANEY, formerly the defendant’s Vice President of Marketing and Sales, hedged when asked about the distal sleeve and increased flexibility. He didn’t recall and he didn’t remember anything on that subject. (Tr. at 2171). However, he did say:

Q Has Intermedies in the past addressed the issue of flexibility in any of the stems?

A I can recall it being a topic of discussion for the revision system.

Q Did Intermedies undertake any design changes to achieving increased—

THE COURT: To achieve.

MR. JONES: Yes.

Q —to achieve increased flexibility in its revision stem?

A I believe so.

Q What design changes were those?

A The feature of a slotted distal stem in the revision prosthesis was done to achieve that.

(Tr. at 2178).

Finally, the APR II Design Rationale states: “What is the purpose of the modular sleeves? Decreases stiffness, saves bone, increases surgical options.” (Plaintiffs Exh. 14 at 1).

Similarly, an APR II-T document distributed at its national sales meeting in November 1992, included the following statement:

Another clinic problem often associated with non-cemented hip prostheses is thigh pain. It has been suggested that distal stiffness mismatch is one of the causes of end of stem pain. It is widely accepted that more flexible implants are needed to reduce stress shielding and post-operative thigh pain.

(Tr. at 1398) (Defendant’s Exh. AAO at 079100).

All of the above evidence indicating that the APR II was designed to intend the shaft to be flexible by keeping the shaft diameter smaller than the distal sleeve diameter was corroborated by Dr. Burstein, who conducted bending tests on the APR II shaft. He found that by using the 4mm distal sleeve, the stem shaft above the distal sleeve is “300 percent more flexible” than a solid stem having the same diameter as the sleeve, (Tr. at 194, 229-30), or “a threefold increase in the flexibility of the stem when you compare it with and without the sleeve with the proper diameter.” (Tr. at 359). Using the +2 mm sleeve will increase flexibility in the stem shaft by 100 percent. (Tr. at 194).

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When questioned about whether the APR II practices the 023 patent claim limitation regarding enabling flexing of the stem shaft, Dr. Burstein testified that it did. He explained that the APR II prevents toggling, (Tr. at 130) and reduces stress shielding (Tr. at 130-133). In explaining how the APR II reduces stress shielding, Dr. Burstein described how the design of the APR II enabled flexing of the stem shaft:

Q. You mentioned stress shielding. Does the APR II practice or achieve the advantages of the 023 patent with respect to stress shielding?

A. Yes, it does, and it does it in the same way.

In addition, [the APR II] prevents loads from being transmitted distally.

Now the way you prevent bending loads from being transmitted distally is to make the stem flexible. Then if it deforms a little bit it doesn’t transmit much bending load. The stiffer the stem, the more bending load it can transmit when the bone deforms.

So the patent teaches that the way you prevent the transmission of bending loads is to make a portion of the stem of diameter smaller than the sleeve so that it is flexible, so that you enable flexing of that portion of the stem that’s above the sleeve.

Q. Does the APR II system, including the sleeve, practice the teachings with respect to the length of the sleeve contained in the 023 patent at 5, lines 34 through 44?

A. Yes.

The APR II has a sleeve that is long enough so that it does not hurt the bone, it is sufficiently long, and it is sufficiently short to leave over a portion of the stem that provides greatly increased flexibility of the stem.

[T]he APR II device has a sleeve, which according to the patent is long enough to result in low stresses and short enough to result in a section of stem of reduced diameter which increases flexibility.

(Tr. 131-32 and 135-36).

Thus, a review of the evidence indicates that (1) the APR II stem is designed with a taper so that it can be fitted with a complementary tapered distal sleeve that is not affixed to the bone, (2) the diameter of the stem shaft above the distal tip is smaller than the diameter of the distal sleeve, and (3) the intention of designing the distal sleeve to have a greater diameter than the stem shaft was not only to fill the canal, but also to allow or enable the stem to be less rigid and more flexible. In this way, both toggling and stress shielding would be prevented.

(2)

Limitation (ii):

“Distal Tip Integral With The Distal End of the Stem”

(a)

Claims Construction

(i)

Patent Language and Specification

Limitation (ii) of claim 1 states that the 023 patent improvement consists of “a distal tip integral with the distal end of the stem.” Patent at 6:65. In order to construe the limitation, the terms “distal tip,” “integral” and “distal end of the stem” have to be interpreted.

Referring to the drawings included in the specification, the patent describes the stem, reference number “22”, as that portion of the femoral prosthesis that is inserted into the resected femur. At the proximal end of the stem are the prosthetic neck and the wedge-shaped affixation area, both of which are “unitary with the stem.” Patent at 3:23-26. The stem is inserted into the passage reamed by the surgeon (called the “cavity”), and is advanced downwards until the stem is fully within the passage. Patent at 3:35-38. By definition, the “distal” end of the stem is that portion of the stem furthest from the point of attachment at the hip joint.

Located at the distal end of the stem is a tip, which the patent calls the “distal tip,” referred to as number “40” in the specification references. The specification describes the location of the distal tip in the following manner:

A distal tip is located at the distal end of the stem, spaced axially downwardly from

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the affixation surface, so as to extend downwardly into [the] passage and be positioned so that [the] distal tip is seated within harder portions of the bone of the wall of [the] femur, namely, within either dense cancellous bone or cortical bone, when the affixation surface is seated properly within the cavity.

Patent at 3:45-52.

The 023 patent’s claims limitations and specification further describe the distal tip as comprising of the following characteristics:

First, the distal tip is “integral” with the distal end of the stem. The term “integral” will be explained below.

Second, the distal tip is constructed of a bio-compatible material, such as a cobalt-chrome steel alloy.

Third, the distal tip has a generally cylindrical external peripheral surface extending along the length of the distal tip. The axial length of the external peripheral surface of the tip must be long enough to provide an area of contact between the distal tip and the wall of the cavity large enough to maintain a relatively low level of stress on the wall of the femur at the location of the distal tip in response to transverse forces at the distal tip. As explained above, the axial length of the distal tip’s external surface must also be short enough to expose a segment of the stem shaft above the distal tip and below the affixation surface in order to enable flexing of the shaft by means of a shaft diameter that is smaller than the diameter of the external surface of the tip.

Fourth, the external peripheral surface has a diameter complementary to the cavity in which it sits, so that the external peripheral surface of the distal tip engages, or presses against, the harder bone of the cavity wall and is confined against transverse movements within the cavity.

Fifth, the external peripheral surface has a fixation-resistant surface finish which prevents the distal tip from affixing to the wall of the cavity, thus allowing (i) the distal tip and distal end of the stem to rotate around the tip’s central axis relative to the wall of the femur, and (ii) axial movement of the distal tip and distal stem relative to the wall of the femur, in response to forces applied to the prosthesis. The fixation-resistant finish is described as “a very smooth surface finish, such as that which is attained by polishing and buffing the cobalt-chrome steel alloy.” Patent at 4:1-3.

Sixth, the distal tip’s central bore has a taper which is complementary to the taper on the distal end of the stem, thus allowing securing of the tip onto the stem by slipping the central bore of the distal tip over the distal end of the stem. This method of securing prevents movement of the distal tip relative to the distal end of the stem.

In addition to the above, the patent provides for the distal tip to be modular. As used in the industry, “modularity” means that the distal tip can be removed and replaced by another tip on the same stem. In this way, distal tips having bigger external peripheral surface diameters but the same central bore diameter can be fitted onto one stem, thus providing the surgeon with a variety of tip sizes to accommodate the patient’s inner femur cavity without having to use a different sized stem for each different sized proximal portion of the prosthesis.

Modularity in the 023 patent is created through use of the complementary tapers between the distal end of the stem and the central bore of the distal tip, which is also the method that secures the tip onto the distal end of the stem. Claim 4 of the 023 patent provides that the distal tip described by claim 1 must include “securing means for securing the distal tip to the stem for selective removal and replacement of the distal tip.” Patent at 7:30-32. The specification states that “it is preferable that [the] distal tip be removable selectively from [the] stem.” Patent at 4:47-49. Towards this end, through the use of the complementary tapers for securing the tip onto the stem, the distal tip can be “selected from a series of distal tips offered in a range of outside diameters so that a surgeon may choose the diameter for [the] external peripheral surface appropriate for the size of the passage into which the distal tip will be fitted.” Patent at 4:64-68. The specification also describes the advantages and benefits of modularity:

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The ability to remove and replace the distal tip with another distal tip selected from distal tips offered in a range of sizes enables greater versatility in fitting in that a wide variety of size combinations is made available in the joined stem and distal tip so as to enable independent sizing at the proximal portion of the stem without multiplying the number of stems needed to achieve such versatility. In providing such modularity between the stem and the distal tip, a greater choice is made available in the materials selected for the stem, as well as for the distal tip, so that the stem can be made even more flexible for better accommodation of loads during use.

Patent at 6:31-43.

Dr. Burstein explained the concept of “distal modularity” as described in the 023 patent for the Court in the following manner:

THE COURT: I heard a lot mentioned about modularity. What does that mean in lay language?

THE WITNESS: It means, Your Hon- or, that for every component that fits the proximal end of the femur, there are more than one component that can be put on the distal end, more than one diameter. So if we have a patient that has this size canal up on top and a big canal on the bottom, we can select a big tip, put it on the prosthesis, and put the prosthesis in the patient.

What that means is that this one part, the proximal portion, will fit people with different size canals and fit each one with a complete fit which will prevent toggling and allow it to move up and down, and these tips fit not only this size end, not only this size proximal end, but bigger proximal ends and smaller proximal ends. So with about five sizes on the proximal end and about five sizes on the distal end, you can fit 25 different sized patients. So you go into the operating room, instead of 25 different prostheses, you have five prostheses and five tips, but you can still fit 25 different size patients.

(Tr. at 363-364).

With these characteristics of the distal tip in mind, the term “integral” can be better understood. As used in the claim limitation, integral means that when the distal tip is secured to the stem, the tip and stem act in a unified manner. The patent specification explains that the “[djistal tip is integral with the distal end of the stem, so

that all movements of the distal end of the stem result in corresponding movements of the distal tip.”

Patent at 4:44-16 (emphasis supplied).

In order to provide such unitary movement of the tip and stem in response to forces acting on the prosthesis, or to put it another way, in order to prevent any movement of the stem relative to the distal tip, claim 5 provides that the means for securing the distal tip to the stem include “a securing mechanism responsive to relative axial movement between the stem and the distal tip for securing and releasing the distal tip and the stem.” Patent at 7:33-36.

Thus, in the Court’s view the phrase “distal tip integral with the distal end of the stem” means that there is a tip secured to the distal end of the stem, such that the tip and stem act as one unitary piece.

(ii)

The Patent’s Prosecution History and Extrinsic Evidence

This interpretation of “a distal tip integral with the distal end of the stem” is also supported by the patent’s prosecution history. In response to the Patent Examiner’s rejections of initial 023 patent claims 1-6 on the ground that the claims were unpatentable over the Witzel patent, the 023 patent applicants distinguished the Witzel device by, among other things, pointing to the fact that the sleeve of the Witzel device was uncoupled to the stem and did not act in a unitary fashion with the stem:

In Witzel, a small sleeve of synthetic resin material is first secured in the medullary canal, and then the shaft of a femoral stem is inserted into the sleeve. The shaft can move relative to the sleeve, but there is no displacement of the sleeve relative to the bone of the femur during service. In the construction of the present claims, the distal tip is affixed to the distal end of the stem prior to insertion into the medullary canal, and flexing of the shaft of the femoral stem during service is accommodated by displacement of the distal tip relative to

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the surrounding bone of the femur. Among those advantages is the distribution of stresses during service and the ability to use a material other than the synthetic resin material disclosed by Wit-zel to accommodate those stresses. Thus, in the Witzel construction, the articulating surfaces between the stem and the sleeve are of limited area, resulting in relatively higher stresses and the possibility for the formation of resin debris as the sleeve wears during use.

(Plaintiffs Exh. 568 at 50-51).

Dr. Burstein also corroborated this interpretation of “integral” by explaining that the patent uses the term integral to describe the attachment of the distal tip to the stem, and to describe the motion of the tip and stem relative to the bone:

Q Now, would you explain in lay terms what the patent teaches in column 4, lines 44 to 46?

A The patent is teaching the function and meaning of the attachment between the tip and the stem. The patent is saying that the tip and stem must be integral, and integral is defined two ways in the patent. It is what would happen if the tip and the stem were made of one piece. That’s one example of integral given in the patent. So that would be if you just made it without any junction at all and didn’t assemble them together but made it as a simple piece. That’s what the patent means by integral.

Also, integral should be thought of as having each motion of the stem correspond to a motion of the tip itself. That is, there should be no relative, no meaningful relative motion between the tip component and the stem. So we can think of it in either way as a unitary or integral.

(Tr. at 152-53).

(b)

Infringement Determination

The defendant contends that the APR II does not meet the claim limitation language, because the APR II does not utilize a distal tip. Rather, the defendant contends that the APR II utilizes a “sleeve,” which is different from a “tip.” Moreover, the defendant maintains that the APR II sleeve is not integral with the “end of the stem,” but rather is attached and integral with the mid-point of the stem shaft.

According to the defendant, the terms “tip” and “sleeve” denote two different items in the context of orthopedic devices. The defendant claims that the term “distal tip” refers to “an end cap or other component which is relatively short as compared to the component (in this case, the stem shaft) with which it is associated.” Defendant’s Post-Trial Brief at 5. In addition, in the defendant’s view a “tip” usually defines the end of the combined components, and encapsulates the components. On the other hand the term “sleeve,” according to the defendant, denotes “generally, a hollow tubular machined part designed to fit over a substantial portion (often the majority of the length) of the second component with which it is associated.” Defendant’s Pos1>-Trial Brief at 5. Moreover, the sleeve does not encapsulate the components.

With respect to the distal tip being “integral with the distal end of the stem,” the defendant contends that the APR II sleeve is not integral with the distal “end” of the stem, because the complementary tapers of the APR II stem shaft and sleeve provide for connection of the sleeve at the mid-point of the stem, and not at the end of the stem.

The Court is unpersuaded by the defendant’s interpretation of the claim limitation. In the Court’s view, the defendant’s interpretation is incorrectly based on a comparison of the APR II to the Omniflex, rather than to the 023 claims. Moreover, the defendant’s interpretation impermissibly adds additional limitations to the patent claim.

Contrary to the defendant’s reasoning, the limitations of the distal tip do not require that it be short relative to the stem, nor that it encapsulate the end portion of the stem that it covers. Indeed, there is no requirement at all that the 023 patent distal tip be enclosed at one end. The claims limitations only provide that the distal tip (i) be generally cylindrical, (ii) be constructed of a bio-compatible material, (iii) have an axial length (a) long enough to provide an area of contact between the tip and the wall of the cavity in

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order to maintain a lower level of stress on the wall at the location of the tip, and (b) short enough to expose a segment of the stem shaft above the tip in order to enable flexing of the shaft, (iv) have an outside diameter complementary to the cavity so that transverse movement of the stem is prevented, (v) have a fixation-resistant external surface finish that is a smooth finish, and (vi) have a central bore taper that is complementary to the stem taper, allowing the tip to be secured to the distal end of the stem and providing for modularity of the tip relative to the stem.

Thus, although the Court recognizes that in common usage a tip is different than a sleeve, in this case the Court believes that the 023 patent’s claims limitations do not distinguish between a “tip” and a “sleeve.” As long as the device that is used conforms to the claims limitations outlined above, it is considered a “distal tip” even if it is a sleeve.

This interpretation of a “distal tip” finds support in the patent’s prosecution history, which indicated that the terms “tip” and “sleeve” are used interchangeably. In rejecting most of the 023 patent claims on the ground that they were unpatentable under Witzel’s device, the Patent Examiner described the Witzel “tip” as performing “essentially the same function” as the 023 patent distal tip. (Plaintiffs Exh. 568 at 35). Technically, however, the Witzel device employed a sleeve, or a “sheath” as described in the 023 patent,

see

Patent at 3:56, 3:60-61, made of resin.

The Court’s construction of a “distal tip” finds support in the testimony of Dr. Bur-stein, who referred to the APR II sleeve and described how a sleeve could be used as a “distal tip” within the meaning of the claim limitation:

Q What is a “sleeve” in biomedical terms?

A A sleeve is, as is the common language, is a hollow cylindrical member.

Q And does that definition satisfy or does the tip described in the claim in the 023 patent, satisfy that definition?

A Yes. The tip of the 023 patent is a hollow cylindrical member. The tip in the 023 patent could also be called quite accurately a sleeve.

THE COURT: So when you use the word “sleeve,” that is synonymous with “tip” which is synonymous with “distal end”?

THE WITNESS: No, Your Honor.

THE COURT: The distal end could be the stem?

THE WITNESS: Yes, Your Honor. But even tip and sleeve need not be synonymous. It depends how the sleeve is used.

If the sleeve is attached so that it has a position at the bottom ... of the stem, it is a distal tip. It is also a sleeve.

THE COURT: So you say it is synonymous then?

THE WITNESS: If it is used in that way. In this usage it is synonymous because it is used as a distal tip. This sleeve is used as a distal tip.

Now when we say distal end, the patent is very clear on the definition, the distal end of the stem is everything below the affixation surface.

Q In [Plaintiffs] Exhibit 846, you used the term “distal tip.” To what did you refer?

A I referred to the sleeve which is put over the distal end of the stem, and is used as a distal tip. It becomes a distal tip when it is affixed in the way described by the 023 patent, in the manner described by the 023 patent. That is now a distal tip. It is also a sleeve. You can see a sleeve in the abstract. You can see a tip only when it is attached to the prosthesis.

(Tr. at 136-138).

Accordingly, the Court finds that the defendant’s construction of the term “distal tip,” namely that the term encompasses a “tip” that is short relative to the stem, and which encapsulates the end of the stem, adds external limitations not found in the claims language, and is erroneous.

Likewise, the Court believes that the defendant has erroneously construed the claim limitation by contending that in order to be integral with the distal end of the stem, the

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distal tip or sleeve must mechanically connect with the stem at the end portion of the stem.

The patent specifies by reference to diagrams that the stem of the prosthesis is that part of the prosthesis underneath the affixation surface, and that the distal end portion (reference number “44” in figure 3) of the stem (reference number “22”) is that portion of the stem having a complementary taper with the central bore of the distal tip,

see

Patent at 4:49-56 (referring to figure 3), to which the distal tip connects. The limitations of claim 1 also define a shaft portion of the stem, which is described in the claim as that part of the stem located between the affixation surface and the distal tip.

Nothing in this language indicates that in order to be integral with the “distal end of the stem,” the distal tip or sleeve must mechanically connect with the stem at the end portion of the stem. Rather, the claim defines the distal end of the stem to be that part of the stem below the stem shaft. If this were not the case, then the limitation language concerning the varying length of the distal tip relative to the cavity wall would be meaningless. Thus, once a stem shaft is created by connecting the tip to the end portion of the stem through the means of complementary tapers, the distal tip becomes integral with the distal end of the stem, irrespective of where on the stem that connection precisely occurs.

The Court, therefore, rejects the defendant’s construction of the phrase “distal tip integral with the distal end of the stem.” In the Court’s view, the phrase means that there is a tip or sleeve of a certain configuration and make-up as set forth in the patent’s claims limitations, which is secured to the distal end of the stem by means of complementary tapers between the tip or sleeve and the stem, such that the tip and distal end of the stem act and move together as one unitary piece in response to forces exerted on the prosthesis.

Under this interpretation of the claim limitation, the Court finds that the APR II sleeve is and acts in fact as a “distal tip integral with the distal end of the stem.” The uncontested facts state that the central bore of the APR II sleeve is formed with a taper that is complementary to the taper on the APR II stem, such that when the sleeve is secured to the APR II stem the sleeve and stem act in unitary fashion. In addition, by purposefully creating a stem shaft above the point of attachment of the sleeve to the stem, the APR II sleeve is secured to, and integral with, the distal end of the APR II stem.

According to the uncontested facts and evidence before the Court, the APR II sleeve also meets all of the other configuration requirements of the distal tip set forth in the claims limitations.

First, the APR II sleeve is constructed of a bio-compatible material, in this case a titanium alloy.

Second, the APR II sleeve is cylindrical, and its axial length is both long enough to maintain a relatively low level of stress along the wall of the femur at the point where it contacts the wall, and short enough to create an exposed stem shaft above the sleeve in order to enable flexing of the shaft.

Third, the APR II sleeve has a diameter that is complementary to the cavity in which it sits, so that its external surface engages the harder bone of the cavity wall and prevents transverse movement of the stem and sleeve.

Fourth, the APR II sleeve is modular. The sleeve has two sizes, + 2 mm and + 4 mm. The complementary tapers between the stem and sleeve allow for one sized sleeve to be removed and replaced by another sized sleeve. Indeed, the evidence adduced at trial clearly indicates that the APR II sleeve was designed to take advantage of modularity. In addition to the previously cited testimony of Belen, the Intermedies Director of Marketing, and Cindrion, President of Intermedies, describing the necessity of marketing the APR II sleeve in order to remedy Intermedics’s loss of market sales due to the APR I’s commercial failure, other testimony by IOI officials and various company documents establish the need for In-termedies to market a modular distal tip.

Among the documents are an Intermedies brochure entitled “FIT WITHOUT FOR

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FEIT,” with a heading “Optimal Fit that Doesn’t Sacrifice Bone.” This brochure includes the following promotional pitch:

The new APR II Hip System is the first hip prosthesis that can be easily adapted

intraoperatively

for an optimal fit that does not require excessive bone removal. Better Distal Fit

Surgeons have the alternative of adding a 2mm or 4mm distal sleeve for a tighter, more congruent fit. The ability to increase stem diameter without going to a larger implant can help preserve proximal bone.

(Defendant’s Exh. JP at 000539).

Ronnie G. Burchett, the Group Product Manager for IOI Hip Systems, states the following in a videotape entitled “Selling Strategies in Orthopedics APR II Hip System”:

Ron Burchett: ... People, such as Osteon-ics and Intermedies, S-ROM, came out with a modular system, they have sleeves now of some sort or another. Everybody that doesn’t have a sleeve is preaching against a sleeve. If you look at the .. trends in industry, you look at the new systems that are coming out, you look at the Howmedica systems, the Osteonics systems, other systems, you are starting to see more and more modularity, more sleeves. I think a few years from now, those same people that are preaching against another interface, a sleeve, will have a sleeve.

(Plaintiffs Exh. 895 at 3-4).

Another Intermedies document refers to Osteonics and the Omniflex modular tip, as follows:

OSTEONICS — Osteonics has just recently joined the ranks of the top players in the hip market. Since 1988 the company has enjoyed better than 20% growth every year. Market share has increased by almost 10 points during the same period, (11.5 to 20%). The company’s strong management, well-trained sales force, and innovative product designs have contributed to its share gains. The Omniflex for both pressfit and cemented use, and the Omnifit for cemented use are the company’s flagship brands.

The Omniflex capitalized on an emerging modular trend with its choice of heads and its modular distal

tips.... Osteonics will continue to have a strong presence in the hip market.

The modular approach simplifies hospital inventories, allows greater intra-operative flexibility, and in the event of some implant failures, simplifies reversions.

Overall, the trend toward providing more anatomically precise fits through press fit, modular and custom prostheses is at the beginning of the growth curve, with most of the market potential still ahead[.]

(Plaintiffs Exh. 670 at 6-9) (emphasis supplied).

Significantly, the evidence reveals that the APR II was marketed with the distal sleeve as a strong selling point. In this regard, Burchett testified as to the importance of the distal sleeve:

Q During the time you worked for In-termedies Southern California and now as a salesman in Montana, was it your practice to always make the sleeve available to doctors in the operating room who were implanting APR II devices?

A Yes.

Q To your knowledge, has IOI ever distributed any APR II literature in which the distal sleeve was not promoted as an advantageous feature of the product?

A No, not to the best of my knowledge.

(Plaintiffs Exh. 760 at 13, 22).

MARC M. VREEDE, the defendant’s product engineer and now a sales agent for the defendant, testified by deposition that the distal sleeve is a selling point for the APR II:

Q In connection with the surgeons that you mentioned before, who have mentioned or used the Omniflex product with the distal tip, have you ever tried to convince them to use the APR II with distal sleeve instead of the Omniflex?

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A Yes.

(Tr. at 1253; Plaintiffs Exh. 781 at 5).

Finally, as will be explained in the next section, the APR II sleeve also meets the claim limitation that its external peripheral surface must have a fixation-resistant surface finish.

(3)

Limitation (v):

A Fixation Resistant Surface-Finish

(a)

Claims Construction

(i)

Patent Language, Specification and Prosecution History

Limitation (v) of claim 1 provides in relevant part that the distal tip have a “fixation-resistant surface-finish on the external peripheral surface” for the purpose of maintaining the distal tip unaffixed to the cavity wall of the femur, whereby allowing axial movement relative to the wall of the femur. By remaining unaffixed to the femur, axial displacement of the distal tip and the distal end of the stem is permitted in response to forces applied to the prosthesis during its use.

The defendant contends that the term “fixation-resistant surface finish” means that the finish on the distal tip’s external surface must be a “very smooth” surface finish, with surface characteristics at least as smooth as those which are achieved by buffing and polishing cobalt-chrome metal. In support of this contention, the defendant cites to the following language in the 023 patent’s specification: “[T]he fixation-resistant finish on the external peripheral surface is a very smooth finish, such as that which is attained by polishing and buffing the cobalt-chrome steel ahoy.” Patent at 3:67-4:3.

According to the defendant, the APR II sleeve does not have such a finish. The defendant claims that when manufactured, the APR II sleeve contains “circumferential markings,” and that the sleeve’s outer surface was not polished or buffed until June 1992. Moreover, the defendant contends that the current buffing of the sleeve is unrelated to the flexation or axial movement of the stem, and that even after buffing there is a surface roughness that does not follow the patent’s teachings. Defendant’s Post-Trial brief at 9-10.

The Court disagrees with the defendant’s interpretation of this claim limitation, because it impermissibly seeks to add an external limitation from the specification to the broader claim language.

See Electro Medical,

34 F.3d at 1054 . Nothing in the

claims

language states that the surface must be “very” smooth. Rather, 023 patent claims 11 and 12, referring to the fixation-resistant surface finish identified in claim 1, provide that the finish “is a smooth finish on the external peripheral surface of the distal tip ... wherein the distal tip is constructed of a metal alloy and the fixation resistant finish

comprises a polished surface.”

Patent at 8:24-29 (emphasis supplied).

In describing the preferred embodiments, the patent specification states:

The external peripheral surface is provided with a fixation-resistant surface finish so that the distal tip will not be affixed to the wall of the femur and will remain unaffixed to the femur during use of the prosthesis. [The] [d]istal tip is constructed from a bio-compatible material, one such material being a cobalt-chrome steel alloy, and the fixation-resistant surface on the external peripheral surface is a very smooth surface finish, such as that which is attained by polishing and buffing the cobalt-chrome steel alloy.

Patent at 3:61-4:3.

Thus, according to the language of the claims, and as elucidated by the patent’s specification, the external peripheral surface finish must (i) be a smooth finish that comprises a polished finish, and (ii) be for the purpose of maintaining the distal tip unaf-fixed to the femur. The claim limitation language does not require that the surface actually be polished or “very” smooth; only that it constitutes (“comprises”) a polished surface.

This construction of the term “fixation-resistant surface finish” is supported by the patent’s prosecution history. In discussing the Freeman patent, the Patent Examiner noted that one of the types of tips used by the Freeman device had an outer surface

*784

that was smooth. According to the Patent Examiner, “[i]t is presumed that all non-fixating surfaces are smooth, typically polished surfaces.” (Plaintiffs Exh. 568 at 36-37). The Patent Examiner also concluded that it would be obvious to anyone skilled in the art that such smooth surfaces prevent affixation to the bone: “It would have, been obvious to one with ordinary skill in the art to make the non-affixing surfaces of the Freeman device polished and smooth to prohibit bone ingrowth (i.e. fixation to the bone).” (Plaintiffs Exh. 568 at 37).

Although it seems clear that the kind of surface finish described by the patent claim is a smooth finish comprising a polished surface, neither the 023 patent claims nor the patent description define what is meant by “smooth” and “polish.” These definitions were, however, provided by extrinsic evidence offered to help the Court understand some of the fundamental metallurgy involved.

(ii)

Extrinsic Evidence

Dr. Burstein explained how the terms “smooth” and “polish” are used in the context of machining metals. He referred to Plaintiffs Exhibit 704, which is a publication by the American Society of Mechanical Engineers (“ASME”) entitled:

An American National Standard, Surface Texture

(Surface Roughness, Waviness, and Lay), dated April 30, 1986. Appendix B of the publication includes the specification for producing various surface textures. (Plaintiffs Exh. 704 at 23).

According to the Appendix, “[sjmoothness and roughness are relative, i.e., surfaces may be smooth or rough for the purpose intended; what is smooth for one purpose may be rough for another.” (Plaintiffs Exh. 704 at 23). A chart is then provided in the Appendix, which indicates that a polished surface is defined as a surface having a relative roughness of 32 microinehes or less. Thus, according to the ASME, a surface is smooth for the purpose of constituting a polished surface if its relative roughness is 32 microinehes or less.

Dr. Burstein described the smoothness limitations of 023 patent’s distal tip, and related it to the ASME standard:

Q What does the patent teach with respect to the surface characteristics of the sleeve or the tip?

A The patent teaches in order for this to work it must be free to move up and down in the bone in accordance with how the prosthesis normally wants to move. That is, under load this prosthesis will move on the order of a thousandth of an inch or two, and it must be free to do so, and in order to do so, you cannot allow the distal end sleeve or tip to become fixed to the bone. If it becomes fixed to the bone it transects the bone. So, by having an affi-xation resisting surface, that will not allow the bone to grow into or into the surface, it becomes free to move up and down and also free to twist ... and you do that, the patent says, by providing smooth surfaces. And the patent gives an example. It says if, for example, you are using cobalt-chrome, you might want to have the surface polished. Well, if you are using titanium, which is another material you might or might not use the same processing, but you are going to finish it so that it has the same surface finish, that is, it has a smooth surface finish.

Q Would you explain what [the ASME standard] is?

A This is a standard which is practiced by the American National Standards Institute and the American Society of Mechanical Engineers in noting the types of surface finish that can be provided by different manufacturing processes.

In simple words, if an engineer wants to provide a certain surface finish and wants to know how to go about doing it, he can [look at the standard] and determine what type of manufacturing process will provide those surface finishes.

Q What microinehes are referred to after polishing?

A Polishing starts at 32 microinehes and then goes down to a half microinch.

Q So polishing ranges from 32 [mi-croinehes] down?

*785

32 [microinches] down would fall under the specification of a polished surface.

Now, an affixation [resistant] surface is certainly achieved with a 32 mieroineh finish; that you can see machining marks or any other marks on [the surface], is simply indicative of the specification of 32 mi-croinches.

If you look with a high enough power, you will see the hills and valleys and ups and downs that constitutes a 32 microinch finish. But it is the number itself that tells you how smooth it is and the specification calls for a smoothness which certainly would promote, which certainly would provide an affixation-resistant surface.

(Tr. at 132-33, 145, 147).

Significantly, Dr. Burstein’s explanation of how “smooth” and “polish” are defined within the context of the claim limitation was not refuted by the defendant during Burstein’s cross-examination or by the introduction of other evidence.

Accordingly, the Court interprets the claim limitation as requiring the distal tip’s external peripheral surface finish to be (i) a smooth finish that comprises or is consistent with a polished surface, i.e. a surface finish of 32 microinches or less in accordance with the ASME standard, and (ii) for the purpose of maintaining the distal tip unaffixed to the femur.

(b)

Infringement Determination

Plaintiffs Exhibit 96-3 is a copy of the APR II manufacturing blueprint for the APR II distal sleeve. In the legend of the blueprint there is a notation “Mach Surf,” and underneath this notation is the number “32” with a “v” next to it.

Dr. Burstein testified that the notation “Mach Surf’ means machine surface, and that the number 32 with the v next to it signifies that the surface finish is to be less than 32 microinches in roughness. (Tr. at 142 — 43). Dr. Burstein concluded that the APR II distal sleeve surface was therefore affixation resistant because it had a surface finish that was smooth, and consistent with a polish. (Tr. at 144-147 and 233-35). His testimony was not refuted by the defendant. Indeed, it was supported by the APR II distal sleeve surface measurements conducted by the defendant’s expert Dr. Pugh. Using a profilometer to measure the distal sleeve’s surface smoothness, Dr. Pugh recorded the smoothness at approximately 27 microinches. (Tr. at 234-35).

Therefore, based on the APR II distal sleeve blueprint specification, as corroborated by the unrefuted testimony of Dr. Bur-stein and Dr. Pugh’s measurements, the Court finds that the APR II distal sleeve’s external peripheral surface is to have a smoothness of less than 32 micrometers, which comprises or constitutes a polished surface. The defendant’s contentions that the APR II distal sleeve’s surface does not meet the claim limitation because of circumferential marks on its surface, or that the distal sleeve is not polished, miss the point concerning what degree of roughness constitutes smooth, within the scope of the limitation, and are rejected.

Moreover, contrary to the defendant’s contention, the Court also finds that the surface finish of the distal sleeve of the APR II is for the purpose of maintaining the distal sleeve unaffixed to the femur.

This finding is supported by the previously cited testimony of Frederick S. Georgette, the IOI Manager of Material Sciences, who testified in a deposition that the APR II distal sleeve was designed so that when implanted in the bone, it would be capable of axial and rotational movement relative to the bone. (Tr. at 1244r-45). The finding is also supported by the deposition testimony of JAMES L. DALE, the IOI Manager of Product Development, who also testified that the APR II distal sleeve was designed to avoid fixation to the femur and move axially and rotationally relative to the femur. (Tr. at 1221). Dale’s deposition testimony was not refuted by the defendant.

Finally, the Court’s finding is supported by the testimony of Dr. Burstein, who also concluded that the APR II distal sleeve’s surface finish was for the purpose of maintaining the distal sleeve unaffixed to the bone, and to enable axial and rotational movement relative to the bone. (Tr. at 132-33).

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C.

Other Evidence of Infringement: Development of the APR II Distal Sleeve After the February 1988 AAOS Meeting

When the defendant started to design the APR II in early 1987, it did not consider a sleeve component. Belen, the Intermedies Director of Marketing, testified that prior to February 1988, he was not aware of “any writing or document at IOI recording an idea for using sleeves with the APR II system.” (Tr. at 1022-1023). Nor is there any evidence that, prior to February 1988, APR II designer Dr. Lawrence Dorr recommended the use of a distal sleeve.

At a meeting of the American Association of Orthopedic Surgeons (“AAOS”), held in early February 1988 in Atlanta, James Dale and at least five of his associates at In-termedies were shown a demonstration and obtained literature describing the plaintiffs newly introduced Omniflex hip implant with the patented modular distal tip. At this meeting Dale admits receiving an Omniflex brochure on which was stated, “U.S. Patent Pending.” Dale took this Omniflex literature back to the Intermedies office in Texas. Pri- or to its attendance at this AAOS meeting, Intermedies never worked with a distal sleeve, and there is no record of any involvement by Intermedies with a distal sleeve or tip.

Seven days after returning from the February 1988 AAOS meeting, Dale issued a memorandum to his staff instructing his hip group to develop a “modular distal stem” for a new hip implant to be known as APR II, intended to replace the failing APR I product. The memorandum is dated February 18, 1988, and is Plaintiffs Exh. 49A. In its response to the plaintiffs first set of requests for admissions (Nos. 1-30), Intermedies admitted that the Dale memorandum is the earliest written document which refers to Intermedies developing a “modular distal stem”:

Request No. 13

(a) State the date when Defendant or any employee, agent or representative thereof first had knowledge of the device marketed by STRYKER or OSTEONICS under the designation ‘Omniflex’, ‘Omnifit’ or ‘Omnifit II’.

(b) State the date(s) when Defendant or any employee, agent or representative thereof had knowledge of the ’023 Patent in Suit.

Response to Request No. 13

With regard to Defendant’s first awareness of the OMNIFLEX device, that awareness occurred in or about 1988 through Plaintiffs advertisement in trade journals and at an AAOS meeting.

Apparently, various persons saw those ads and attended the AAOS meeting. Defendant will produce Document Nos. IOI 000736-749, which documents are illustrative of the trade journal ads which brought the OMNIFLEX device to defendant’s attention. Defendant’s first awareness of the ’023 patent occurred on or about January 5, 1990, when John Merkling saw a reference to it in the O.G.

Request for Admission No. 29

Admit that PX-49A,

dated February 18, 1988,

is the earliest written document in IOI’s possession, custody or control which states IOI’s intention to manufacture a modular distal stem, sleeve or tip member for use with the APR II hip system.

Response to Request for Admission No. 29

Defendant denies that PX-49A refers to or states Defendant’s intention to manufacture a modular distal “tip member” for use with the APR II hip system.

As presently informed, however, defendant admits that PX-I9A is the earliest written document which refers to a “modular distal stem” for use with the APR II hip system.

Request for Admission No. 30

Admit that PX-49A,

dated February 18, 1988,

is the earliest written document known to IOI which states IOI’s intention to manufacture a modular distal stem, sleeve or tip member for use with the APR II hip system.

*787

Response to Request for Admission No. 30

Defendant denies that PX-49A refers to or states Defendant’s intention to manufacture a modular distal “tip member” for use with the APR II hip system. As presently informed, however,

defendant admits that PX-49A is the earliest written document which refers to a “modular distal

stem”

for use with the APR II hip system.

(Plaintiffs Exhs. 150 at 13-14, 707 at 13-14) (emphasis supplied).

Ronnie Burchett also testified about the all-important 1988 AAOS meeting at which the newly patented Omniflex was first revealed:

Q Do you recall attending the 1988 AAOS meeting in Atlantic (sic), Georgia?

A Yes.

Q Do you recall seeing the Omniflex prosthesis displayed at the 1988 AAOS meeting?

A I believe so, yes.

Q Did you go to the 1988 AAOS meeting with a group of people from IOI?

A Yes.

Q About how many people did you go with?

A It would be a guess on my part. I would imagine there were at least 40.

Q Now, did you make any writing at all prior to February 4,1988 which refers to a hip implant system having a modular distal sleeve?

A Other than an outline or blueprint, no, no formalized census (sic) of any sort.

Q And you have not produced any such drawing or outline to us in this matter; is that correct?

A Correct.

Q

To your knowledge was the Omniflex prosthesis the first product on the market to provide distal modularity via the use of a metal distal tip or sleeve component?

A

With a metal sleeve, yes, I believe so.

(Tr. at 1472-1473) (emphasis supplied).

Significantly, none of the three persons who claim credit for conceiving the APR II hip implant — Dr. Lawrence Dorr, James Dale and Ronnie Burchett — produced any documentary evidence that the distal sleeve component was conceived prior to the February 1988 AAOS conference. Rather, the evidence indicates that the sleeve was considered only after the conference.

Dr. Dorr testified that he designed the APR II between the period of 1986 and 1989. He testified that he made drawings and templates and used certain X-rays during this period. Strangely, no such drawings or templates or X-rays were produced by the defendant. Dr. Dorr testified that he worked in concert with engineers and made models during the design period. No such models were produced by the defendant.

After a long discussion with regard to the design and function of the APR II, Dr. Dorr finally reached the subject of the distal sleeve. He stated that in fitting the implant in C bone patients, where the femur is like a “stovepipe” and is difficult to fit, he made the decision “to make a sleeve.”

So, it was at that point that I made a decision that I would make a sleeve that would go onto the implant to allow me to continue my principle of a good stable fit top and bottom.

BY MR. JONES:

Q Can you show the Court from the devices that are here in the courtroom, some of the sleeves that have been developed for use with the APR II?

A When I made that sleeve, I made it so that it fit this stem in this region....

(Tr. at 730).

Dr. Dorr testified that he initially made the sleeve to fit the whole length of the stem, but then he reduced the length of the sleeve and tried it on the mid-portion of the stem, not on the tip. He also testified that he got the idea for a hollow cylindrical sleeve for use with the APR II stem from the plastic sleeve of Dr. Leo Whiteside’s device. However, the record in this case reveals no corroborating evidence as to that important as

*788

sertion. There is

no

documentary evidence of any kind by any witness on behalf of Intermedies that it or Dr. Dorr even contemplated working on a distal sleeve prior to February 1988.

Interestingly, the defendant did produce a copy of a template used by Dr. Dorr with regard to the distal sleeve (Defendant’s Exh. HH). This drawing by Dr. Dorr was dated May 9, 1988, well after the disclosure by Osteonics at the February 1988 meeting. Significantly, this was Dr. Dorr’s “initial attempt” during the design process. (Tr. at 773).

Further, Dr. Dorr testified that he normally and regularly attended the meetings of the American Academy of Orthopedic Surgeons, and reluctantly admitted that he attended the key February 1988 conference in Atlanta. However, he could not recall whether he made a writing recording a design for the APR II distal sleeve at any time prior to the Atlanta conference:

Q Is it a fact that you normally and usually attend the regular meetings of the AAOS?

A Yes.

Q Is it a further fact that at your deposition you could not recall whether you did or did not attend the February 1988 AAOS meeting in Atlanta?

A I couldn’t recall whether I attended? Q Yes.

A I guess I didn’t recall whether I attended that day or that year. I would think I did.

Q And did you make a writing before February 1988, recording your idea for an APR II distal stem with complementary locking surfaces?

A Distal sleeve?

Q Distal sleeve, yes.

A I don’t recall.

THE COURT: What is the question? Was there a writing made?

MR. DIAZ: Yes, did you make a writing before February 1988 recording your idea for an APR II distal sleeve with complementary locking tapered surfaces?

Q And the answer, Doctor?

A I answered, I don’t recall whether I made any writings or not.

Q Please look at Exhibit 509. This is a memorandum from Mr. Dale of IOI to Mr. Belen. You know both of those gentlemen?

A Yes.

Q And the second page of the memo, Mr. Dale states under “APR II hip design — ” or hip system, “(a), APR II hip system, under that, (a) design hip implant (20 sizes) modular distal stem.”

Do you see that?

A Yes.

Q And that memo was written, I will represent to you that the February 1988 AAOS meeting was held in or about February 2nd through 9th of 1988. Do you accept that representation?

A Yes.

Q So Mr. Dale’s memo, Exhibit 509, was written about two weeks after that meeting, correct?

A Yes.

MR. DIAZ: I will correct the record, the meeting was February 4th through 9th, 1988

Q And so let me repeat the question. Was Mr. Dale’s memo, Exhibit 509, written about two weeks after that AAOS meeting in February of 1988?

A Yes.

Q Now, IOI has admitted that Exhibit 509, which has previously been identified as a deposition exhibit 49-A, is the first IOI document which refers to a modular distal stem for use with the APR II system. It did so in request to our request for admission 30 and it has been marked as Plaintiffs Exhibit 707 in your book. Will you accept that representation?

A Yes.

Q

Did you bring with you any writing which you made or caused to be made prior to February 18, 1988, which records or reflects your work or ideas for an APR II modular distal stem?

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A

No.

(Tr. at 822-826) (emphasis supplied).

The second person claiming to have conceived the idea for the distal modularity in the APR II is James L. Dale who was employed by Intermedies between 1984 and 1988. He was the Manager of Product Engineering between 1986 and 1988, and in early 1988 had design responsibility for all In-termedies products.

Dale testified that in 1987 Intermedies felt there was a need to install the concept of distal modularity in the design of the APR II. Dale claims that in 1987 he originated the idea for a distal sleeve by “tak[ing] the distal portion and attaching] it to the stem.” Dale’s “creation” was made of plastic. Mleg-edly, he made prototypes in that material. Dale testified that he showed “his” plastic distal sleeve to Dr. Dorr at, of all places, the February 1988 AAOS meeting in Atlanta. According to Dale, Dr. Dorr did not like the idea and rejected it, because he was “concerned about plastic wear debris which has been shown to lead to problems” (Tr. at 1528-1529). Dale also claims that in 1987 he considered a tapered lock mechanism on the stem.

The Court does not credit this testimony by Dale. The first document that Dale could produce to corroborate his testimony was a drawing or diagram made by Mark Vreede in June, 1988, showing a titanium alloy sleeve (Defendant’s Exh. ASF). Moreover, Dale’s testimony is contradicted by his deposition testimony regarding his first knowledge of a metal sleeve:

Question: Is it fair to say that prior to seeing a copy of Plaintiff’s Exhibit 6-61 (the Omniflex brochure), you had no firsthand knowledge of a prosthetic hip system — hip stem, which incorporated a metal distal sleeve or tip component?

Answer: I didn’t know of any.

(Tr. at 1569).

Q Can you identify any IOI writing dated prior to February 4, 1988, which uses the phrase, modular distal tip or modular distal stem?

A No, I can’t.

Q Now, can you identify any writing pri- or to February 18, 1988, which refers to design work carried out by IOI on a modular distal tip or modular distal stem?

A No, I can’t.

(Tr. at 1580).

Dale readily admitted that he attended the AAOS meeting in Atlanta in February 1988, and received the Omniflex brochure:

Q Did you in particular go to the February 1988 AAOS meeting in Atlantic (sic)?

A Yes.

Q And did others from Intermedies also attend that meeting?

A Yes.

Q Now, how did — how was it that you first became aware of the Omniflex at that time?

A I saw one of their brochures which pictured this implant.

Q And under what circumstances did you see that brochure?

A Well, it was at the show. One of the fellows who was with it [sic] had picked it up somewhere and he gave me a copy.

Q Do you recall who?

A No, I don’t.

Q But it was one of the Intermedies employees?

A Yes, that’s true.

Q Why was that brochure given to you?

A I try to gather what I could of those kind of materials to see what our competition is doing. It is always interesting to see what type of products we were facing in the marketplace.

Q From the time you received that piece of product literature pertaining to the Om-niflex in early February of ’88, do you recall any mention or any use of that literature other than in this lawsuit?

A No, I don’t.

Q What influence, Mr. Dale, did the Om-niflex product and literature have on the APR II product?

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A I can’t think of any insurance (sic influence) that it had.

(Tr. at 1589-1541).

Dale also stated that he placed the Omni-flex brochure in his flies (Tr. at 1581). Dale’s testimony that he did not keep any of the sketches or documents referring to the sleeve that he allegedly created prior to February 1988, but that he kept the Omniflex brochure, defies credulity and is a further ground for disbelieving his testimony.

Ronnie G. Burchett also claims a part in the design of the APR II and its distal sleeve. Burchett joined Intermedies in 1986 as Product Manager Marketing for Hips and was made Group Manager in 1989. In that position he was responsible for overseeing the development of hip implants. He left Intermedies in February 1992 and is presently a sales representative for the defendant in the State of Montana.

Burchett admitted that he saw the Omni-flex at the February 4-9, 1988 AAOS meeting. According to his testimony, he was there with at least forty other Intermedies employees — not the five testified to by other witnesses.

Burchett also testified that he was collaborating with Dr. Dorr, a Dr. Gustke, Belen and Dale in the design of the APR II. Apparently, by coincidence, in late 1987, he “wanted a two-piece component ... (with) a proximal body and a separate distal stem” attached to the body by a Morse type of taper. Then, again coincidentally, during the hunting season in the fall of 1987 he drew a sketch on a yellow legal pad on co-employee Fred Tripp’s dining room table. Burchett testified that “It was determined at that point by myself that it should be some kind of metallic sleeve mechanism.” There are no sketches, records or documents of any kind emanating from this idea of Burchett, until after Intermedies obtained the Omniflex brochure at the AAOS meeting in February 1988. The Court does not credit this testimony.

In addition, Burchett relates that in the fall of 1987 Dale thought about a plastic sleeve as something similar to a finger trap. The Court also does not credit this testimony. The record, the documentary evidence and the lack of corroborative documentary evidence reveal otherwise. Burchett is the third person to conceive of the idea of a distal sleeve prior to February 1988, without any documentary or paper trail.

The Court finds that there is no Intermed-ies document prior to February 9,1988, stating specifically or in substance that there is a need to incorporate distal modularity in the APR II hip implant; nor is there any such document referring to a distal sleeve. There are no Intermedies drawings, or sketches, or memoranda, or records of any kind with regard to a modular distal sleeve prior to February 1988. All of the Intermedies documents referring to distal modularity and the distal sleeve started to appear only after the Atlanta AAOS meeting in February 1988.

The first documentary record of Intermed-ics’s involvement with the distal sleeve is Plaintiffs Exh. 49A, the February 18, 1988 memorandum from Dale to Belen discussing, among other things, the development of a modular distal stem. The second Intermed-ies record of a distal sleeve is a memorandum by Burchett to Dale on March 16, 1988 (Defendant’s Exh. PX), some five weeks after the AAOS meeting of February 1988. Following this memorandum is the diagram of the hip implant with a distal sleeve, made on May 9, 1988. (Defendant’s Exh. HH). Subsequently, a memorandum from Burchett dated June 8, 1988 mentions a “distal locking sleeve.” A June 15, 1988 teleconference between Dale and Dr. Dorr refers to an APR prototype with a modular sleeve (Defendant’s Exh. ARZ) and a July 12, 1988 teleconference note discusses the distal sleeve (Defendant’s Exh. ASA). On August 10,1988, Dale received a memorandum from Mark Vreede. Under the words APR II sleeve was the notation “working on prototype drawings for a taper lock sleeve.” (Plaintiffs Exh. 72). There was no prior IOI document referring to a taper lock sleeve. However, the Omni-flex brochure kept by Dale in his file, contained a similar notation. Also, Vreede’s notebook entry of August 1, 1988 contained the words “round distal sleeve” similar to the language in the Omniflex brochure.

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D.

Conclusions and Findings as to Literal Infringement

The Court finds that the APR II device incorporates each and every feature and component of claims 8, 10 and 12 of the 023 patent, and therefore literally infringes on the patent claims. In sum, the Court makes the following findings based on the record, testimony and other evidence stated above:

A.

Limitation (Hi)

1. The term “enabling flexing” is construed as allowing the stem shaft of the device to flex and move axially upwards, by the use of a distal tip attached to the distal end of the stem which (i) is of a larger diameter than the stem shaft, and (ii) is not affixed to the bone.

2. The Court finds that (1) the APR II stem is designed with a taper so that it can be fitted with a complementary tapered distal sleeve that is not affixed to the bone, (2) the diameter of the stem shaft above the distal tip is smaller than the diameter of the distal sleeve, and (3) the intention of designing the distal sleeve to have a greater diameter than the stem shaft was not only to fill the canal, but also to allow or enable the stem to be less rigid and more flexible. In this way, both toggling and stress shielding would be prevented.

B.

Limitation (ii)

1. The phrase “distal tip integral with the distal end of the stem,” is construed to mean that there is a tip secured to the distal end of the stem, such that the tip and stem act as one unitary piece.

2. The Court finds that the defendant’s construction of the term “distal tip,” namely that the term encompasses a “tip” that is short relative to the stem, and which encapsulates the end of the stem, is erroneous and adds unintended limitations to the claims language.

3. The Court construes the claim limitation so that the 023 patent’s claims limitations do not distinguish between a “tip” and a “sleeve.” As long as the implement that is used conforms to the claims limitations, it is considered a “distal tip” even if it is a sleeve.

4. The Court finds that the APR II sleeve is, and acts, in fact as a “distal tip integral with the distal end of the stem.”

5. The Court finds that the defendant has erroneously construed the claim limitation by contending that in order to be integral with the distal end of the stem, the distal tip or sleeve must mechanically connect with the stem at the end portion of the stem. Nothing in the limitation language indicates that in order to be integral with the “distal end of the stem,” the distal tip or sleeve must mechanically connect with the stem at the end portion of the stem. Rather, the claims language defines the distal end of the stem to be that part of the stem below the stem shaft. Thus, once the tip is connected to the end position of the stem through the means of complementary tapers, the distal tip becomes integral with the distal end of the stem, irrespective of where on the stem that connection precisely occurs.

6. The Court finds that the central bore of the APR II sleeve is formed with a taper that is complementary to the taper on the APR II stem, such that when the sleeve is secured to the APR II stem the sleeve and stem act in unitary fashion. In addition, by purposefully exposing a stem shaft above the point of attachment of the sleeve to the stem, the APR II sleeve is secured to, and integral with, the distal end of the APR II stem.

7. The Court finds that the APR II sleeve also meets all of the other configuration requirements of the distal tip set forth in the claims limitations.

C.Limitation (v)

1. The Court construes the claim limitation as requiring the distal tip’s external peripheral surface finish to be (i) a smooth finish that comprises or is consistent with a polished surface, i.e. a surface finish of 32 mieroinches or less, and (ii) for the purpose of maintaining the distal tip unaf-fixed to the femur.

2. The Court finds that the APR II distal sleeve’s external peripheral surface is to have a smoothness of less than 32 micrometers, which comprises or constitutes a pol

*792

ished surface. The defendant’s contentions that the APR II distal sleeve’s surface does not meet the claim limitation because of circumferential marks on its surface, or that the distal sleeve is not polished, miss the point concerning what degree of roughness constitutes polish, and are rejected.

3. The Court finds that the surface finish of the distal sleeve of the APR II is for the purpose of maintaining the distal sleeve unaffixed to the femur.

4. The Court finds that there was a literal infringement by Intermedies in its APR II and APR II-T, of claims 8,10 and 12 of the 023 patent.

D.

The February AAOS Meeting

1. The Court finds that there is no In-termedies document prior to February 18, 1988, stating specifically or in substance that there is a need to incorporate a distal modular sleeve in the APR II hip implant; nor is there any such document referring to a distal sleeve. There are no Intermed-ies drawings or sketches or memoranda or records of any kind with regard to a modular distal sleeve prior to February 1988. All of the Intermedies documents referring to the modular distal sleeve started to appear only after the Atlanta AAOS meeting in February 1988.

2. The Court finds that the representatives of Intermedies first learned about the Omniflex and its distal modular sleeve and the pending 023 patent at the Academy of Orthopedic Surgeons meeting in February 1988. The Intermedies personnel took the Osteonics brochure back to their office. They then copied the concept of distal modularity, including a tapered stem and the modular distal sleeve component, and introduced it into their APR II hip implant.

3. The Court does not credit the testimony of Dr. Dorr, James Dale or Ronnie Burchett that they created, conceived or designed the concept of a tapered stem or the modular distal sleeve.

4. The Court finds that after Intermedies deliberately copied the distal modularity concept of the Omniflex, their APR II hip implant became an instant commercial success and salvaged the defendant’s hip implant business. The difference between the APR I and APR II is, essentially, the addition of the tapered stem and modular distal sleeve in the APR II.

2. Infringement Under the Doctrine of Equivalents

A

The Legal Standard

Under the doctrine of equivalents, a Court may find infringement when the accused device performs substantially the same function in substantially the same way to achieve substantially the same result that the patent in suit does.

Conroy,

14 F.3d at 1574 ;

London v. Carson Pirie Scott & Co.,

946 F.2d 1534, 1538 (Fed.Cir.1991) (citing

Graver Tank,

339 U.S. at 608 , 70 S.Ct. at 856 ). The purpose of the doctrine of equivalents is to ensure that the patentee is not deprived of the benefits of his or her patent by competitors “who appropriate the essence of an invention while barely avoiding the literal language of the claim.”

London,

946 F.2d at 1538 ;

Loctite Corp. v. Ultraseal Ltd.,

781 F.2d 861, 869 (Fed.Cir.1985).

There are two aspects to the doctrine of equivalents. The first aspect, described above, concerns protecting the patent from infringement in situations where, although the literal language of the claims are not copied, the essence of the patent is. The second aspect of the doctrine concerns ensuring that the exclusiveness of the patent’s claims are not extended to cover a device which, although falling within the literal meaning of the claims, is “so far changed in principle” from the patented device that it performs the same function in a substantially different way.

See Graver Tank,

339 U.S. at 608-609 , 70 S.Ct. at 856 (setting forth both aspects of the doctrine of equivalents). This second aspect has become known as the “reverse doctrine of equivalents.”

The Federal Circuit has explained the relationship between the doctrine of equivalents and the reverse doctrine of equivalents in the following manner:

Infringement is defined in 35 U.S.C. § 271 (a) as the unlicensed making, using

*793

or selling of a patentee’s claimed invention. Recognizing frailties of language and limitations on human foresight, the law acknowledges that one may appropriate another’s patented contribution not only with a product precisely described in a patent claim (literal infringement) but also with a product that is not quite so described but is in

fact

“substantially the same thing, used in

substantially

the same

way,

to achieve substantially the same result” (doctrine of equivalents). The law also acknowledges that one may only appear to have appropriated the patented contribution, when a product precisely described in a patent claim is in fact “so

far

changed in principle” that it performs in a “substantially different way” and is not therefore an appropriation (reverse doctrine of equivalents).

SRI Int’l v. Matsushita Elec. Corp. of America,

775 F.2d 1107, 1123 (Fed.Cir.1985) (in banc) (emphasis in original).

The Federal Circuit has also explained, however, that application of the doctrine of equivalents is the exception, not the rule, and should not be available as the second prong of every infringement charge. “[I]f the public comes to believe (or fear) that the language of patent claims can never be relied on, and that the doctrine of equivalents is ... regularly available to extend protection beyond the scope of the claims, then claims will cease to serve their intended purpose.”

London,

946 F.2d at 1538 .

There are two limitations on the doctrine of equivalents. First, the doctrine of equivalents will not extend to an infringing device that is found in the prior art at the time the patent was issued. Second, under the doctrine of prosecution history estoppel, the patentee is not allowed to recapture through equivalence certain claims coverage given up during prosecution.

Loctite,

781 F.2d at 870 .

What constitutes equivalency, or for that matter non-equivalency under the reverse doctrine of equivalents, is to be determined against the context of the patent, the prior art, and the particular circumstances of the case.

Graver Tank,

339 U.S. at 609 , 70 S.Ct. at 856 ;

SRI Int’l,

775 F.2d at 1124 . The inquiry into equivalency is a factual one, and does not require “complete identity of every purpose and in every respect” between the patent and the accused device.

Graver Tank,

339 U.S. at 609 , 70 S.Ct. at 857 . Factors to consider in the inquiry include (i) the purpose for which an ingredient is used in a patent, (ii) the qualities it has when combined with the other ingredients, (iii) the function which it is intended to perform, (iv) whether the accused product resulted from independent research, and (iv) whether persons reasonably skilled in the art would have known of the interchangeability of an ingredient not contained in the patent with one that was.

SRI Int’l,

775 F.2d at 1124 .

When a patentee establishes literal infringement, the accused infringer may undertake the burden of going forward to establish the fact of non-infringement under the reverse doctrine of equivalents. If the accused infringer makes a

prima facie

ease, the patentee, who retains the burden of persuasion on infringement, must rebut that

prima facie

case.

SRI Int’l,

775 F.2d at 1123-24 .

Thus, where literal infringement has been established, a defense of non-infringement based on the reverse doctrine of equivalents may be raised by the accused infringer. The key issue of inquiry under the reverse doctrine of equivalents is whether the principle of the patent has been so far changed in the accused device that the accused device performs the function of the claimed invention in a substantially different way.

SRI Int’l,

775 F.2d at 1124 . Merely using a device, however, which meets the patent claims in a different way than that described in the patent specification does not preclude liability for infringement of the patent.

Id.

(“One who takes a claimed structure and merely uses it in a way that differs from that in which a specification-described embodiment uses it, does not thereby escape infringement.”).

B.

The Defendant’s Equivalency Contentions

The defendant explicitly raises the defense of non-infringement under the reverse doc

*794

trine of equivalents, and contends that the APR II functions in a substantially different way from the 023 patent.

According to the defendant, the principal objective of the 023 patent is to “more advantageously address the problem of proximal stress shielding commonly associated with cementless hip prostheses” by incorporating a stem and modular distal tip component in combination, and purposefully designing the stem geometry and tip surface characteristics to “impart relatively enhanced flexibility to the prosthesis stem shaft to insure that it flexes meaningfully and so that the distal portion of the prosthesis pistons within the femoral implant.” Defendant’s Post Trial Brief at 12. The defendant further contends that the mode of operation that is the “principle” of the 023 patent is the use of a distal tip of “the shortest length possible” to address proximal stress shielding by

“purposefully enhancing

the otherwise

inherent flexation

of the stem under load.” Defendant’s Post-Trial Brief at 12.

On the other hand, the defendant contends that the APR II addresses the problem of proximal stress shielding by trying to prevent proximal motion and stem loosening through use of better proximal fixation techniques and collar loading. According to the defendant, the APR II does not operate on the principle of enhancing stem flexation through design of the stem and distal tip. Rather, the APR II operates on the principle of inhibiting movement of the prosthesis along its entire route, in order to promote better affixation of the prosthesis at the proximal end of the femur. To achieve this, the defendant claims that the APR II incorporates a larger wedge-shaped affixation surface, with an anatomic curvature and an improved porous coating. Moreover, the defendant contends that the role of the distal sleeve in the APR II is to fill the canal and prevent relative motion between the implant and the femur, and not to enhance flexing of the stem. Defendant’s Post-Trial Brief at 13.

In addition to raising a defense to literal infringement under the reverse doctrine of equivalents, the defendant raises two other defenses in response to Osteonics’s allegation of infringement under the doctrine of equivalents. The first defense is that the APR II does not meet the function-way-result test for equivalence set forth in

Graver Tank

and its progeny. The second defense is based on prosecution history estoppel. According to the defendant, when claim 1 was amended to add the limitation language reciting a stem shaft diameter smaller than the distal tip diameter for the purpose of enabling flexing of the stem shaft, the patentee surrendered any coverage of devices having similarly differentiated stem shaft and distal tip diameters that are not for the purpose of enabling flexing of the stem shaft.

Except for the issue of prosecution history estoppel, the Court is of the opinion that the contentions and defenses raised by the defendant with regard to the doctrine of equivalents are the same as the contentions raised in its defense under the reverse doctrine of equivalents. Accordingly, the Court will not consider the contentions and defenses raised by the defendant with respect to the doctrine of equivalents independently from its consideration of Intermedics’s defense under the reverse doctrine of equivalents.

C.

Equivalence of the APR II and the 023 Patent

As explained in the previous section dealing with claims interpretation, the primary objectives of the 023 patent are to eliminate toggling of the prosthesis and to prevent stress shielding in the proximal area of the femur. The principle it uses to prevent stress shielding is reduction of stress at the distal end of the stem by enabling the stem shaft of the prosthesis to flex and move axially upwards and rotationally on its axis, relative to the bone. This is accomplished by the use of a modular distal tip attached to the distal end of the stem which (i) is of a larger diameter than the stem shaft above it, (ii) is not affixed to the bone, and (iii) is integral with the stem through connection by complementary tapers between the tip’s central bore and the stem shaft. Toggling is eliminated by requiring the distal tip to be the same size as the cavity it sits in, so that it engages the inner wall of the femur.

There is no basis to the defendant’s contention that the 023 patent requires “the

*795

shortest tip possible” to enhance shaft flexibility. Such an interpretation is inappropriate because it adds an external limitation to the claim not found in the claim language.

See

discussion in Section II.l.B(2)(b). Rather, as explained previously, the length of the tip must be long enough to maintain a relatively low level of stress on the femur wall, and short enough to enable shaft flexing. Contrary to the defendant’s assertions, the APR II is not “so far changed in principle” from the 023 patent, that it can be said to perform the same functions and achieve the same results, in substantially

a different way.

Based on the evidence described in the previous section of this Opinion and the findings made therein, the APR II uses a modular distal sleeve which is unattached to the bone, thus allowing micromotion of the stem axially upwards and rotationally about its axis, relative to the bone. The modular distal sleeve surface finish is fixation resistant, and is configured to have a diameter greater than that of the stem shaft above it, thus enabling flexibility of the stem. It is also long enough to maintain a low level of stress along the femur wall. Moreover, the sleeve is made to be the same size as the cavity it sits in, thus preventing transverse motion of the stem. Finally, it is secured onto the stem shaft be means of complementary tapers between the stem and the central bore of the sleeve.

Thus, notwithstanding the changes from the APR I that are incorporated in the proximal portion of the APR II to achieve a tighter fit at the proximal end of the femur, the APR II operates on the same principle of preventing stress concentration at the distal end of the stem as does the 023 patent. That is to say, the intention of the APR II stem and sleeve design is to prevent stress from concentrating at the distal end of the stem by allowing flexibility and axial motion of the stem. The APR II also operates on the same principle as the 023 patent to prevent toggling; namely, use of the distal sleeve to confine transverse movement of the stem. Indeed, the same functions are performed by the APR II as the 023 patent (allowing 'flexing and axial micromotion of the stem), with the same results achieved (prevents stress at the distal end of the stem and, therefore, reduces stress shielding at the proximal end of femur), in substantially the same way (use of a particularly configured modular distal sleeve that is integral with the stem but does not affix to the bone).

The Court’s conclusion that the APR II operates on the same principle as the 023 patent in the same way, is further supported by consideration of two of the factors of equivalency set forth in

Graver Tank

and

SRI Int’l :

namely, whether the APR II resulted from independent research, and whether persons reasonably skilled in the art would have known of the interchangeability of an ingredient not contained in the 023 patent with one that was, such as, for example, the interchangeability of a distal sleeve and a distal tip. As explained earlier, the APR II and its distal sleeve were

not

developed independently of the 023 patent; they were copied from the Omniflex brochure distributed at the February, 1988 AAOS meeting in Atlanta. Moreover, Dr. Burstein testified, as someone reasonably skilled in the art, that the APR II distal sleeve, as well as the sleeve’s surface finish, is interchangeable with the 023 patent’s distal tip. Similarly, he testified that the anatomic configuration of the proximal portion of the APR II prosthesis does not render it different in principle than the 023 patent.

Thus, the Court concludes that the defendant has not met its burden with respect to the reverse doctrine of equivalents, and its defense of non-infringement based on that doctrine is rejected. For similar reasons, there is also no merit to the defendant’s contentions that there is no infringement under the doctrine of equivalents.

D.

Prosecution History Estoppel

The Court also rejects the defendant’s contention that the doctrine of prosecution history estoppel precludes a finding of infringement of equivalents in this case. As explained above, prosecution history estoppel limits the range of equivalents covered by a patent claim when the claim has been distinguished from relevant prior art during prosecution of the patent. Whatever subject matter was distinguished from the patent claim is deemed surrendered by the patentee, and

*796

cannot be recaptured by claims of infringement under the doctrine of equivalents.

See Southwall Techs.,

54 F.3d at 1578-79 (citing-cases).

In the Court’s view, prosecution history estoppel is not applicable in this case for two reasons. First, as the Court has already determined, Intermedies intended to enable flexing of the APR II stem shaft when it designed the stem diameter to be less than the distal sleeve diameter. A finding of literal infringement of the claim limitation precludes a defense of prosecution history estoppel.

Id.,

at 1578;

Loctite,

781 F.2d at 870 .

Second, assuming

arguendo

there has been no literal infringement, it is the Court’s opinion that by amending the language of claim 1 to include the limitation regarding stem-tip diameters, the patentee did not surrender any device which has a stem shaft diameter less than the distal tip diameter with the difference in diameters being other than for the purpose of enabling flexing of the stem shaft.

When a court applies the doctrine of prosecution history estoppel, “a close examination must be made as to, not only what was surrendered, but also the reason for such a surrender.”

Southwall,

54 F.3d at 1580 (quotations and citations omitted). The fact that claims were narrowed does not always mean that the doctrine of prosecution history estoppel “completely prohibits a patentee from recapturing some of what was originally claimed.”

Loctite,

781 F.2d at 871 (quotations and citations omitted).

Here, a close examination of the prior art distinguished by the patentee reveals that the reasons for adding the claims limitation language was to clarify that, unlike the prior art, the 023 distal tip was integral with the stem and not affixed to the bone, thus enabling the corresponding axial movement of the tip and stem in response to the shaft flexation resulting from the tip-stem diameter design. The sleeve of the Witzel device and the tip of the Freeman device, which were distinguished by the patentee, were affixed to the bone. Moreover, the Witzel stem was not integral with the sleeve. Thus, although each device did have a stem diameter smaller than the distal tip diameter, affixing the tip or sleeve to the bone counteracted any flexing of the stem. In the Court’s view, what was surrendered by the patent claim amendment was any device having a smaller stem shaft diameter than the diameter of the distal tip, but where the tip or sleeve was either affixed to the bone or not connected in integral fashion with the stem. Nothing in the history of the 023 patent’s prosecution indicates that the plaintiff surrendered a stem with a smaller diameter than the tip which was not intended to enable flexing.

E.

Conclusion and Findings as to Equivalents

The Court finds that the APR II is not “so far changed in principle” from the 023 patent, that it can be said to perform the same functions and achieve the same results, in substantially

a different way.

In sum, the Court makes the following findings based on the record, the testimony and the other evidence stated above:

1. The Court concludes that the defendant has not met its burden with respect to the reverse doctrine of equivalents. The Court also concludes that there is no merit to the defendant’s contentions that the APR II does not infringe the 023 patent under the doctrine of equivalents.

2. The Court finds that the APR II uses a modular distal sleeve which is unattached to the bone, thus allowing micromotion of the stem axially upwards and rotationally about its axis, relative to the bone. The modular distal sleeve surface finish is fixation resistant, and is configured to have a diameter greater than that of the stem shaft above it, thus enabling flexibility of the stem. It is also long enough to maintain a low level of stress along the femur wall. Moreover, the sleeve is made to be the same size as the cavity it sits in, thus preventing transverse motion of the stem. Finally, it is secured onto the stem shaft by means of complementary tapers between the stem and the central bore of the sleeve.

3. The Court finds that the APR II operates on the same principle of preventing stress concentration at the distal end of the stem as does the 023 patent. That is

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to say, the intention of the APR II stem and sleeve design is to prevent stress from concentrating at the distal end of the stem by allowing flexibility and axial motion of the stem. The APR II also operates on the same principle as the 023 patent to prevent toggling; namely, use of the distal sleeve to confíne transverse movement of the stem. The Court also finds that the same functions are performed by the APR II as the 023 patent (allowing flexing and axial micromotion of the stem), with the same results achieved (prevents stress at the distal end of the stem and, therefore, reduces stress shielding at the proximal end of femur), in substantially the same way (use of a particularly configured modular distal sleeve that is integral with the stem but does not affix to the bone).

4. The Court concludes that prosecution history estoppel in not applicable in this case. First, it is precluded because the Court had determined the APR II literally infringes the 023 patent claims at issue. Second, assuming there has been no literal infringement, the Court finds that by amending the language of claim 1 during the prosecution of the patent, the patentee did not surrender any device which has a stem shaft diameter less than the distal tip diameter, with the difference in diameters being other than for the purpose of enabling flexing of the stem shaft. Rather, the Court finds that what was surrendered by the patent claim amendment was any device having a smaller stem shaft diameter than the diameter of the distal tip, but where the tip or sleeve was either affixed to the bone or not connected in integral fashion with the stem.

III. AS TO UNENFORCEABILITY:

INEQUITABLE CONDUCT AND INVALIDITY

In addition to the defense of non-infringement, the defendant also alleges that the 023 patent is unenforceable. The grounds for this contention are (1) the 023 patent applicants, namely inventors Averill and Cohen, Osteonies’s patent liaison Zarnowski and Os-teonies’s patent counsel Jacob (the “applicants” for the purposes of this section), engaged in inequitable conduct before the Patent Office when they applied for the patent, and (2) the patent is invalid because (i) the claims limitations at issue are indefinite, and (ii) the patent’s claims have been rejected by the Patent Office upon reexamination. The Court shall consider each of these asserted grounds of unenforceability.

1. Inequitable Conduct

The defendant alleges that the conduct of the applicants with regard to the filing and prosecution of the 023 patent application violated the applicants’ duty to disclose information material to patentability.

Essentially, Intermedies contends that the applicants intentionally withheld material information from the Patent Office regarding the Whiteside Total Hip System (“Whiteside device”). The Whiteside device was a hip prosthesis developed by DR. LEO WHITE-SIDE and marketed by the Dow Corning Wright Corp. (“Dow Corning”) several years prior to the 023 patent application in January, 1988. According to Intermedies, the Whiteside device employed a modular distal sleeve and many of the other features of the 023 patent claims, and therefore was “highly material” prior art that should have been disclosed in the 023 patent application and prosecution. Intermedies contends that the applicants’ failure to do so constitutes inequitable conduct and renders the 023 patent unenforceable.

On the other hand, Osteonies contends that reference to the Whiteside device was not material to the examination by the Patent Office of the 023 patent claim, and that the device was cumulative of other prior art referred to in the patent’s application and prosecution. The plaintiff further contends that there was no intent to deceive the Patent Office in connection with the non-disclosure of the Whiteside reference.

In addition, Osteonies contends that the defendant’s contentions regarding its alleged inequitable conduct have already been ruled upon and rejected by United States Magistrate Judge Michael L. Orenstein’s decision of March 1, 1993,

Stryker Corp. v. Intermedies Orthopedics, Inc.,

148 F.R.D. 493 (E.D.N.Y.1993). That decision dealt with

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the issue of compelling Osteonics’s patent counsel to respond to questions focusing on Intermedics’s defense of inequitable conduct. Judge Orenstein ruled that in order to vitiate the attorney-client privilege and compel responses, the defendant had to establish a

prima facie

case of common law fraud.

See id.

at 497 (citing

American Optical Corp. v. United States,

179 U.S.P.Q. 682 , 684, 1973 WL 20128 (Ct.C1.1973)). After reviewing the evidence before him, Judge Orenstein held that the defendant had not established a

prima facie

case of fraud because there was no evidence of an intent by the applicants to deceive the Patent Office, and the Whiteside device was only “modestly” material.

Stryker,

148 F.R.D. at 498 -99 & n. 10. Accordingly, Judge Orenstein denied the defendant’s motion to compel disclosure of the privileged communications.

Osteonics contends that Intermedies did not appeal Judge Orenstein’s findings and ruling, and therefore his decision is now the “law of the case” with regard to In-termedics’s defense of inequitable conduct. The Court disagrees. The strong public interest in enforcing the duty of candor when dealing with the Patent Office militates against precluding the defense of inequitable conduct on the basis of the “law of the ease.”

Cf. Thompson-Hayward Chemical Co., v. Rohm and Haas Co.,

745 F.2d 27, 32-33 (Fed.Cir.1984) (where plaintiff filed two infringement suits covering the same patent and the Federal Circuit determined in the appeal of one of the suits that the plaintiffs patent was invalid due to inequitable conduct, the defendant’s failure to raise the patent’s invalidity in an answer to the amended complaint in the second suit, filed after the decision in the first suit, does not prevent the Court from considering the plaintiffs inequitable conduct in the second suit). Indeed, Judge Orenstein noted that his decision “does not preclude defendants from presenting their defense of inequitable conduct before the trial judge.”

Stryker,

148 F.R.D. at 499 n. 11.

Accordingly, the Court will consider In-termedics’s defense of inequitable conduct.

A.

Applicable Legal Standard

Pursuant to 37 C.F.R. § 1.56 , “[e]ach individual associated with the filing and prosecution of a patent application has a duty of candor and good faith in dealing with the [Patent] Office, which includes a duty to disclose to the Office all information known to that individual to be material to patenta-bility as defined in this section.” The intentional failure to disclose such material information is deemed inequitable conduct before the Patent Office, and subjects the patent to unenforceability.

Molins PLC v. Textron, Inc.,

48 F.3d 1172 , 1178 & n. 6 (Fed.Cir.1995) (citing cases).

Inequitable conduct includes “affirmative misrepresentation of a material fact, failure to disclose material information, or submission of false material information, coupled with an intent to deceive.”

Id.

(citing

J.P. Stevens & Co. v. Lex Tex, Ltd.,

747 F.2d 1553, 1559 (Fed.Cir.1984),

cert. denied,

474 U.S. 822 , 106 S.Ct. 73 , 88 L.Ed.2d 60 (1985)). In this case, the defendant alleges that the applicants failed to disclose certain prior art in the 023 patent application, namely the Whiteside device. To prevail on its claim of inequitable conduct, Intermedies must offer clear and convincing proof “of the materiality of the prior art, knowledge chargeable to the applicants] of that prior art and of its materiality, and the applicants’] failure to disclose the prior art, coupled with an intent to mislead the PTO.”

Molins,

48 F.3d at 1178 ;

accord LaBounty Mfg., Inc. v. United States Int’l Trade Comm’n.,

958 F.2d 1066, 1070 (Fed.Cir.1992) (the failure to disclose prior art constitutes inequitable conduct if the defendant shows by clear and convincing evidence that (1) the prior art withheld from the Patent Office was material, and (2) that the patentee and/or its patent counsel manifested a deceptive intent to withhold the material information).

Proof of inequitable conduct may be rebutted by a showing of non-materiality, lack of knowledge of materiality or lack of an intent to deceive. The Federal Circuit has described the relevant burdens of proof in the following manner:

[0]ne who alleges a ‘failure to disclose’ form of inequitable conduct must offer

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clear and convincing proof of: (1) prior art or information that is material; (2) knowledge chargeable to applicant of that prior art or information and of its materiality; and (3) failure of the applicant to disclose the [prior] art or information resulting from an intent to mislead the PTO. That proof may be rebutted by a showing that: (a) the prior art or information was not material (e.g., because it is less pertinent than or merely cumulative with prior art or information cited to or by the PTO); (b) if the prior art or information was material, a showing that applicant did not know of that art or information; (c) if applicant did know of that art or information, a showing that applicant did not know of its materiality; (d) a showing that applicant’s failure to disclose art or information did not result from an intent to mislead the PTO.

FMC Corp. v. Manitowoc Co.,

835 F.2d 1411, 1415 (Fed.Cir.1987).

Once the threshold findings of materiality and intent are established, “the court must weigh them to determine whether the equities warrant a conclusion that inequitable conduct occurred.”

Molins,

48 F.3d at 1178 . A determination of inequitable conduct is appropriate when “in light of all the particular circumstances, the conduct of the patentee is so culpable that its patent should not be enforced.”

LaBounty Mfg.,

958 F.2d at 1070 .

See also FMC Corp.,

835 F.2d at 1415 (“Thus, a balancing of overlapping considerations is involved in determining, in view of all the circumstances, the presence or absence of inequitable conduct.”).

With regard to the requirement of materiality, the patent regulations set forth a detailed definition of the term.

See

37 C.F.R. § 1.56 (b) (1994). The current definition, however, is the result of a revision to the regulation in 1992. The patent in suit was prosecuted from January 1988 until December 1989. Accordingly, the standard of materiality in effect at the time of the 023 patent’s prosecution must be used for the purposes of determining whether Osteonics’s conduct was inequitable. That standard was set forth in the former regulation,

see

37 C.F.R. § 1.56 (1991) (revised as of March 16, 1992), and defined information as being material when “there is a substantial likelihood that a reasonable examiner would consider it important in deciding whether to allow the application to issue as a patent.”

See Mo-lins,

48 F.3d at 1179 n. 8 (explaining the materiality standard under the old and revised regulation);

Merck & Co., Inc., v. Danbury Pharmacol, Inc.,

873 F.2d 1418, 1421 (Fed.Cir.1989).

Moreover, to be material “[t]he matter misrepresented need only be within a reasonable examiner’s realm of consideration.”

Id.

If the information allegedly withheld “is not as pertinent” as that considered by the examiner, or is “merely cumulative” to that considered by the examiner, it is not material.

Molins,

48 F.3d at 1179 .

The materiality of information is often described in terms of a spectrum ranging from high materiality to low materiality. In addition, materiality is often determined based upon the result of a Patent Office proceeding reassessing patentability in light of information not originally disclosed. For example, the reasonable rejection of claims in reliance on a reference, originally undisclosed to the Patent Office, during a reissue proceeding establishes the materiality of that reference.

Id.

(citing

J.P. Stevens,

747 F.2d at 1562 ). With regard to the failure to disclose prior art, determinations that the undisclosed prior art is material have been made in the following circumstances: (i) the withheld reference is highly material when no single piece of cited prior art taught the combination present in the reference, (ii) the undisclosed prior art is material when it discloses more relevant features than cited prior art, and (iii) the withheld reference is highly material where it is the only prior art cited in foreign patent applications, or where it has been used in rejecting the claims in the foreign application.

See Molins,

48 F.3d at 1180 (summarizing findings of materiality and citing cases).

With regard to the element of an intent to deceive, the Federal Circuit recognizes that direct proof of wrongful intent is rarely available, and an intent to deceive may instead be inferred from evidence of the circumstances surrounding the applicant’s conduct.

Id.,

*800

LaBounty Mfg.,

958 F.2d at 1076 . Intent “is most often proven by ‘a showing of acts the natural consequences of which are presumably intended by the actor.’”

Molins,

48 F.3d at 1180 ;

Merck & Co.,

873 F.2d at 1422 (quoting

Kansas Jack, Inc. v. Kuhn,

719 F.2d 1144, 1151 (Fed.Cir.1983)).

However, knowledge of the prior art alone is not culpable intent.

See Allen Organ Co. v. Kimball Int’l, Inc.,

839 F.2d 1556, 1568 (Fed.Cir.),

cert. denied,

488 U.S. 850 , 109 S.Ct. 132 , 102 L.Ed.2d 104 (1988). Nor does a finding that the conduct amounts to gross negligence itself justify an inference of an intent to deceive.

Molins,

48 F.3d at 1181 & n. 11. Rather, “ ‘the involved conduct, viewed in light of all the evidence, including evidence indicative of good faith, must indicate sufficient culpability to require a finding of intent to deceive.’ ”

Id.

(quoting

Kingsdown Medical Consultants, Ltd. v. Hollister, Inc.,

863 F.2d 867, 876 (Fed.Cir. 1988) (in banc),

cert. denied,

490 U.S. 1067 , 109 S.Ct. 2068 , 104 L.Ed.2d 633 (1989)).

Inferences of an intent to deceive are often related to the strength of the materiality of the withheld reference. Thus, the failure to cite to the Patent Office a material reference cited elsewhere in the world “justifies a strong inference that the withholding was intentional.”

Molins,

48 F.3d at 1182 . Similarly, submitting information to the Food and Drug Administration (“FDA”) while withholding it from the Patent Office is evidence of an intent to deceive.

Merck & Co.,

873 F.2d at 1420, 1422 .

B.

Determination of Inequitable Conduct

In the Court’s view, there was no inequitable conduct on the part of the patentees during prosecution of the 023 patent because the Whiteside device is not material and the defendant has failed to show that the patentees acted with the requisite intent to deceive the Patent Office.

(1)

Materiality of the Whiteside Device

Dr. Leo Whiteside testified by videotape deposition. He has been associated with Dow Corning and the development of prosthetic devices for many years, and is still associated with that company. Dr. White-side testified that initially, his Whiteside Total Hip System entailed a stem-type femoral device consisting of a cobalt-chromium metal stem with a cobalt-chromium modular head, proximal porous coating and a distal cylindrical stem. The principal method of preventing proximal stress shielding in the original Whiteside device was (i) to use a cylindrical non-porous stem made of a less flexible metal, which press fit into the medullary canal so as to be rigid and which would not bear axial loading because it slipped relative to the bone, and (ii) to provide fixation of the device at the proximal end of the femur. (Defendant’s Exh. ATL at 17-18 and 65-66).

Dr. Whiteside disclosed a femoral component sleeve to Dow Corning in 1984. He testified that he derived the concept of a sleeve, which he called a “femoral component spacer sleeve,” from one of the knee implants he had developed. The purpose of the spacer sleeve was to space and fill the distal end of the canal, which tended to be larger than the proximal end of the canal in older patients:

[T]he medullary canal of the femur gets large as the patient ages. I found I needed something to add to the distal portion of the femoral component in order to make it fit into a femur with a large medullary canal, in order to make the entire implant fit in a large medullary canal.

(Defendant’s Exh. ATL at 20). Moreover, the sleeve would allow centering of the stem in a cemented implant, and also a better press-fit of the distal stem portion in a non-cemented implant when the upper femur and canal sizes did not match. (Defendant’s Exh. ATL at 75-78). Promotional material by Dow Corning advertised the Whiteside femoral sleeve — composed of the hard plastic me-thylmethacrylate or acrylic — as used to center the stem in the distal femoral canal, minimize distal stem toggle, allow for a uniform cement mantle, and enhance proximal stress transfer and prosthesis fixation.

{See, e.g.,

Defendant’s Exh. Cl). Although the acrylic sleeve fit over the metal stem and was “attached” by friction to it, it is not secured to the stem.

*801

According to the defendant, the Whiteside device is “highly material” on the following grounds: (1) the Whiteside device employs the concept of distal modularity; (2) the 023 patent has been subjected to reexamination on the basis,

inter alia,

of the Whiteside device, (3) although marketed as a cemented implant, the Whiteside device could be employed as a cementless implant without any structural change, and thereby meet the purposes of the 023 patent, and (4) there are so many commonalities between the Whiteside device and the 023 patent, that the Whiteside device should have been revealed to the Patent Office.

Moreover, the defendant contends that the Whiteside device is not a cumulative reference, and that in particular the Witzel patent referred to by the applicants in the patent prosecution is not cumulative of the White-side device.

The Court is not persuaded by the defendant’s contentions. With regard to the distal modularity feature of the Whiteside device, the Court believes that although the White-side device used a modular sleeve, i.e., several sleeves with different sized outer diameters could fit each of the various-sized White-side stems,

(see

particularly Defendant’s Exhs. CJ, CK, CL [delineating the various “femoral sleeves” corresponding to each sized stem], Defendant’s Exhs. Cl and CL [describing the “femoral sleeve” as allowing for “independent prosthetic sizing of proximal and distal femur”], and Defendant’s Exh. ATK at 44-48 [video deposition testimony of KENNETH W. RUSSELL describing the various sleeve sizes]), this feature in and of itself, in the Court’s view, would not make the Whiteside reference material.

The more fundamental or pertinent aspect of the distal modularity practiced by the 023 patent is that the distal tip locks onto the stem so that it acts integrally with the stem. The integral nature of the 023 patent’s distal tip to the stem is not practiced by the White-side device because the friction fit of the sleeve to the stem does not lock the sleeve onto the stem. The Whiteside stem can move relative to the sleeve and does not act in an integral fashion with it. Dr. Whiteside admitted in his videotaped deposition that he did not design his device so that the sleeve and stem are integral. (Plaintiffs Exh. 807 at 31-33).

This difference in distal modularity was explained by Dr. Burstein in the context of distinguishing the Whiteside device and Wit-zel patent from the 023 patent:

Q Dr. Burstein, you testified — let me ask you this: Is the distal modularity taught by the 023 patent, the same incorporated into the Whiteside Total Hip System whether implanted cementless or unce-mented?

A No, completely different.

Q Please explain the difference to the Court between the Whiteside and the 023, in distal modularity?

A The 023 patent has an integral tip. What the Whiteside patent does is provide a spacer sleeve which can articulate against the prosthesis and against the b

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