PTAB

IPR2016-00817

Smith & Nephew Inc v. Arthrex Inc

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Petition
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1. Case Identification

2. Patent Overview

  • Title: Bioabsorbable Interference Screw
  • Brief Description: The ’216 patent discloses a tapered, bioabsorbable interference screw for use in anterior cruciate ligament (ACL) reconstruction. The invention is directed at securing a tissue graft within a bone tunnel by creating an interference fit, with the screw's taper allegedly providing increased fixation without increasing the difficulty of insertion.

3. Grounds for Unpatentability

Ground 1: Claims 1-7 are obvious over Endo-Fix

  • Prior Art Relied Upon: Endo-Fix (a 1995 sales brochure distributed by Acufex).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the Endo-Fix brochure discloses a tapered bioabsorbable interference screw for ACL reconstruction that meets every limitation of the challenged claims except for the body having a length of "about 35 mm." Endo-Fix teaches a screw with a tapered body, a threaded tip with a greater taper than the body for easy insertion, and a drive socket. Petitioner contended that Endo-Fix’s six-slot “Torx head” drive socket satisfies the limitation for "radially-extending slots for receiving a driver having three radially-extending protrusions" under the Broadest Reasonable Interpretation (BRI), which covers three or more slots. Endo-Fix also discloses cannulation for a guide pin (claim 3) and various screw diameters consistent with the dependent claims.
    • Motivation to Combine: Not applicable as a single-reference ground. However, Petitioner argued it would have been obvious to modify the length of the Endo-Fix screw to 35 mm. The petition asserted four reasons: (1) merely changing a size or dimension is not patentable; (2) prior art disclosed a range of interference screw lengths that included 35 mm; (3) screw length was a known result-effective variable where longer screws provided better fixation; and (4) there was a specific motivation in the art to use longer screws to secure a larger portion of the ligament.
    • Expectation of Success: A person of ordinary skill in the art (POSA) would have expected that lengthening the known Endo-Fix screw to a dimension already used in the field would predictably result in a functional screw with enhanced fixation, a well-understood principle.

Ground 2: Claims 1-7 are obvious over Endo-Fix in view of Weiler

  • Prior Art Relied Upon: Endo-Fix (a 1995 sales brochure), Weiler (a 1998 journal article).
  • Core Argument for this Ground: This ground provides an alternative invalidity theory for the drive socket limitation. If the claims are construed to require only three slots, Weiler teaches a superior "trilobe" (three-slot) drive socket that a POSA would have been motivated to incorporate into the Endo-Fix screw design.
    • Prior Art Mapping: Endo-Fix teaches all elements of the claimed screw except for the specific drive socket configuration, assuming a narrow construction. Weiler explicitly discloses a three-groove "trilobe" socket for bioabsorbable interference screws that is nearly identical to the one shown in the ’216 patent.
    • Motivation to Combine: Petitioner argued a POSA would combine these references because Weiler’s study directly compared the performance of various drive sockets, including the "Acufex" screw (the Endo-Fix screw), which has a Torx-style drive. Weiler concluded that the Acufex screw was prone to "drive failure during screw insertion." In contrast, Weiler found that the "trilobe" socket withstood significantly higher torque. Therefore, a POSA would have been motivated to substitute Weiler’s stronger, more reliable trilobe socket for the weaker Torx socket in the Endo-Fix screw to solve the known problem of drive failure.
    • Expectation of Success: The substitution of one known drive socket for another to achieve the predictable benefit of increased torque resistance would have been a simple design choice with a high expectation of success.

Ground 3: Claims 1-7 are obvious over Simon in view of Weiler

  • Prior Art Relied Upon: Simon (Patent 5,891,146), Weiler (a 1998 journal article).
  • Core Argument for this Ground: This ground parallels the logic of Ground 2, but uses Simon as the primary reference. Petitioner argued that Simon discloses a tapered bioabsorbable screw with a hexagonal drive socket, and a POSA would have been motivated to replace Simon’s socket with the superior trilobe socket taught by Weiler.
    • Prior Art Mapping: Simon discloses all features of the claimed screw except the 35 mm body length (which Petitioner argued was an obvious modification) and the specific three-slot drive socket. Weiler supplies the teaching of the three-slot trilobe socket.
    • Motivation to Combine: Weiler's study also showed that hex drive sockets (like Simon's) failed at lower torques than the trilobe socket. A POSA would have been motivated by Weiler's direct comparison to substitute the trilobe socket into Simon's screw design to increase insertion strength and prevent drive failure, yielding the claimed invention.
  • Additional Grounds: Petitioner asserted additional obviousness challenges, including that Simon alone renders the claims obvious (relying on the same length-modification arguments as with Endo-Fix) and that European Patent Application EP '459 renders the claims obvious (arguing the ’216 patent is not entitled to its claimed priority date).

4. Key Claim Construction Positions

  • "body" versus "tip": Petitioner argued that based on the claim language separately reciting a "body" and a "tip disposed of the body," the two are distinct components. This construction is critical because claim 1 requires the "body" to be "about 35 mm long." If the tip is separate, the prior art must disclose a screw with a 35 mm body, not a 35 mm total length. The petition argued the claims are obvious under either interpretation.
  • "radially-extending slots": Petitioner argued that under the BRI, the claim language "radially-extending slots for receiving a driver having three radially-extending protrusions" should be construed to mean three or more slots, not exactly three. This interpretation allows prior art references with six-slot drives (like the Torx head of Endo-Fix and the hex drive of Simon) to meet the claim limitation. The combination grounds with Weiler were presented as an alternative in case the Board adopted a narrower "exactly three" construction.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-7 of the ’216 patent as unpatentable under 35 U.S.C. §103.