PTAB

IPR2016-00819

Smith & Nephew Inc v. Arthrex Inc

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1. Case Identification

2. Patent Overview

  • Title: Method of Interference Fixation for ACL Reconstruction
  • Brief Description: The ’977 patent is directed to a method of anterior cruciate ligament (ACL) reconstruction using a specific type of bioabsorbable interference screw. The method involves securing a ligament graft within a tibial tunnel using the screw, which is characterized as being tapered with threads extending along substantially its entire length to achieve an "interference fit."

3. Grounds for Unpatentability

Ground 1: Claims 1-2 and 4-6 are obvious over Simon

  • Prior Art Relied Upon: Simon (Patent 5,891,146).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Simon, which discloses a bioabsorbable orthopedic interference screw for ACL reconstruction, taught every feature of the screw described in independent claims 1 and 6 of the ’977 patent. This included a fully cannulated, tapered body with threads extending along its length. Petitioner asserted that Simon described the conventional use of this screw in an ACL procedure, meeting most of the claimed method steps. For the limitation requiring the screw’s body to fill "all but 5-10 mm of the tunnel" (limitation [c3]), Petitioner contended this was an obvious design choice. A POSITA would have been aware of teachings for both soft tissue and bone block fixation that established known, overlapping ranges for screw and tunnel lengths. Selecting a screw length to leave a 5-10 mm gap was merely the result of routine optimization to maximize fixation without the screw protruding, which was a known problem to be avoided.
    • Motivation to Combine: Although a single reference ground, the motivation for arriving at the 5-10 mm gap was based on general knowledge in the art. A POSITA would be motivated to select a screw length that maximized graft engagement within the tunnel, a known result-effective variable, leading predictably to a dimension within or overlapping the claimed range.
    • Expectation of Success: A POSITA would have had a high expectation of success in applying the Simon screw in a conventional ACL procedure and selecting an optimal length, as this involved applying well-understood principles to achieve predictable results.

Ground 2: Claims 2-3 are obvious over Simon in view of Weiler and Hannay

  • Prior Art Relied Upon: Simon (Patent 5,891,146), Weiler (a 1998 article in the American Journal of Sports Medicine), and Hannay (Patent 3,575,080).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground specifically addressed the "Delta drive socket" limitation in claim 2 and its features in dependent claim 3. Petitioner asserted that Simon disclosed a standard hexagonal drive socket. The Weiler article identified a known problem with such sockets: a risk of drive failure during insertion due to insufficient torque resistance. Weiler showed that a "trilobe" socket withstood significantly higher torque. Hannay, in turn, disclosed a high-torque drive socket design featuring a hexagonal core with three radially extending slots in every other annular face, matching the configuration claimed in the ’977 patent.
    • Motivation to Combine: A POSITA, aware of the drive failure problem identified by Weiler with Simon's hex socket, would be motivated to find a stronger alternative. The Weiler study pointed toward a trilobe design. A POSITA would combine Weiler's trilobe concept with Hannay's hex-core-with-slots design for two predictable reasons: to increase the number of surfaces for distributing drive forces (improving torque resistance) and to allow for the use of a standard hex-head screwdriver if a specialized driver was unavailable.
    • Expectation of Success: Combining these known design elements to solve a known problem would have yielded predictable results, and thus a POSITA would have had a high expectation of success.

Ground 3: Claims 1-2 and 4-6 are obvious over Endo-Fix

  • Prior Art Relied Upon: Endo-Fix (a 1995 Acufex sales brochure).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that the Endo-Fix brochure, distributed to medical professionals before 1998, disclosed a fully cannulated, bioabsorbable, and tapered interference screw for ACL reconstruction that met all structural elements of the screw in claims 1 and 6. While Endo-Fix did not explicitly detail every method step, Petitioner asserted these steps were conventional for the screw's intended use and would have been implicitly understood by a POSITA. As in Ground 1, Petitioner argued the 5-10 mm gap limitation was obvious based on established prior art knowledge regarding the routine optimization of screw and tunnel lengths for bone block and soft tissue fixation procedures.
    • Motivation to Combine: The motivation to select a screw length resulting in a 5-10 mm gap was driven by the common goal of maximizing fixation, a known result-effective variable that a POSITA would routinely optimize.
    • Expectation of Success: A POSITA would have expected success in using the Endo-Fix screw in a conventional ACL surgery and selecting an appropriate length, as it involved no more than the application of standard surgical principles.

  • Additional Grounds: Petitioner asserted a parallel obviousness challenge (Ground 4) for claims 2-3 based on Endo-Fix in view of Weiler and Hannay, relying on the same drive socket modification theory presented in Ground 2.

4. Key Claim Construction Positions

  • "body" vs. "tip": Petitioner dedicated significant argument to construing the terms "body" and "tip." It argued that dependent claims 4 and 5, which introduce a "smooth and unthreaded" tip, compel a construction where the "body" recited in independent claims 1 and 6 is a distinct component that does not include the tip. Therefore, the "body" is the fully threaded portion of the screw, excluding the unthreaded distal end. This construction was critical to Petitioner's arguments, as claim limitations requiring the "body" to fill all but 5-10 mm of the tunnel and have threads extending along its length would not apply to the entire screw.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-6 of Patent 6,629,977 as unpatentable.