PTAB

IPR2019-00123

Cook Incorported v. Medtronic, Inc.

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1. Case Identification

2. Patent Overview

  • Title: Medical Devices with Shape Memory Alloy Elements
  • Brief Description: The ’141 patent relates to medical devices, such as implantable stents, constructed from a shape memory alloy (SMA). The purported invention is an improvement wherein the device uses an SMA that exhibits reversible stress-induced martensite (SIM) behavior at body temperature, as opposed to prior art devices that relied on temperature-induced martensite (TIM) behavior for deployment.

3. Grounds for Unpatentability

Ground 1: Obviousness over Cragg, Pops, and Tanaka - Claims 1-22 are obvious over Cragg in view of Pops and Tanaka.

  • Prior Art Relied Upon: Cragg (a 1983 article in Radiology), Pops (a 1970 article in Metallurgical Transactions), and Tanaka (Patent 4,490,112).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Cragg disclosed all elements of the claimed device except for the specific type of SMA. Cragg taught a medical device comprising a coiled nitinol stent delivered via a hollow catheter and guidewire, but its SMA relied on TIM (heat-sensitivity) for deployment. Petitioner asserted that both Pops and Tanaka taught that SMAs exhibiting the claimed SIM behavior (also called pseudoelasticity) at body temperature were well-known. Pops disclosed this property in copper-zinc-based alloys, while Tanaka disclosed it in nitinol alloys used in implantable medical devices (orthodontic braces).
    • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would have been motivated to substitute the TIM-based alloy in Cragg's device with a SIM-based alloy from Pops or Tanaka to solve a known problem. Cragg explicitly described "difficulties" with its device, including premature transformation and the need for inconvenient cold saline flushes to control deployment. A POSITA would combine the references to create a superior device where deployment is controlled by mechanical stress (i.e., removing the catheter restraint) rather than temperature, thus obviating Cragg's known issues and the "substantial inconvenience for physicians."
    • Expectation of Success: The proposed modification was a simple substitution of one known material for another in a known device to achieve a predictable improvement. Since Tanaka and others taught the use of SIM alloys in medical devices, a POSITA would have had a reasonable expectation that the resulting device would work as intended.

Ground 2: Obviousness over Cragg, Tanaka, and Suzuki - Claims 1-22 are obvious over Cragg in view of Tanaka and Suzuki.

  • Prior Art Relied Upon: Cragg (1983 Radiology article), Tanaka (Patent 4,490,112), and Suzuki (a 1982 article in Titanium & Zirconium).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground largely mirrored Ground 1 but introduced Suzuki as further evidence of the state of the art. Petitioner argued Suzuki disclosed a nitinol SMA with reversible SIM behavior ("super-elasticity") at body temperature for use in implantable medical devices. Crucially, Suzuki was said to teach that SIM-based SMAs are “used in medical fields, in the same way as” TIM-based SMAs, directly suggesting their interchangeability.
    • Motivation to Combine: The motivation was identical to Ground 1—solving the known problems in Cragg's device. This was reinforced by Suzuki's explicit teaching that SIM alloys were of "major interest for functional materials" and could be substituted for TIM alloys in medical applications. Petitioner argued it would have been obvious to make this substitution, which involved merely replacing one type of nitinol alloy with another, more functionally advantageous type of nitinol alloy.
    • Expectation of Success: As with Ground 1, Petitioner argued a POSITA would have a high expectation of success, as the modification was a predictable solution to a known problem using materials explicitly described as suitable for such medical applications.

4. Key Technical Contentions (Beyond Claim Construction)

  • Simple Substitution: The petition’s central technical theme was that the ’141 patent’s alleged invention represented a simple and obvious substitution. It asserted that replacing the TIM-based alloy in Cragg's known stent system with a well-known SIM-based alloy, as taught by Pops, Tanaka, or Suzuki, was a predictable design choice to solve a known problem, not an inventive step.
  • Curing Prosecution Deficiencies: Petitioner emphasized that, unlike the art considered during the original prosecution (e.g., Balko), the prior art asserted in the petition explicitly disclosed SMAs with the required reversible SIM behavior at body temperature. This directly addressed the evidentiary deficiency that had previously led the patent examiner to allow the claims.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under §325(d) would be inappropriate because the asserted grounds and prior art combinations were not substantively considered by the USPTO during prosecution. It highlighted that Pops was entirely new art. While Tanaka and Suzuki were cited in an Information Disclosure Statement (IDS), they were never applied in a rejection. Furthermore, Petitioner alleged that the patent owner had submitted an incomplete and non-certified translation of the Japanese-language Suzuki reference during prosecution, which omitted key figures that clearly illustrated the alloy's SIM behavior.

6. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-22 of Patent 6,306,141 as unpatentable.