PTAB

IPR2017-00373

Smith & Nephew Inc v. ConforMIS Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Patient-Specific Orthopedic Instruments
  • Brief Description: The ’169 patent describes a method for creating a patient-specific surgical instrument for orthopedic implant surgery. The method uses a first image data set, such as magnetic resonance imaging (MRI), to create a surface on the instrument that matches the patient's joint anatomy, and a second, different type of image data set, such as an x-ray, to determine the orientation of a tool guide on the instrument.

3. Grounds for Unpatentability

Ground 1: Claims 29-30 are obvious over CAOS in combination with Radermacher and Woolson.

  • Prior Art Relied Upon: CAOS (a 1998 article by Radermacher et al.), Radermacher (WO 93/25157), and Woolson (Patent 4,841,975).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of these references taught every limitation of the challenged claims. CAOS disclosed creating patient-specific surgical instruments (“individual templates”) using a first image data set (computerized tomographic, or CT, scans) to create an exact-fitting surface and a second image data set (topograms) to identify the "bone axis" for aligning the instrument's tool guides. Radermacher, a closely related reference by the same lead author, explicitly taught that MRI data could be used interchangeably with CT data to create the patient-specific surface that "copies the surface of the osseous structure." Petitioner contended that substituting the MRI taught by Radermacher for the CT in CAOS was an obvious design choice. Finally, Woolson taught the well-established and critical practice of using a second image data set (x-ray or CT) to determine the patient's mechanical axis and orient cutting guides perpendicular to it to ensure long-term surgical success. This supplied the rationale for using the second image data (topograms in CAOS, or x-rays per claim 30) to orient the guide relative to the mechanical axis.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine CAOS and Radermacher because they address the same problem, share an author, and present MRI and CT as known, interchangeable alternatives for imaging bone contours. A POSITA would combine this with Woolson’s teachings because aligning implants with the mechanical axis was an essential, standard practice for successful knee arthroplasty, and Woolson explicitly taught using imaging like x-rays for this purpose. This combination would improve the CAOS procedure in a predictable way.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because the combination involved substituting one known imaging modality for another (MRI for CT) and applying a standard, necessary alignment technique (orienting guides to the mechanical axis) to achieve the predictable result of a properly fitted and aligned surgical guide.

Ground 2: Claims 29-30 are obvious over Swaelens alone or in combination with Woolson.

  • Prior Art Relied Upon: Swaelens (WO 95/28688) and Woolson (Patent 4,841,975).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted Swaelens alone taught a method of creating a patient-specific instrument (“model”) based on two sets of image data. Swaelens disclosed using a first set (MRI data) to generate a "negative image" of the joint, creating a patient-specific surface that "fits perfectly." Swaelens then added "functional elements," such as saw or drill guides, to this model based on a second set of "additional digital information from outside" that specified the position, direction, and angle for a cut. Petitioner argued this second set of digital information constituted the claimed second image data set. In the alternative, Petitioner argued it would have been obvious to combine Swaelens with Woolson. A POSITA would have used the teachings of Woolson—using x-ray or CT data to determine the mechanical axis and plan cuts—to supply the "additional digital information" in Swaelens, thereby ensuring the guides were properly aligned for a successful surgery.
    • Motivation to Combine: A POSITA would combine Swaelens and Woolson to improve the clinical outcome of the Swaelens procedure. Woolson taught that aligning cuts relative to the mechanical axis was critical for the long-term success of all knee replacement systems. Therefore, a POSITA would be motivated to apply this standard, widely accepted practice to the Swaelens system by using x-ray or CT data (per Woolson) as the second set of image data to ensure the saw guide was properly oriented.
    • Expectation of Success: Success would be expected and predictable, as it involved applying a standard-of-care alignment technique (from Woolson) to a patient-specific instrument creation method (from Swaelens) to ensure the instrument performed its function correctly and safely. For dependent claim 30, using x-ray data specifically would have been obvious, as both Woolson and the general knowledge in the art identified it as a primary tool for determining the mechanical axis.

4. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 29-30 of Patent 8,551,169 as unpatentable under 35 U.S.C. §103.