PTAB

IPR2017-00510

Smith & Nephew Inc v. ConforMIS Inc

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1. Case Identification

2. Patent Overview

  • Title: Patient-Specific Orthopedic Instruments
  • Brief Description: The ’158 patent discloses methods for making a patient-matched surgical tool for joint replacement surgery. The method uses a first set of image data (e.g., CT or MRI) to create a tool with a contact surface that conforms to the patient's joint anatomy, and a second set of image data (e.g., X-ray) to determine a joint axis for orienting a surgical guide on the tool.

3. Grounds for Unpatentability

Ground 1: Obviousness over CAOS, Woolson, and Alexander - Claims 1-3, 5-7, 11-14, 19-28, 30, 31, 33-35, 37-41, 45, 46, 51-56, 58, 59, 61-63, and 65 are obvious over CAOS in combination with Woolson and Alexander.

  • Prior Art Relied Upon: CAOS (a 1998 journal article on computer-assisted orthopedic surgery), Woolson (Patent 4,841,975), and Alexander (WO 00/35346).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the prior art taught every element of the challenged claims. CAOS, a foundational reference, disclosed creating patient-specific "individual templates" for knee surgery. It taught using first image data (CT or MRI) to create a 3D model and then a physical tool with a contact surface that "fit[s] exactly on the bone." CAOS further taught using second image data (topograms, a type of scout image) to identify the "bone axis" and orient the tool's surgical guides relative to that axis. Woolson taught the well-known practice of using second image data (X-ray or CT) to determine a patient's mechanical axis and orient cutting guides perpendicular to it to ensure proper implant alignment. Alexander was cited for its disclosure that imaging techniques like CT and MRI are useful for generating an image of cartilage surfaces, not just bone. Petitioner argued this made it obvious to match the tool's contact surface to cartilage in addition to bone, as taught by CAOS.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine CAOS with Woolson because both address the same problem in knee arthroplasty—accurate implant placement—and recognize that alignment with the mechanical axis is critical for surgical success. A POSITA would have found it a simple design choice to apply Woolson's conventional axis-alignment technique using X-rays to the patient-specific template of CAOS. Combining Alexander was argued to be a predictable modification, as a POSITA would know that a joint surface includes both bone and cartilage, and Alexander taught a known method to visualize cartilage for creating a more comprehensive patient-matched surface.
    • Expectation of Success: A POSITA would have had a high expectation of success. Combining these references involved applying known techniques (axis alignment from X-rays, surface matching from CT scans) for their intended purposes, leading to the predictable result of a precisely fitted and accurately aligned surgical guide.

Ground 2: Obviousness over CAOS, Woolson, Alexander, and Radermacher - Claims 4, 29, 32, 36, 57, 60, and 64 are obvious over the combination of Ground 1 in view of Radermacher.

  • Prior Art Relied Upon: CAOS, Woolson, Alexander, and Radermacher (WO 93/25157).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the primary combination to address claims specifying MRI as the first image data type (claim 4) and the inclusion of linkages or connectors on the surgical tool (e.g., claims 29, 32, 57). Petitioner asserted that while CAOS itself suggests MRI use, Radermacher explicitly disclosed using MRI data to create a patient-matched "individual template" with a surface that "copies the surface of the osseous structure." Radermacher also taught templates with "engagement points" (i.e., linkages or connectors) for attaching additional components, such as separate cutting or drilling guides.
    • Motivation to Combine: A POSITA would combine Radermacher with the core combination because Radermacher (who is also the first-named author of CAOS) addresses the identical technical problem. Modifying CAOS to use MRI as taught by Radermacher would be a simple substitution of one known imaging modality for another. Likewise, adding linkages for modularity was a known design feature for surgical tools, as shown by Radermacher, to increase versatility.

Ground 3: Obviousness over CAOS, Woolson, Alexander, and Chao - Claims 8-10 and 42-44 are obvious over the combination of Ground 1 in view of Chao.

  • Prior Art Relied Upon: CAOS, Woolson, Alexander, and Chao (a 1995 journal article on preoperative planning).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claims requiring the second image data to be from a "standing or weight-bearing x-ray." Petitioner contended this was a well-known technique for improving the accuracy of mechanical axis determination. Chao explicitly taught the use of standing, weight-bearing X-rays of the lower extremity to measure "mechanical axial alignment for preoperative planning of knee osteotomies."
    • Motivation to Combine: A POSITA performing the method of CAOS and Woolson would be motivated to use the specific X-ray technique from Chao to achieve a more accurate measurement of the mechanical axis under realistic load conditions. This modification was presented as the use of a known improvement to one part of an existing process (axis determination) to enhance the overall result, a classic rationale for obviousness.
  • Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground 4) based on the core combination in view of Arima (a 1995 journal article). This ground targeted claims requiring implant positioning based on alternative reference axes, such as the epicondylar or anteroposterior axis, arguing Arima taught these as known, predictable substitutions for the mechanical axis to achieve correct rotational alignment of the implant.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-65 of Patent 7,981,158 as unpatentable.