PTAB

IPR2017-00778

Smith & Nephew Inc v. ConforMIS Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Patient-Specific Orthopedic Surgical Tool
  • Brief Description: The ’302 patent describes a patient-specific surgical tool, such as a cutting guide or block, for use in joint replacement surgery. The tool features a surface that is "substantially a negative" of a patient's articular joint surface, created from medical imaging data, and includes at least two drilling holes for guiding surgical instruments.

3. Grounds for Unpatentability

Ground 1: Obviousness over Radermacher, Alexander, and Woolson - Claims 1-3, 5-8, 11, 20-21, 24-25, 28-29, 34-37, and 47 are obvious over Radermacher in view of Alexander and Woolson.

  • Prior Art Relied Upon: Radermacher (International Publication No. WO 93/25157), Alexander (International Publication No. WO 00/35346), and Woolson (Patent 4,841,975).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the core elements of independent claim 1 were well-known in the prior art. Radermacher was asserted to teach creating a patient-specific "individual template" (a block) using MRI or CT data, with a contact surface that is a negative "copy" of the patient's "natural" joint surface for precise placement. Petitioner contended this surface inherently corresponds to the claimed "articular surface," which includes cartilage. To the extent Radermacher was viewed as only mapping bone, Alexander explicitly taught using MRI to image and create detailed 3D reconstructions of articular cartilage for surgical planning. The final key limitation, "first and second drilling holes," was allegedly disclosed by Woolson, which showed a conventional cutting guide with two drill holes corresponding to the common two-pegged implants of the era. Radermacher's primary example showed only one drill hole because it corresponded to an exemplary single-peg implant.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine these references to achieve a predictable result. A POSITA would modify Radermacher’s template to include two drill holes, as taught by Woolson, simply to accommodate the prevalent two-pegged implants, a routine design choice based on the selected hardware. A POSITA would also have been motivated to use Alexander's specific cartilage imaging techniques with Radermacher's template-making process. This combination would create a more accurate guide that fits over the patient’s existing cartilage, simplifying the surgical procedure by eliminating the need to first remove cartilage for the guide to fit, which aligns with Radermacher’s goals of increased accuracy and reduced surgical time.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success, as the combination involved applying a known imaging technique (Alexander) to a known template-creation process (Radermacher) and incorporating a standard feature (Woolson's two drill holes) to work with common implants.

Ground 2: Obviousness over Radermacher, Alexander, Woolson, and Kenna - Claims 13, 18, and 38 are obvious over the combination of Ground 1, further in view of Kenna.

  • Prior Art Relied Upon: Radermacher (WO 93/25157), Alexander (WO 00/35346), Woolson (Patent 4,841,975), and Kenna (Patent 4,646,729).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground specifically addressed claims directed to a tibial surgical tool. Petitioner argued that while Radermacher primarily illustrated a femoral template, its method was described as applicable to any "osseous structure," including the tibia. Kenna was introduced as it explicitly disclosed a "tibial positioning/fixation jig" with two drilling holes for creating holes for implant pegs in the tibial plateau. Therefore, the combination of Radermacher's patient-specific template method with Kenna's tibial-specific guide would render the challenged tibial claims obvious. This ground also asserted that aligning drill holes relative to the mechanical axis (claim 18) was a conventional practice taught by both Woolson and Kenna to ensure long-term implant stability.
    • Motivation to Combine: A POSITA performing a total knee arthroplasty, which routinely involves preparing both the femur and tibia, would have been motivated to apply the patient-specific guide concept from Radermacher to the tibial side of the joint. It would have been a natural and obvious step to combine Radermacher's technique with a conventional tibial guide like Kenna's to achieve the same benefits of improved accuracy and fit that Radermacher taught for the femur. The combination represented using a known technique (patient-specific guides) on a known device (tibial cutting block) for its intended purpose.
    • Expectation of Success: A POSITA would have expected success in creating a patient-specific tibial guide, as it involved applying an established method to a different but analogous anatomical location using standard, well-understood surgical guides and principles.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground 3) against all challenged claims based on Radermacher, Fell (International Publication No. WO 00/59411), Woolson, and Kenna. This ground relied on a similar theory but substituted Fell for Alexander to demonstrate the obviousness of creating a surface negative to the patient's cartilage, as Fell taught using MRI data to create patient-specific meniscal implants that mate with articular cartilage.

4. Relief Requested

  • Petitioner requested the institution of an inter partes review and cancellation of claims 1-3, 5-8, 11, 13, 18, 20-21, 24-25, 28-29, 34-38, and 47 of the ’302 patent as unpatentable.