PTAB

IPR2017-00779

Smith & Nephew Inc v. ConforMIS Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Patient-Specific Surgical Cutting Guides
  • Brief Description: The ’302 patent relates to patient-specific surgical tools, or "cutting guides," for use in joint repair surgery. The tools feature a surface that is "substantially a negative" of a patient's articular surface, created from imaging data, and include multiple drilling holes to guide surgical instruments.

3. Grounds for Unpatentability

Ground 1: Obviousness over Radermacher, Alexander, and Woolson - Claims 9-10, 12, 30-33, and 39-43 are obvious over Radermacher in view of Alexander and Woolson.

  • Prior Art Relied Upon: Radermacher (WO 93/25157), Alexander (WO 00/35346), and Woolson (Patent 4,841,975).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of references teaches all limitations of the challenged claims, which depend from independent claim 1.
      • Radermacher taught creating a patient-specific "individual template" for joint surgery using MRI or CT scan data. This template included a "contact face" that was a negative copy of the patient’s osseous (bony) structure to ensure a unique fit. It also disclosed using guides, such as a single drill hole, for surgical tools.
      • Alexander taught using MRI to specifically obtain detailed three-dimensional images of a patient's articular cartilage to assess its condition, separate from the underlying bone.
      • Woolson taught a "conventional cutting guide" for knee surgery that included two drilling holes, corresponding to the two pegs on a standard femoral prosthesis.
    • Motivation to Combine (for §103 grounds): A person of ordinary skill in the art (POSITA) would combine Radermacher and Woolson because the number of drill holes in a cutting guide was a simple design choice dependent on the implant being used. Since two-peg implants and corresponding two-hole guides (per Woolson) were commonplace, it would have been obvious to modify Radermacher’s single-hole example to a two-hole version for use with such implants. A POSITA would combine Radermacher with Alexander to create a template that fits the patient’s cartilage surface, not just the bone. This would simplify surgery by eliminating the need to first remove cartilage before placing the guide, a predictable improvement consistent with Radermacher's goal of increasing surgical accuracy.
    • Expectation of Success (for §103 grounds): A POSITA would have had a reasonable expectation of success, as the combination involved applying a known imaging technique (Alexander) to a known surgical guide system (Radermacher) and incorporating a standard design feature (Woolson's dual drill holes).

Ground 2: Obviousness over Radermacher, Alexander, Woolson, Kenna, and Hofmann - Claims 14-17 and 19 are obvious over Radermacher, Alexander, and Woolson in view of Kenna and Hofmann.

  • Prior Art Relied Upon: Radermacher (WO 93/25157), Alexander (WO 00/35346), Woolson (Patent 4,841,975), Kenna (Patent 4,646,729), and Hofmann (a 1991 journal article).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claims dependent on claim 13, which specifies that the guide is for a tibial surface and that drilling holes define a path through the tibial plateau at a predetermined slope. Petitioner asserted that it was obvious to apply Radermacher's patient-specific guide concept to the tibia, as the reference stated its technique could be used for any osseous structure.
      • Kenna taught a conventional tibial cutting jig secured by drilling pins horizontally through the tibial plateau.
      • Hofmann taught the benefits of resecting the tibia at a specific posterior slope (parallel to the normal slope, between 0 and 7 degrees) to improve the strength and stability of the knee replacement.
    • Motivation to Combine (for §103 grounds): A POSITA would combine the primary references with Kenna and Hofmann to create a patient-specific tibial guide. The motivation was to apply Radermacher's superior patient-specific fitting technology to the tibia, a standard part of knee arthroplasty, and incorporate common fixation techniques (Kenna) and optimal, clinically-proven cutting angles (Hofmann) to improve the procedure. Orienting Kenna's pin holes parallel to Hofmann's recommended tibial resection cut would be an obvious modification to prevent interference, thereby achieving the claimed predetermined slope.
    • Expectation of Success (for §103 grounds): Success was predictable, as it involved adapting a known guide technology to a different but analogous bone and incorporating well-established surgical cutting and fixation principles to achieve known benefits.

Ground 3: Obviousness over Radermacher, Fell, Kenna, Hofmann, and Woolson - Claims 9-10, 12, 14-17, 19, 30-33, and 39-43 are obvious over Radermacher in view of Fell, Kenna, Hofmann, and Woolson.

  • Prior Art Relied Upon: Radermacher (WO 93/25157), Fell (WO 00/59411), Kenna (Patent 4,646,729), Hofmann (a 1991 journal article), and Woolson (Patent 4,841,975).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground was similar to the others but substituted Fell for Alexander to demonstrate the obviousness of creating a guide surface that is a negative of the articular cartilage.
      • Fell taught creating a patient-specific meniscal implant (which replaces cartilage) by using MRI to map the contours of the patient's femoral and tibial surfaces, including the articular cartilage.
    • Motivation to Combine (for §103 grounds): Petitioner argued that Radermacher itself provided the motivation by stating that surgical procedures were "lagging behind the technology of implant manufacture." A POSITA, spurred by this, would look to advanced patient-specific implant technology like that in Fell and adapt its cartilage-mapping techniques to Radermacher's surgical guides. This would create a guide that fits the natural, unprepared joint surface, simplifying the surgery. The other references were combined for the same reasons as in Grounds 1 and 2.
    • Expectation of Success (for §103 grounds): The combination of known elements from the same field of endeavor (knee surgery) to achieve the predictable result of a better-fitting surgical guide would have been expected to succeed.

4. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 9-10, 12, 14-17, 19, 30-33, and 39-43 of Patent 8,062,302 as unpatentable.