PTAB

IPR2020-00265

Medacta USA Inc v. RSB Spine LLC

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1. Case Identification

2. Patent Overview

  • Title: Bone Plate System
  • Brief Description: The ’234 patent describes a bone plate system for surgical arthrodesis (fusion) of adjacent bones, particularly vertebral bodies. The system features a base plate designed to be implanted between bones to retain bone graft material and control limited movement to promote fusion.

3. Grounds for Unpatentability

Ground 1: Obviousness over Michelson ’045 - Claims 35, 37, and 39

  • Prior Art Relied Upon: Michelson ’045 (WO 2000/066045A1).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Michelson ’045, which discloses various interbody spinal fusion implants, teaches every limitation of the challenged claims. Specifically, implant 400 of Michelson ’045 was asserted to be a "base plate" that is sized for an "inter-fit" between vertebral bodies, retains bone graft material, and permits force transmission. For the "means for permitting movement" limitation of claim 35[g], Petitioner contended that while Michelson ’045 shows circular screw holes, it also explicitly teaches a desire to allow for "one degree of freedom" for the vertebrae to settle. Petitioner argued a person of ordinary skill in the art (POSITA) would have found it obvious to modify the disclosed circular holes into vertical slots to achieve this expressly stated function, as slots inherently provide movement in a single direction. Petitioner further mapped features of Michelson ’045's implant to the dependent claims, arguing its structure includes lateral tabs (claim 37) and recessed end portions with screw holes (claim 39).
    • Motivation to Combine (for §103 grounds): As this is a single-reference ground, the motivation was internal to Michelson ’045. Petitioner asserted a POSITA would be motivated to modify the circular holes into slots to directly implement the reference’s own stated goal of allowing vertebral settling with only "one degree of freedom," a result that the disclosed large circular holes would not predictably achieve.
    • Expectation of Success: Petitioner contended that modifying a circular hole into a slot is a simple, elementary design choice, and a POSITA would have had a high expectation of success in achieving the predictable result of controlled, single-axis movement.

Ground 2: Obviousness over Fraser ’106 in view of Michelson ’045 - Claims 35, 37, and 39

  • Prior Art Relied Upon: Fraser ’106 (Patent 6,432,106) and Michelson ’045 (WO 2000/066045A1).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Fraser ’106 is a spinal fixation assembly that discloses a base plate for stabilizing vertebrae for fusion, meeting most limitations of claim 35. Fraser ’106's implant fits between vertebrae, is distinct from bone graft material, and uses bone screws for fixation. However, Petitioner noted that Fraser ’106 discloses locking screws that do not allow for relative movement or settling of the vertebrae. To supply this missing element, Petitioner turned to Michelson ’045.
    • Motivation to Combine: Petitioner asserted a POSITA would combine the Fraser ’106 implant with the teachings of Michelson ’045 for several reasons. First, both references are analogous art, as they address spinal implant devices for fixation and support. Second, Fraser ’106 teaches that its implant has fins to allow for settling, yet its locking screws would prevent this, creating an inconsistency a POSITA would seek to resolve. A POSITA would have looked to known solutions for controlled movement, such as the vertical slots taught in Michelson ’045, to modify Fraser ’106 to permit the desired settling. This combination was framed as a simple substitution of a known element (locking screws) with another known element (screws in slots) to achieve a predictable improvement.
    • Expectation of Success: Petitioner argued there would be a high expectation of success, as modifying the screw holes of the Fraser ’106 plate to incorporate slots is a straightforward mechanical change with predictable effects on implant movement and bone settling.

4. Key Claim Construction Positions

  • "Base Plate": Petitioner proposed construing this term as "a fixation plate...which is distinct from bone graft material...and is not used with a load-bearing fusion cage." This construction relied on a prosecution history disclaimer where the patent owner distinguished prior art (Fraser ’222) by arguing its claims did not cover implants using separate, load-bearing cages. Petitioner argued this disclaimer was clear and unambiguous, thereby limiting the claim scope.
  • "means for permitting movement": For this means-plus-function term in claim 35[g], Petitioner identified the function as "permitting movement of at least one of the first and second bone bodies relative to the base plate." Petitioner asserted the corresponding structure disclosed in the ’234 patent specification is "the bone screw slot 48" and its equivalents. This construction was central to the obviousness arguments, which focused on the implementation or modification of screw holes into slots.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and cancellation of claims 35, 37, and 39 of Patent 6,984,234 as unpatentable.