Oticon Medical Ab v. Cochlear Ltd

1. Case Identification

• Case #: IPR2019-00975
• Patent #: 9,838,807
• Filed: April 15, 2019
• Petitioner(s): Oticon Medical AB; Oticon Medical LLC; William Demant Holding A/S
• Patent Owner(s): Cochlear Limited
• Challenged Claims: 1-12, 14, 16, 17, 25, 28, 33-35, 37-41, 45-47

2. Patent Overview

• Title: Anchoring Fixture for Anchoring a Prosthesis in the Skull Bone
• Brief Description: The ’807 patent discloses a screw-shaped anchoring fixture for securing bone-anchored hearing devices to a patient's skull. The fixture includes a main body for implantation and a flange that acts as a stop to prevent over-penetration of the bone.

3. Grounds for Unpatentability

Ground 1: Obviousness over Westerkull and Choi - Claims 1-12, 14, 16, 25, 28, 33-35, 38, 39, 45, and 46 are obvious over Westerkull in view of Choi.

• Prior Art Relied Upon: Westerkull (Patent 7,116,794) and Choi (Patent 6,981,873).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Westerkull, which relates to an anchoring fixture for a bone-conduction hearing aid, teaches most limitations of the independent claims, including a screw thread apparatus, a flange functioning as a stop, and its configuration for use in the skull behind the ear. However, Petitioner contended Westerkull may lack a "circumferential groove" on the threaded side of the fixture. This alleged deficiency was addressed by Choi, a reference for dental implants. Choi was argued to disclose a series of "minute screwed grooves" on a settling portion of an implant, which functions as the claimed circumferential groove to improve stability, disperse stress into the cortex bone, and prevent bone loss (osteolysis).
  • Motivation to Combine: Petitioner asserted a person of ordinary skill in the art (POSITA) would combine these references because both address the same fundamental problems in the analogous art of bone-anchored fixtures: improving initial stability, promoting long-term osseointegration, and preventing bone loss. A POSITA would have been motivated to incorporate Choi's stability-enhancing grooves into Westerkull's hearing aid fixture to achieve the known benefits of improved bonding and stress distribution, thereby creating a more reliable implant.
  • Expectation of Success: A POSITA would have a reasonable expectation of success because combining these known elements for their intended purposes was a predictable application of established principles in bone implant design.

Ground 2: Obviousness over Westerkull, Choi, and Håkansson - Claim 17 is obvious over the combination of Westerkull, Choi, and Håkansson.

• Prior Art Relied Upon: Westerkull (Patent 7,116,794), Choi (Patent 6,981,873), and Håkansson (WO 98/55049).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground builds on the combination of Westerkull and Choi from Ground 1 to address the limitations of claim 17, which requires a fixture with at least six screw turns starting from the location of maximum screw thread radius. Petitioner argued that the primary combination might be seen as disclosing fewer than six turns. Håkansson, which also discloses a skull bone anchored implant, was introduced because it explicitly teaches a screw with six turns to ensure the implant does not loosen under external force.
  • Motivation to Combine: The motivation was presented as routine design optimization. A POSITA, recognizing that stability is a key biomechanical parameter, would understand that the number of screw threads is a result-effective variable. To improve the stability of the Westerkull/Choi fixture, a POSITA would have found it obvious to increase the number of threads to six, as taught by Håkansson, to achieve the predictable result of a more secure implant.
  • Expectation of Success: A POSITA would expect success in modifying the thread count, as it is a common and predictable design choice in mechanical engineering and implant design to enhance stability.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including:

  • Claims 37 and 47 over Westerkull, Choi, and Westerkull (Patent 7,074,222), where the secondary Westerkull reference was used to teach a specific flange-to-thread diameter ratio (10-20% larger).
  • Claims 28, 40, and 41 over Westerkull, Choi, and Brånemark (WO 2006/065205), where Brånemark was used to teach modifying surface roughness on different parts of the fixture to enhance biocompatibility.

4. Key Claim Construction Positions

• Preamble - "for anchoring a prosthesis to a skull bone": Petitioner argued this preamble phrase should be given no patentable weight. It was contended that the phrase merely states an intended use and does not add any structural limitations to the apparatus, as the body of the claim fully recites the components of the anchoring fixture.
• "circumferential groove": Petitioner proposed this term means "a channel, distinct from the screw thread and distinct from the flange, extending around the cylindrical portion of the main body of the anchor." Critically, Petitioner argued a POSITA would understand from the patent that this groove is configured to exert a radial compressive force on the bone to improve stability upon implantation.
• "means for exerting a compression...": For this means-plus-function limitation in claim 35, Petitioner argued the corresponding structure in the ’807 patent is the second portion of the main body (adjacent to the flange) that has a wider inner diameter than the main screw threads, including the circumferential grooves.

5. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-12, 14, 16, 17, 25, 28, 33-35, 37-41, and 45-47 of the ’807 patent as unpatentable.