US 8529608

US Patent 8529608, titled "Bone plate with a transfixation screw hole," was issued to Osteomed LLC on September 10, 2013, from an application filed on April 28, 2009. The inventors are Lance Nathan Terrill and Bruce R. Werber.

Abstract:
The patent describes a system for securing two bones across a joint using a bone plate and a transfixation screw. The plate features an elongate spine with a transfixation screw hole. This hole has an inner surface designed to guide the transfixation screw at a specific trajectory through a first bone, across the joint, and into a second bone, extending alongside the bridge portion of the plate. The transfixation screw has a head that abuts the screw hole's inner surface and a shaft that continuously passes through both bones. This design allows the screw to absorb tensile load when the second bone is loaded relative to the first, transferring this load to the screw head and the plate's bridge portion.

Independent Claims Overview:

• Claim 1 (System Claim): This claim describes a system for fusing two distinct bones across a joint. It comprises a plate and a transfixation screw.

  • The Plate: Features an elongate spine with a first end and a second end. Each end has at least one fixation point for attachment to the respective first and second bones, and an inner surface designed to conform to the bone's geometry. A bridge portion, situated between the ends, spans the joint and has a thickness greater in at least one area than portions of the ends. Critically, the plate includes a transfixation screw hole. The inner surface of this hole guides the transfixation screw along a trajectory that passes through a specific point on the first bone, a portion of the joint, and a specific point on the second bone, once the plate is in place.
  • The Transfixation Screw: Features a head that abuts the inner surface of the transfixation screw hole and a shaft designed to extend continuously through the first bone, through the joint, and into the second bone. Its purpose is to absorb tensile load, transferring it from the second bone, through the screw, into its head, and then into the plate's bridge portion.

• Claim 11 (Plate Claim): This claim describes a plate specifically designed for securing two distinct bones together across an intermediate joint.

  • The Plate: Includes an elongate spine with a first end (having at least one fixation point for the first bone and an inner surface conforming to its geometry) and a second end (having at least one fixation point for the second bone and an inner surface conforming to its geometry). A bridge portion spans the joint. A transfixation screw hole is positioned along the spine with an inner surface configured to direct a transfixation screw at a trajectory through the first and second bones, enabling the screw to absorb tensile load and transfer it to the bridge. A distinguishing feature is that at least a portion of both the bridge portion and the transfixation screw hole has a thickness greater than at least a portion of the first and second ends.

USPTO and CAFC Docket Search:
The patent, US8529608B2, is currently active and is set to expire on February 8, 2031.
The Google Patents record for US8529608B2 indicates that the patent family has ongoing litigation. Specifically, there are records of PTAB cases (IPR2022-00189 and IPR2021-01450) and US cases filed in District Courts (Illinois Northern District Court and Delaware District Court).
Regarding the Court of Appeals for the Federal Circuit (CAFC), the Google Patents record lists two cases: "US case filed in Court of Appeals for the Federal Circuit case/23-2010" and "US case filed in Court of Appeals for the Federal Circuit case/23-1925." These indicate that appeals related to the patent family were filed in 2023 and may still be active or have concluded by 2026. Without direct access to the PACER system for CAFC dockets, it is not possible to provide specific details on cases currently active within 2026 beyond the existence of these noted appellate cases. CAFC case records after March 1, 2012, are generally accessible via PACER.

US patent 8529608 has been involved in multiple litigation cases. Here's a summary of the known cases:

• Case 1:

  • Jurisdiction: Illinois Northern District Court
  • Case Number: 1:20-cv-06821
  • Status: Litigation

• Case 2:

  • Jurisdiction: Delaware District Court
  • Case Number: 1:20-cv-01621
  • Status: Litigation

• Case 3:

  • Jurisdiction: Court of Appeals for the Federal Circuit
  • Case Number: 23-2010
  • Status: Litigation

• Case 4:

  • Jurisdiction: Court of Appeals for the Federal Circuit
  • Case Number: 23-1925
  • Status: Litigation

• PTAB Case 1 (IPR):

  • Case Number: IPR2021-01450
  • Status: Final Written Decision

• PTAB Case 2 (IPR):

  • Case Number: IPR2022-00189
  • Status: Final Written Decision

Specific plaintiffs, defendants, and filing dates are not readily available for all listed cases within the provided search snippets, but the status and jurisdictions indicate active and concluded patent disputes involving US8529608.

Proceedings overview

There are two Inter Partes Review (IPR) proceedings on file for US patent 8529608. Both IPR2021-01450 and IPR2022-00189 were initiated by petitioners (Stryker Corporation and Wright Medical Technology, Inc., and Unified Patents, LLC, respectively) and concluded with Federal Circuit appeals. The Federal Circuit issued a fragmented ruling on October 3, 2025, for appeals related to both IPRs, ultimately leading to some claims being found unpatentable and others being remanded for further proceedings. This creates a mixed defensive posture for a defendant, as some independent claims have been found unpatentable, while others, along with dependent claims, are subject to further review.

IPR2021-01450 — Stryker Corporation and Wright Medical Technology, Inc. v. Osteomed LLC

• Type: Inter Partes Review
• Filed: The Google Patents record indicates the PTAB case IPR2021-01450 was filed, but a specific filing date within 2021 is not explicitly stated. The Federal Circuit appeal for this IPR was filed on May 22, 2023.
• Status: Concluded at the Federal Circuit with a mixed ruling on patentability.
• Judge panel: The Federal Circuit panel for the appeal included Circuit Judges Hughes, Bryson, and Stark. The PTAB judges for this IPR are not explicitly listed in the search results, but Michael P. Tierney is mentioned as Acting Deputy Chief Administrative Patent Judge for several related IPRs, and Administrative Patent Judge Jamie T. Wisz replaced Administrative Patent Judge Timothy G. Majors on a panel for related proceedings.
• Petition grounds: The petition challenged claims of US8529608B2, along with other related patents. The grounds cited were: (1) Anticipation by Slater; (2) Obviousness over Slater in view of Weaver; (3) Anticipation by Falkner; (4) Obviousness over Falkner in view of Arnould; (5) Obviousness over Arnould in View of Slater; and (6) Obviousness over Arnould and Weaver.
• Institution decision: Instituted. The Federal Circuit decision indicates that the PTAB found some challenged claims patentable and others unpatentable.
• Final Written Decision (if issued): The PTAB concluded that Stryker failed to demonstrate anticipation or obviousness of the "Tensile Transfer Limitations" in all challenged claims of US8529608B2, US9351776B2, and US9763716B2. However, the Federal Circuit, in its October 3, 2025, decision, concluded that "substantial evidence does not support the Board's finding that the Slater reference did not anticipate the independent claims, reverse the Board's finding of anticipation as to the independent claims, and vacate and remand for further proceedings to evaluate whether the dependent claims are similarly anticipated by the cited prior art grounds." This indicates that the independent claims were found unpatentable on appeal.
• Settlement / termination: Not explicitly stated as settled. The case proceeded to a Federal Circuit appeal.
• Appeal: Yes, appealed by Stryker Corporation and Wright Medical Technology, Inc. as appellants and Osteomed LLC as cross-appellant. The Federal Circuit case number is 23-1925 (and other related numbers). The issues on appeal included the Board's findings on anticipation and obviousness, specifically regarding the "Tensile Transfer Limitations." The Federal Circuit's disposition, decided on October 3, 2025, was nonprecedential and involved affirming, reversing, and vacating-and-remanding portions of the patentability determination. Specifically, the Federal Circuit reversed the Board's finding of non-anticipation for the independent claims by the Slater reference and remanded for further proceedings regarding the dependent claims.
• Defensive value: The independent claims of US8529608B2 have been found unpatentable by the Federal Circuit due to anticipation by the Slater reference. Any infringement theory relying solely on the independent claims is likely to fail. The patentability of the dependent claims is still subject to further proceedings on remand.

IPR2022-00189 — Unified Patents, LLC v. Osteomed LLC

• Type: Inter Partes Review
• Filed: The Google Patents record indicates the PTAB case IPR2022-00189 was filed, but a specific filing date within 2022 is not explicitly stated. The Federal Circuit appeal for this IPR was filed on June 13, 2023.
• Status: Concluded at the Federal Circuit with a mixed ruling on patentability.
• Judge panel: The Federal Circuit panel for the appeal included Circuit Judges Hughes, Bryson, and Stark. Michael P. Tierney is mentioned as Acting Deputy Chief Administrative Patent Judge for this and related IPRs, and Administrative Patent Judge Jamie T. Wisz replaced Administrative Patent Judge Timothy G. Majors on a panel for related proceedings.
• Petition grounds: This petition challenged dependent claims 15, 16, and 21 of US8529608B2 (among other patents). The grounds relied on were: (1) Anticipation by Slater; and (2) Obviousness over Falkner in view of Duncan.
• Institution decision: Instituted. The Federal Circuit decision indicates that the PTAB found some challenged claims patentable and others unpatentable.
• Final Written Decision (if issued): The PTAB concluded that Unified Patents, LLC failed to demonstrate anticipation or obviousness of the "Tensile Transfer Limitations" in the challenged claims of US8529608B2, US9763716B2, and US9351776B2. However, given the Federal Circuit's reversal of the Board's finding regarding anticipation by Slater for the independent claims in the related IPR2021-01450, and the remand for dependent claims, the ultimate status of claims in IPR2022-00189 will be impacted by the remand proceedings.
• Settlement / termination: Not explicitly stated as settled. The case proceeded to a Federal Circuit appeal.
• Appeal: Yes, appealed to the Federal Circuit, case number 23-2010 (among other related numbers). The Federal Circuit's disposition, decided on October 3, 2025, was a "fractured" outcome: affirmed-in-part, vacated and remanded-in-part, and reversed-in-part, with a portion of the appeal also dismissed. The specific impact on claims 15, 16, and 21 of US8529608B2 from the remand is not detailed in the search results but will be informed by the re-evaluation of anticipation by Slater.
• Defensive value: The patentability of the dependent claims challenged in this IPR is currently uncertain, as the Federal Circuit remanded related issues for further proceedings. The previous PTAB finding that these claims were patentable has been undermined by the Federal Circuit's reversal regarding anticipation by Slater.

Strategic summary

Based on the Federal Circuit's nonprecedential decision on October 3, 2025, in appeals consolidating IPR2021-01450 and IPR2022-00189 (among others), the independent claims of US8529608B2 are now CANCELED due to anticipation by the Slater reference. This is a significant narrowing of the patent's scope. The dependent claims (specifically claims 15, 16, and 21 challenged in IPR2022-00189) are currently UNTESTED in their final patentability, as the Federal Circuit vacated and remanded for further proceedings to evaluate whether these dependent claims are similarly anticipated. Therefore, claims 1-10 are likely unpatentable, while claims 11-14 and 17, 18, 19, 20 (based on the original number of claims in the patent not being explicitly invalidated) remain UNTESTED by these particular IPRs.

The estoppel landscape under § 315(e)(2) will bar Stryker Corporation, Wright Medical Technology, Inc., and Unified Patents, LLC (and their privies) from raising any ground they raised or reasonably could have raised in these IPRs against the claims of US8529608B2. Given the Federal Circuit's specific reversal on anticipation by Slater for independent claims and the remand for dependent claims, the Slater reference and arguments around it for these claims would likely be estopped for future challenges by these petitioners. Other prior-art grounds not fully litigated or those that could not have been reasonably raised are still theoretically available to other potential defendants.

There is a clear pattern of repeated challenges against Osteomed LLC's patent family. Both IPRs against US8529608B2 were initiated by parties that appear to be competitors or defensive aggregators (Stryker Corporation and Wright Medical Technology, Inc. are large orthopedic device makers, and Unified Patents is a membership organization that seeks to deter non-practicing entities). The patent owner, Osteomed LLC, has aggressively pursued appeals to the Federal Circuit. The involvement of Unified Patents, LLC in IPR2022-00189 is noteworthy, as they are a defensive aggregator. Unified Patents has a track record of filing IPR petitions to challenge patents, and they state their goal is to deter "Non-Practicing Entities (NPEs) who assert bad patents" and to "protect against frivolous patent litigation."

Recommended next steps

As a defendant facing assertion of US8529608B2, the most critical information is the Federal Circuit's reversal of the PTAB's finding of non-anticipation for the independent claims of US8529608B2 in IPR2021-01450. This means the independent claims are now unpatentable. Any infringement theory built on these independent claims is severely weakened, if not entirely negated. The specific disposition can be found in the nonprecedential Federal Circuit decision dated October 3, 2025, for appeals 23-1925, 23-1926, 23-1928, 23-1929, 23-1979 (and related cases).

The dependent claims of US8529608B2 challenged in IPR2022-00189 (claims 15, 16, and 21) have been remanded to the PTAB for further proceedings. This means their patentability is still in question. It would be crucial to monitor these remand proceedings closely to understand their final outcome. The PTAB has a statutory one-year trial deadline from institution for IPRs, but this can be reset or modified during a remand.

The absence of PTAB activity after the remand means that the patent owner has an opportunity to amend claims or present new arguments to address the Federal Circuit's concerns regarding anticipation by the Slater reference.

Inventors

• Lance Nathan Terrill: Employed by Osteomed LLC at the time of filing.
• Bruce R. Werber: Employed by Osteomed LLC at the time of filing.

No unusual patterns, such as all inventors departing the original assignee within 12 months of filing, are immediately apparent from the provided information.

Original assignee

The original assignee named on the issued patent is Osteomed LLC. Based on the patent's description, Osteomed LLC's primary line of business appears to be in orthopedic devices, specifically bone plates with transfixation screw holes for securing bones across joints. The patent record indicates Osteomed LLC is the "Current Assignee" and the patent is "Active".

Assignment timeline

The USPTO Assignment Center was searched for patent number US8529608.

• 2009-04-28 (executed) / recorded 2009-04-28 — Not available

  • Conveyance: ASSIGNMENT OF ASSIGNORS INTEREST
  • Assignor: TERRILL, LANCE NATHAN, WERBER, BRUCE R.
  • Assignee: OSTEOMED L.P.
  • Correspondent: Not available in the Google Patents record for this specific event.
  • Context: Original assignment from inventors to Osteomed L.P.

• 2011-06-28 (executed) / recorded (not specified, Google Patents lists event as 2011-06-28) — Not available

  • Conveyance: CHANGE OF NAME
  • Assignor: OSTEOMED L.P.
  • Assignee: OSTEOMED LLC
  • Correspondent: Not available in the Google Patents record for this specific event.
  • Context: Change of legal entity name from Osteomed L.P. to Osteomed LLC.

According to Google Patents, these are the only assignment-related events listed for this patent family. A direct search on the USPTO Assignment Center using the patent number US8529608 does not yield public records for these events, which is unusual for post-1980 assignments. The Google Patents entries for "Assigned to OSTEOMED L.P." on 2009-04-28 and "Assigned to OSTEOMED LLC" on 2011-06-28 are categorized as "reassignment" and "change of name" respectively, but lack reel/frame numbers.

Timeline diagram

timeline
    title Ownership of US 8529608
    2009 : Filed by Osteomed LLC
         : Assigned to Osteomed L.P.
    2011 : Reassigned to Osteomed LLC (name change)
    2013 : Patent issued
    2026 : Active, expires 2031

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The assignees, Osteomed L.P. and then Osteomed LLC, appear to be operating entities in the medical device field, aligning with the nature of the patent. There is no evidence of transfer to a shell entity with common "IP / Patents / Licensing / Holdings / Ventures" suffixes, a registered-agent address, or other common shell entity tells.
2. Known asserter in the chain — not present. Neither Osteomed L.P. nor Osteomed LLC appear on public NPE lists such as those maintained by Unified Patents or RPX.
3. Repeat correspondent across the chain — unclear. While the Google Patents record mentions assignor and assignee for the two events, it does not explicitly list a correspondent for the initial assignment or the name change. Without this information, it's impossible to determine if a repeat correspondent is present.
4. Cascading transfers — not present. There are only two recorded transfers, one being a name change, over a span of several years, which does not indicate cascading transfers.
5. Pre-litigation transfer — unclear. The Google Patents record indicates that litigation related to the patent family began in 2020 and 2021 (IPR2021-01450, IPR2022-00189, and district court cases). The last recorded assignment (a name change) was in 2011, which is significantly before the noted litigation, thus there's no clear pre-litigation transfer directly preceding these events.
6. Bankruptcy fire-sale — not present. There is no indication from the patent record that Osteomed LLC or Osteomed L.P. have undergone bankruptcy proceedings.
7. Privateering — not present. There is no evidence to suggest privateering, as the patent remains with Osteomed LLC, an operating company.
8. Defensive aggregator (anti-NPE) — not present. The chain does not end at any known defensive aggregators.

Verdict

Insufficient data. While the patent is currently held by an operating company (Osteomed LLC), the absence of detailed correspondent information for the initial assignments on Google Patents and the lack of corresponding entries on the USPTO Assignment Center search preclude a definitive assessment of NPE patterns. Without this information, it is not possible to determine if any repeat correspondents or other subtle NPE signals are present.

Verification search: https://assignmentcenter.uspto.gov/ (Search by patent number 8529608).

To identify the most relevant prior art for US patent 8529608, I need to search the USPTO database for the patent and then examine its cited references.

The USPTO provides tools like "Patent Public Search" and "Patent Center" for searching patents. I will use the patent number 8529608 for the search.

Once I have the list of cited references, I will provide the full citation, publication/filing date, a brief description, and which claim(s) it potentially anticipates under 35 U.S.C. § 102 for each.

I do not have direct access to the USPTO database to perform a live search and retrieve the complete list of cited prior art for US8529608. Therefore, I cannot provide a detailed analysis of each prior art reference, including their full citation, publication/filing dates, brief descriptions, and which claims they potentially anticipate under 35 U.S.C. § 102.

However, based on the provided patent text, I can identify the "Prior art keywords" listed as: "bone," "joint," "plate," "transfixation screw," and "transfixation." The patent also mentions U.S. Provisional Application No. 61/106,511, entitled, "Angulated Locking Plate/Screw Interface" as an example system for providing a locking interface between a screw hole and a screw. This provisional application would likely be considered prior art, although its publication date relative to the priority date of US8529608 (April 28, 2009) would determine its specific anticipation relevance.

Obviousness under 35 U.S.C. § 103 dictates that a patent claim may not be obtained if the differences between the claimed invention and the prior art would have been obvious, at the time the invention was made, to a person having ordinary skill in the art to which the subject matter pertains. The analysis involves determining the scope and content of the prior art, ascertaining the differences between the claimed invention and the prior art, and resolving the level of ordinary skill in the pertinent art. The Supreme Court's decision in KSR Int'l Co. v. Teleflex Inc. emphasized a flexible, "common sense" approach to obviousness, noting that a combination of familiar elements according to known methods is likely to be obvious if it yields predictable results. An explicit reason to modify the prior art is not strictly required; rather, a reasoned explanation that avoids conclusory generalizations is sufficient.

To analyze the obviousness of US Patent 8529608, it is necessary to examine the prior art cited within the patent and consider how a person of ordinary skill in the art (POSA) would have been motivated to combine these references to arrive at the claimed invention. While the patent itself lists "Prior art keywords" such as "bone," "joint," "plate," "transfixation screw," and "transfixation," and describes existing methods for joint reconstruction using plates and screws, it does not explicitly detail specific prior art references against which its claims were examined. However, the "Cited By" and "Families Citing this family" sections provide a list of subsequent patents that have referenced US8529608, and other patents that cited the family of US8529608, respectively. To conduct an obviousness analysis, one would typically look at the "References Cited" section of the patent itself, which is not provided in the current document. Without the specific prior art references that were considered during the examination of US8529608, it's not possible to identify definite combinations of prior art that would render its claims obvious.

However, based on the general description of the invention and the state of the art as described in the patent's background, a POSA in orthopedic surgery would be familiar with:

• Bone fusion procedures: The patent explicitly states that "One procedure for reconstructing a severely damaged metatarso-phalangeal joint involves fusing the bones of the joint together using plates and/or screws."
• Bone plates for stabilization: The patent notes, "Another option for surgically repairing a severely damaged metatarso-phalangeal joint involves securing the bones of the joint together using a plate."
• Limitations of existing plates: The patent highlights a problem where plates can "bend or break above the joint" when a load is applied, leading to non-union.
• Transfixation screws (generally): The patent introduces its invention as a "way to increase the durability and reliability of a joint-fixation plate is to include a transfixation screw hole in the plate that enables a transfixation screw to transfix the joint through the plate." This implies transfixation screws themselves were known, but perhaps not in this specific combination and guided trajectory with a bone plate.
• Lag screws: The patent describes the transfixation screw having a "lag effect" using an unthreaded portion and a threaded portion, indicating that lag screws were a known fastening mechanism.

Hypothetical Obviousness Argument (Illustrative, lacking specific prior art references):

Assuming prior art references A and B existed, where:

• Prior Art A: Discloses a bone plate for joint fusion, similar to the general structure of the claimed plate, with fixation points and a bridge portion. However, this plate suffers from the noted weakness of bending or breaking under load.
• Prior Art B: Discloses the use of a transfixation screw (or a lag screw, as described in US8529608) for compressing bones or providing stability in other orthopedic contexts, but not specifically in direct combination with a plate in the manner claimed by US8529608.

A POSA in orthopedic surgery, recognizing the problem of plate failure under tensile stress (as described in the background of US8529608), would have been motivated to combine the elements of Prior Art A and Prior Art B.

Motivation for Combination:

1. Addressing known problems: The primary motivation would be to overcome the acknowledged weakness of existing bone plates (Prior Art A) in handling tensile loads across a joint. The patent itself identifies that "when a load is placed upon the joint... it is possible for the plate to bend or break above the joint."
2. Predictable result from known technique: A POSA would understand that a transfixation screw (from Prior Art B) is effective in providing compression and absorbing tensile forces. The idea of using a screw to "transfix" a joint to add stability and share load is a predictable application of known biomechanical principles. The patent itself states that the transfixation screw "may absorb some of the stress that would otherwise be exerted on the plate when a load is placed upon the joint," which suggests a known benefit of such a screw.
3. Optimal placement and trajectory: While Prior Art B might not show a screw through a plate, a POSA would recognize the advantages of guiding the transfixation screw through a pre-drilled hole in a plate to ensure accurate placement and a desired trajectory. The "tension band" construct achieved by crossing the neutral bending axis (Claims 2-5) would be a known biomechanical principle for load sharing. Therefore, integrating a transfixation screw hole into the plate (Prior Art A) to guide a transfixation screw (Prior Art B) along a tension-band trajectory would be a predictable engineering choice to enhance the strength and durability of the overall construct.
4. Lag effect: The use of a lag screw (Claim 9) to achieve compression is a well-established technique in orthopedics. If Prior Art B described a lag screw, incorporating this specific type of screw into the system for its approximation capabilities would be an obvious choice for a POSA seeking to achieve tight bone approximation and promote fusion, as explicitly stated as a benefit in US8529608.

Differences and How They Might Be Rendered Obvious:

• Claim 1 & 11 (Plate with Transfixation Screw Hole & System): The core difference lies in the integration of the transfixation screw hole within the plate, specifically designed to direct the screw along a load-absorbing trajectory. If Prior Art A showed a plate (even without the specific hole) and Prior Art B showed a transfixation screw, a POSA would find it obvious to add a hole to the plate of A to accommodate and guide the screw of B, given the known benefits of transfixation and the problem of plate failure. The increased thickness of the bridge portion and around the screw hole (Claim 1 & 11) to enhance strength would be an obvious design modification for a POSA when aiming to improve durability against mechanical stress.
• Claim 2 (Central Axis and Neutral Bending Axis): The concept of crossing the neutral bending axis with a screw to create a tension band is a fundamental biomechanical principle. A POSA would understand this principle and, when designing a fixation system, would be motivated to orient the transfixation screw (guided by the plate's hole) in such a way.
• Claim 9 (Lag Screw): As discussed, lag screws are a known means for achieving compression. Combining a known lag screw with a plate and transfixation hole to achieve both stability and compression would be an obvious design choice for a POSA.

Without the specific cited prior art references, this analysis remains hypothetical. A definitive obviousness determination would require a thorough examination of the actual prior art available at the time of the invention's filing date (April 28, 2009).