DCT
1:18-cv-01976
RSB Spine LLC v. Xtant Medical Holdings Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: RSB Spine, LLC (Delaware)
- Defendant: Xtant Medical Holdings, Inc. (Delaware)
- Plaintiff’s Counsel: Morris, Nichols, Arsht & Tunnell LLP
- Case Identification: 1:18-cv-01976, D. Del., 12/13/2018
- Venue Allegations: Venue is alleged to be proper in the District of Delaware on the basis that Defendant is a Delaware corporation.
- Core Dispute: Plaintiff alleges that Defendant’s Irix-A and Irix-C spinal fusion systems infringe two patents related to bone plate stabilization systems and methods for their use.
- Technical Context: The technology concerns interbody spinal fusion devices, which are implants used to stabilize adjacent vertebrae to encourage bone growth and fusion, a common surgical treatment for degenerative disc disease.
- Key Procedural History: The complaint alleges that Plaintiff provided Defendant with notice of infringement of the '537 patent via a letter on July 5, 2018. Subsequent to the filing of this complaint, both asserted patents were challenged in inter partes review (IPR) proceedings filed in December 2019. In decisions issued in January 2023, the Patent Trial and Appeal Board (PTAB) confirmed the patentability of all asserted claims in this case, a factor that may strengthen their presumption of validity.
Case Timeline
| Date | Event |
|---|---|
| 2003-04-21 | Priority Date for U.S. 6,984,234 and U.S. 9,713,537 Patents |
| 2006-01-10 | Issue Date for U.S. 6,984,234 Patent |
| 2017-07-25 | Issue Date for U.S. 9,713,537 Patent |
| 2018-07-05 | Plaintiff sends notice letter to Defendant regarding '537 Patent |
| 2018-12-13 | Complaint Filed |
| 2019-12-13 | IPR proceedings initiated against both asserted patents |
| 2023-01-12 | IPR Certificate issued for U.S. 6,984,234 Patent |
| 2023-01-13 | IPR Certificate issued for U.S. 9,713,537 Patent |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 6,984,234 - "Bone Plate Stabilization System and Method for its Use"
- Patent Identification: U.S. Patent No. 6,984,234, "Bone Plate Stabilization System and Method for its Use," issued January 10, 2006.
The Invention Explained
- Problem Addressed: The patent describes disadvantages of prior art spinal fixation devices, including insecure locking of screws to the plate leading to screw backout, and overly rigid fixation causing "stress shielding," which can prevent proper bone fusion. (’234 Patent, col. 2:5-24).
- The Patented Solution: The invention is a low-profile bone plate system designed to be inserted between adjacent vertebrae. It employs screws inserted at specific, divergent angles to achieve a stronger anchor in the bone. (’234 Patent, Abstract). The system also includes a retaining plate or other means to cover the screw heads, preventing them from backing out, while still allowing for some micromotion that is beneficial for bone healing. (’234 Patent, col. 2:40-60; Fig. 1).
- Technical Importance: This design sought to provide a stable construct that resists screw backout while avoiding stress shielding, thereby addressing key failure modes of earlier spinal fusion systems. (Compl. ¶24).
Key Claims at a Glance
- The complaint asserts independent claims 1 (method), 22 (system), and 35 (system). (Compl. ¶42).
- Claim 1 (Method): Requires the steps of (1) inserting a base plate between bones, (2) introducing a first screw at an angle of about 20° to 60°, (3) introducing a second screw at an angle of about 20° to 70°, and (4) covering the screws to prevent them from backing out.
- Claim 22 (System): Requires (1) a base plate with first and second screw holes angled at about 20°-60° and 20°-70° respectively, (2) first and second bone screws, and (3) a "bone screw retaining means" to cover the screws.
- Claim 35 (System): Requires (1) a base plate sized for an "inter-fit" to retain bone graft material, (2) bone screws to retain the plate, and (3) a "means for...permitting movement" of a bone body relative to the plate, which is a means-plus-function limitation.
U.S. Patent No. 9,713,537 - "Bone Plate Stabilization System and Method For Its Use"
- Patent Identification: U.S. Patent No. 9,713,537, "Bone Plate Stabilization System and Method For Its Use," issued July 25, 2017.
The Invention Explained
- Problem Addressed: The patent addresses similar problems as its parent '234 patent, focusing on providing a stable fixation that supports fusion without the drawbacks of prior systems. (’537 Patent, col. 2:1-31).
- The Patented Solution: The invention is a bone stabilization system with a base plate specifically "configured to fit primarily between anterior portions of adjacent vertebral bones' lip osteophytes." (’537 Patent, Abstract). By anchoring into the lip osteophyte—a dense, strong part of the vertebra—and fitting between them, the plate is designed to bear weight and hold the bones for fusion while sharing the load with the bone graft material. (’537 Patent, col. 4:50-66).
- Technical Importance: This design further refines the interbody plate concept by explicitly leveraging the superior bone quality of the vertebral lip osteophytes for anchoring, aiming to create a more robust and reliable fusion construct. (Compl. ¶24).
Key Claims at a Glance
- The complaint asserts independent claims 1, 15, and 21, all directed to a system. (Compl. ¶68).
- Claim 1 (System): Requires (1) a base plate configured to fit between lip osteophytes, (2) a plurality of bone screws, (3) a first screw hole oriented toward the side surface of the first bone, and (4) a second screw hole oriented toward the lip osteophye of the second bone.
- Claim 15 (System): Requires a base plate configured to fit between lip osteophytes "without covering significant portions of the top surfaces of the bone bodies" and screws that "anchor primarily into the lip osteophytes."
- Claim 21 (System): Requires a base plate with a "first bone engaging region fully extending uninterrupted between lateral extents of the first end" and configured to fit between lip osteophytes.
III. The Accused Instrumentality
Product Identification
- The complaint names the Irix-A™ Lumbar Integrated Fusion System and the Irix-C™ Cervical Integrated Fusion System as the "Accused Products." (Compl. ¶40).
Functionality and Market Context
- The Irix-A™ Lumbar system is described as an implant for the lower spine, consisting of an "integrated titanium ring, surrounded by an outer PEEK ring and three screws." (Compl. ¶36). The complaint provides an image of the Irix-A™ Lumbar Integrated Fusion System, showing a composite PEEK and metal implant with three screws. (Compl. ¶35).
- The Irix-C™ Cervical system is described as a "standalone low-profile anterior cervical integrated fusion system" for the neck, featuring an "integrated endoskeleton, surrounded by an outer PEEK ring and two screws." (Compl. ¶39). It is alleged to include "two locking screws protected by a resilient locking arm mechanism." (Compl. ¶38). An image of the Irix-C™ Cervical Integrated Fusion System is provided, illustrating a two-screw implant with what is described as a locking arm mechanism. (Compl. ¶37).
- Both products are alleged to be used for treating degenerative disc disease by performing spinal fusion. (Compl. ¶36, ¶39).
IV. Analysis of Infringement Allegations
'234 Patent Infringement Allegations
| Claim Element (from Independent Claim 22) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a base plate having bottom surface and first and second ends, the first end comprising a first bone screw region... and the second end comprising a second bone screw region... | The Accused Products include a base plate having first and second ends and respective bone screw regions including bone screw holes extending therethrough. | ¶51 | col. 4:3-9 |
| a first bone screw hole extending therethrough at an angle relative to the bottom surface of the base plate ranging from about 20° to about 60°, and... a second bone screw hole extending therethrough at an angle relative to the bottom surface of the base plate ranging from about 20° to about 70° | A first bone screw hole extends at an angle of 20 to 60 degrees relative to the bottom surface of the base plate and a second bone screw hole extends at an angle from 20 to 70 degrees relative to the bottom surface of the base plate. | ¶51 | col. 6:26-34 |
| a first bone screw capable of securing the base plate to a first bone... and a second bone screw capable of securing the base plate to a second bone | The Accused Products include first and second bone screws capable of securing the base plate to the first and second bones, respectively. | ¶52 | col. 5:10-14 |
| a bone screw retaining means for securedly covering at least a part of the first and second bone screws to prevent the bone screws from backing out | The Accused Products include bone screw retaining means for securedly covering at least part of the first and second bone screws to prevent the bone screws from backing out of the first and second bones. | ¶53 | col. 6:35-41 |
Identified Points of Contention
- Scope Questions: A central question may be whether the composite titanium and PEEK structure of the Accused Products (Compl. ¶36, ¶39) constitutes a "base plate" as the term is used in the ’234 Patent, which depicts a unitary metallic structure. (e.g., ’234 Patent, Fig. 2).
- Technical Questions: Claim 22 requires a "bone screw retaining means." The complaint alleges the Irix-C system's "resilient locking arm mechanism" (Compl. ¶38) meets this limitation. This raises the question of whether this mechanism is structurally and functionally equivalent to the "retaining plate" and "set screw" disclosed in the patent's specification. (’234 Patent, col. 6:35-41).
'537 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a base plate... configured to fit primarily between anterior portions of adjacent vertebral bones' lip osteophytes to bear weight to hold the vertebral bones while sharing weight with bone graft material for fusion | The Accused Products further include base plates configured to fit primarily between anterior portions of adjacent vertebral bones' lip osteophytes to bear weight to hold the vertebral bones while sharing weight with bone graft material for fusion. | ¶72 | ’537 Patent, Abstract |
| a first of the bone screw holes... opens at least partially toward the side surface of a first of the vertebral bones | The Accused Products have a first of the bone screw holes... that extends at least partially from the top surface of a base plate and opens at least partially toward the side surface of a first of the vertebral bones. | ¶74 | ’234 Patent, col. 6:44-50 |
| a second of the bone screw holes... opens at least partially toward the lip osteophyte of a second of the vertebral bones | The Accused Products also have a second of the bone screw holes... that extends at least partially from the top surface of a base plate and opens at least partially toward the lip osteophyte of a second of the vertebral bones. | ¶75 | ’234 Patent, col. 6:50-54 |
Identified Points of Contention
- Scope Questions: Claim 1 requires the plate to fit "primarily between" lip osteophytes, and Claim 15 adds the limitation "without covering significant portions of the top surfaces." These relative terms ("primarily," "significant") are undefined and will likely be key subjects of claim construction.
- Technical Questions: The claims require specific screw trajectories relative to bone anatomy. The infringement analysis will depend on factual evidence of how the Accused Products are implanted and interact with the "side surface" and "lip osteophyte" of the vertebrae during actual use.
V. Key Claim Terms for Construction
The Term: "bone screw retaining means" (’234 Patent, Claim 22)
- Context and Importance: This is a means-plus-function term, so its scope is limited to the corresponding structure disclosed in the specification and its equivalents. Practitioners may focus on this term because the infringement allegation against the Irix-C product's "resilient locking arm mechanism" (Compl. ¶38) will turn on whether that structure is equivalent to the patent's disclosed structure.
- Intrinsic Evidence for Interpretation: The specification explicitly discloses the corresponding structure as a "retaining plate 50" that is fixed in place by a "set screw." (’234 Patent, col. 6:35-41; Figs. 6-7). This defines the literal scope of the term, and any infringement argument against a different structure must prove equivalence.
The Term: "configured to fit primarily between... lip osteophytes" (’537 Patent, Claim 1)
- Context and Importance: The definition of "primarily" is critical, as it dictates the required placement of the device. The dispute will likely focus on how much, if any, of the device can sit outside the space between the lip osteophytes and still meet this limitation.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The term "primarily" suggests the fit does not have to be exclusive or perfect. The specification's general goal is to anchor in the strong osteophyte bone, which could be achieved even with some overlap. (’537 Patent, col. 2:32-54).
- Evidence for a Narrower Interpretation: The abstract states the plate is configured to fit "primarily between" the osteophytes, and figures like Fig. 1 show the plate situated neatly within the inter-vertebral space, suggesting a more constrained, specific fit. (’537 Patent, Abstract; Fig. 1).
VI. Other Allegations
- Indirect Infringement: The complaint alleges both induced and contributory infringement. The basis for inducement is Xtant’s alleged provision of "instruction materials, training, and services" that direct surgeons to use the products in an infringing manner. (Compl. ¶62, ¶91). The basis for contributory infringement is the allegation that the products are a material component specifically made for infringing use and not a staple article of commerce. (Compl. ¶63, ¶93).
- Willful Infringement: Willfulness is alleged for both patents. For the ’537 Patent, the allegation is based on pre-suit knowledge stemming from a July 5, 2018 notice letter. (Compl. ¶96). For the ’234 Patent, the complaint alleges Xtant had knowledge of the patent and its infringement, linking this knowledge to at least the date it received notice regarding the related ’537 Patent. (Compl. ¶61, ¶66).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of definitional scope: can terms of degree, such as "primarily between...lip osteophytes" and "without covering significant portions," be construed with sufficient clarity to determine infringement? The resolution of these qualitative terms will be central to the dispute over the '537 patent.
- A key technical question will be one of structural equivalence: does the accused "resilient locking arm mechanism" constitute an equivalent to the "bone screw retaining means" (i.e., a plate and set screw) disclosed in the '234 patent under the legal standard for means-plus-function claims?
- A key contextual question will be the impact of the IPR proceedings: how will the arguments and evidence presented by the patent owner to successfully defend the validity of the asserted claims before the PTAB be used by the parties to shape claim construction and infringement arguments before the district court?