DCT
2:25-cv-00927
Zehnder Consulting Lnhaber DR Thomas Zehnder v. Highridge Medical LLC
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Zehnder Consulting, Inhaber Dr Thomas Zehnder (Switzerland)
- Defendant: Highridge Medical, LLC (Delaware)
- Plaintiff’s Counsel: Garteiser Honea, PLLC
- Case Identification: 2:25-cv-00927, E.D. Tex., 09/03/2025
- Venue Allegations: Plaintiff alleges venue is proper in the Eastern District of Texas because Defendant maintains a regular and established place of business in the district, both through direct employees, such as a Human Resources Executive located in Allen, Texas, and through authorized "Supplier Agents" over whom Defendant allegedly exercises control.
- Core Dispute: Plaintiff alleges that Defendant’s Tether™ Vertebral Body Tethering System, a non-fusion spinal implant, infringes a patent related to elastic stabilization systems for the vertebral column.
- Technical Context: The technology concerns medical devices for treating spinal deformities like scoliosis, focusing on systems that correct curvature while aiming to preserve motion rather than permanently fusing the vertebrae.
- Key Procedural History: The complaint alleges that Defendant had knowledge of the patent-in-suit as early as 2007, when the patent was cited during the patent prosecution of an application owned by Defendant's predecessor-in-interest, Zimmer Spine, Inc. This allegation forms the basis for the willfulness claim.
Case Timeline
| Date | Event |
|---|---|
| 2002-05-21 | U.S. Patent No. 8,414,618 Priority Date |
| 2007-06-19 | Alleged date of notice via citation in predecessor's patent prosecution |
| 2013-04-09 | U.S. Patent No. 8,414,618 Issues |
| 2025-09-03 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 8,414,618 - "Elastic Stabilization System For Vertebral Columns"
- Patent Identification: U.S. Patent No. 8,414,618, "Elastic Stabilization System For Vertebral Columns," issued April 9, 2013 (’618 Patent).
The Invention Explained
- Problem Addressed: The patent's background section describes the drawbacks of prior art spinal stabilization systems, particularly those that result in "osseous fusion (stiffening) of affected vertebrae" (’618 Patent, col. 1:17-18). It also notes that earlier elastic systems often could not adequately transmit both tensile and compressive forces or were too complex to implant (’618 Patent, col. 1:31-44).
- The Patented Solution: The invention is a vertebral implant system comprising an "elastically bendable connecting element" and multiple bone screws (’618 Patent, Abstract). The key feature is that the connecting element (e.g., a plastic rod) is flexible enough to be passed through the seats of the bone screws "even when the [screws] are not situated on one and the same axis" (’618 Patent, col. 2:37-39; Fig. 2). This accommodates the natural and surgically-created variations in screw placement, simplifying implantation while providing flexible stabilization.
- Technical Importance: The described solution provides a method for stabilizing spinal segments to correct deformities without requiring permanent fusion, which is particularly advantageous for preserving motion in patients (’618 Patent, col. 1:26-29).
Key Claims at a Glance
- The complaint asserts independent claim 1 and reserves the right to assert additional claims (Compl. ¶¶31, 32).
- Essential Elements of Claim 1:
- A vertebral column implant comprising a "connecting element" and a "plurality of bone screws."
- Each screw has a "seat" for the connecting element, which fixes the element in place.
- The connecting element has "bending elasticity" between adjacent vertebrae for "flexible elastic stabilization."
- The connecting element is made of an "elastic material" and is "bendable elastically about every axis of its cross-section" so it can be passed through misaligned screw seats.
- The connecting element stabilizes the vertebral column by "elastic adjustment of... both tensile and compressive forces between successive bone screws."
III. The Accused Instrumentality
Product Identification
- The Tether™ Vertebral Body Tethering System ("Tether System") (Compl. ¶30).
Functionality and Market Context
- The complaint alleges the Tether System is a "non-fusion spinal device intended for treatment of idiopathic scoliosis" (Compl. ¶31). Its operation involves placing "anchors and vertebral body screws" into the vertebral body, to which a "SULENE® polyethylene terephthalate (PET) tensioning cord is secured." This cord is described as providing a "lateral tension band across the convex side of the spine" to correct the curvature (Compl. ¶31). A product image in the complaint shows a flexible cord threaded through the heads of several bone screws implanted along a spinal column (Compl. ¶31, Figure).
IV. Analysis of Infringement Allegations
'618 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A vertebral column implant comprising a connecting element and a plurality of bone screws... | The Tether System, which includes a "SULENE® polyethylene terephthalate (PET) tensioning cord" and "Anchors and vertebral body screws" | ¶¶30, 31 | col. 2:32-35 |
| each of the bone screws having a seat for the connecting element, the seat of the screwhead... fixing the connecting element in the seat... | The PET cord is "secured to the vertebral body screws with set screws to connect the levels of the construct." | ¶31 | col. 3:4-5 |
| the connecting element being made of an elastic material, bendable elastically about every axis of its cross-section in such a way that the connecting element is passed through... the seats... even when the seats are not situated on one and the same axis | The PET cord is a flexible, elastic element that is shown threaded through multiple screws along a curved spinal segment. | ¶31 | col. 2:35-39 |
| the connecting element elastically stabilizing a vertebral column... by elastic adjustment of the connecting element of both tensile and compressive forces between successive bone screws. | The PET cord provides a "lateral tension band across the convex side of the spine that, on insertion and tensioning, partially corrects the curvature." | ¶31 | col. 2:20-24 |
Identified Points of Contention
- Scope Questions: A potential dispute may arise over whether the accused "PET tensioning cord" is equivalent to the "connecting element" described in the patent. The analysis may question whether a flexible cord, which is typically strong in tension but weak against buckling under compression, can meet all the functional and structural requirements of the claimed element.
- Technical Questions: Claim 1 requires the connecting element to stabilize the spine via adjustment of "both tensile and compressive forces." The complaint describes the accused Tether System as providing a "lateral tension band" (Compl. ¶31). This raises the question of what evidence exists that the accused PET cord transmits compressive forces as required by the claim, or if its function is limited to applying tension.
V. Key Claim Terms for Construction
The Term: "connecting element"
- Context and Importance: This term is the central component of the invention. Its construction will determine whether the accused product's flexible "tensioning cord" is within the claim's scope. Practitioners may focus on whether the term implies a certain level of structural rigidity or resistance to buckling.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim language itself is broad, not specifying a particular shape or material beyond being "elastic." The specification refers to the component generally as a "connecting element" (’618 Patent, col. 2:33).
- Evidence for a Narrower Interpretation: The specification states that the connecting element achieves "sufficient... compressive strength, and resistance to buckling to transmit the forces to be expected lastingly and reliably" (’618 Patent, col. 2:28-31). This language may support an interpretation that excludes elements, like a flexible cord, that cannot meaningfully resist compressive forces.
The Term: "elastic adjustment of... both tensile and compressive forces"
- Context and Importance: This functional limitation is a primary point of potential dispute. The infringement analysis depends on whether the accused product's mechanism of action satisfies both the "tensile" and "compressive" requirements.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party could argue that the system as a whole manages both forces, even if the "connecting element" itself primarily handles tension, thereby meeting the limitation.
- Evidence for a Narrower Interpretation: The patent's background criticizes prior art where "the system works only in flexion (tension) but not in extension (compression)" (’618 Patent, col. 1:31-33). This statement suggests the inventors intended to claim an element that is itself capable of actively transmitting both types of forces, potentially narrowing the term's scope to exclude tension-only devices.
VI. Other Allegations
Indirect Infringement
- The complaint alleges induced infringement under 35 U.S.C. § 271(b), asserting that Defendant provides "brochures, manuals, instructional documents, and/or similar materials" that instruct surgeons and other end users on how to use the accused Tether System in an infringing manner (Compl. ¶36).
Willful Infringement
- The complaint alleges willful infringement based on pre-suit knowledge of the ’618 Patent. The specific basis for this allegation is that Defendant's predecessor, Zimmer Spine, Inc., cited the ’618 Patent during its own patent prosecution activities "at least as early as 2007" (Compl. ¶38). The complaint includes a screenshot from a patent database purporting to show this citation history (Compl. ¶38, Figure).
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of technical function: does the accused Tether System's flexible "tensioning cord," described in the complaint as a "tension band," perform the claimed function of elastically adjusting "both tensile and compressive forces," or does a potential limitation to tensile-only operation create a fundamental mismatch with the claim language?
- The case will also likely turn on a question of definitional scope: can the claim term "connecting element," which the patent specification describes as having "resistance to buckling," be construed to read on the accused product's flexible PET cord, or does the intrinsic evidence limit the claim to semi-rigid structures capable of transmitting both tension and compression?