Expandable Intervertebral Implant with Segmented Struts
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Solution Overview
Problem
Current intervertebral implants face challenges such as excessive bone removal during insertion, non-uniform engagement with vertebral bodies, and over-distracting the disc space due to fixed heights and surface projections, which can lead to instability and impaired bone growth.
Innovation Solution
An expandable intervertebral implant with a body transitionable between initial and expanded configurations, featuring axial walls with recessed regions or slots, and an expansion member that displaces to outwardly expand the implant, allowing for better conformity with vertebral endplates and reduced height during insertion, while maintaining support and facilitating bone growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If an expandable implant with multiple arms and a wedge is used to expand the implant height, then the implant can achieve expanded configuration, but the wedge occupies significant portion of the inner chamber reducing capacity to receive bone growth inducing material
Solution Approach 1:
The expansion mechanism is divided into multiple struts (first strut, second strut, third strut) that can be independently actuated. Each strut has an expandable portion with articulation joints that allow sequential expansion. This segmentation enables the implant to expand in stages, creating space for bone growth material without requiring a single large wedge to occupy the entire inner chamber.
Solution Approach 2:
The struts are configured to nest within each other during the expansion process. The expandable portions of the struts contain articulation joints and connecting structures that allow one component to be positioned within another during expansion. This nesting arrangement minimizes the space required for the expansion mechanism within the inner chamber while still achieving the desired implant height expansion.
2Reliability
If teeth or surface projections are added to the bearing surfaces to prevent implant migration, then implant stability is improved, but the overall implant height increases requiring over-distraction of the disc space
Solution Approach 1:
The bearing surfaces are configured to transition from a compressed state during insertion to an expanded state after implantation. The expandable portions of the struts allow the bearing surfaces to dynamically adjust their configuration. During insertion, the implant maintains a compact profile; after insertion, expansion provides enhanced bearing surface area and stability without requiring protruding teeth that would increase the initial insertion height.
Solution Approach 2:
Instead of adding height in the vertical dimension through protruding teeth, the invention enhances stability by expanding in the lateral dimension. The struts expand outwardly to increase the footprint and bearing surface area of the implant, providing stability through increased surface area rather than increased height, thereby avoiding over-distriction of the disc space.
3Device complexity
If fixed height implants are used to maintain disc space height, then implant simplicity is maintained, but over-distraction of the disc space occurs during insertion
Solution Approach 1:
The implant transitions from a static fixed-height design to a dynamic expandable design. The struts with articulation joints allow the implant to be inserted in a compressed state at a lower height, then expanded in situ to the target disc space height. This dynamic capability eliminates over-distriction during insertion while maintaining the relatively simple overall structure of the implant body.
4Ease of operation
If threaded implants are used to facilitate insertion into the disc space, then insertion is simplified, but excessive bone removal is required from the vertebral bodies
Solution Approach 1:
The implant uses multiple expandable struts that can be independently actuated and positioned. This segmentation allows the implant to be inserted in a compact configuration without requiring threaded engagement, then expanded after insertion to achieve the desired disc space height and stability, eliminating the need for over-reaming and tapping of the vertebral bodies.
Data Source
AI summary
An expandable intervertebral implant including an implant body transitionable between initial and expanded configurations, and having first and second axial walls spaced apart along a transverse axis with at least one of the walls defining a recessed region when the implant body is in the initial configuration. An expansion member co-acts with the axial wall to transition the implant body to the expanded configuration wherein the recessed region is outwardly expanded generally along the transverse axis. In another embodiment, the expansion member includes a first portion displaced along an axially extending slot formed in one of the walls, and a second portion displaced between the walls to transition the implant body to the expanded configuration. In a further embodiment, the first portion of the expansion member defines a passage extending therethrough having an inner transverse dimension sized larger than an outer transverse dimension of the second portion.