Expandable Interbody Spacer Maintains Length During Height Adjustment
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Solution Overview
Problem
Existing expandable interbody spacers for spinal implants increase in length when transitioning from a low-profile to a high-profile configuration, which can lead to neural impingement and require repositioning, complicating surgical procedures and potentially causing tissue damage.
Innovation Solution
An expandable interbody spacer design featuring a housing with endplates that expand uniformly in height without changing length, utilizing a locking screw mechanism that rotates to move the actuator and endplates simultaneously into a high-profile configuration, maintaining the same footprint and preventing longitudinal growth, thus avoiding neural impingement and simplifying surgical placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If expandable spacers are used to provide adjustable height, then ease of operation and adaptability are improved, but the spacer increases in length when expanded which may require removal of more existing disc and repositioning
Solution Approach 1:
The patent transitions the expansion from longitudinal dimension to vertical dimension. The actuator moves vertically within the housing to elevate the endplates, maintaining constant longitudinal length while achieving height adjustment. This dimensional change resolves the contradiction by providing adaptability without increasing length.
Solution Approach 2:
The patent employs a dynamic actuator mechanism that can be adjusted to different vertical positions within the housing. The actuator includes an adjustable arm that can be positioned at multiple heights, allowing the endplates to be elevated to different levels while maintaining the same longitudinal footprint, thus providing adaptability without length increase.
2Device complexity
If expandable spacers are used to avoid stocking multiple sizes, then device complexity is reduced, but the spacer increases in length which complicates surgical placement
Solution Approach 1:
The patent resolves the surgical placement complexity by changing the expansion dimension from longitudinal to vertical. The actuator elevates endplates vertically within the housing, maintaining constant longitudinal length. This eliminates the need for repositioning during surgery and simplifies placement procedures while still providing size adjustability.
Solution Approach 2:
The dynamic actuator mechanism allows for post-insertion adjustment of spacer height without requiring removal or repositioning of the device. The adjustable arm can be positioned at different vertical levels after insertion, providing size customization while maintaining the same longitudinal footprint and simplifying surgical placement.
3Ease of operation
If the actuator is allowed to rotate freely, then ease of operation is improved, but the locking screw would translate longitudinally causing length change
Solution Approach 1:
The patent extracts the translational movement component from the actuator's rotation. The actuator is constrained to rotate about a fixed longitudinal axis without translating longitudinally. This separation allows free rotation for ease of operation while preventing longitudinal translation that would change spacer length.
Solution Approach 2:
Instead of allowing the actuator to translate longitudinally during rotation, the patent inverts the mechanism by constraining rotation to a fixed axis and achieving height adjustment through vertical movement of the endplates. This inversion maintains constant length while preserving operational ease through the adjustable mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The spacer facilitates easier implantation and positioning, maintains anatomical stability, and prevents tissue impingement by maintaining the same length and footprint before and after expansion, enhancing surgical efficiency and patient outcomes.
Implementation Method 1
The actuator includes a threaded opening formed in the proximal wall that is aligned with the rear opening of the housing. A locking screw is provided that is threadingly connected to the threaded opening of the actuator. Rotation of the locking screw in a first direction translates the actuator in a proximal direction relative to the housing
Data Source
AI summary
An expandable interbody spacer for the spine is provided. The interbody spacer includes a housing, a top endplate and a bottom endplate. An actuator is located inside the housing between the top and bottom endplates. A locking screw is configured to drive the actuator and move the endplates between collapsed and expanded configurations. Variations of the expandable spacer are provided in which the endplates move bilaterally outwardly into uniform and parallel expansion along the latitudinal axis, the endplates angulate about a pivot point along a longitudinal axis such that the distal end of the spacer increases in height relative to the proximal end, and the endplates angulate about a pivot along a lateral axis such that the height along one lateral side of the spacer increases in height relative to the other lateral side.