Expandable Interbody Implant Wedge Mechanism
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Solution Overview
Problem
Current spinal disorder treatments, such as fusion and implantable prosthetics, often require significant bone removal and may not adequately address nerve compression and sagittal balance, limiting their effectiveness in relieving pain and restoring mobility.
Innovation Solution
An expandable interbody implant system that can be inserted at various angles and expanded to increase the intervertebral disc space, featuring a wedge mechanism with ramps on endplates that allows for incremental deployment to restore sagittal balance and decompress nerves, while minimizing bone removal during surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fusion and implantable prosthetics are used, then spinal stabilization is achieved, but significant bone removal is required and nerve compression and sagittal balance are not adequately addressed
Solution Approach 1:
The implant includes an expandable cage with a movable wedge that can be adjusted post-insertion to change the expansion distance between endplates. This dynamic adjustment capability allows the implant to adapt to different spinal conditions and achieve proper sagittal balance without requiring extensive pre-surgical bone removal, as the final positioning can be optimized after the implant is in place
Solution Approach 2:
The implant allows modification of geometric parameters (expansion distance, angulation) after insertion. The wedge can be repositioned along the ramps to change the expansion distance, and the inserter can be articulated to different angles during insertion. This parameter adjustability enables the same implant to address varied spinal pathologies without requiring different implant sizes or extensive bone removal
2Strength
If traditional implants are used, then spinal support is provided, but nerve compression and sagittal balance are not adequately addressed
Solution Approach 1:
The expandable cage with adjustable wedge provides dynamic adaptation capability. After insertion, the wedge can be moved to different positions on the ramps to change the expansion distance, allowing the implant to adequately address nerve compression by expanding to the required degree and to restore sagittal balance by adjusting the lordotic angle, while maintaining strong spinal support
Solution Approach 2:
The single implant design integrates multiple functions: spinal support through the endplates and structure, nerve decompression through adjustable expansion distance, and sagittal balance restoration through adjustable angulation. The ramps and wedge mechanism enable the same implant to perform all three functions by varying the expansion parameters, eliminating the need for multiple specialized implants
3Adaptability or versatility
If expandable implant with wedge mechanism is used, then adjustable expansion and sagittal balance restoration are achieved, but device complexity increases
Solution Approach 1:
The wedge is positioned within the expandable cage structure, nested between the endplates. The ramps are integrated into the endplate surfaces, and the wedge slides along these embedded ramps. This nested arrangement allows the adjustment mechanism to be contained within the implant footprint without requiring additional external components, reducing overall device complexity while maintaining adjustability
Solution Approach 2:
The ramps act as an intermediary mechanism between the wedge and the endplates. Instead of requiring complex motorized or robotic adjustment systems, the simple ramp-wedge interface provides mechanical advantage for expanding the cage. The ramps translate linear wedge movement into radial expansion of the cage, simplifying the adjustment mechanism while enabling precise control over expansion distance and angulation
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 system provides effective fusion, decompression, and sagittal balance restoration with reduced bone removal, enhancing pain relief and mobility by allowing continuous angulation and adjustable expansion to fit different spinal conditions.
Implementation Method 1
ramps configured to reduce friction as the wedge translates relative to the endplates
Data Source
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AI summary
A device includes an upper endplate having an engagement surface, an inner surface and first projections extending from the inner surface. The first projections each include a first inclined surface. A lower endplate includes an engagement surface, an inner surface and second projections extending from the inner surface. The second projections each include a second inclined surface. A wedge is positioned between the endplates. The wedge includes first mating parts that engage the first inclined surfaces and second mating parts that engage the second inclined surfaces. The wedge is movable relative to the endplates to move the device between a first configuration having a first height between the engagement surfaces and a second configuration having an increased second height between the engagement surfaces. Methods of use are disclosed.