Expandable Interbody Implant With Dual-Screw Spacing and Angulation
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Solution Overview
Problem
Existing expandable interbody devices face limitations in expansion range, instability during expansion, and inadequate load-bearing surfaces, leading to subsidence and undesired shifts in positioning within the intervertebral space, posing challenges in treating spinal disorders.
Innovation Solution
The development of highly adjustable interbody devices that can selectively increase or decrease spacing and angle between endplates, featuring a moving mechanism with set screws and sliding frames to facilitate expansion and contraction, allowing for precise adjustment and stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If expandable interbody devices are used to provide additional spacing capability, then the device can be introduced in a collapsed state and expanded to produce additional spacing, but the devices have limited ranges of expansion
Solution Approach 1:
The interbody device is divided into multiple expandable segments or cells that can be independently or collectively expanded. This segmentation allows the device to achieve a wider overall expansion range while maintaining manageable complexity in each individual segment, resolving the contradiction between expansion range and device complexity.
Solution Approach 2:
The device employs a nested expansion mechanism where smaller expandable elements are contained within larger ones, allowing for multi-stage expansion. This nested structure enables extended expansion ranges while keeping the collapsed profile compact and the overall device structure organized and manageable.
2Strength
If existing interbody devices are used, then they provide static spacing, but they have inadequately-sized load-bearing surfaces leading to subsidence of spinal surfaces
Solution Approach 1:
The device transitions from a static spacing structure to a dynamic expandable structure that can be adjusted post-implantation. This dynamic capability allows the load-bearing surfaces to be expanded in situ, increasing their area and improving load distribution to prevent subsidence, while maintaining the initial compact structure for easy implantation.
Solution Approach 2:
The device allows changing the physical parameters of the load-bearing surfaces by expanding the interbody device after implantation. This parameter change increases the surface area and distributes loads more effectively, preventing subsidence while maintaining the benefits of a compact initial structure.
3Length of moving object
If expandable devices are used to increase spacing, then additional spacing is produced, but the load-bearing surfaces experience significant loads during expansion
Solution Approach 1:
The device is pre-configured with expansion mechanisms and structural support elements that are prepared before implantation. This preliminary preparation ensures that during the expansion process, the load-bearing surfaces are already structured to distribute forces effectively, reducing peak stresses while achieving the required spacing increase.
Solution Approach 2:
The expansion process is designed to be dynamic and controlled, allowing gradual increase in spacing while simultaneously activating load-distribution mechanisms. This dynamic approach ensures that loads are managed throughout the expansion process, preventing excessive stress on any single area while achieving the desired spacing.
4Length of moving object
If existing expandable interbody devices are expanded, then spacing is increased, but the load-bearing surfaces move relative to one another causing instability and undesired shifts in positioning
Solution Approach 1:
The device employs asymmetric locking mechanisms or asymmetric structural features that engage differently on each side during expansion. This asymmetry provides inherent stability by creating interlocking features that prevent relative movement and positional shifts while still allowing the controlled expansion needed to increase spacing.
Solution Approach 2:
The device introduces intermediary elements such as locking mechanisms, guide features, or coupling structures that mediate between the expanding components. These intermediaries ensure that as spacing increases, the load-bearing surfaces remain stable and maintain their relative positioning, preventing undesired shifts during the expansion process.
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 solution provides enhanced stability and adjustability, minimizing subsidence and positioning shifts, while effectively supporting spinal curvature correction and fusion, addressing the limitations of existing devices.
Implementation Method 1
sliding frames to facilitate expansion and contraction
Implementation Method 2
enhanced stability and adjustability, minimizing subsidence
Data Source
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AI summary
Expandable spinal implants, systems and methods are disclosed. An expandable spinal implant may include a first endplate, a second endplate, and a moving mechanism that is operably coupled to the first and second endplates. The moving mechanism may include a wedge, a first sliding frame and a second sliding frame disposed on opposite sides of the wedge, a screw guide housing a rotatable first set screw and a rotatable second set screw opposite the first set screw. The first set screw may be operably coupled to the second sliding frame and the second set screw may be operably coupled to the wedge. The moving mechanism may operably adjust a spacing between the first and second endplates upon simultaneous rotation of the first and second set screws and operably adjust an angle of inclination between the first and second endplates upon translating the first set screw or second set screw.