Expandable Intervertebral Cage with Unilateral Balloon Actuation
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Solution Overview
Problem
Conventional cages between vertebrae lack expandability, leading to difficulties in adjusting paravertebral height post-discectomy, potentially causing dislocation or slippage between vertebrae due to non-parallel surface expansion in existing expandable systems.
Innovation Solution
An expandable cage with a unilateral movement mechanism utilizing a balloon to adjust height, featuring a body with a space, ribs for stability, a moveable part, a balloon for inflation, and a compression element to control movement, ensuring proper fit between vertebrae.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a standard height cage is placed between vertebrae, then the cage can be easily manufactured and installed, but it cannot adjust to varying paravertebral height requirements
Solution Approach 1:
The cage incorporates a moveable part that can shift position within the cage body, transforming a static structure into a dynamic one. This allows the effective height of the cage to be adjusted after implantation by moving the moveable part between different positions, thereby adapting to varying paravertebral height requirements without requiring multiple cage sizes.
Solution Approach 2:
The cage is divided into distinct segments: a body, a moveable part, and a balloon. This segmentation allows the moveable part to be positioned independently within the body, enabling height adjustment while maintaining a relatively simple overall structure. The segmented design facilitates the expansion mechanism without significantly increasing manufacturing complexity.
2Adaptability or versatility
If an expandable system is used to adjust cage height, then paravertebral height can be adjusted, but the expansion causes non-parallel surface movement leading to dislocation or slippage
Solution Approach 1:
The expansion mechanism is designed to be asymmetric in its action: the balloon expands unilaterally to push the moveable part in one direction only, rather than expanding symmetrically from all sides. This unilateral expansion ensures that the parallel surfaces of the cage remain parallel during height adjustment, preventing dislocation or slippage between vertebrae while still achieving the desired height adaptability.
3Length of stationary object
If the cage height is increased to compensate for disc space loss, then paravertebral height is maintained, but the vertebrae may be spaced apart more than needed causing instability
Solution Approach 1:
The dynamic moveable part allows the cage to achieve its full height potential only when needed, rather than being permanently set at maximum height. The moveable part can be positioned to provide exactly the right amount of height compensation required for each patient's specific condition, maintaining paravertebral height while avoiding excessive vertebral spacing that would compromise stability.
4Adaptability or versatility
If a non-expandable cage is used, then the cage structure is simple and reliable, but it cannot compensate for variations in disc space height after discectomy
Solution Approach 1:
The cage is segmented into a body and a moveable part that can be manufactured separately using standard processes. The moveable part is designed to fit within the body and can be positioned at different heights. This segmentation allows both components to be manufactured using relatively simple, standardized processes, while the assembled structure provides the desired adaptability for compensating disc space variations.
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 expandable cage effectively compensates for the opening between vertebrae by allowing controlled unilateral movement of the moveable part, preventing dislocation and ensuring a stable fit between vertebrae, thus maintaining optimal paravertebral height.
Implementation Method 1
at least one balloon (4) which applies the required force to the moveable part (3) such that the moveable part (3) will move unilaterally
Data Source
Figure 1~2
AI summary
The present invention relates to an expandable cage (i) which is placed between the vertebrae, is moveable when preferred, closes the opening between the vertebrae upon being moved, and hence can be integrated in any intervertebral opening; said expandable cage comprising at least one body (2) comprising at least one space (21) and at least one rib (22); at least one moveable part (3) which is located inside the body (2) and has at least one bearing area (31), at least one base (32), and at least one nail (33), said moveable part being moved unilaterally by means of the balloon (4); at least one balloon (4) which applies the force required to be applied on the base (32) of the moveable part (3) for ensuring unilateral movement of the moveable part (3); at least one hole (5) through which the balloon (4) can pass; and at least one compression element (6) which supplies the required fluid to the balloon