Expandable Cage Graft Distribution for Low-Trauma Spinal Fusion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fusion cage systems fail to effectively distribute bone graft material throughout the intervertebral space, leading to premature failure due to unfilled pockets, difficulty in insertion and positioning, increased patient trauma, and potential backout through large annulotomy openings.
Innovation Solution
A laterovertically-expanding frame system with a central beam and interconnected beams that expand laterally and vertically, allowing for uniform distribution of bone graft material, minimizing voids, and preventing backout, while maintaining a low-profile insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional fusion cages are designed to be oversized relative to the disc space to distract the disc space, then the disc space can be distracted, but it becomes difficult to insert and position properly
Solution Approach 1:
The cage is designed with expandable beams that can be compressed during insertion and then expanded to the predetermined configuration within the disc space. This dynamic transformation allows the cage to be inserted in a compact state and then achieve its full distraction capability after placement, resolving the contradiction between insertion ease and distraction strength.
Solution Approach 2:
The expandable beams are configured to be nested or collapsed into a compact form that fits within the delivery system for insertion. Once positioned, the beams are deployed to their expanded configuration to provide the necessary disc space distraction. This nesting principle allows the cage to transition from a small insertable form to a large functional form.
2Ease of operation
If new fusion cages are designed to be inserted at a low height and expanded vertically, then insertion becomes easier, but they create pockets in the intervertebral space that are not filled with bone graft material
Solution Approach 1:
The cage incorporates a porous bone graft receptacle that allows bone graft material to be distributed throughout the intervertebral space. The porous structure enables uniform graft distribution while eliminating pockets, ensuring complete filling of the space and maintaining fusion reliability.
Solution Approach 2:
The cage serves multiple functions: it provides structural support for disc space distraction, facilitates easy insertion through low-height design, and enables uniform bone graft distribution through its porous receptacle. This multi-functionality resolves the contradiction by combining insertion ease with fusion reliability.
3Stability of the object's composition
If a large annulotomy is created to accommodate a stable cage, then cage stability is improved, but patient trauma increases
Solution Approach 1:
The cage transitions from a compact insertable state to an expanded stable state after placement. This dynamic expansion allows the cage to achieve full stability within the disc space without requiring a large annulotomy opening, thereby reducing patient trauma while maintaining cage stability.
Solution Approach 2:
The cage expands vertically and laterally within the disc space after insertion, utilizing the three-dimensional space available. This dimensional transformation allows the cage to achieve stability through expansion within the existing annulotomy opening rather than requiring a larger opening for initial insertion.
4Strength
If expandable cages are used to distract the disc space, then disc space distraction is achieved, but the cages cannot expand laterally beyond the annulotomy to increase the lateral footprint
Solution Approach 1:
The cage is designed with different expansion characteristics in different directions: vertical expansion for disc space distraction and controlled lateral expansion within the annulotomy boundaries. This local quality differentiation allows the cage to achieve distraction while adapting to the anatomical constraints of the annulotomy opening.
Solution Approach 2:
The cage utilizes parameter changes in its expansion behavior, expanding vertically to a greater extent than laterally. This differential parameter change allows the cage to achieve the necessary disc space distraction while maintaining appropriate lateral dimensions that fit within the annulotomy opening.
Data Source
AI summary
An expansion member for distributing graft material through a cage and into an intervertebral space is provided. The expansion member has a central beam with an entry port in fluid communication with an exit port for distribution of the graft material. The central beam is inserted into a cage having a reversible collapse from an expanded state into a collapsed state, the expanded state forming a graft distribution window. The expanded state, for example, can be configured to open the graft distribution window which at least substantially closes upon the reversible collapse.