Expandable Intervertebral Cage With Bone Graft Windows
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Solution Overview
Problem
Current lumbar interbody fusion systems lack the ability to effectively expand and accommodate bone growth material, limiting their ability to stimulate and stabilize the spinal column post-surgery.
Innovation Solution
An expandable intervertebral cage assembly with an elongate body and expander mechanism that allows selective expansion, incorporating bone graft windows and a cap to contain fusion material, facilitating bone growth and stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional fixed support systems are used, then structural stability is provided, but the ability to accommodate and contain bone graft material is limited
Solution Approach 1:
The cage assembly transitions from a fixed structure to an expandable dynamic structure. The expandable body allows the cage to be inserted in a compressed state and then expanded within the intervertebral space, increasing the internal volume available for bone graft material while maintaining structural integrity. This dynamic adaptation resolves the contradiction between providing structural stability and accommodating variable quantities of bone graft material.
Solution Approach 2:
The cage assembly is divided into distinct functional components: an expandable body, an expander mechanism, bone graft windows, and a containment cap. This segmentation allows each component to perform its specific function - the expandable body provides structural stability, the bone graft windows enable material loading, and the cap ensures containment. The segmented design resolves the contradiction by allowing the system to maintain stability while adapting to different bone graft requirements.
2Strength
If the cage body is made rigid for structural support, then mechanical strength is provided, but expandability and adaptability are reduced
Solution Approach 1:
The cage body incorporates an expandable mechanism that allows it to transition from a compact insertion state to an expanded support state. The rigid structure is maintained in the expanded configuration to provide mechanical strength, while the ability to change volume through expansion provides adaptability to different intervertebral spaces. This dynamic capability resolves the contradiction between rigidity for strength and flexibility for adaptability.
Solution Approach 2:
The expander mechanism is nested within the expandable cage body, allowing the expander to be stored inside the cage during insertion. Once positioned, the expander is deployed to expand the cage body to its full structural capacity. This nested arrangement allows the rigid support structure to be compacted for insertion while maintaining its full strength characteristics when expanded, resolving the contradiction between mechanical strength and expandability.
3Reliability
If bone graft material is loaded into the cage, then fusion stimulation is enhanced, but secure containment of the material becomes challenging
Solution Approach 1:
The containment function is separated into distinct components: bone graft windows for material loading and a dedicated containment cap. The cap acts as a separate containment mechanism that can be inserted into the cage body to secure the bone graft material. This segmentation resolves the contradiction by providing a simple, dedicated containment solution rather than requiring a complex integrated system, thereby enhancing fusion reliability while minimizing device complexity.
Solution Approach 2:
The containment cap is designed to be inserted into the cage body before or during bone graft material loading. This preliminary action of placing the cap creates a secure containment environment in advance, ensuring that the bone graft material remains contained during insertion and after implantation. This preliminary containment action enhances fusion reliability while maintaining device simplicity.
Data Source
AI summary
An expandable assembly for insertion into an intervertebral space is presented. The assembly, in particular aspects, includes an elongate body comprising an upper portion and a lower portion. The assembly may include an expander that is sized and shaped for insertion between the upper portion and lower portion, thereby selectively expanding the upper portion away from the lower portion. The elongate body may also include one or more bone graft windows.