Expandable Spinal Cage Single-Step Bone Graft Packing
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Solution Overview
Problem
Current methods for packing bone graft into expandable spinal cages are time-consuming and frustrating, involving a two-step process that can be difficult due to small holes and messy allograft, especially when trying to cram graft through them.
Innovation Solution
A method and system for pre-packing and post-packing a spinal implant, such as an expandable cage, with bone graft all at once, using ports that match the diameter of delivery instruments like syringes or funnels, ensuring the graft is tightly pressed against endplates for better fusion, and including features like articulating endcaps and anti-backout mechanisms for easier handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a two-step process is used for packing bone graft into expandable cages, then the graft can be packed, but the process becomes time-consuming and frustrating
Solution Approach 1:
The patent combines the pre-packing and post-packing steps into a single integrated operation. The expandable cage is designed with an open configuration that allows bone graft to be loaded once during implantation, eliminating the need for separate pre-packing and post-packing steps. This merging of operations directly resolves the contradiction by reducing the number of steps while maintaining complete graft delivery.
Solution Approach 2:
The patent utilizes the dynamic expandable configuration of the cage to enable single-step packing. The cage transitions from an open, accessible configuration during implantation to a closed, locked configuration after expansion, allowing the packing operation to be performed once during the dynamic transition period. This dynamic approach eliminates the need for repeated access operations.
2Strength
If small holes are used in the cage, then the cage structure is maintained, but it becomes difficult to cram graft through them
Solution Approach 1:
The patent segments the bone graft delivery function from the structural function of the cage. The cage walls are designed with multiple small holes that maintain structural integrity, while a separate bone graft delivery system with a cannula and plunger provides a large-bore pathway for graft insertion. This segmentation allows both small holes for strength and easy graft insertion through the delivery system.
Solution Approach 2:
The patent introduces an intermediary bone graft delivery system that mediates between the surgeon's hand and the small holes in the cage. The delivery system includes a cannula that fits through the small holes and a plunger that pushes graft material through the holes into the cage. This intermediary device solves the contradiction by providing a mechanism to force graft through small openings without compromising cage structure.
3Reliability
If the cage is expanded and locked into final position before packing, then the cage is stable, but post-packing becomes difficult and time-consuming
Solution Approach 1:
The patent performs the bone graft packing action preliminarily, during the implantation phase before final cage expansion and locking. The open configuration of the cage during insertion allows graft to be loaded in advance, so that when the cage is expanded and locked into its final stable position, the packing is already complete. This preliminary action eliminates the need for time-consuming post-packing operations.
Solution Approach 2:
The patent exploits the dynamic states of the cage during implantation. The cage transitions from an open, accessible configuration (allowing easy graft loading) to a closed, stable configuration (providing final stability). By performing packing during the dynamic transition period when the cage is still open, the system achieves both easy packing and final stability without requiring separate operations.
Data Source
AI summary
A method of treating a spine includes implanting a spinal implant within a patient. The spinal implant includes a first member having a first wall defining an axial passageway and a first opening, the first opening being in communication with the axial passageway. A second member includes a second wall defining an axial channel having the first member disposed therein, the second wall defining a second opening in communication with the axial channel. Bone graft is injected through the first opening and into the axial passageway and through the second opening and into the axial channel after the spinal implant is implanted within the patient.