Expandable Spinal Implant Wedge Stabilization
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Solution Overview
Problem
Existing expandable interbody devices for spinal reconstruction are unstable during expansion, leading to undesired shifts in positioning within the intervertebral space due to load-bearing surfaces moving relative to each other and the inserter.
Innovation Solution
An expandable spinal implant system comprising a first and second endplate with an expansion mechanism that includes wedges and a rod assembly, allowing the implant to be deployed between a contracted and expanded position in the disc space between vertebral bodies, thereby stabilizing the positioning during expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If existing expandable interbody devices are expanded, then the implant height is increased to restore disc space, but the load-bearing surfaces move relative to each other and the inserter causing instability and undesired shifts in positioning
Solution Approach 1:
The endplate is divided into multiple segments (first endplate and second endplate) that can move independently relative to each other during expansion. Each endplate has its own load-bearing surface that maintains stable engagement with the vertebral body while the implant expands, preventing the entire structure from shifting as a single unit.
Solution Approach 2:
The inserter acts as an intermediary component that engages with the expansion mechanism (wedges) rather than directly with the endplates. This intermediary connection allows the inserter to control expansion while the endplates maintain stable positioning through their engagement with the vertebral bodies, preventing undesired shifts.
2Shape
If high angulation spacers are placed into the intervertebral space, then the anterior disc space is corrected, but a high amount of force is required to place the spacers
Solution Approach 1:
The implant transitions from a static, pre-set angle to a dynamic structure that can adjust its configuration during insertion and expansion. The expandable design allows the implant to be inserted in a compact state requiring minimal force, then expanded in-situ to achieve the desired high angulation for disc space correction, avoiding the need to force a rigid high-angle spacer into place.
Solution Approach 2:
The implant's geometric parameters (height, angle, volume) are changed after insertion rather than being fixed beforehand. The device is inserted with one set of parameters (compact, low profile) and then expanded to achieve different parameters (expanded height, high angulation), allowing disc space correction without requiring high insertion forces.
3Length of moving object
If the implant is expanded by moving wedges laterally, then the endplates are separated to restore disc height, but the mechanism requires precise control to maintain stability
Solution Approach 1:
The expansion mechanism combines multiple functions into a single integrated system: the wedges simultaneously separate the endplates, maintain alignment through their engagement with both endplates, and provide controlled expansion through lateral movement. This merging of functions reduces the need for separate control mechanisms and simplifies the overall control requirement.
Solution Approach 2:
The expansion mechanism is designed so that the wedges engage symmetrically with both endplates, creating equipotential conditions where forces are distributed evenly during expansion. This symmetric engagement ensures that both endplates separate uniformly, maintaining stability and alignment without requiring complex differential control mechanisms.
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 system effectively stabilizes the expandable spinal implant during expansion, preventing undesired shifts and ensuring precise positioning within the intervertebral space, thus enhancing the reliability of spinal reconstruction surgeries.
Implementation Method 1
The rod assembly is disposed within the first wedge aperture and second wedge aperture and operably engaged with the first wedge to move the first wedge in a lateral direction and operably engaged with the second wedge to move the second wedge in an opposing lateral direction
Implementation Method 2
an expansion mechanism disposed between the first endplate and the second endplate, the expansion mechanism including a first wedge disposed between the first endplate and second endplate
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An expandable spinal implant is provided having first and second endplates hinged along one end or otherwise connected by pins, protrusions and channels, or similar mechanisms and an expansion mechanism(s) disposed therebetween configured to expand the first and second endplates from each other. Also provided are expandable spinal implants that may be expanded in a parallel manner to increase the height of the device while maintaining a lordotic angle. Other spinal implants may provide dual expansion whereby both height and lordotic angle are adjusted. Various implants, systems and methods are disclosed.