Expandable Intervertebral Cage for Minimally Invasive Spinal Stability
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Solution Overview
Problem
Existing spinal fusion devices are invasive and do not optimally stabilize the spinal segment while creating an environment for effective bone growth and fusion.
Innovation Solution
An expandable intervertebral implant with independently rotatable endplates that can transition between collapsed and expanded configurations, allowing for lateral insertion and adjustable lordosis or kyphosis to restore spinal alignment and facilitate bone fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional spinal fusion devices are used, then spinal stability is achieved, but procedural invasiveness increases and damage to spinal structures occurs
Solution Approach 1:
The implant employs expandable endplates that can transition from a compressed insertion state to an expanded stabilization state. The endplates are configured to expand radially outward after insertion into the disc space, allowing minimally invasive lateral insertion followed by expansion to achieve full stabilizing contact with the vertebral bodies, thereby reducing procedural invasiveness while maintaining spinal stability.
Solution Approach 2:
The implant design allows the endplates to be nested within each other or folded into a compact configuration during insertion, similar to nested dolls. This enables the large-surface-area endplates to be inserted through a small access point via lateral approach, minimizing tissue disruption while providing sufficient surface area for stabilization after expansion.
2Adaptability or versatility
If expandable endplates are used, then adaptability to spinal curvature is improved, but device complexity increases
Solution Approach 1:
The endplates incorporate rotational joints or articulation mechanisms that allow them to rotate and adjust to the natural lordotic or kyphotic curvature of the spine. This dynamic adjustment capability enables the implant to adapt to varying spinal geometries without requiring multiple pre-configured device variants, balancing adaptability with manageable complexity.
Solution Approach 2:
The endplates are designed with curved surfaces and rotational capabilities that conform to the natural curvature of the spine. The ability to rotate and articulate allows the flat or slightly curved endplate surfaces to adapt to the lordotic or kyphotic angles, providing versatility across different spinal regions while using a relatively simple base design.
3Manufacturing precision
If independently rotatable endplates are used, then spinal alignment restoration is improved, but manufacturing complexity increases
Solution Approach 1:
The implant is divided into separable components including first and second endplates that can be manufactured independently and then assembled. This segmentation allows each endplate to be manufactured with precise rotational and articulation features using standard machining processes, reducing overall manufacturing complexity while enabling precise spinal alignment through independent adjustment of each endplate.
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
Minimizes procedural invasiveness and stabilizes the spinal segment, providing an optimal space for bone fusion and early mobilization by adjusting to the natural spinal curvature.
Implementation Method 1
an expansion wedge configured to translate axially between the first endplate and the second endplate so as to move the first endplate and the second endplate between a first, collapsed configuration and a second, expanded configuration
Implementation Method 2
The actuator is engageable with the third component to effect axial translation of the wedge such that the ramps engage the inner surface of at least one of the first component and the second component to move the components between a first, collapsed configuration and a second, expanded configuration
Data Source
Figure 1
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Figure 5
AI summary
An intervertebral implant that iterates between collapsed and expanded configurations includes first and second plates spaced from one another along a first direction and defining bone-contacting surfaces facing away from each other along the first direction. An expansion assembly is positioned between the plates with respect to the first direction and includes a first support wedge that supports the first plate and defines a first ramp and a second support wedge that supports the second plate and defines second and third ramps. The expansion assembly includes an expansion wedge defining a fourth ramp. The first, second, third, and fourth ramps are each inclined with respect to a second direction that is substantially perpendicular to the first direction. At least one of the first and second support wedges is slidable along the respective supported first or second plate. The implant includes an actuator configured to apply a drive force to the expansion wedge so as to cause 1) the fourth ramp to ride along the third ramp so as to increase a distance between the bone-contacting surfaces along the first direction, and 2) the second ramp to ride along the first ramp, thereby further increasing the distance, thereby iterating the implant from the collapsed to the expanded configuration.