Expandable Intervertebral Cage With Sequential Wedge Expansion
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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 bone growth, necessitating a need for minimally invasive devices that provide optimal spinal fusion support.
Innovation Solution
An expandable intervertebral implant with independently rotatable and slidable endplates, featuring an expansion mechanism that allows for controlled expansion and contraction, enabling precise adjustment of the spinal segment's height and lordosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an expandable intervertebral implant with independent endplate expansion is used, then spinal segment stabilization and bone growth environment are improved, but device complexity increases
Solution Approach 1:
The implant is divided into independently expandable endplates (first endplate and second endplate) that can be expanded separately relative to each other. Each endplate has its own expansion mechanism with support wedges and ramps, allowing independent adjustment of each spinal segment while maintaining overall stabilization.
Solution Approach 2:
The endplates are designed with dynamic expansion capabilities, transitioning from a collapsed configuration during insertion to an expanded configuration for stabilization. The ramps and support wedges enable controlled dynamic adjustment of the endplate spacing and orientation during the surgical procedure.
2Adaptability or versatility
If an expandable implant with multiple ramps and support wedges is used, then adaptability for spinal fusion is improved, but ease of operation deteriorates
Solution Approach 1:
The expansion mechanism serves multiple functions: the ramps facilitate controlled expansion, the support wedges provide structural support during insertion, and the independent endplate expansion enables adjustment of both spacing and lordosis. This multi-functionality increases adaptability for spinal fusion while maintaining operational simplicity through integrated design.
Solution Approach 2:
The support wedges are positioned within the endplates and the ramps are integrated into the wedge structures. The nested arrangement of these components allows compact storage during insertion and enables sequential expansion through a coordinated action of the nested elements, simplifying the surgical operation.
3Object-affected harmful factors
If a collapsed configuration implant is used for insertion, then procedural invasiveness is reduced, but spinal segment stabilization is worsened
Solution Approach 1:
The implant transitions dynamically from a collapsed configuration during insertion (minimizing invasiveness) to an expanded configuration after placement (providing stabilization). The ramps and support wedges enable this dynamic transformation, allowing the device to adapt its structure based on the surgical phase requirements.
Solution Approach 2:
The implant is inserted in a pre-collapsed configuration to minimize procedural invasiveness, and then expanded in situ to achieve spinal segment stabilization. This preliminary action of insertion followed by expansion allows the device to overcome the contradiction between minimally invasive placement and effective stabilization.
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 implant provides minimally invasive spinal fusion support by stabilizing the spinal segment and allowing for optimal bone growth, facilitating quick healing and improved patient function and mobility.
Implementation Method 1
The expansion assembly 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 a second ramp and a third ramp. The expansion assembly includes an expansion wedge that defines a fourth ramp, wherein each of the first, second, third, and fourth ramps is inclined with respect to a second direction that is substantially perpendicular to the first direction.
Implementation Method 2
The actuator is 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 first and second bone-contacting surfaces along the first direction, and 2) the second ramp to ride along the first ramp
Data Source
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.