Expandable Intervertebral Cage Using Flexure Members
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Solution Overview
Problem
Minimally invasive intervertebral fusion procedures face limitations due to the restricted size of surgical access, which restricts the size of implants that can be inserted, affecting the stability and bone growth area within the disc space.
Innovation Solution
The development of an expandable intervertebral body fusion device with a unitary monolithic body and flexure members that can be inserted in a compressed configuration and expanded within the disc space to achieve a larger mediolateral footprint, providing greater support and stability for the vertebrae.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a minimally invasive surgical approach is used, then patient discomfort and recovery time are reduced, but the size of the implant that can be inserted is limited
Solution Approach 1:
The implant is designed with a nested structure where the body segments are positioned within each other in a compressed configuration, allowing the implant to be inserted through a small minimally invasive access. After insertion, the segments are deployed outward to expand the implant to its full size within the disc space, effectively nesting the final large structure within a small insertion profile.
Solution Approach 2:
The implant transitions from a static compressed configuration during insertion to an expanded static configuration after implantation. The flexure members enable this dynamic transformation, allowing the implant to change its volume and footprint after being inserted through a minimally invasive approach, thus resolving the contradiction between small insertion size and large final size.
2Strength
If the implant size is increased to provide greater support and stability, then the surgical access opening must be enlarged, but this increases the invasiveness of the procedure
Solution Approach 1:
The implant body segments are nested within each other in the compressed configuration, allowing the large final implant size to be achieved through a small access opening. The nested structure enables the implant to expand to its full support-providing size after insertion without requiring a large surgical access.
Solution Approach 2:
The implant is divided into multiple body segments connected by flexure members, allowing the structure to be compressed into a smaller insertion profile while maintaining the capability to expand to a large stable configuration within the disc space. The segmentation enables the implant to achieve both small insertion size and large final size for support.
3Area of stationary object
If the implant footprint is increased within the disc space, then bone growth area is improved, but the device complexity increases
Solution Approach 1:
The implant body is segmented into multiple sections connected by flexure members, allowing the structure to expand to a large footprint within the disc space. The segmentation enables the complex expanded configuration to be achieved through a relatively simple compression-expansion mechanism, balancing the large bone growth area with manageable device complexity.
Solution Approach 2:
The implant uses dynamic expansion from a compressed to an expanded configuration to achieve a large footprint for bone growth. The flexure members enable this transformation with a relatively simple mechanical structure, avoiding the need for complex mechanisms while still achieving the desired large bone contact area.
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 expanded device offers more robust support and a larger footprint within the disc space, enhancing stability and bone growth area without increasing the size of the initial access opening, thus improving the effectiveness of minimally invasive spinal fusion procedures.
Implementation Method 1
a plurality of body segments interconnected with each other by flexure members
Implementation Method 2
A threaded opening can be formed in one or more of the anterior body segment and the posterior body segment. The body is configured to be mediolaterally expanded from a compressed configuration to an expanded configuration by interaction of an expansion tool with the threaded opening
Data Source
AI summary
Disclosed herein are systems and methods for intervertebral body fusion that provide more robust support within the disc space. Intervertebral body fusion devices can have a unitary monolithic body including a plurality of body segments interconnected with each other by flexure members. Devices be configured to be inserted through an opening in a compressed configuration and then expanded within the disc space to an expanded configuration. In the expanded configuration, devices can have a greater mediolateral or transverse to the disc space footprint. This wider footprint provides greater support for the vertebrae relative to the size of the opening through which the device is inserted.