Zero-Profile Fusion Cage with In-Line Single Piece Fixation
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Solution Overview
Problem
Current spinal fusion devices often require the insertion of plates and fixation devices that can cause patient discomfort and are difficult to position, particularly due to their profile and the need for high-angle insertion.
Innovation Solution
A zero-profile intervertebral fusion device that uses a single staple to secure the fusion cage to vertebral bodies, with tynes that traverse the anterior wall of the cage at an angle, allowing for smaller incisions and independent cage and staple insertion, and optionally utilizing shape memory materials for compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plates and fixation devices are inserted on the anterior surface of vertebral bodies, then fixation strength is improved, but patient discomfort and device profile increase
Solution Approach 1:
The fixation device transitions from anterior surface attachment to lateral/oblique insertion through the cage body, changing the dimensional approach from frontal to side/angled entry. This allows the fixation elements to engage vertebral bodies through the cage structure rather than requiring anterior plate placement, thereby reducing the proud profile and associated patient discomfort while maintaining fixation strength
2Reliability
If plates with fixation devices are used, then fixation reliability is improved, but device complexity and insertion difficulty increase
Solution Approach 1:
The fixation elements are integrated directly into the cage structure as a unified device rather than separate plate and screw components. The fixation elements emerge from the cage body and engage vertebral bodies directly, eliminating the need for separate anterior plate placement and reducing overall device complexity while maintaining fixation reliability through the combined cage-fixation element structure
Solution Approach 2:
The cage structure serves multiple functions: it provides intervertebral spacing, contains bone graft material, and integrates fixation elements for vertebral body engagement. This multi-functionality eliminates the need for separate anterior plates, reducing device complexity while maintaining comprehensive fixation capability
3Strength
If high-angle insertion is used for fixation devices, then fixation strength is improved, but ease of operation deteriorates
Solution Approach 1:
Instead of inserting fixation devices through high-angle approaches from the anterior surface, the fixation elements are inserted laterally or obliquely through the cage body from the side. This inverts the traditional insertion approach, allowing for more straightforward lateral access that simplifies the insertion procedure while still achieving adequate fixation strength through the vertebral bodies
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
This solution reduces patient discomfort by minimizing the device profile, facilitating easier insertion, and promoting bone fusion through compression of the graft, while allowing for more precise and balanced fixation of the cage to vertebral bodies.
Implementation Method 1
optionally utilizing shape memory materials for compression
Data Source
AI summary
Methods for securing a intervertebral cage to one or more levels of the spine with fixation. The fixation, which is typically a staple, is intended to be driven perpendicular to the proximal face of the cage and in-line with the inserter. After the cage is placed and positioned according to surgeon preference, a single piece fixation clip is then deployed and fixed in a manner that produces a zero-profile device.