Extension Ready Spinal Support System Design
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Solution Overview
Problem
Conventional spinal rod extension systems require disturbance or modification of existing connections between spinal support rods and pedicle screws, leading to increased surgical trauma and recovery times.
Innovation Solution
The development of an 'extension ready' spinal support system that allows for extension without disturbing existing connections, utilizing polyaxial or monoaxial extension receptacles that can be mounted directly to existing base rod receptacles, thereby maintaining the integrity of the existing spinal support structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional extension systems are used to add spinal support rods, then extension capability is achieved, but existing connections between base rod and pedicle screws must be disturbed or modified
Solution Approach 1:
The extension system is divided into separate modular components: an extension receptacle that attaches to the exterior of the base rod receptacle, a pivot member with pivot axis, and an extension rod. This segmentation allows the extension components to be added without disturbing the existing base rod-pedicle screw connection, resolving the contradiction between achieving extension capability and preserving existing connection integrity.
Solution Approach 2:
The extension receptacle serves as an intermediary component that interfaces between the existing base rod receptacle and the new extension rod. It attaches to the exterior threads of the base rod receptacle, providing a mounting structure for the extension rod without requiring modification of the original pedicle screw-base rod connection, thus maintaining reliability while enabling extension.
2Ease of operation
If set screw is removed from interior threads to accommodate extension receptacle, then extension can be implanted, but base spinal support rod must be reset
Solution Approach 1:
The base rod receptacle is designed with exterior threads that are pre-configured to receive the extension receptacle. This preliminary design feature allows the extension system to be attached without removing the set screw from the interior threads, eliminating the need to reset the base spinal support rod and reducing surgical time while maintaining ease of extension implantation.
3Adaptability or versatility
If extension receptacle is mounted piggyback to base receptacle, then extension is achieved, but base receptacle connection must be disturbed
Solution Approach 1:
The extension receptacle attaches to the base rod receptacle by mounting on its exterior surface, utilizing the radial dimension of the base receptacle structure. This external mounting approach allows extension capability to be added without disturbing the internal connection structure between the base rod and pedicle screw, achieving extension while maintaining connection simplicity.
4Adaptability or versatility
If polyaxial structure is used between base receptacle and extension receptacle, then rotational flexibility is provided, but axial length increases
Solution Approach 1:
The polyaxial rotation capability is segmented into two separate components: the base rod receptacle maintains its original structure, while the extension receptacle incorporates the polyaxial pivot mechanism. This segmentation allows rotational flexibility to be added only where needed for extension, avoiding unnecessary axial length increase in the base structure while providing the required adaptability.
Data Source
AI summary
An “extension ready” spinal support system that enables the extension to be accomplished with minimal disturbance to an existing spinal support structure to which the extension system is coupled. In some embodiments, the existing spinal support rod and pedicle screws can remain intact while extension subassemblies are mounted directly to the existing base rod receptacles. The extension subassemblies include a skirt portion that surrounds and engages the existing base receptacle to prevent splaying of the base receptacle. Additional resistance to splaying may be provided by a canted thread arrangement between the skirt and the base receptacle. In some embodiments, the extension receptacle is provided with a low profile (i.e., shortened axial length from the base rod receptacle) by providing a monoaxial rotation structure that rotates about but does not pitch relative to the extension axis and is shorter relative to polyaxial rotation structures.