Pedicle Screw Assembly With Spring-Retained Tulip Extension Alignment
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Solution Overview
Problem
Existing pedicle screw assemblies face difficulties in maintaining the stability and alignment of tulip extensions, which can collapse inward or spread outward, making it challenging to load connecting elements or tools, and may lead to damage or separation.
Innovation Solution
The pedicle screw assembly incorporates a tulip extension with deflectable retention springs and a support ring that maintains the parallel alignment of extension tabs, preventing inward or outward movement, and allows for easy removal when needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If tulip extensions are made flexible to allow loading, then ease of operation is improved, but structural stability deteriorates causing extensions to collapse or spread
Solution Approach 1:
The extension tabs are designed to be dynamically adjustable between open and closed positions. The deflectable retention spring enables the tabs to move from a closed storage position to an open loading position, and back again. This dynamic capability allows the system to adapt its state based on operational needs while maintaining structural integrity through the spring's restoring force.
Solution Approach 2:
The retention spring changes the physical state of the extension tabs by applying elastic force. When deflected, the spring transitions from a restrained state to an extended state, changing the positional parameter of the tabs. This parameter change enables the tabs to open for loading while the spring's elastic properties ensure they return to their original stable configuration.
2Reliability
If retention features are made permanent to prevent damage, then reliability is improved, but ease of disassembly deteriorates
Solution Approach 1:
The retention system is designed to be dynamically reversible rather than permanently fixed. The deflectable retention spring provides continuous retention force during normal operation to prevent damage, but can be deliberately deflected to release the support ring. This dynamic design allows the same mechanism to provide both reliable retention and easy disassembly.
Solution Approach 2:
The retention spring serves dual functions: it automatically retains the support ring during operation without additional fastening mechanisms, and it can be manually deflected to enable self-release. The spring's elastic energy stores the retention function, and when released, it allows the support ring to be easily removed without tools or complex procedures.
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 solution ensures stable and reliable loading of connecting elements by maintaining the tulip extension's shape and alignment, reducing damage and facilitating assembly and disassembly.
Implementation Method 1
The tulip extension includes a deflectable retention spring along the first extension tab
Data Source
AI summary
A pedicle screw assembly includes a tulip having a pocket that receives a head of the screw body. The pedicle screw assembly includes a tulip extension that extends from the tulip including first and second extension tabs extending from first and second side walls of the tulip. The tulip extension has a lumen defined between the first and second extensions and slots defined between the first and second extensions aligned with rod openings of the tulip. The tulip extension includes a deflectable retention spring along at least one of the extension tabs. A support ring is coupled to the extension tabs for support. The retention spring retains the support ring on the extension tabs but is releasable to allow removal of the support ring.