Cluster Derotation Assembly for Axial Slip-Free Spinal Correction
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Solution Overview
Problem
Existing spinal derotation techniques face challenges in safely and effectively applying forces to multiple spinal column segments to correct spinal deformities like scoliosis, as they often result in unwanted and detrimental forces on individual vertebrae.
Innovation Solution
A cluster derotation assembly that includes a plurality of locking tubes linked by a link member, with tube clips and wing nuts to secure pedicle screws, minimizing axial slippage and allowing simultaneous derotation of multiple vertebrae by dispersing forces evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If forces are applied to multiple spinal column segments to correct spinal deformities, then derotation of the spinal column is achieved, but unwanted and detrimental forces are imposed on individual vertebrae
Solution Approach 1:
The cluster derotation assembly divides the spinal column into multiple segments, each secured by a separate locking tube and pedicle screw. This segmentation allows independent control of each vertebral segment while applying forces distributed across the entire spinal column, preventing concentration of harmful forces on any single vertebra.
Solution Approach 2:
Multiple locking tubes are combined into a single cluster assembly that functions as one integrated unit. The link member connects all locking tubes, allowing them to move and rotate together as a group, enabling simultaneous derotation of multiple vertebrae while distributing forces evenly across the entire spinal segment.
2Productivity
If multiple locking tubes are connected to apply forces to multiple vertebrae, then simultaneous derotation is achieved, but axial slippage occurs between the locking tubes
Solution Approach 1:
The link member serves as an intermediary component that connects multiple locking tubes while preventing axial slippage between them. It transmits forces and movements from one locking tube to another while maintaining rigid axial alignment, ensuring that all locking tubes move together without sliding relative to each other.
Solution Approach 2:
Instead of allowing the locking tubes to move independently and then trying to control their relative positions, the design inverts the approach by mechanically coupling them through the link member so that their movements are inherently synchronized. The locking tubes are designed to move only as a group, eliminating axial slippage by definition.
3Reliability
If forces are dispersed throughout the affected spinal segments, then safe derotation is achieved, but the device complexity increases
Solution Approach 1:
The link member performs multiple functions simultaneously: it connects multiple locking tubes, distributes forces evenly across the spinal segments, prevents axial slippage between tubes, and maintains rigid geometric relationships between all components. This multi-functionality reduces the need for additional separate components, actually simplifying the overall device despite the increased number of locking tubes.
Data Source
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AI summary
In a cluster derotation assembly, a tube clip for joining a locking tube to a link member. The tube clip has a first clip arm and a second clip arm joined to a threaded shaft. One or both of the first clip arm and the second clip arm has an inner surface configured to engage with a complementary surface of a locking tube.