Breakoff Extender Tabs for Minimally Invasive Spinal Rod Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Positioning spinal rods within receivers anchored to patient vertebrae is challenging, especially in minimally invasive procedures where visibility and space are limited, and existing systems require additional retracting and reduction instrumentation.
Innovation Solution
A spinal-correction system with capped tab extenders and a tab remover, which includes a screw assembly with frangibly connected extender tabs to a threaded uni-axial or multi-axial rod receiver, allowing for rod reduction and tissue retraction without the need for additional external instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional pedicle-screw assemblies are used with separate retractors and reduction instrumentation, then rod positioning and reduction can be achieved, but device complexity and number of required instruments increase
Solution Approach 1:
The patent combines multiple functions (retraction, rod positioning, and reduction) into a single integrated pedicle-screw assembly. The extender tabs are directly connected to the rod receiver, eliminating the need for separate retractors and reduction instrumentation while maintaining all necessary functions for successful rod positioning and reduction.
Solution Approach 2:
The pedicle-screw assembly is designed with multi-functionality, where the extender tabs serve both as structural components for rod attachment and as retraction elements. The same assembly that secures the rod also provides the necessary retraction capability, reducing the total number of instruments needed.
2Reliability
If additional external retractors and reduction instrumentation are used, then rod reduction can be achieved, but cost and space requirements increase
Solution Approach 1:
The patent merges the reduction capability directly into the pedicle-screw assembly through the extender tabs. This integration eliminates the need for separate external reduction instrumentation, maintaining reliable rod reduction capability while reducing the quantity of instruments required.
3Strength
If extender tabs are permanently attached to rod receiver, then structural strength is improved, but ease of removal and repositioning deteriorates
Solution Approach 1:
The patent employs a dynamic attachment system where the extender tabs are initially secured to the rod receiver with sufficient strength for the procedure, but can be easily removed and repositioned if needed. The frangible connection allows for controlled detachment when removal is required, providing both strength during use and ease of modification.
Solution Approach 2:
The extender tabs are designed as separable components that can be independently removed from the rod receiver. This segmentation allows the tabs to be detached and repositioned without affecting the entire assembly, providing flexibility while maintaining structural integrity during the procedure.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A spinal-correction system having (i) a receiver including a base and opposing arms extending proximally from the base forming a rod-receiving cavity, (ii) a pair of extender tabs, each extender tab having threaded inner walls for receiving threads of a setscrew, (iii) a pair of tab extenders each being connectable releasably to one of the extender tabs, (iv) a cap instrument connectable releasably to the tab extenders, and (v) a pair of breakoff sections, each connecting one of the extender tabs to one of the receiver arms, and each being readily breakable for separating the extender tab from the receiver arm. The distal base defines a bonescrew cavity to receive a bonescrew head so that the head can move relative to the base. Each receiver arm has threaded inner walls for receiving setscrew threads. The rod-receiving cavity has geometry corresponds to geometry of the setscrew and a spinal-correction rod.