Breakaway Screw Tower for Percutaneous Cervical Rod Insertion
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Solution Overview
Problem
Existing spinal fixation systems for cervical spine applications in minimally invasive surgery (MIS) are cumbersome and time-consuming, often requiring difficult rod reduction and causing significant disruption to patient musculature.
Innovation Solution
A single-use screw tower that attaches to existing screws, featuring a distal end for engaging the screw head and a proximal end for instrumentation, with a breakable design allowing easy rod insertion and removal without the need for an open incision, facilitating percutaneous screw and rod insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional spinal fixation system is used with a closed tower design, then the rod can be securely held during insertion, but the rod reduction becomes difficult and time-consuming
Solution Approach 1:
The tower is divided into two separate halves that can be independently manipulated. The first half remains attached to the screw while the second half can be separated to facilitate rod removal, allowing the rod to be securely held during insertion while enabling easy reduction without time-consuming manual manipulation
Solution Approach 2:
The breakpoint feature acts as an intermediary mechanism between the two tower halves. This controlled separation point allows the tower to function as a unified structure during rod insertion (securing the rod reliably) while enabling easy separation for rod removal (reducing time loss)
2Object-affected harmful factors
If percutaneous screws are used in cervical spine applications, then minimally invasive surgery is achieved, but few options exist for rod insertion without open incision
Solution Approach 1:
The breakable tower design allows the second half to be separated and removed percutaneously after rod insertion, eliminating the need for open incision while maintaining ease of operation. The segmented structure enables the tower to facilitate rod insertion through minimal access and then be discarded without requiring muscle disruption
Solution Approach 2:
The tower is designed as a single-use disposable instrument that is discarded after rod insertion. This eliminates the need for complex retrieval mechanisms and open incisions, as the tower remains in the patient only temporarily during the insertion process and is then removed percutaneously or left to dissolve
3Device complexity
If a single-use instrument is used that attaches to existing screws, then device complexity is reduced, but the instrument must remain open along the rod slot to allow screw intermeshing
Solution Approach 1:
The tower is divided into two halves connected at the breakpoint, creating an open structure along the rod slot area. This segmentation allows screw intermeshing while maintaining sufficient structural integrity through the distributed chevron features and controlled break point, reducing overall device complexity
Solution Approach 2:
The tower has different structural properties in different regions: the distal end with chevrons provides strong engagement with the screw, while the proximal region along the rod slot remains open for screw intermeshing. This localized quality differentiation allows the instrument to maintain necessary stability where needed while enabling screw access where required
Data Source
AI summary
A screw tower that is a single-use instrument that attaches to existing screws but remains open along a rod slot to allow for screws to intermesh and prevent interference of adjacent screws during screw and rod insertion. The screw tower interfaces with existing features of the screws to facilitate screw insertion, rod insertion, rod reduction, and locking cap insertion in a percutaneous approach. The tower is broken in half and removed from patient to end with a completed construct.