Anterior Vertebral Plate Closed Thread Screw Locking
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Solution Overview
Problem
Conventional anterior vertebral body plates and screws for cervical spine stabilization lack a reliable locking mechanism, leading to potential screw backout and complications due to the use of additional locking elements that can become disengaged and migrate into soft tissues, or require additional steps and thickness that are not suitable for a low profile profile.
Innovation Solution
A low profile anterior vertebral body plate system using closed thread screws with an integrally formed locking element that engages the plate, featuring a final flat pitch thread to secure the screw in place without additional locking elements, allowing for polyaxial attachment and secure fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional locking elements (set screws, retaining rings, cams) are used to secure screws to the plate, then screw security is improved, but device complexity and risk of migration increase
Solution Approach 1:
The patent merges the locking function into the screw itself by incorporating a closed thread at the tip of the screw shaft. This integrated design eliminates the need for separate locking elements like set screws, retaining rings, or cams, thereby reducing device complexity while maintaining screw security through the self-locking closed thread structure that prevents screw backout
2Reliability
If additional locking elements are added to the plate, then screw locking reliability is improved, but the risk of elements migrating into soft tissues increases
Solution Approach 1:
By integrating the locking function directly into the screw as a closed thread at its tip, the patent eliminates separate locking elements that could migrate into soft tissues. The closed thread remains on the screw shaft and engages with the plate hole flange, providing reliable locking without creating additional components that could become dislodged and migrate
3Reliability
If cover plates or overlying locking features are added to the plate, then screw coverage is improved, but plate thickness increases
Solution Approach 1:
The patent eliminates the need for separate cover plates or overlying locking features by integrating the locking function into the screw itself. The closed thread at the screw tip engages directly with the plate hole flange, providing screw coverage and locking reliability without adding additional plate thickness or height
4Ease of manufacture
If standard threaded holes are used in the plate, then manufacturing simplicity is maintained, but screw backout occurs
Solution Approach 1:
The patent maintains simple standard threaded holes in the plate for easy manufacturing while preventing screw backout by integrating a closed thread at the screw tip. The closed thread engages with the flange of the plate hole, creating a mechanical interlock that prevents backout without complicating the plate manufacturing process
Data Source
AI summary
Provided is a novel system that includes a low profile anterior vertebral body plate and closed thread screws for the fixation and stabilization of the cervical spine, the closed thread screw having an integral novel screw locking mechanism of an uppermost closed thread having a flat pitch, which engages and attaches the plate so as to lock the screw into the plate until an intentional, simultaneous combination of outward pulling force and counter-clockwise torque is applied to release the closed thread screw from the plate. Also provided is a method of stabilizing cervical vertebrae using the disclosed system.