Push-off Driver for Polyaxial Bone Screws
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Solution Overview
Problem
Existing drivers for polyaxial screws often become stuck during removal from the screw, causing difficulty for surgeons and increasing risk to patients due to the 'sticking' phenomenon.
Innovation Solution
A push-off driver with a handle, a threaded driver sleeve, and an inner driver featuring a release mechanism, such as a button mechanism with spheres or spring-loaded pins, that allows for easy detachment by preventing the driver from moving proximally and forcing the screw off the inner driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional driver is used to insert polyaxial screws, then the screw can be driven into the patient, but the driver becomes stuck inside the screw recess during removal
Solution Approach 1:
The driver system transitions from a static connection to a dynamic one through the release mechanism. The inner driver can be selectively locked to or dislocked from the screw head, allowing the connection state to change based on operational needs. This dynamic capability enables easy removal after screw insertion without forcing or jarring.
Solution Approach 2:
The release mechanism acts as an intermediary between the inner driver and the screw head. It provides controlled engagement and disengagement, mediating the connection and separation processes. The spheres and recesses serve as intermediary elements that facilitate reliable locking during insertion and clean release during removal.
2Ease of manufacture
If the driver is designed with a simple connection structure, then manufacturing is easier, but the driver becomes stuck during removal
Solution Approach 1:
The driver is segmented into distinct functional components: the outer sleeve, the inner driver, and the release mechanism with spheres. This segmentation allows each component to be manufactured separately using standard machining processes, while the assembly of these simple parts creates the sophisticated locking and releasing functionality needed to prevent sticking during removal.
3Reliability
If the driver uses a locked connection mechanism, then the screw can be securely driven, but the driver cannot be easily removed from the screw
Solution Approach 1:
The driver connection operates in periodic cycles: locked during screw insertion to ensure security, then unlocked for rapid removal. The release mechanism enables this periodic transition, allowing the system to alternate between secure engagement and easy disengagement states, eliminating the need for time-consuming removal procedures.
Data Source
AI summary
A method and device for inserting screws into a patient, such that when the device is removed the device does not stick to the screw. The device, being a push-off driver, may have a handle, an inner driver, and a threaded driver sleeve having a button mechanism and a plurality of spheres, and an inner sleeve. The method includes the steps of assembling a push-off driver attaching a bone screw to the push-off driver inserting the bone screw and detaching the bone screw from the driver by unthreading the threaded driver sleeve from the polyaxial screw which causes the spheres in the recess of the inner driver to back up against the start of the recess and causing the threaded driver sleeve to “push-off” the polyaxial screw from the inner driver.