Pedicle Screw Insertion Instrument with Selective Locking Mechanism
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Solution Overview
Problem
Current polyaxial pedicle screw insertion instruments require continuous clinician input to maintain secure engagement with the screw, lacking a mechanism for selective locking and unlocking, which can lead to instability during spinal fixation procedures.
Innovation Solution
A screw insertion instrument featuring an inner shaft and a knob assembly that can be selectively coupled and decoupled, allowing for rotational and translational support, enabling secure engagement and controlled placement of pedicle screws with a locking mechanism that prevents accidental disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking mechanism is added to prevent accidental disengagement, then reliability is improved, but device complexity increases
Solution Approach 1:
The detent mechanism automatically engages with the gear teeth to lock the knob assembly to the inner shaft, and automatically disengages when the knob is rotated to the unlocked position. This self-actuating system eliminates the need for continuous clinician input while maintaining secure engagement, resolving the contradiction between reliability and complexity.
2Measurement precision
If continuous clinician input is required to maintain engagement, then control precision is improved, but ease of operation deteriorates
Solution Approach 1:
The system transitions from a static locked state to a dynamic selectively lockable state. The knob assembly can be rotated between locked and unlocked positions, allowing the clinician to maintain precise control only when needed (during insertion) while easily releasing the instrument afterward. This dynamic capability resolves the contradiction between control precision and ease of operation.
3Ease of operation
If the knob assembly is decoupled from the inner shaft, then ease of operation is improved, but stability deteriorates
Solution Approach 1:
The detent mechanism acts as an intermediary between the knob assembly and the inner shaft. When locked, it provides stable mechanical coupling; when unlocked, it allows free rotation. This intermediary component enables the system to switch between stability and ease of operation as needed, resolving the contradiction between these two parameters.
Data Source
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AI summary
An instrument for selectively coupling with a pedicle screw is disclosed. The instrument includes an inner shaft, wherein the distal tip is configured to engage a pedicle screw and the proximal end configured to be selectively engaged with a knob, and a knob assembly configured to advance over the inner shaft, wherein the distal end is configured to engage the tulip of the pedicle screw and the proximal end is configured to selectively engage the inner shaft. A method for selectively coupling the instrument to a pedicle screw is also disclosed.