Polyaxial Screwdriver Self-Aligning Ratchet Mechanism
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Solution Overview
Problem
Current pedicle screw systems for spinal fixation face challenges in the complexity of use, engagement of screw heads, and screw loading during installation, leading to inefficiencies and potential inaccuracies.
Innovation Solution
A polyaxial screwdriver with a screw engaging end featuring semi-cylindrical cutouts and cylindrical structures that self-align with the screw head, combined with a ratchet mechanism for secure attachment and automatic locking, allowing for precise and easy advancement or retraction of the screw within the vertebra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pedicle screw systems are used, then spinal fixation can be achieved, but the complexity of use and manipulation of parts increases
Solution Approach 1:
The patent combines the screwdriver handle, shaft, and engaging structure into a single integrated tool assembly. The T-shaped engaging structure merges the engagement interface and manipulation functions into one component, reducing the number of separate parts that need to be assembled and manipulated during the spinal fixation procedure.
Solution Approach 2:
The screwdriver is designed with a universal engaging structure that can interface with different screw head configurations. The T-shaped engaging structure serves multiple functions: it engages the screw head, provides rotational leverage, and includes a release mechanism for disengagement, eliminating the need for multiple specialized tools.
2Reliability
If complex engagement structures are used, then secure attachment of screwdriver to screw head is achieved, but the ease of operation decreases
Solution Approach 1:
The engaging structure is pre-configured with the T-shaped geometry that automatically aligns with and engages the screw head upon insertion. The spring-loaded mechanism is pre-set to engage at a specific depth, eliminating the need for manual adjustment or complex alignment procedures during operation.
Solution Approach 2:
The spring-loaded engaging structure automatically engages and disengages based on the insertion and removal motions of the screwdriver. The mechanism self-regulates the engagement force through the spring, providing secure attachment without requiring additional fastening steps or complex operational procedures.
3Ease of operation
If manual screw advancement methods are used, then screw installation can be performed, but precision and control during screw loading improve
Solution Approach 1:
The spring-loaded engaging structure provides tactile feedback to the operator during screw advancement. The spring force varies with the engagement depth, giving the operator real-time feedback on the screw's position and resistance, enabling precise control of the advancement process while maintaining ease of operation.
Data Source
AI summary
A polyaxial screwdriver for inserting a bone screw in a vertebra. A polyaxial bone screw assembly includes a coupling element. When a screw engaging end of the polyaxial screwdriver is lowered on the head of the bone screw, the complimentary surfaces of the screw engaging end of the screwdriver and the head of the screw self-align. A ratchet mechanism formed in the screwdriver provides progressive and automatic locking of the polyaxial screwdriver to the coupling element and prevents the accidental unthreading from the coupling element. In another embodiment of the polyaxial screwdriver, a collet slides over the outside surface of the upper end of the coupling element and locks on to the coupling element. In yet another embodiment of a polyaxial screwdriver, the outer sleeve of the polyaxial screwdriver has a split end that securely engages the coupling element.