Retaining Screw Driver Assembly With Frictional Engagement
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Solution Overview
Problem
Bone screws often slip off during orthopedic surgery and become lost in soft tissue, making retrieval difficult due to lack of secure attachment to the driver.
Innovation Solution
A retaining screw driver assembly with a shaft, sliding member, and activator that uses an axial slot and cross-pin to advance the sliding member into a retaining position, creating frictional engagement with the screw head, allowing secure attachment and release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bone screws are not secured to the driver during implantation, then the surgical procedure is simpler and faster, but the screws slip off and become lost within surrounding muscle tissue
Solution Approach 1:
The driver features a dynamic retention mechanism where the distal end of the sliding member can move between a first position (screw retained) and a second position (screw released). This dynamic system allows the surgeon to secure the screw during implantation and then easily release it after implantation, resolving the contradiction between retention reliability and procedural efficiency
Solution Approach 2:
The sliding member acts as an intermediary element between the driver shaft and the screw head. It provides frictional engagement with the screw head through its distal end, creating a reliable connection during implantation while allowing controlled release afterward, thus preventing screw loss without complicating the procedure
2Reliability
If bone screws are secured to the driver with specific mating features, then the screws remain attached during implantation, but the device becomes more complex and less compatible with various screw types
Solution Approach 1:
The driver is designed with universal compatibility through the frictional engagement mechanism. The distal end of the sliding member provides a general-purpose friction interface that can accommodate different screw head types without requiring specific mating features, allowing the same driver to work with various bone fixation devices while maintaining secure attachment
Solution Approach 2:
The retention mechanism relies on frictional engagement rather than fixed geometric mating features. By changing the engagement parameter from rigid geometric matching to friction-based contact, the system achieves both reliable attachment and versatility across different screw types, simplifying the overall device design
3Reliability
If bone screws are secured to the driver, then the screws can be reliably implanted, but retrieval becomes difficult if the bone area is surrounded by a large amount of soft tissue
Solution Approach 1:
The dynamic sliding member mechanism allows the surgeon to transition from a retained state during implantation to a released state for retrieval. The activator enables easy repositioning of the sliding member to the second position, facilitating straightforward screw removal even when surrounded by soft tissue, thus resolving the retrieval difficulty while maintaining implantation security
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The assembly ensures the bone screw remains attached to the driver during implantation and can be easily released post-implantation, preventing loss and facilitating retrieval, and is compatible with various screw types due to frictional engagement rather than specific mating features.
Implementation Method 1
the distal end of the sliding member being raised up by the ramp so as to be at or above an outer surface of the mating end of the shaft to frictionally engage with an inner surface in a head of a bone fixation device
Data Source
AI summary
An apparatus can include a shaft having a mating end and a driving end and having an axial slot; a sliding member located within the axial slot; and an activator to advance the sliding member towards the mating end of the shaft; wherein the axial slot includes a surface proximate the mating end to move a distal end of the sliding member into a retaining position.