Self-Retaining Bone Screw Driver With Active Engagement Mechanism
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Solution Overview
Problem
Conventional self-retaining bone screwdrivers often experience unintentional disengagement due to passive retaining mechanisms, which is unacceptable in surgical settings where bone screws could be lost, and active mechanisms are cumbersome or require excessive force.
Innovation Solution
A bone screw and self-retaining driver system with an active engagement mechanism, featuring a tubular outer shaft with a tri-lobe tip that mates with the screw head and an internal rod with a threaded tip that securely engages with the screw, allowing for precise placement and advancement of the screw without manual holding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive retaining mechanisms are used in bone screwdrivers, then the device structure is simple, but the reliability of screw retention is poor leading to unintentional disengagement
Solution Approach 1:
The patent applies the dynamics principle by implementing an active engagement mechanism where the inner shaft can dynamically adjust its position relative to the outer shaft. The inner shaft is movable within the outer shaft and can be rotated to engage or disengage from the bone screw, transforming a static passive retention system into a dynamic active retention system that reliably secures the screw during insertion
Solution Approach 2:
The patent applies the nesting principle by placing the inner shaft within the outer shaft, creating a compact two-shaft structure. The distal end of the inner shaft with external threading is nested inside the tubular outer shaft, allowing the smaller engagement component to be contained within the larger structural component, achieving space-efficient design with enhanced retention capability
2Reliability
If active retaining mechanisms are used in bone screwdrivers, then the reliability of screw retention is improved, but the device becomes cumbersome and requires excessive force to operate
Solution Approach 1:
The patent applies the segmentation principle by dividing the driver into two independent functional shafts: the outer shaft that provides structural support and torque transmission, and the inner shaft that provides active retention through threading engagement. This segmentation allows each component to be optimized for its specific function, maintaining ease of operation while achieving reliable retention
Solution Approach 2:
The patent applies the intermediary principle by using the threaded distal end of the inner shaft as a mediating engagement element between the driver and the bone screw. This threaded intermediary component facilitates smooth engagement and secure retention without requiring excessive force, acting as a buffer that enables reliable connection while maintaining operational ease
3Ease of operation
If a magnetized driving bit is used to hold the screw, then the screw can be initially held inline, but the holding power is poor and the screw can easily tilt or disengage
Solution Approach 1:
The patent applies the mechanics substitution principle by replacing the magnetic field-based retention system with a mechanical threading engagement system. Instead of relying on magnetic attraction that provides insufficient holding power, the inner shaft's external threading mechanically engages with the bone screw's internal threading, providing superior mechanical retention that prevents tilting and disengagement while maintaining alignment ease
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 system provides a compact, easy-to-use active engagement mechanism that securely attaches the screw to the driver, preventing disengagement during screw insertion into bone fragments, allowing for precise placement and reducing bone fracturing.
Implementation Method 1
A distal end of this inner rod can include a male threaded tip... the threaded tip at the distal end of the inner rod is exposed out of an opening defined in the center of the tri-lobed tip of the outer shaft of the driver... a user holding the bone screw can rotate the thumbwheel to cause the threaded tip of the inner rod to engage with, and secure to, a corresponding threaded shaft defined in the head of the screw
Implementation Method 2
the tip at the distal end of the outer shaft can be shaped to mate or engage with a head of the bone screw. In one example, the bone screw head can define a tri-lobe recess area into which a correspondingly shaped tri-lobe of the outer shaft of the driver can be inserted. This construction allows the bone screw to be rotationally torqued by the tip of the outer shaft when the tip is engaged with the screw head
Data Source
AI summary
Techniques disclosed herein include systems and methods for a bone screw and self-retaining driver. The system includes a mechanism that enables a bone screw to be rigidly attached to a screwdriver for manipulation and transfer of bone fragments and grafts to a fixation site, such as during surgery. The system includes a cannulated bone screw that has a drive connection that engages with a drive structures of a screwdriver. The bone screw also includes a structural connector that securely attaches to or receives an internal shaft or rod of the screwdriver. The internal shaft or rod of the screwdriver can rotate and slide independent of an outer shaft of screwdriver. Accordingly, the internal shaft of the screwdriver can rigidly connect with the bone screw enabling applied torque to the screwdriver to be transferred to the bone screw, without the bone screw falling off of the drive connection.