Retaining Driver System With Cam-Actuated Undercut Engagement
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Solution Overview
Problem
Existing surgical fastener drivers, such as those for bone screws, often fail to securely retain the fasteners, leading to potential disengagement and complications like injury or damage, due to inadequate retention mechanisms that are prone to accidental knock-off or require excessive force.
Innovation Solution
The implementation of a retaining driver system with a bone screw featuring an undercut driving orifice and a retaining element that engages through an access window, utilizing a cam-actuated mechanism for secure retention and easy release, ensuring full engagement and minimizing the risk of screw knock-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a tapered tip is used for frictional engagement with the screw, then the driver can engage the screw, but it is subject to accidental knock-off
Solution Approach 1:
The retaining element transitions from a retracted state during insertion to an extended state during retention, dynamically adapting its position to provide friction engagement during insertion and positive mechanical retention during fastening. This dynamic transformation resolves the contradiction between ease of engagement and retention security.
Solution Approach 2:
The retaining element acts as an intermediary mechanism between the driver body and the screw, providing a dedicated retention function that mediates between the need for easy engagement and secure retention. The element extends to engage the undercut feature, creating a positive mechanical link that prevents knock-off while maintaining ease of operation.
2Reliability
If bone wax is used as an improvised screw holder, then the screw can be retained, but there is no guarantee of full engagement and accidental knock-off remains a risk
Solution Approach 1:
The retaining element automatically engages the undercut feature of the driving orifice through its own geometric design, eliminating the need for external materials like bone wax. The element's shape and movement are self-sufficient to provide complete engagement and secure retention, ensuring manufacturing precision without improvised solutions.
3Reliability
If threaded engagement mechanisms are used, then the screw can be retained, but they are slow to engage or disengage and are easily damaged
Solution Approach 1:
The invention extracts the retention function from complex threaded mechanisms and implements it through a simple, direct mechanical engagement system. The retaining element engages the undercut feature through a straightforward geometric interface, eliminating the complexity and slowness of threaded mechanisms while maintaining retention security and improving engagement speed.
4Reliability
If split tip drivers are used, then retention is provided, but they require high pull-out force, don't fully address knock-off potential, and have compromised torsional strength
Solution Approach 1:
The driver tip is segmented into a retaining element that can extend and retract independently from the main driver body. This segmentation allows the retaining element to provide retention through undercut engagement while the main driver body maintains full torsional strength, resolving the contradiction between retention capability and structural integrity.
5Reliability
If external sleeves such as nitinol or rubber sleeves are used, then retention is provided, but they are bulky, impede visualization, and may require manual reset between screws
Solution Approach 1:
The retaining element is nested within the driver body, extending only when needed to engage the undercut feature. This nested configuration eliminates the bulk and visualization obstruction of external sleeves while maintaining retention security. The element retracts into the driver body after use, eliminating the need for manual reset between screws.
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 positive retention of bone screws, eliminating tissue snagging and preserving visualization, allowing for kinematic engagement and release without significant force, maintaining performance even as the driver wears, and eliminating the need for manual resetting between screws.
Implementation Method 1
In some implementations, the actuating element includes a linear cam.
Data Source
AI summary
Systems and methods for providing and using improved retaining drivers and screws. An undercut feature of the bone screw allows a corresponding selectively protruding retaining feature of the driver engage the undercut feature to retain the bone screw on the driver until selectively released.