Bone Anchor Extension Device with Spring-Loaded Coupling
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Solution Overview
Problem
In minimally invasive surgery, existing extension devices for bone anchors face challenges in efficiently attaching receiving parts to implanted screws, guiding stabilization rods, and breaking off extension tabs while minimizing space occupation and ensuring reliable handling and assembly.
Innovation Solution
The extension device features elongate shafts with coupling portions and a spring element that exerts a compression force along a longitudinal axis, allowing secure engagement and snap-on attachment of receiving parts without rotational movement, and includes removable extension tab portions for guiding and fixing stabilization rods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing extension devices use rotational movement or lateral snapping to attach receiving parts, then attachment can be achieved, but tactile feedback is poor and misalignment may occur
Solution Approach 1:
Instead of using lateral snapping or rotational movement to attach the receiving part, the patent inverts the approach by using longitudinal compression force applied along the longitudinal axis. The spring element pushes the engagement portions together in the same direction as the receiving part is inserted, providing intuitive tactile feedback and preventing misalignment.
Solution Approach 2:
The patent changes the directional parameter of the attachment force from lateral or rotational to longitudinal. By applying compression force along the longitudinal axis through the spring element, the engagement portions are urged in mutually opposite directions towards each other, creating reliable attachment with clear tactile feedback matching the insertion direction.
2Ease of operation
If extension devices occupy more space to facilitate assembly tasks, then handling ease improves, but space occupation increases which is undesirable in minimally invasive surgery
Solution Approach 1:
The extension device integrates multiple functions into a single compact structure: the tabs with engagement portions attach to the receiving part, the elongate shafts guide the stabilization rod, and the spring element provides attachment force. This multi-functionality allows the device to perform multiple tasks without requiring additional space-occupying components.
Solution Approach 2:
The patent merges the attachment mechanism, guidance function, and fixation elements into a single integrated extension device. The tabs, shafts, and spring element work together as one unit, eliminating the need for separate tools or devices for each function, thereby reducing overall space occupation while maintaining ease of operation.
3Strength
If engagement portions are designed for secure clamping, then attachment strength improves, but device complexity increases
Solution Approach 1:
The spring element automatically exerts compression force to urge the engagement portions towards each other when the receiving part is inserted. This self-actuating mechanism secures the attachment without requiring additional actuators, motors, or complex control systems, thereby maintaining attachment strength while minimizing device complexity.
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
This solution enhances the ease and reliability of attaching receiving parts to bone anchors, facilitates the handling of stabilization rods, and improves the tactile feedback during assembly, reducing the risk of misalignment or hindrance in minimally invasive procedures.
Implementation Method 1
A spring element is provided at the coupling portion to exert a compression force onto the receiving part to urge the engagement portions in mutually opposite directions towards each other
Data Source
AI summary
An extension device for a bone anchor includes at least one tab, which includes an elongate shaft portion that forms part of a channel for providing a stabilization rod to a rod receiving recess of a receiving part of the bone anchor, and a coupling portion, which is provided at a distal end of the elongate shaft portion and which is configured to be coupled to the receiving part. The coupling portion includes a first engagement portion for engaging a first engagement face of the receiving part and a second engagement portion for engaging a second engagement face of the receiving part. A spring element is provided at the coupling portion, the spring element exerting a compression force to urge the first and second engagement portions in mutually opposite directions towards each other and towards the corresponding first and second engagement faces along a longitudinal axis defined by the extension device and the receiving part when being coupled together.