Anchor Driver Assembly Axial Compliance Mechanism
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Solution Overview
Problem
Current anchor driver assemblies face challenges in preventing over-insertion of anchors into bone, which can lead to damage, and existing solutions often compromise ease of use due to friction and obstructive suture management.
Innovation Solution
A driver assembly with an internal spring for axial retraction of the outer shaft, coupled to a knob located on the proximal handle, allowing independent movement of the outer shaft relative to the inner shaft, and a linkage mechanism that facilitates easy rotation without friction, ensuring the sleeve is securely inserted into the bone without over-insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If visual markers (laser marks) are used to control anchor over-insertion, then the anchor can be protected from over-insertion damage, but the system becomes more complex and relies on user attention to markers that may not be visible or may be disregarded
Solution Approach 1:
The driver assembly automatically protects the anchor from over-insertion through its mechanical design. The compression spring and stop mechanism self-regulate the insertion depth without requiring external markers or user intervention. The system serves itself by using the insertion force itself to trigger the protection mechanism.
Solution Approach 2:
The compression spring is pre-loaded to provide cushioning before over-insertion can occur. The spring absorbs excess insertion energy by compressing, creating a mechanical buffer that prevents the anchor threads from contacting bone at excessive depths. This beforehand cushioning action occurs automatically during the insertion process.
2Reliability
If internal springs are used to provide axial compliance and protect the anchor from over-insertion, then the anchor is protected, but friction between the knob and handle grip makes the knob difficult to turn
Solution Approach 1:
The driver assembly is segmented into functionally independent components: the compression spring handles axial compliance and over-insertion protection, while the knob and handle grip are designed for rotational operation. This segmentation allows each component to optimize its specific function without interfering with the other, separating the axial and rotational motion paths.
Solution Approach 2:
The drive shaft acts as an intermediary between the knob rotation and the anchor insertion. It transmits rotational motion from the knob to linear insertion motion of the anchor, while the compression spring provides axial compliance independently. This intermediary mechanism decouples the rotational and axial functions, reducing friction interference.
3Reliability
If two separate screwing steps are required for the sleeve and locking plug, then the anchor system can be securely locked, but the procedure becomes more complex and time-consuming
Solution Approach 1:
The driver assembly merges the sleeve insertion and locking plug installation into a single integrated operation. The dual-knob design allows both the sleeve and locking plug to be advanced simultaneously through coordinated rotation of the knobs, reducing the number of separate steps while maintaining secure locking through the combined action of both components.
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 solution effectively protects the anchor from over-insertion damage while enhancing user comfort and ease of use, ensuring successful delivery of the sleeve into bone with reduced friction and improved control.
Implementation Method 1
An internal spring permits axial retraction of the outer shaft, which is coupled to the anchor sleeve
Implementation Method 2
the axial compliance reaction force is internal to the driver assembly
Implementation Method 3
Connection members extending along the spring create an axial stop between a drive housing and a center housing of the driver assembly
Implementation Method 4
rotation of the outer knob is not affected by friction
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Driver assemblies are configured to protect a threaded sleeve of an anchor from damage due to over-insertion. An internal spring permits axial retraction of an outer shaft coupled to the sleeve independent of the inner shaft and the handle. Connection members extending along the spring create an axial stop between a drive housing and a center housing of the driver assembly. The drive housing is allowed to travel proximally in response to axial loading against the spring, while travel distally is limited by the engagement between the connection members and receivers on the center housing.