Joint Prosthesis Hinge Axle Pin Segmentation for Jam Prevention
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Solution Overview
Problem
Existing joint endoprostheses with bending hinges, particularly for knee joints, are susceptible to dysfunction due to wear and disease, and their installation can be complicated by jamming of pin stubs during the expansion process.
Innovation Solution
The axial pin of the joint endoprosthesis is designed with two bearing regions and a joining region that is divided by a plane intersecting the casing at two points, allowing for wide guidance and tilting compensation, preventing jamming, and featuring complementary pin stubs with half-pegs for secure alignment, eliminating the need for separate rotation prevention mechanisms and spreading springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pin stubs are designed to be spreadable for insertion purposes, then the ease of installation is improved, but the risk of jamming during the spreading process increases
Solution Approach 1:
The axial pin is segmented into two pin stubs that can be separated from each other. This segmentation allows the pin to be inserted in a compact state and then spread into the hinge holes, facilitating easy installation while the controlled spreading mechanism prevents jamming
Solution Approach 2:
The pin stubs are designed with dynamic characteristics, allowing them to be movable relative to each other during installation. The pin stubs can be spread apart using spreading tools and then locked in position, providing both ease of installation and operational reliability
2Ease of operation
If the pin stubs are made telescopic for compact insertion, then the ease of insertion is improved, but the complexity of the pin structure increases
Solution Approach 1:
The pin is divided into two separate pin stubs that can be positioned relative to each other. This segmentation provides the telescopic functionality needed for easy insertion without requiring complex telescoping mechanisms, as the stubs can be simply moved apart and locked
Solution Approach 2:
The pin stubs are designed with preliminary positioning features such as bearing regions and joining regions that guide their relative movement. Complementary coaxial recesses are pre-formed to facilitate the telescopic movement, reducing the need for additional complex mechanisms
3Reliability
If the pin stubs are spread into aligned hinge holes, then the reliability of the connection is improved, but the difficulty of installation increases
Solution Approach 1:
The installation process utilizes dynamic spreading of the pin stubs, which can be easily separated and positioned using simple spreading tools. The stubs are spread into the aligned hinge holes and then locked in place, providing reliable connection while maintaining installation simplicity
Solution Approach 2:
Spreading tools act as intermediaries to facilitate the separation and positioning of the pin stubs. These tools enable the stubs to be spread into the hinge holes without requiring complex installation procedures, maintaining ease of installation while ensuring reliable connection
Data Source
AI summary
A joint prosthesis has a bending hinge, which is formed by a hinge fork and an axle pin, which comprises two axle stubs, which are arranged in an installation position for insertion, in which installation position the axle stubs are retracted in a coupling piece, and in an expanded position after implantation by movement in the axial direction into aligned hinge holes of the hinge fork, wherein the axle pin has two bearing areas at the ends of the axle pin and a joining area lying therebetween, and the axle pin is separated in the joining area along a plane extending in the axial direction, which plane intersects with the jacket of the axle pin at two points.