Modular Elbow Prosthesis Stem and Articulating Component
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Solution Overview
Problem
Conventional linked and unlinked elbow prostheses face challenges in assembly accuracy and cost due to the need for precise hole drilling and limited joint space, and unlinked designs have difficulties with pin removal and bearing replacement.
Innovation Solution
A modular elbow prosthesis with a stem structure and articulating component featuring C-shaped body portions, wave-like anti-rotation patterns, and a fastener system that cooperatively interlock to inhibit translation and rotation, allowing for easier assembly and potential for less bone removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional linked elbow prosthesis uses a retaining pin through a large hole drilled through the humerus, then the prosthesis components can be connected together, but the assembly cost and time increase due to high-accuracy drilling requirements and expensive tooling
Solution Approach 1:
The invention extracts the retaining pin function from a transverse configuration and relocates it to a longitudinal configuration within the ulnar stem. This allows the retaining pin to be inserted through the ulnar bone rather than requiring a large hole through the humerus, eliminating the need for high-accuracy drilling and expensive tooling while maintaining secure connection of the prosthesis components
Solution Approach 2:
The invention introduces a modular bearing component as an intermediary element between the humeral and ulnar components. This bearing component can be independently inserted and secured with a retaining pin, serving as a mediator that connects the two main components without requiring direct alignment through the humerus, thereby simplifying the assembly process and reducing costs
2Adaptability or versatility
If unlinked elbow prosthesis uses a transverse retaining pin, then the bearing components can be held together by natural soft tissues, but pin removal and bearing replacement become difficult
Solution Approach 1:
The invention segments the prosthesis into modular components (humeral component, bearing component, and ulnar stem) that can be independently accessed and manipulated. The bearing component can be independently removed from the ulnar stem by accessing it through the distal end of the ulnar stem, allowing for easy bearing replacement without removing the entire prosthesis or disturbing the soft tissue coupling
Solution Approach 2:
Instead of inserting the retaining pin transversely through the patient's arm as in conventional designs, the invention inverts the approach by inserting the retaining pin longitudinally through the distal end of the ulnar stem. This inversion allows the pin to be accessed and removed from the same distal end, making bearing replacement straightforward while maintaining the unlinked design that relies on soft tissue coupling
3Strength
If conventional elbow prosthesis requires drilling a large hole through the humerus for retaining pin insertion, then the components can be securely connected, but the procedure time and tooling costs increase significantly
Solution Approach 1:
The invention extracts the retaining pin insertion path from the humerus and relocates it to the ulnar stem. This allows the retaining pin to be inserted through the distal end of the ulnar stem without requiring a large hole through the humerus, significantly reducing assembly time and eliminating the need for expensive drilling tooling while maintaining secure connection strength through the bone-anchored ulnar stem
Data Source
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AI summary
An elbow prosthesis according to the present teachings can include a stem structure and an articulating component. The stem structure can be operable to be positioned in a bone of a joint. The stem structure can include a stem portion that is operable to be positioned in the bone and a C-shaped body portion having a first retaining mechanism formed thereon. The articulating component can have a second retaining mechanism formed thereon. One of the first and second retaining mechanisms can comprise an extension portion and a first anti-rotation portion. The other retaining mechanism can comprise a receiving portion and a second anti-rotation portion. The articulating component can be advanced from an insertion position to an assembled position, such that the first and second mechanisms cooperatively interlock to inhibit translation and rotation of the articulating component relative to the C-shaped body portion of the stem structure.