Variable Angle Humeral Tray Axial Adjustment Mechanism
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Solution Overview
Problem
Current reverse shoulder prostheses lack the ability to adjust the angle of the humeral tray relative to the humeral stem, limiting the surgeon's flexibility during surgical procedures and potentially compromising the stability and fit of the prosthesis.
Innovation Solution
A variable angle tray system is introduced, featuring a plate with a through hole and a variable angle stem that can be axially repositioned, including washers and a pin mechanism to secure the components, allowing for adjustable axial positioning and locking of the tray relative to the humeral stem.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed angle humeral tray is used, then the device complexity is reduced, but the adaptability to different surgical conditions deteriorates
Solution Approach 1:
The humeral tray incorporates a variable angle mechanism that allows the tray to be adjusted between different angular positions (e.g., 0 degrees and 45 degrees) relative to the humeral stem. This dynamic adjustment capability enables the tray to adapt to different surgical conditions and patient anatomies while maintaining a relatively simple overall device structure through controlled movement rather than multiple fixed components.
Solution Approach 2:
The tray assembly is divided into separable components including the humeral stem, the tray body, and an angle adjustment mechanism. This segmentation allows the angle adjustment function to be isolated in a specific module that can be operated independently, providing adaptability without requiring the entire device to be complex. The segmented design enables straightforward assembly and disassembly while maintaining adjustability.
2Adaptability or versatility
If a variable angle tray mechanism is added, then the adaptability improves, but the ease of operation deteriorates
Solution Approach 1:
The angle adjustment mechanism is pre-configured with stop positions and guide features that automatically align components during assembly. The tray includes pre-formed angular orientations that can be directly engaged without requiring complex manipulation, allowing surgeons to quickly select and lock into predetermined angles rather than performing complex adjustment procedures during surgery.
Solution Approach 2:
The variable angle mechanism incorporates self-aligning features such as tapered surfaces, cam profiles, and automatic locking positions that guide the assembly process and maintain proper angular relationships without requiring precise manual intervention. The design allows the tray to self-lock at selected angles through simple actuation, reducing the operational burden on the surgeon while maintaining ease of assembly.
3Manufacturing precision
If the tray angle is fixed, then the manufacturing precision requirements are reduced, but the fit and stability in different positions deteriorate
Solution Approach 1:
The tray design incorporates adjustable angular parameters that can be modified during implantation to match the specific anatomical requirements of each patient. By changing the angular parameter of the tray relative to the humeral stem, the system achieves optimal fit and stability for different surgical scenarios without requiring extremely high manufacturing precision for each individual angle configuration. The mechanism allows post-manufacturing adjustment of the critical angular parameter.
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 surgeon's ability to customize the angle of the humeral tray, improving the fit and stability of the prosthesis, thereby facilitating more precise and effective surgical implantation and post-operative function.
Implementation Method 1
the appendage is sized to be received by the humeral stem via a friction fit
Implementation Method 2
a pin including a threaded head and a longitudinal shaft extending from the threaded head, the pin being insertable into the first opening, where the threaded head is sized to engage the threads of at least one of the first washer and the post
Data Source
AI summary
A partial reverse shoulder prosthesis includes a humeral stem and a variable angle tray including a plate including a through hole including at least two cutouts oriented horizontally across from one another, and a repositionable variable angle stem occupying at least a portion of an internal cavity defined by the through hole and including a first washer including threads at least partially defining a first opening, a post at least partially occupying the internal cavity, and a pin insertable into the first opening and having a threaded head sized to engage the threads of at least one of the first washer and the post; wherein the wall of the internal cavity is sized to retain the first washer and at least a portion of the post.