Modular Tuberosity Components for Shoulder Joint Stability
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Solution Overview
Problem
Prosthetic designs for shoulder arthroplasty often result in reduced muscle function, instability, and loss of external rotation, particularly in reverse shoulder arthroplasty, due to altered muscle tension and moment arms, which impairs patients' ability to perform daily activities.
Innovation Solution
A prosthetic device with a humeral stem, tuberosity, and modular components that modify muscle attachment locations and moment arms to increase deltoid and rotator cuff muscle tension, facilitating greater joint compression and stability, including a kit with varying tuberosity thicknesses to enhance deltoid wrapping and joint stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional prosthetic designs are used in shoulder arthroplasty, then the device structure is simple, but muscle function is reduced and joint stability is compromised
Solution Approach 1:
The prosthetic device is divided into multiple segments including a humeral stem, proximal segment, and modular tuberosity components. This segmentation allows independent optimization of each component's function while maintaining overall joint stability and muscle function.
Solution Approach 2:
The tuberosity components are positioned at specific distances (at least 20 mm) from the central longitudinal axis of the humeral stem, creating a lateral offset that increases the moment arm for deltoid muscle attachment. This dimensional change restores muscle function while maintaining structural integrity.
2Force
If the tuberosity is positioned closer to the humeral stem, then the device structure is compact, but the deltoid muscle moment arm is reduced and muscle tension is insufficient
Solution Approach 1:
The distance parameter between the tuberosity and the central longitudinal axis is specifically set to at least 20 mm. This parameter change directly increases the deltoid muscle moment arm, thereby restoring muscle tension and function without compromising device stability.
3Adaptability or versatility
If modular components are used to allow size interchangeability, then adaptability is improved, but resistance to component disengagement may be reduced
Solution Approach 1:
The device uses modular proximal segments and tuberosity components that can be independently selected and assembled. This segmentation enables adaptability to different patient anatomies while maintaining secure connections through engineered interfaces.
Solution Approach 2:
The modular components feature curved or spherical engagement surfaces that provide mechanical interlocking. This curvature design maintains resistance to disengagement while allowing for modular assembly and interchangeability of components.
Data Source
AI summary
Disclosed herein is a kit that includes a humeral stem having a central longitudinal axis, the humeral stem configured to attach to a resected bone; a first tuberosity component having a first thickness relative to the central longitudinal axis of the humeral stem; a second tuberosity component having a second thickness relative to the central longitudinal axis of the humeral stem, wherein the first thickness of the first tuberosity component is different than the second thickness of the second tuberosity component; and at least one proximal segment configured to engage at least one of the first tuberosity component and the second tuberosity component. In an embodiment, the first thickness of the first tuberosity component is at least 20 mm relative to the central axis of the humeral stem, and the second thickness of the second tuberosity component is at least 20 mm relative to the central axis of the humeral stem.