Active Hip Disarticulation Prosthesis With Compact Double Parallelogram
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Solution Overview
Problem
Existing hip disarticulation prostheses with a remote center of rotation are bulky, protrude forward, require a second passive joint for stability, and are uncomfortable for sitting, while passive prostheses fail to replicate normal biomechanical functions.
Innovation Solution
A system with an angled planar double parallelogram mechanism, an actuator, and a unique anchoring element that positions the remote rotation center close to the hip natural center, allowing for a compact design that fits within the user's natural leg volume, provides a comfortable sitting position, and reduces the need for a second passive joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the double parallelogram mechanism is joined on the front of the receiving shell close to its edge to place the remote rotation center close to the hip natural center of rotation, then the remote center of rotation is positioned accurately, but the mechanism protrudes forward the user's body leading to unaesthetic aspect and increased bulk
Solution Approach 1:
The patent repositions the anchoring element from the front edge of the receiving shell to the rear side, utilizing the depth dimension of the shell. This spatial relocation allows the double parallelogram mechanism to be integrated without protruding forward, while still achieving the required remote rotation center position through the angled configuration of the mechanism links.
Solution Approach 2:
The patent employs an asymmetric angled configuration of the double parallelogram mechanism links, where the common links are positioned at specific angles relative to the singular links. This asymmetric arrangement optimizes the spatial distribution of the mechanism, allowing it to fit within the receiving shell volume while maintaining the remote rotation center position.
2Stability of the object's composition
If a second passive joint is added to provide constraints and supports for stability in the stance phase, then stability is improved, but the structure becomes more complex and provides discomfort when the user is sitting
Solution Approach 1:
The patent designs the anchoring element to serve multiple functions: it provides the unique connection between the femoral segment and receiving shell, establishes the remote rotation center position, and provides stability constraints during the stance phase. This multi-functional design eliminates the need for a separate second passive joint, reducing structural complexity while maintaining stability.
Solution Approach 2:
The patent merges the functions of the anchoring element and the stability constraint mechanism into a single integrated structure. The anchoring element is configured to provide both the connection function and the stability function through its geometric configuration and orientation, eliminating the need for additional separate components.
3Adaptability or versatility
If the double parallelogram mechanism is positioned to provide remote rotation center close to hip natural center, then gait functionality is improved, but clearance under the shell is reduced making sitting uncomfortable
Solution Approach 1:
The patent utilizes the vertical and depth dimensions of the receiving shell to position the double parallelogram mechanism. By anchoring at the rear side and configuring the links at specific angles, the mechanism is positioned in the upper portion of the shell volume, preserving clearance in the sitting direction while maintaining the required remote rotation center position for gait functionality.
Data Source
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AI summary
The present invention relates to a system (100) for an external hip disarticulation prosthesis comprising an angled planar double parallelogram mechanism, an actuator (60) configured to fold the double parallelogram mechanism and a femoral stem (50) fixed to the double parallelogram mechanism and configured to rotate around a remote rotation center (40), the double parallelogram mechanism comprising an anchoring element (30) configured to provide a unique connection with a receiving shell (400).