Ball-and-Socket Joint Implant with Protrusion-Groove Motion Control
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Solution Overview
Problem
Existing artificial joint implants, particularly ball-and-socket types, face challenges in restricting movement in specific degrees of freedom to mimic natural joint functions effectively, leading to unpredictable joint behavior and increased wear.
Innovation Solution
A joint implant design featuring a ball-and-socket connection with a protrusion engaged in a groove, allowing rotation around two axes and combinations thereof, while restricting movement in at least one degree of freedom, thereby providing guided motion with reduced wear and simpler assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a ball-and-socket joint is used to provide full freedom of movement, then the joint exhibits excellent wear characteristics and high congruency, but the movement cannot be restricted in specific degrees of freedom to mimic natural joint functions
Solution Approach 1:
The joint implant is segmented into a ball head component and a socket component with distinct functional features. The ball head includes a protrusion while the socket includes a groove, creating separate functional zones that together achieve both freedom of movement and motion control through their interaction.
2Reliability
If motion restriction mechanisms are added to limit degrees of freedom, then natural joint function is mimicked, but the joint becomes more complex with additional parts requiring fastening
Solution Approach 1:
The motion restriction function is merged into the basic ball-and-socket structure by integrating the protrusion and groove features directly onto the ball head and socket components. This eliminates the need for separate motion control mechanisms while maintaining the ability to restrict specific degrees of freedom.
Solution Approach 2:
The protrusion-groove interaction serves multiple functions simultaneously: it provides motion restriction in specific degrees of freedom, guides joint movement along desired paths, and maintains structural integrity without requiring additional components. This multi-functionality reduces overall device complexity.
3Reliability
If rails and channels are used to limit movement, then movement is restricted, but the rail cannot rotate in the channel excluding an important degree of freedom
Solution Approach 1:
The protrusion-groove interface is designed to be dynamic rather than rigidly fixed. The protrusion can rotate within the groove while maintaining engagement, allowing the joint to adapt its motion characteristics based on the interaction between these two features while still providing controlled movement restriction.
Data Source
AI summary
An artificial joint implant (1) comprising a first element (2) with a socket (4) and a second element (3) with a ball head (5), wherein said ball head (5) is insertable in said socket (4) such as to form a ball-and-socket connection between said first element (2) and said second element (3), and the movement of said ball head (5) in said socket (4) is restricted by means of a protrusion (6.1; 6.2) engaged in a groove (7), whereby said protrusion (6.1; 6.2) has a central axis A2 and is protruding from the surface of said socket (4) and said groove (7) is provided on the surface of said ball head (5) or vice versa; —said groove (7) is positioned along a great circle of said ball head (5) or of said socket (4), —said protrusion (6.1; 6.2) has a shape allowing rotation of the protrusion around its central axis A2 when received in the groove (7); and—the surface roughness of the protrusion (6.1; 6.2) and/or of the groove (7) is at most 25 micrometers.