Multi-Axis Hip Implant Using Orthogonal Flat Inserts
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Solution Overview
Problem
Current orthopaedic hip implants lack a design that effectively combines rotational capabilities and retention mechanisms to mimic the natural hip joint's range of motion and stability, leading to potential dislocation issues.
Innovation Solution
The acetabular hip implant features a metal shell with a polymeric liner, and a femoral head made of metal and polymeric materials, respectively, with specific flat configurations and rotational axes to allow controlled movement and prevent dislocation, utilizing protrusions and recesses or apertures to enable rotation about specific axes while preventing movement about others, and incorporating extensions for additional retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional ball and socket joint design is used, then the hip implant provides basic rotational movement, but it lacks multi-axis rotational capability and stability control, leading to potential dislocation
Solution Approach 1:
The hip implant is divided into multiple independent rotational components: an acetabular shell component, a first insert with flats, a second insert with flats, and a femoral head component. Each component can rotate independently about a specific axis, enabling multi-axis motion while maintaining stability through controlled degrees of freedom
Solution Approach 2:
The implant uses dynamic flat configurations where the first and second inserts have flats that are orthogonal to each other, creating a mechanism that allows rotation about multiple orthogonal axes while preventing rotation about other axes. This dynamic constraint system adapts to provide stability in one direction while allowing motion in permitted directions
2Adaptability or versatility
If rotational freedom is increased to mimic natural hip joint, then the range of motion improves, but the risk of dislocation increases due to reduced stability
Solution Approach 1:
The flat-on-flat interface between inserts creates a dynamic constraint system that allows rotation about specific orthogonal axes while preventing rotation about other axes. This provides controlled freedom of motion that mimics natural hip joint mechanics while maintaining stability to prevent dislocation
Solution Approach 2:
The implant changes the parameters of rotational freedom by allowing rotation about three orthogonal axes (providing multi-axis motion) while simultaneously constraining rotation about other axes. This parameter control enables natural-like range of motion while preventing harmful dislocation movements
3Reliability
If multiple inserts with flats are used to control rotation, then rotational stability is improved, but the device complexity increases
Solution Approach 1:
The implant is segmented into modular components (acetabular shell, first insert, second insert, femoral head) that can be assembled together. Each component has a specific function and can be manufactured independently, allowing for standardized production and assembly while achieving complex rotational control
Solution Approach 2:
The first and second inserts have asymmetric flat configurations that are orthogonal to each other, creating a unique geometric constraint system. This asymmetric design provides precise rotational control about specific axes while simplifying the overall mechanism compared to symmetric multi-axis joints
Data Source
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AI summary
An acetabular hip implant includes an acetabular shell component, a first insert secured to the acetabular shell component, a second insert secured to the first insert, and a femoral head configured to be secured to the second insert. The first insert is permitted to rotate relative to the acetabular shell about a first axis, the second insert is permitted to rotate relative to the first insert about a second axis, and the femoral head is permitted to rotate relative to the second insert about a third axis.