Internal Joint Cavity Expander with Magnetic Shielding
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Solution Overview
Problem
Existing external joint braces for treating articular cartilage defects are cumbersome and require external pins, hindering daily life, and there is a need for a compact internal joint cavity expander that uses repulsive force between magnets to maintain space in the knee joint without external magnetic leakage.
Innovation Solution
An internal joint cavity expander with plate-shaped magnets and a magnetic shield member to prevent external magnetism leakage, maintaining space between the femur and tibia using repulsive force, allowing for a compact structure and secure support without hindering movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external brace with pins and magnets is used to expand the joint cavity, then the joint cavity can be expanded and the treated cartilage portion is protected, but the structure becomes large and cumbersome, hindering patients' daily life
Solution Approach 1:
The invention extracts the essential functional components (magnets and shield member) from the complex external brace structure, implanting them directly into the joint cavity. This eliminates the need for external pins, skin penetration, and bulky external structures, while retaining the joint cavity expansion function through the magnetic repulsion mechanism between the femur-side and tibia-side magnets.
Solution Approach 2:
The magnetic shield member acts as an intermediary that blocks magnetic field leakage to the external environment. It allows the internal magnets to generate sufficient repulsive force for joint cavity expansion while preventing magnetic interference with external devices and reducing the magnetic effect on surrounding tissues, thus enabling a more compact internal structure.
2Reliability
If pins are attached to bones and extend through the skin, then the joint cavity can be expanded using magnetic repulsion, but hygienic care becomes necessary and patient comfort is reduced
Solution Approach 1:
The invention completely removes the skin-penetrating pins from the system by implanting the magnets directly onto the bone surfaces within the joint cavity. The femur-side magnet is fixed to the femur and the tibia-side magnet is fixed to the tibia, eliminating the need for external pin attachments and associated hygiene problems.
Solution Approach 2:
The invention replaces the mechanical pin-and-external-magnet system with an internal magnetic repulsion system. The magnetic field acts as a non-contact force to maintain joint cavity expansion, eliminating the need for physical pin penetration through the skin and reducing mechanical stress on surrounding tissues.
3Device complexity
If a compact internal structure is used, then patient comfort and hygiene are improved, but the magnetic effect on the outside may increase
Solution Approach 1:
The magnetic shield member serves as a mediator between the internal magnets and the external environment. It is positioned between the magnets and the skin, blocking magnetic field lines from leaking outward while allowing the magnetic repulsion force to act internally between the femur-side and tibia-side magnets, thus maintaining compact structure without external magnetic interference.
Solution Approach 2:
The magnetic shield member is strategically positioned only where needed - covering the surfaces of the magnets that face the skin - while leaving other areas open for magnetic interaction. This localized shielding approach minimizes the overall magnetic effect on the outside while maintaining the compact internal structure and ensuring adequate magnetic repulsion for joint cavity expansion.
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
The internal joint cavity expander effectively maintains space between the femur and tibia using repulsive force, ensuring secure support and preventing external magnetism leakage, thus enhancing patient mobility and hygiene compared to external braces.
Implementation Method 1
the femur-side magnet and the tibia-side magnet on the left side and the right side of the knee joint are disposed so as to constantly face each other and repel each other
Implementation Method 2
The magnetic shield member prevents the magnetism of both magnets from leaking outside without hindering movement of the femur-side magnet relative to the tibia-side magnet
Data Source
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AI summary
An internal joint cavity expander 10 includes femur-side magnets 12, tibia-side magnets 18, and magnetic shield members 24. Each femur-side magnet 12 is a magnet having a plate shape curved into an arc and fixed to a femur 52. Each tibia-side magnet 18 is a magnet having a length smaller than the length of the femur-side magnet 12 and having a plate shape curved into an arc concentric with the arc of the femur-side magnet 12. Each tibia-side magnet 18 is fixed to a tibia 54. The pole disposed on the convex surface of each femur-side magnet 12 is the same as the pole disposed on the concave surface of the corresponding tibia-side magnet 18. The convex surface of each femur-side magnet 12 is disposed so as to face the concave surface of the corresponding tibia-side magnet 18. Each magnetic shield member 24 is disposed so as to cover the entirety of a surface of the corresponding femur-side magnet 12 and the corresponding tibia-side magnet 18 facing the skin throughout the range in which the femur-side magnet 12 moves relative to the tibia-side magnet 18. Each magnetic shield member 24 prevents the magnetism of the corresponding magnets 12 and 18 from leaking outside without hindering the movement of the femur-side magnet 12 relative to the tibia-side magnet 18.