Expandable Joint Implant for CMC Arthroplasty
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Solution Overview
Problem
Current treatments for arthritic degeneration in the carpometacarpal joint, such as CMC joint arthroplasty, often result in anatomical deformation and prolonged rehabilitation periods, and existing implant solutions do not adequately address the need for tissue repair and stabilization while maintaining joint mobility.
Innovation Solution
An expandable, biodegradable implant device with a smooth surface and passages for fibrotic development is used between small bones, which can be inflated to cushion and stabilize the joint, promoting tissue repair and allowing for early rehabilitation by conforming to bony surfaces and maintaining joint mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If CMC joint arthroplasty is performed, then joint mobility is maintained, but anatomical deformation occurs
Solution Approach 1:
The implant device is segmented into multiple functional components: a first portion with a first smooth surface for articulation with one bone, a second portion with a second smooth surface for articulation with another bone, and intermediate tissue for biological integration. This segmentation allows each component to perform its specific function while maintaining overall joint mobility and preventing anatomical deformation.
Solution Approach 2:
Different portions of the implant device have different surface properties tailored to their specific functions. The first and second smooth surfaces provide low friction for bone articulation and mobility, while the intermediate tissue provides biological integration and stability. This local differentiation of properties resolves the contradiction between maintaining mobility and preventing deformation.
2Stability of the object's composition
If traditional implant solutions are used, then joint stabilization is achieved, but tissue repair is insufficient
Solution Approach 1:
The intermediate tissue acts as a mediator between the implant device and the surrounding bone tissue. This intermediate layer promotes biological integration, facilitates tissue repair, and ensures reliable biological fixation while the smooth surfaces provide mechanical stabilization. The intermediary tissue resolves the contradiction by enabling both stabilization and tissue repair simultaneously.
3Stability of the object's composition
If rigid fixation is used, then joint stability is improved, but rehabilitation period is prolonged
Solution Approach 1:
The implant device transitions from an initial rigid stabilization phase to a dynamic rehabilitation phase. The smooth surfaces provide initial stability for healing, while the intermediate tissue progressively integrates with surrounding structures, enabling controlled motion and early rehabilitation. This dynamic progression resolves the contradiction between stability and rehabilitation time.
4Reliability
If joint fusion is achieved, then complete bone fusion occurs, but joint mobility is lost
Solution Approach 1:
The implant device creates localized fusion at the intermediate tissue interface while maintaining mobility at the smooth surface articulation interfaces. This local differentiation allows complete bone fusion to occur where needed for stability while preserving joint mobility where required for function, resolving the contradiction between fusion and mobility.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 2C~2D
AI summary
A soft, expandable, implantable device sized for spacing between small bones comprising a first smooth surface on which a first small bone may slide. Implant (700) includes an opening (704) (passage) extending through the device for promoting fibrotic development through the opening from a direction from both thumb metacarpal (202) and trapezium (204). Passage (704) is optionally distally positioned from a one-way inflation valve (706) included inside an inflation port (702) substantially limiting possible damage to the device due to the insertion pressure of an expansion fluid. An inflation cannula and/or needle may be attached to inflation port (702) and inflation valve (706) for introducing the expansion fluid into the device. Implant (700) is inserted in a deflated mode and is positioned so that thumb metacarpal (202) abuts distal side (703) of the device when expanded and trapezium (704) abuts proximal side (701). Both distal side (703) and proximal side (701) include a smooth surface for allowing relative movement of thumb metacarpal (202) and trapezium (204) with respect to device (700).