Total Wrist Prosthesis Using Segmented Ball-and-Socket Design
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Solution Overview
Problem
Existing prosthetic wrists for total wrist replacement procedures often provide limited range of motion, are prone to dislocation, and result in poorly aligned joints, leading to complications such as infections and premature wear.
Innovation Solution
A wrist prosthesis comprising three separate components - a radial component, a lunate component, and a carpal component - designed to restore wrist function by providing a wide range of motion. The radial component has a semi-spherical concave bearing surface, the lunate component is manufactured from ultrahigh-molecular-weight polyethylene, and the carpal component is made from a high-quality surgical-grade metallic alloy, ensuring self-lubrication, durability, and proper alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a total wrist replacement prosthesis is implemented, then wrist function and range of motion are restored, but the prosthesis is prone to dislocation and premature wear
Solution Approach 1:
The radial component features a spherical bearing surface and the carpal component has a corresponding spherical geometry, creating a ball-and-socket joint configuration. This spherical design allows for multi-directional movement approximating natural wrist motion while maintaining stable articulation that resists dislocation through the geometric interlocking of the spherical surfaces.
Solution Approach 2:
The prosthesis employs different materials for different components: the radial component is made from a metallic alloy providing structural strength and durability, while the carpal component uses ultrahigh-molecular-weight polyethylene providing self-lubricating properties and wear resistance. This composite material approach optimizes both range of motion and reliability by selecting materials that complement each other's functional requirements.
2Ease of manufacture
If existing prosthetic wrists are used, then wrist replacement is achieved, but joint alignment is poor leading to infections and complications
Solution Approach 1:
The alignment system incorporates visual indicators including colored markers and reference points that allow the surgeon to visually confirm proper alignment of the prosthesis components with the anatomical landmarks of the radius and carpal bones. These visual cues enable precise positioning and alignment during the implantation procedure without requiring complex alignment tools.
3Reliability
If wrist fusion procedures are performed, then pain is alleviated, but range of motion is greatly restricted
Solution Approach 1:
The wrist prosthesis is divided into three separate components: a radial component that replaces the distal radius articular surface, a lunate component that replaces the lunate bone, and a carpal component that replaces the proximal carpal row. This segmented design allows each component to be independently positioned and optimized for function, enabling preservation of wrist motion while providing pain relief through replacement of damaged surfaces.
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 described wrist prosthesis achieves a range of motion approximating that of a healthy wrist, provides long-lasting support, and minimizes complications such as dislocation and premature wear, thereby enhancing the quality of life for patients by maintaining wrist functionality.
Implementation Method 1
the lunate component is manufactured from ultrahigh-molecular-weight polyethylene, and the carpal component is made from a high-quality surgical-grade metallic alloy, ensuring self-lubrication, durability, and proper alignment
Data Source
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AI summary
A wrist prosthesis comprising an elongated radial component having two opposite sides, the first side comprising a stem and the second side comprising a concave dish; an elongated carpal component having two opposite sides, the first side comprising a stem, and the second side comprising a ball end; a lunate component having two opposite sides, the first side comprising a cavity adapted to receive said carpal component's ball end and the second side comprising a convex surface adapted to engage said radial component's concave dish; wherein said lunate component freely rotates and swivels with respect to both of said carpal and radia components; wherein said stem of said carpal component is adapted for rigid engagement with one or more carpal and/or metatarsal bones; and wherein said stem of said radial component is adapted for rigid engagement with a radius bone.