Expandable Ring Disassembly Tool for Taper Lock Separation
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Solution Overview
Problem
Current modular prostheses in joint arthroplasty face challenges in securely locking and easily disengaging components, particularly due to the secure tapered connections, which require significant force to separate, and existing disengagement tools are often ineffective or risk breaking the components.
Innovation Solution
A disassembly tool with an expandable ring and threaded body is used to apply radial force, allowing the ring to expand and apply axial force, facilitating the disengagement of the taper lock between the proximal body and distal stem by breaking the ring into pieces to apply axial force, enabling easy removal without excessive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a tapered connection is used to secure the proximal body to the distal stem, then the locking strength is improved, but the difficulty of disengagement increases
Solution Approach 1:
A disengagement tool is introduced as an intermediary device to facilitate the separation of the tapered components. The tool includes a body with a tapered portion that engages with the proximal body and a ring that can be expanded to apply force against the distal stem, enabling controlled disengagement without requiring excessive force to break the tapered lock.
Solution Approach 2:
The disengagement tool is divided into functional segments: a body portion for insertion, a tapered portion for engaging the proximal body, and a separable ring for applying expansion force. This segmentation allows the tool to systematically address different aspects of the disengagement process, making the complex task of separating tapered components more manageable.
2Reliability
If a secure tapered connection is used to lock components, then the reliability of the connection is improved, but the force required for disengagement increases
Solution Approach 1:
The ring component of the disengagement tool is designed to be expandable, transitioning from a compressed state during insertion to an expanded state during disengagement. This dynamic expansion allows the tool to apply the necessary force to overcome the secure tapered connection in a controlled manner, reducing the overall force requirement compared to direct pulling methods.
Solution Approach 2:
The tapered portions of both the proximal body and distal stem, along with the corresponding tapered portion of the disengagement tool, utilize curved geometric surfaces. This curvature allows for gradual engagement and controlled force application during disengagement, distributing the force over a larger area and reducing peak stresses that would otherwise require excessive force to break the connection.
3Ease of operation
If existing disengagement tools are used to separate components, then the ease of disengagement is improved, but the risk of breaking components increases
Solution Approach 1:
The disengagement tool utilizes controlled parameter changes in the ring's expansion state. By gradually expanding the ring from a compressed to an expanded state, the tool applies force in a controlled manner that respects the structural limits of the prosthesis components, reducing the risk of breaking while maintaining ease of disengagement.
Solution Approach 2:
The design of the disengagement tool incorporates a separable ring that can be expanded to apply force, effectively cushioning the disengagement process. This expansion mechanism allows the force to be applied gradually and controlledly, preventing sudden impacts that could break the components, thereby protecting the prosthesis during the disengagement process.
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 tool allows for safe and efficient disengagement of the modular prosthesis components, reducing the risk of damage and simplifying the process, enabling surgeons to easily separate the components without applying excessive force, such as 2000 pounds, and can be used with common wrenches.
Implementation Method 1
an expandable ring surrounding a portion of the body and adapted to engage the proximal body, such that when a radial force is applied to the body, the ring expands, applying an axial force against the proximal body
Data Source
AI summary
A disassembly tool for disassembly of a first component of a prosthesis from a second component of the prosthesis for use in joint arthroplasty. The tool includes a body having an internal bore. At least a portion of the internal bore is threaded for engagement with a thread on the first component of the prosthesis. The tool further includes an expandable ring surrounding a portion of the body and adapted to engage the first component, such that when a radial force is applied to the body, the ring expands, applying an axial force against the first component.