Intramedullary Nail Extractor Hook and Clamping Mechanism
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Solution Overview
Problem
Conventional intramedullary nail extractors tend to slip out of or disengage from the aperture in the nail, making it difficult to extract firmly embedded intramedullary nails from bone.
Innovation Solution
An intramedullary nail extractor with a central body, a rotatable sleeve, and a clamping member, featuring a hook with a radially offset arm and a clamping member with a high friction material or pin for secure engagement and prevention of lateral movement, ensuring reliable clamping and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional extractor tools are used, then the structure is simple, but the extractor slips out of or disengages from the aperture in the nail
Solution Approach 1:
The extractor is divided into multiple functional segments: a central body for insertion, a rotatable sleeve for actuation, and a clamping member with hook for engagement. This segmentation allows each component to perform its specific function optimally while maintaining overall reliability without excessive complexity.
Solution Approach 2:
The extractor employs dynamic elements including a rotatable sleeve that converts rotational motion into linear movement of the clamping member, and a movable hook that transitions from a retracted to an extended engaging position. This dynamic design ensures secure engagement while maintaining manageable structural complexity.
2Force
If the nail is firmly embedded in bone, then extraction requires greater force, but the extractor disengages from the aperture
Solution Approach 1:
The clamping member incorporates a high friction material on its distal end, changing the surface property parameter to increase friction between the extractor and the nail. This allows greater extraction force to be applied without disengagement, while the radial offset of the hook arm provides mechanical advantage to distribute forces effectively.
Solution Approach 2:
The hook and clamping member are combined into an integrated assembly where the hook extends through the clamping member. This merging ensures that both the aperture engagement (hook) and the frictional clamping (clamping member) work simultaneously to maintain reliable engagement under high extraction forces.
3Reliability
If the clamping member contacts the nail with high friction material, then slippage is prevented, but the device complexity increases
Solution Approach 1:
The high friction material is applied locally only to the distal end of the clamping member where contact with the nail occurs, rather than throughout the entire component. This localized application provides the necessary frictional grip while minimizing the increase in overall device complexity.
Solution Approach 2:
The clamping member uses a composite structure combining a base material with a high friction material layer on its surface. This composite approach provides enhanced gripping capability through the high friction material while maintaining the structural integrity and simplicity of the base clamping member design.
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 extractor effectively secures the intramedullary nail, preventing slippage and ensuring successful extraction by forming a firm clamping mechanism that maintains contact during the extraction process.
Implementation Method 1
The rotatable sleeve threadedly engages the threaded intermediate portion of the central body... rotating the rotatable sleeve to secure the clamping member against the intramedullary nail
Implementation Method 2
the clamping member includes a high friction material affixed to a distally facing distal end of the clamping member for contacting the intramedullary nail
Data Source
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AI summary
An intramedullary nail extractor including a central body, a rotatable sleeve and a clamping member. The central body includes a proximal end for attachment to an extractor, a distal end having a hook for engaging an intramedullary nail, and a threaded intermediate portion between the proximal end and the distal end. The rotatable sleeve threadedly engages the threaded intermediate portion of the central body, and the clamping member is operatively engaged by the rotatable sleeve and moveable relative to the central body.