Radiolucent External Fixator with Self-Energizing Collet
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Solution Overview
Problem
Existing external fixation devices are heavy, difficult to manipulate, and not radiolucent, making them cumbersome for surgeons to use and complicating post-operative evaluation, while also requiring mechanical fasteners for adjustments that can be challenging to manage alone.
Innovation Solution
A lightweight, radiolucent external fixator with a wire clamping assembly featuring an internal conical taper and split tapered collet for self-energizing clamping, along with adjustable components optimized for CNC Swiss turning machines, allowing for easy positioning and adjustment with reduced manual effort and improved compatibility with standard wires and tensioning devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional metallic materials are used for external fixators, then strength and stability are provided, but weight increases and radiolucency is lost
Solution Approach 1:
The patent employs composite material construction for the external fixator components, combining materials that provide both mechanical strength and radiolucent properties. The frame and clamping assembly use engineered composites that maintain structural integrity while reducing weight and enabling imaging visibility, directly resolving the contradiction between strength requirements and weight/radiolucency constraints.
2Strength
If mechanical fasteners are used for adjustability, then structural integrity is maintained, but ease of operation deteriorates due to requiring two hands or assistance
Solution Approach 1:
The clamping assembly incorporates a self-adjusting mechanism where the spring-loaded collet automatically engages and secures the wire through elastic deformation and friction. This self-service design eliminates the need for manual fastening operations requiring two hands or assistant help, while the spring mechanism maintains continuous structural integrity through constant elastic force.
Solution Approach 2:
The patent replaces traditional mechanical fasteners (screws, bolts requiring tools) with a spring-elastic mechanism that uses material deformation and friction for securing. This substitution transforms the adjustment system from tool-dependent mechanical fastening to a self-actuating elastic clamping system, improving ease of operation while maintaining strength.
3Force
If heavy metallic structures are used, then clamping force is sufficient, but ease of operation worsens due to difficulty in manipulation
Solution Approach 1:
The patent optimizes the spring constant and elastic properties of the collet material to generate sufficient clamping force through controlled elastic deformation. By changing the material parameters (elastic modulus, yield strength) and geometric parameters (coil density, wire diameter) of the spring mechanism, adequate clamping force is achieved without requiring heavy metallic structures, thereby improving ease of manipulation.
4Strength
If non-radiolucent materials are used, then strength is maintained, but post-operative evaluation becomes complicated
Solution Approach 1:
The external fixator components are constructed from radiolucent composite materials that allow X-ray and other imaging techniques to penetrate and visualize the underlying bone structure. These composites incorporate imaging-transparent materials for the frame and clamping assembly, enabling clear post-operative evaluation of bone healing while maintaining necessary structural strength through engineered material properties.
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 solution provides a more manageable and effective external fixator that is easier to use, reduces the need for manual dexterity, enhances post-operative imaging, and is cost-effective, while maintaining the necessary clamping force for bone stabilization.
Implementation Method 1
There is preferably a spring element that displaces the collet forward into the taper of the main body to ensure when tension is applied to the wire the clamping elements are in the proper relationship
Implementation Method 2
The angle of the taper is acute enough that the clamping action is self energizing
Data Source
AI summary
An external fixator for mounting to a patient's leg or other anatomy to stabilize bones in the patient's leg or other anatomy includes a first ring including a first plurality a slots therein and a second ring including a second plurality of slots therein. A foot-plate has a generally U-shape and a third plurality of slots therein. A first strut is mounted between the first ring and the second ring. The first strut includes an upper tube, a lower tube, a first telescoping element securing the upper tube to the lower tube and first and second end fittings secured to ends of the upper and lower tubes, respectively. The first end fitting secures the first strut to the first ring and the second end fitting secures the first strut to the second ring.