Intramedullary Device With Shape Memory Barbs
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Solution Overview
Problem
Current intramedullary devices fail to consistently bring bone fragments into close proximity and maintain compressive load over a prolonged period, leading to suboptimal healing outcomes due to rapid dissipation of compressive force as the bone relaxes and remodels, and lack of sufficient torsional stability.
Innovation Solution
The development of intramedullary devices made from shape memory materials like Nitinol or PEEK, featuring barbed ends that flare outward to engage the intramedullary canal's circumference, providing enhanced torsional stability and a mechanism to maintain compressive load through shape memory properties, allowing for secure fixation and controlled compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional intramedullary devices with coplanar legs are used, then initial compression between bone fragments is achieved, but the compressive load dissipates rapidly as the bone relaxes and remodels
Solution Approach 1:
The device employs a dynamic mechanism where the distal end can rotate relative to the proximal end about a transverse axis, allowing the barbed distal end to progress from an initial position away from the bone surface to a final position in engagement with the bone surface. This dynamic adjustment enables the device to maintain compressive load despite bone relaxation and remodeling over time.
Solution Approach 2:
The device changes the angular parameter of the distal end relative to the proximal end through rotation, transforming the geometric configuration to maintain effective compression. By adjusting the angle between the proximal and distal ends, the device compensates for bone relaxation and maintains the compressive force throughout the healing period.
2Stability of the object's composition
If traditional intramedullary devices with coplanar legs are used, then insertion into the intramedullary canal is achieved, but sufficient torsional stability is not provided to the fusion site
Solution Approach 1:
The device transitions from a simple coplanar leg structure to a three-dimensional configuration where the distal end can rotate about a transverse axis perpendicular to the longitudinal axis of the device. This dimensional change allows the barbed distal end to engage the bone surface in a manner that provides torsional stability, preventing rotation around the longitudinal axis of the device.
Solution Approach 2:
The device introduces asymmetry by allowing the distal end to rotate to a specific engagement position where the barbs contact the bone surface. This asymmetric positioning of the distal end relative to the proximal end creates a mechanically stable configuration that resists torsional forces, as the barbed engagement creates a preferred orientation that must be overcome for rotation to occur.
3Length of moving object
If devices with barbed ends are used to grip the intramedullary canal wall, then compression between bone fragments is generated, but the bone fragments are not brought into sufficiently close proximity
Solution Approach 1:
The dynamic rotation of the distal end allows progressive approximation of the bone fragments. As the distal end rotates into engagement with the bone surface, it pulls the distal bone fragment closer to the proximal bone fragment, thereby reducing the gap between fragments while simultaneously maintaining compressive force through the barbed engagement.
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
These devices effectively bring bone fragments into close contact, maintain compressive load for extended healing periods, and offer improved torsional stability, accelerating the healing process by ensuring consistent pressure distribution and preventing motion between bone fragments.
Implementation Method 1
devices made from shape memory materials like Nitinol or PEEK, featuring barbed ends that flare outward to engage the intramedullary canal's circumference
Data Source
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AI summary
An apparatus for securing a first bone fragment to a second bone fragment, wherein the apparatus comprises a fusion device, wherein the fusion device comprises a shaft having a first end and a second end; a first bone-engaging feature formed on the shaft at a first location, wherein the first bone-engaging feature includes at least one barb that may be advanced along with the first shaft into a hole in the first bone fragment; and a second bone-engaging feature formed on the shaft at a second location, wherein the second bone- engaging feature includes at least one barb that may be advanced along with the second shaft into a hole in the second bone fragment. The first and second ends of the shaft are prevented from being withdrawn from the respective holes in the first and second bone fragments when the corresponding barbs are in an unbiased condition.