Wire Cutter for Cancellous Bone Cavities
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Solution Overview
Problem
Existing methods for creating bone cavities, particularly in cancellous bones, are inadequate as they fail to effectively cut through soft tissues, hindering the migration and penetration of orthopaedic pastes, and often pose risks such as high pressure-related issues, stress concentration, and retrieval challenges with broken or entangled devices.
Innovation Solution
A wire cutter device comprising a restrainer and an elastic wire with a driver, which creates a cavity by rotating to protrude the wire into the bone, allowing for controlled cutting and easy retrieval, using a biocompatible metallic wire with sufficient strength and elasticity to break soft tissue networks without fracturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an inflatable balloon structure is used to create bone cavity, then the device can expand to create space, but it lacks sufficient cutting ability to break soft tissue networks and has poor lift capability
Solution Approach 1:
The patent extracts the cutting function from the expansion function by introducing a separate cutting wire that protrudes from the balloon surface. This wire is specifically designed to cut soft tissue networks while the balloon provides cavity expansion, allowing both functions to operate independently and effectively.
Solution Approach 2:
The balloon structure is designed to serve multiple functions: it expands to create cavity space, provides a mounting surface for the cutting wire, and enables controlled tissue disruption. The cutting wire itself serves dual purposes by both cutting soft tissues and creating initial pathways for paste injection.
2Quantity of substance
If high pressure fluid is used to expand the balloon, then the cavity can be created effectively, but high pressure-related risks increase in clinical procedures
Solution Approach 1:
The cutting wire performs preliminary action by cutting soft tissue networks before paste injection. This pre-cutting creates pathways that reduce the resistance to paste flow, allowing for effective cavity filling at lower pressures and thereby reducing high pressure-related clinical risks.
3Quantity of substance
If a rigid structure is used to expand the cavity, then the cavity creation is effective, but stress-concentrated spots and fresh cracks are generated in the fractured bone
Solution Approach 1:
The patent employs a flexible balloon structure instead of rigid expanders. This flexible membrane distributes expansion forces uniformly across the bone cavity walls, avoiding stress concentration points and preventing fresh cracks in already fractured or osteoporotic bone while still achieving effective cavity creation.
4Device complexity
If a non-inflated linear filler tool is used to expand bone cavity, then the device can be simple, but retrieval becomes extremely difficult if the filler breaks or becomes entangled
Solution Approach 1:
The cutting wire is nested within or attached to the balloon structure in a controlled manner. The wire protrudes from the balloon surface in a predetermined configuration, allowing it to be deployed effectively for cutting while maintaining a controlled attachment that facilitates retrieval if needed, unlike freely moving linear fillers.
5Quantity of substance
If prior art cavity creation devices are used, then cavity expansion is achieved, but they lack the function of cutting into the cancellous portion of bone to facilitate paste penetration
Solution Approach 1:
The patent segments the cavity creation process into distinct functional components: the balloon handles cavity expansion while the cutting wire handles soft tissue disruption. This segmentation allows each component to be optimized for its specific function, with the wire creating channels through cancellous bone and soft tissues to facilitate paste penetration while the balloon provides the necessary cavity volume.
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 device enables efficient creation of bone cavities by breaking soft tissue networks, facilitating the injection of orthopaedic pastes and ensuring safe, accurate, and reliable procedures, particularly in fractured or osteoporotic bones, while minimizing risks associated with prior methods.
Implementation Method 1
an elastic wire with a driver, which creates a cavity by rotating to protrude the wire into the bone
Implementation Method 2
allowing for controlled cutting and easy retrieval, using a biocompatible metallic wire with sufficient strength and elasticity to break soft tissue networks
Data Source
Figure 1
Figure 2
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AI summary
A wire cutter suitable for creating a cavity in cancellous bone includes a restrainer and a cutting wire, wherein a portion of the cutting wire will protrude from a slot formed on the restrainer to the outside of the restrainer and inside a bone, when the cutting wire is advanced in a tunnel formed in the restrainer and toward a closed end of the tunnel.