Partially Insulated Bone Screw for Precise Electrical Stimulation
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Solution Overview
Problem
Conventional methods for stimulating bone growth and tissue healing, such as using wire electrodes and screws, face issues like electrode failure, imprecise placement, energy inefficiency, and potential adverse effects due to untargeted electrical stimulation, and require complex power supplies for alternating current systems.
Innovation Solution
A system utilizing a partially insulated screw with a variable anodization layer to direct and control direct current flow, allowing precise targeting of electrical stimulation to specific areas, combined with a battery-powered DC stimulation system that conserves power and improves patient mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire electrodes are used to stimulate bone growth, then bone growth stimulation is achieved, but the electrodes are susceptible to failure requiring additional surgery and placement is imprecise causing current to pass through unnecessary areas
Solution Approach 1:
The electrode is segmented into multiple independent contact points along its length, with each segment capable of being independently activated. This allows precise targeting of specific bone regions while avoiding unnecessary areas, and if one segment fails, others continue to function, maintaining treatment reliability.
Solution Approach 2:
Different segments of the electrode are designed with varying electrical properties and contact characteristics to optimize stimulation at specific locations. The electrode structure includes insulating coatings on portions of the shaft to control current distribution, ensuring current is delivered precisely where needed in the bone tissue.
2Stability of the object's composition
If conventional screws are used for mechanical fixation, then bone immobilization is achieved, but the screws do not provide electrical stimulation capability and are prone to loosening and infection
Solution Approach 1:
The screw is designed to perform multiple functions simultaneously: it provides mechanical fixation to immobilize bone fragments and also serves as an electrode to deliver electrical stimulation for bone growth. This multi-functionality eliminates the need for separate fixation and stimulation devices, reducing surgical complexity and potential complications.
Solution Approach 2:
The screw combines conductive materials (for electrical stimulation) with mechanically strong materials (for fixation). The shaft may have conductive portions and insulating portions, creating a composite structure that integrates electrical and mechanical functions while maintaining structural integrity and resistance to loosening.
3Reliability
If alternating current is used for bone growth stimulation, then bone growth is stimulated, but complex power supplies are required
Solution Approach 1:
The system changes the electrical parameter from alternating current to direct current for bone stimulation. Direct current can be generated by simple batteries without requiring complex power supply circuits, while still achieving effective bone growth stimulation. This parameter change simplifies the overall device complexity while maintaining therapeutic effectiveness.
4Use of energy by moving object
If electrical current is applied through conventional screws, then bone stimulation is attempted, but the current is not focused on anatomical areas where it is most desired and could have adverse effects
Solution Approach 1:
The electrode screw is designed with insulating coatings on specific portions of its shaft, creating localized conductive zones that focus current delivery to specific anatomical regions. This allows precise control of current pathways to target areas needing stimulation while avoiding sensitive structures, improving energy efficiency and reducing adverse effects.
Solution Approach 2:
The insulating coating acts as an intermediary that controls and directs current flow. By strategically placing insulating material on the screw shaft, the design guides current through desired bone pathways while blocking current from entering unnecessary or potentially harmful areas, achieving focused therapeutic delivery.
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 system effectively stimulates bone growth and tissue healing with reduced energy consumption, improved precision, and minimized adverse effects, enhancing recovery and pain control while extending battery life and reducing surgical complications.
Implementation Method 1
anodization layer on its shaft provides partial insulation to control current flow
Implementation Method 2
an electrical conductor electrically connectable to the shaft for conveying current through the shaft
Data Source
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AI summary
A system for use in stimulating bone growth, tissue healing, and/or pain control is described. The system includes a screw, a battery, a controller, and means for connecting the battery such that current is routed from the battery through the screw and thence to a target area of interest requiring treatment. The screw includes an elongate shaft having a length extending between opposite ends. The shaft has an insulating coating extending along at least a portion of the length. The thickness of the insulating coating at various portions of the shaft is modulated to optimally direct current to a target area of interest requiring treatment. The controller adjusts the duty cycle of the current flow over the treatment period