Magnetic Feedback for Non-Invasive Adjustable Spinal Implants

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Solution Overview

Problem

Current treatments for scoliosis, such as fusion surgery and bracing, often result in limited spinal flexibility, pain, and complications like infection, while existing distraction devices for bone lengthening are cumbersome and ineffective in managing scoliosis progression.

Innovation Solution

An external adjustment device that uses a magnetic system to non-invasively control the distraction or compression of medical implants, allowing for precise adjustment of spinal curvature or bone lengthening without the need for invasive procedures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If fusion surgery is performed to treat scoliosis, then spinal stability is improved, but spinal flexibility is reduced and pain occurs

Engineering Contradiction:
Improvespinal stabilityVSAvoidspinal flexibility
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The patent applies the dynamics principle by replacing static fusion constructs with a dynamic, adjustable implant system. The implant includes an adjustable length rod connected to vertebral bodies via bone anchors, allowing the spinal curvature to be dynamically corrected and the implant length adjusted non-invasively over time using magnetic fields, thereby maintaining spinal flexibility while achieving stability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by enabling continuous adjustment of the implant's effective length and magnetic field strength. The external magnet can be positioned at different distances from the implant to vary the magnetic force, and the implant itself can be adjusted to different lengths, allowing precise control over the corrective force applied to the spine without surgical intervention.

Inventive Principle:
Principle #35Parameter changes

2Length of moving object

If traditional distraction devices are used for bone lengthening, then bone growth is achieved, but the devices are cumbersome and require invasive procedures

Engineering Contradiction:
Improvebone lengthVSAvoiddevice simplicity
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical distraction devices with a magnetic field-based adjustment system. Instead of requiring mechanical components, gears, or manual surgical adjustments, the implant is controlled remotely through magnetic fields generated by an external magnet, significantly simplifying the device architecture while maintaining the bone lengthening function.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the external controller and the implanted device. The magnetic field serves as the transmission medium for delivering corrective force to the implant without direct mechanical contact or invasive procedures, enabling non-invasive adjustment of the bone lengthening process.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If adjustable implants are made non-invasively controllable, then patient compliance improves, but precise control becomes difficult to achieve

Engineering Contradiction:
Improvepatient complianceVSAvoidcontrol precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements feedback by incorporating sensors within the implant that detect the position and orientation of the external magnet. This feedback information is used to automatically adjust the magnetic field strength and direction, ensuring precise control of the implant's corrective action while allowing patients to independently operate the device without requiring complex manual adjustments.

Inventive Principle:
Principle #23Feedback

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

This device enables controlled and safe adjustment of spinal curvature or bone lengthening, reducing pain and complications, and improving patient compliance and treatment efficacy for scoliosis and other bone-related disorders.

Implementation Method 1

an array of magnetic sensors, such as Hall effect sensors, to receive information about the changing magnetic field characteristics

Methodology Applied
Scientific EffectMagnetic field interaction: Magnetic Field

Implementation Method 2

The magnet array is configured to determine a gap between the external adjustment device and the adjustable medical implant

Methodology Applied
Scientific EffectMagnetic coupling: Magnetism

Implementation Method 3

an array of magnetic sensors, such as Hall effect sensors, to receive information about the changing magnetic field characteristics

Methodology Applied
Scientific EffectHall effect: Hall Effect

Data Source

PatentEP3137000B1System for informational magnetic feedback in adjustable implants
Publication Date: 2023.08.23 NUVASIVE SPECIALIZED ORTHOPEDICS INC

AI summary

According to some embodiments, systems and methods are provided for non-invasively detecting the force generated by a non-invasively adjustable implantable medical device and/or a change in dimension of a non-invasively adjustable implantable medical device. Some of the systems include a non-invasively adjustable implant, which includes a driven magnet, and an external adjustment device, which includes one or more driving magnets and one or more Hall effect sensors. The Hall effect sensors of the external adjustment device are configured to detect changes in the magnetic field between the driven magnet of the non-invasively adjustable implant and the driving magnet(s) of the external adjustment device. Changes in the magnetic fields may be used to calculate the force generated by and/or a change in dimension of the non-invasively adjustable implantable medical device.