Magnetic Field Gradient Localization for Surgical Alignment

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Solution Overview

Problem

Current methods for distal locking in intramedullary nailing, such as the freehand technique, rely heavily on fluoroscopic imaging, leading to radiation exposure for patients and surgical teams, and are time-consuming, with a steep learning curve and high complexity, necessitating a more efficient and radiation-free alignment solution.

Innovation Solution

A fully implantable wireless electronic device, ATOMS (Addressable Transmitters Operated as Magnetic Spins), generates a 3D magnetic field gradient to provide accurate 3D position information, allowing for precise alignment of locking screws in bones without fluoroscopic imaging, using a 3D magnetic Hall sensor, integrated circuit chip, and radiofrequency coil to transmit data and align surgical instruments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If fluoroscopic imaging is used for distal locking alignment, then alignment accuracy is achieved, but radiation exposure increases and surgery time increases

Engineering Contradiction:
Improvealignment accuracyVSAvoidradiation exposure
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the fluoroscopic imaging system (optical/electromagnetic system) with a magnetic field-based positioning system. Magnetic sensors detect field gradients generated by known coil configurations, providing 3D spatial information without radiation. This substitution eliminates harmful radiation exposure while maintaining alignment accuracy through magnetic field localization.

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

Solution Approach 2:

The patent introduces magnetic field gradients as an intermediary between the surgical instrument and the imaging system. Instead of directly using fluoroscopic X-rays, the system uses magnetic fields as a mediator to transmit spatial information. The magnetic sensors detect these field gradients, allowing indirect measurement of position and orientation without direct radiation exposure to bone and soft tissue.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If fluoroscopic imaging is used for distal locking alignment, then alignment accuracy is achieved, but surgery time increases

Engineering Contradiction:
Improvealignment accuracyVSAvoidsurgery time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The magnetic field-based system enables continuous real-time positioning without the intermittent nature of fluoroscopic imaging. The magnetic sensors continuously detect field gradients as the surgical instrument moves, providing uninterrupted spatial information. This continuous measurement capability eliminates the need for repeated fluoroscopic cycles, significantly reducing surgery time while maintaining continuous alignment accuracy.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system performs preliminary positioning and alignment assessment using magnetic field detection before final locking screw insertion. By pre-determining the optimal trajectory and position through magnetic sensor feedback, the surgeon can execute the final alignment more quickly and accurately, reducing overall surgery time compared to iterative fluoroscopic adjustments.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If fluoroscopic imaging system is used, then alignment capability is provided, but device complexity and learning curve increase

Engineering Contradiction:
Improvealignment capabilityVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential positioning function from the complex fluoroscopic imaging system. Instead of requiring a complete fluoroscopy suite with image processing software and radiation safety infrastructure, the system uses simplified magnetic sensors and field gradient detection. This extraction maintains alignment capability while dramatically reducing device complexity and the learning curve for surgical staff.

Inventive Principle:
Principle #2Taking out (Extraction)

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

Reduces radiation exposure and surgery time by enabling precise alignment of locking screws in a matter of seconds, improving the efficiency and safety of intramedullary nailing procedures while minimizing the need for complex equipment and expertise.

Implementation Method 1

a magnetic sensor to sense a magnetic field value at a location of the sensor

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

A magnetic field gradient is applied across a distal portion of the intramedullary nail... providing a 3D magnetic field gradient

Methodology Applied
Scientific EffectMagnetic field gradient: Magnetic Field

Implementation Method 3

a radiofrequency coil to wirelessly transmit the magnetic field value from the sensor

Methodology Applied
Scientific EffectRadiofrequency transmission: Electromagnetic Induction

Data Source

PatentEP3809987B1Surgical alignment by magnetic field gradient localization
Publication Date: 2024.02.21 CALIFORNIA INST OF TECH
  • EP3809987B1 patent drawingFigure 1
  • EP3809987B1 patent drawingFigure 2
  • EP3809987B1 patent drawingFigure 3

AI summary

A three dimensional magnetic sensor attached to a surgical nail is located based on an applied monotonic magnetic field gradient. Another three dimensional magnetic sensor locates a surgical drill. A display generates a real time image of the relative alignment of the surgical drill and of the surgical nail, allowing a surgeon to repair bone fractures.