Magnetic Sensor Array for Bone Registration in Orthopaedic Surgery

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Solution Overview

Problem

Current computer-assisted orthopaedic surgery (CAOS) systems face challenges in efficiently registering bony anatomy due to difficulties with fiducial markers and anatomical planes, particularly in minimally invasive procedures, which increases surgery time and exposure to infection.

Innovation Solution

A magnetic sensor array comprising a substrate with a central three-dimensional magnetic sensor and multiple one-dimensional sensors, capable of measuring the magnetic field generated by magnets implanted in the bone, allowing for precise determination of the magnetic source's position and orientation, and transmitting this data to a CAOS system for accurate image rendering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a typical registration process using a probe to touch bone locations is used, then the bone can be registered with the CAOS system, but the surgery time increases and patient exposure to infection increases

Engineering Contradiction:
Improvebone registration accuracyVSAvoidsurgery time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical probe-based registration system with a magnetic field-based registration system. Magnets are implanted in the bone, and magnetic sensors detect their positions to automatically determine bone geometry and orientation, eliminating the need for manual probing and significantly reducing surgery time while maintaining registration accuracy

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

Solution Approach 2:

The magnets are implanted into the bone before the surgical procedure begins. This preliminary placement of magnetic markers allows the bone registration to be performed automatically at the start of the procedure without requiring time-consuming manual measurement during the surgery itself

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If fiducial markers and anatomical planes are used for bone registration, then the CAOS system can determine bone contour and orientation, but the registration becomes challenging and time-consuming

Engineering Contradiction:
Improvebone contour and orientation determinationVSAvoidregistration process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical probe-based registration with automatic magnetic field detection. The magnetic sensors detect the magnetic field signatures of implanted magnets, automatically calculating bone contour and orientation without requiring complex manual procedures or fiducial markers, thereby simplifying the overall registration process

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

Solution Approach 2:

The patent introduces magnets as intermediary elements implanted in the bone. These magnets serve as detectable markers that mediate between the bone structure and the magnetic sensors, enabling automatic detection of bone geometry and orientation without direct mechanical interaction or complex fiducial marker systems

Inventive Principle:
Principle #24Intermediary (Mediator)

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 magnetic sensor array reduces surgery time by providing accurate and efficient registration of bony anatomy, minimizing exposure to infection, and improving the precision of image rendering in orthopaedic procedures.

Implementation Method 1

measuring the magnetic field generated by magnets implanted in the bone

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP1803413B1Magnetic sensor array for bone registration in computer-assisted orthopaedic surgery
Publication Date: 2010.04.07 DEPUY PROD INC
  • EP1803413B1 patent drawingFigure 1
  • EP1803413B1 patent drawingFigure 2
  • EP1803413B1 patent drawingFigure 3

AI summary

A magnetic sensor array for bone registration in computer-assisted orthopaedic surgery includes a first three-dimensional magnetic sensor secured to a substrate in a central location of the substrate. A number of second three-dimensional magnetic sensors are secured to the substrate at a first distance from the first magnetic sensor. Additionally, a number of one-dimensional magnetic sensors are secured to the substrate at a second distance from the first magnetic sensor greater than the first distance. Additional magnetic sensors of any dimension may also be included. The magnetic field sensitivity of the first and second three-dimensional magnetic sensors may be less than the magnetic field sensitivity of the one-dimensional magnetic sensors. The sensing range of the first and second three-dimensional magnetic sensors may be greater than the sensing range of the one-dimensional magnetic sensors. The magnetic sensor array may also include a processing circuit coupled to the magnetic sensors.