Magnetic Bone Registration in Orthopaedic Surgery

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Solution Overview

Problem

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

Innovation Solution

A method involving a magnetic source, such as cylindrical dipole magnets, implanted in the bone to generate a magnetic field, sensed by a magnetic sensor array to determine its position, allowing for precise registration of bone contours and orientation without interfering magnetic fields, and transmitting data for graphically rendered images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional fiducial marker and anatomical plane registration methods are used, then bone registration can be achieved, but surgery time increases and patient exposure to infection risk 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 sensing system. Magnetic sensors detect the position and orientation of implanted magnetic markers without requiring physical contact with the bone, eliminating the time-consuming manual probing process while maintaining registration accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Magnetic markers are implanted in the bone prior to the registration process, allowing the system to automatically detect their positions using magnetic sensors. This preliminary placement of markers enables rapid automated registration without requiring time-consuming manual measurement of anatomical landmarks during surgery.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If traditional fiducial marker and anatomical plane registration methods are used, then bone registration can be achieved, but surgery time increases and patient exposure to infection risk increases

Engineering Contradiction:

Improvebone registration accuracyVSAvoidinfection risk

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If magnetic sources are implanted in the bone, then registration accuracy improves and surgery time decreases, but device complexity increases

Engineering Contradiction:

Improveregistration efficiencyVSAvoidregistration system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts the registration markers from the external environment and implants them directly into the bone. This integration of markers within the bone structure simplifies the overall system by eliminating the need for external positioning devices and complex alignment procedures, reducing system complexity while improving registration efficiency.

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

This approach reduces surgery time by providing accurate and efficient bone registration, minimizing exposure to infection, and simplifying the registration process for complex anatomical areas like the hip joint.

Implementation Method 1

The position of the magnetic source may be determined based on a magnetic field generated by the magnetic source. Determining a position of the magnetic source may include sensing the magnetic field.

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentUS8862200B2Method for determining a position of a magnetic source

Publication Date: 2014.10.14 DEPUY SYNTHES PROD INC

AI summary

A method for determining a position of a magnetic source includes measuring a magnetic field generated by the magnetic source and determining components of the three-dimensional magnetic flux density of the magnetic field at a plurality of points in space based on such measurement. The method also includes estimating a position of the magnetic source and determining components of a theoretical three-dimensional magnetic flux density at the plurality of points in space based on the estimated position. The position of the magnetic source may then be determined by minimizing the difference between the components of the measured and corresponding theoretical three-dimensional magnetic flux density components.