Electromagnetic Tracking for Computer-Assisted Surgery

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Solution Overview

Problem

Current tracking systems in computer-assisted surgery face challenges such as the need for visible line of sight in passive systems, size constraints of trackable members, and difficulty integrating sensors into disposable instruments, which affect precision and usability during surgeries like Total Knee Replacement.

Innovation Solution

A computer-assisted surgery system utilizing two accelerometer-based trackable members affixed to a bone, with a processing unit that calculates orientation and position data to enable tracking in three degrees of freedom, allowing for precise tracking without the need for continuous line of sight and compact, disposable instrument integration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If passive optical tracking elements are used, then no power source is needed and the system is simpler, but continuous line of sight is required which limits surgical flexibility

Engineering Contradiction:

Improvetracking system complexityVSAvoidsurgical positioning flexibility

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent replaces passive optical tracking elements with active electromagnetic transmitters that emit signals independently of line of sight. This substitution allows tracking without requiring visual contact between sensors and trackable members, enabling greater surgical flexibility while maintaining reasonable system complexity through wireless communication protocols.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces electromagnetic fields as an intermediary medium for tracking, replacing direct optical line-of-sight requirements. The electromagnetic transmitters and receivers act as intermediaries that can penetrate tissues and obstacles, allowing tracking signals to pass through the body without requiring direct visual contact between trackable members and sensors.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If traditional trackable members are used, then tracking can be achieved, but the noticeable size affects precision and integration into disposable instruments

Engineering Contradiction:

Improveposition and orientation tracking precisionVSAvoidtrackable member size

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent integrates electromagnetic transmitters directly into disposable surgical instruments, eliminating the need for separate trackable members. This integration allows the tracking functionality to be built into single-use instruments like cutting guides, reducing overall size while maintaining precision and enabling precise tracking without bulky external components.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent merges the tracking functionality with the surgical instrument itself by integrating electromagnetic transmitters into the instrument structure. This consolidation eliminates separate trackable members and reduces the overall volume required for tracking, allowing precise position and orientation measurement without adding noticeable size to the surgical tool.

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If active transmitters are used in sterile zones, then tracking precision is improved, but the presence of wires complicates the surgical procedure

Engineering Contradiction:

Improvetracking precisionVSAvoidsurgical procedure simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces wired electromagnetic transmitters with wireless communication systems. The wireless transmitters eliminate physical connections to sterile zones, allowing high-precision tracking through wireless signal transmission while maintaining surgical simplicity by removing wires and connectors from the sterile field.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables precise tracking of surgical instruments and bones in three degrees of freedom, improving surgical precision and reducing the need for continuous visualization of computer screens, while allowing for the use of disposable instruments with integrated sensors.

Implementation Method 1

a first inertial sensor unit producing at least orientation-based data, the first inertial sensor unit being an accelerometer-based unit adapted to be affixed to the bone

Methodology Applied

Scientific EffectAccelerometer: Accelerometer

Data Source

PatentUS9115998B2Tracking system and method

Publication Date: 2015.08.25 ORTHOSOFT ULC

AI summary

A tracking system is provided for tracking objects. A first and a second trackable member each have an inertial sensor unit producing at least orientation-based data. A processing unit receives the orientation-based data from the trackable members. The processing unit has an orientation calculator calculating an orientation of the second trackable member with respect to the first trackable member from the orientation-based data of the trackable members, whereby the processing unit calculates an orientation of the objects. A method for tracking objects is also provided.