Ultrasonic Patient-Limb Tracking Without Invasive Bone Trackers

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Solution Overview

Problem

Conventional surgical navigation systems require invasive implantation of trackers in bones, causing additional trauma and reducing surgical visibility, and are prone to dislodgment, compromising tracking accuracy.

Innovation Solution

A non-invasive tracking apparatus using ultrasonic sensors and trackable elements that couple to a patient limb, allowing for accurate tracking without invasive implantation, utilizing ultrasonic waves to transmit and receive signals for precise bone location determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If invasive implantation of trackers is used to track bone movement, then tracking accuracy is improved, but patient trauma and surgical complexity increase

Engineering Contradiction:

Improvetracking accuracyVSAvoidpatient trauma

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical invasive implantation system with an ultrasonic wave-based tracking system. Instead of physically implanting trackers into the bone, the system uses ultrasonic sensors to emit and receive waves that reflect off the bone, enabling non-invasive tracking of bone movement and position with high accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces ultrasonic waves as an intermediary between the tracking system and the bone. The ultrasonic sensors act as mediators that transmit information about bone position and movement without requiring direct physical contact or implantation, thus eliminating patient trauma while maintaining tracking accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If invasive implantation of trackers is performed, then tracking reliability is improved, but additional surgical steps and time are required

Engineering Contradiction:

Improvetracking reliabilityVSAvoidsurgical time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent eliminates the time-consuming invasive implantation process by substituting it with a non-invasive ultrasonic tracking method. The ultrasonic sensors can be applied externally to the skin and begin tracking immediately without requiring surgical incisions, tracker implantation, or manual bone registration steps.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If tracking arrays are extended from the bone to increase accuracy, then tracking precision is improved, but surgical site visibility is reduced

Engineering Contradiction:

Improvetracking precisionVSAvoidsurgical site visibility

Core Design Contradiction:

Measurement precisionVSIllumination intensity

Solution Approach 1:

The patent replaces the physical tracking arrays that would extend from the bone with external ultrasonic sensors. These sensors are positioned on the skin surface and emit ultrasonic waves through the soft tissue to detect bone position, eliminating the need for visible tracking structures in the surgical field while maintaining high tracking precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If multiple trackers are attached to the bone to increase accuracy, then tracking reliability is improved, but risk of dislodgment and surgical complexity increase

Engineering Contradiction:

Improvetracking reliabilityVSAvoidtracker configuration complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces multiple physical trackers that would need to be attached to the bone with a single or few ultrasonic sensors positioned externally. The ultrasonic waves penetrate the soft tissue and reflect off the bone, providing reliable tracking information without the complexity of attaching and securing multiple trackers to the bone surface.

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 accurate and non-invasive tracking of patient limbs, improving surgical precision and reducing patient trauma by eliminating the need for invasive tracker implantation and potential dislodgment issues.

Implementation Method 1

one or more ultrasonic sensors coupled to the interior surface of the body and the interior surface of wing portion, the one or more ultrasonic sensor being configured to transmit ultrasonic waves to and receive ultrasonic waves from the bone

Methodology Applied

Scientific EffectUltrasonic waves: Ultrasound

Data Source

PatentEP4384108B1Tracking apparatus for tracking a patient limb

Publication Date: 2025.08.20 MAKO SURGICAL CORP

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AI summary

A tracking apparatus for tracking a bone of a patient limb is provided. The tracking apparatus includes a body configured to couple to the patient limb. The body includes first and second arms each including an exterior and opposing interior surface and opposing sides connecting the exterior and interior surfaces. The tracking apparatus also includes a wing portion extending from one of the sides of the first or second arm, the wing portion sharing the interior surface of the first or second arm. The tracking apparatus also includes one or more ultrasonic sensors coupled to the interior surface of the body and the interior surface of wing portion, the one or more ultrasonic sensor being configured to transmit ultrasonic waves to and receive ultrasonic waves from the bone. The tracking apparatus also includes one or more trackable elements coupled to the body and the wing portion.