Virtual Patient Anatomy Alignment Via Indirect Tracking

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Solution Overview

Problem

In robotic-assisted surgery, particularly in procedures like hip replacements, there is a challenge in tracking patient anatomy due to limited access and interference from soft tissue, making it difficult to rigidly attach tracking markers and accurately measure joint measurements without moving the patient.

Innovation Solution

A method using a tracking system to acquire point probe locations and landmark locations relative to a tracking marker, generating a transformation matrix to determine lengths and offsets of anatomical structures, and aligning virtual representations based on predefined models.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a tracking marker is rigidly attached to the first anatomical structure for continuous six-degree-of-freedom tracking, then tracking accuracy is improved, but surgical access is restricted and soft tissue interference increases

Engineering Contradiction:

Improvetracking accuracyVSAvoidsurgical access

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent introduces a second anatomical structure as an intermediary that can be easily accessed and instrumented. A tracking marker is attached to this second structure instead of the first anatomical structure, allowing indirect tracking of the first structure through measured relationships between the two structures. This mediator approach resolves the conflict by providing tracking capability without restricting surgical access to the primary target anatomy.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the direct mechanical attachment of a tracking marker to the first anatomical structure with an indirect measurement system. Instead of mechanically fixing the tracker to the target bone, the system uses a tracked instrument or probe to measure relationships between the first and second anatomical structures, substituting direct mechanical tracking with indirect measurement-based tracking.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If the patient is repositioned to collect anatomical measurements between joints, then measurement accuracy is improved, but procedure time increases and patient comfort decreases

Engineering Contradiction:

Improvejoint measurement accuracyVSAvoidprocedure time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements a dynamic tracking system that can measure anatomical relationships in multiple patient positions rather than requiring repositioning for each measurement. The tracking marker and measurement system remain in place while the patient moves, allowing the system to capture anatomical data dynamically across different positions and then process this data to determine accurate joint measurements without requiring the patient to be repositioned for each specific measurement.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent performs preliminary attachment of the tracking marker to the second anatomical structure before the surgical procedure begins. This preliminary setup enables continuous tracking throughout the procedure, eliminating the need for time-consuming repositioning and re-measurement activities during surgery. The tracking infrastructure is established in advance to support measurements taken in various positions.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If a tracking marker is securely attached to the first anatomical structure, then tracking reliability is improved, but soft tissue interference and occlusion of optical trackers increase

Engineering Contradiction:

Improvetracking reliabilityVSAvoidsoft tissue interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses a second anatomical structure as a mediator that is more accessible and has less soft tissue interference. The tracking marker is attached to this intermediary structure rather than the primary target anatomy, reducing soft tissue interference and optical occlusion while maintaining tracking reliability through measured relationships between the two structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250302538A1Virtual alignment of patient anatomy

Publication Date: 2025.10.02 SMITH & NEPHEW INC

AI summary

Systems and methods for tracking in a surgical procedure are disclosed herein. The method involves receiving a predefined model of a first anatomical structure, determining an alignment axis and center of rotation of the first anatomical structure with respect to a second anatomical structure, and acquiring point probe locations using a tracking system. The position and orientation of the first anatomical structure relative to a tracking marker are registered based on the point probe locations. Landmark locations associated with fixed landmarks on the first anatomical structure are acquired and registered relative to the tracking marker. A transformation matrix is generated between the center of rotation and the landmarks, and updated landmark locations are acquired. The method further determines anatomical structure characteristics based on the transformation matrix, updated landmark locations, and the predefined model.