Inertial Sensor Limb Alignment System

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Solution Overview

Problem

Current joint replacement procedures, such as knee joint replacements, often rely on complex and costly computer navigation systems or simple 'eyeballing' methods, which are not accurate enough to reliably align and position prosthetic implant components relative to the bones and soft tissues.

Innovation Solution

A system utilizing inertial sensors and processors to calculate the mechanical axes of the femur and tibia, providing accurate alignment and positioning of prosthetic components without the need for extensive training or expensive navigation systems, by coupling orientation devices with the tibia and femur to determine the mechanical axes and angles, and using these data for precise cut verification and implant placement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complex computer navigation systems are used, then measurement precision of limb alignment is improved, but device complexity and cost increase

Engineering Contradiction:

Improvelimb alignment accuracyVSAvoidnavigation system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The navigation system is divided into separate modular components: inertial sensors attached to bones, orientation devices coupled to surgical instruments, and a processor. Each component performs a specific function, allowing the system to be configured flexibly without requiring a complete complex navigation system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces complex mechanical computer navigation systems with inertial sensors and processors that calculate mechanical axes and alignment angles through mathematical computations, eliminating the need for bulky hardware and extensive training while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If simple eyeballing methods are used, then device complexity is reduced, but measurement precision of limb alignment deteriorates

Engineering Contradiction:

Improvealignment method simplicityVSAvoidprosthetic placement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system uses the patient's own anatomical landmarks and bone structures as reference points for determining mechanical axes. The inertial sensors and orientation devices work with the patient's anatomy itself rather than requiring external complex positioning systems, enabling accurate alignment through self-referential measurement.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If computer navigation systems are used, then measurement precision is improved, but loss of time for training and setup increases

Engineering Contradiction:

Improvealignment accuracyVSAvoidtraining and setup time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system uses disposable or single-use inertial sensors and orientation devices that are attached directly to the patient's bones and surgical instruments. These components do not require calibration or training to use, eliminating setup time while maintaining measurement precision throughout the procedure.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Measurement precision

If complex navigation systems are used, then measurement precision is improved, but cost of the procedure increases

Engineering Contradiction:

Improvelimb alignment accuracyVSAvoidprocedure cost

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent substitutes expensive mechanical computer navigation systems with inertial sensors and processors that perform calculations through mathematical algorithms. This replacement dramatically reduces equipment cost while maintaining the ability to determine mechanical axes and alignment angles with high precision.

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

This approach allows for accurate and reproducible limb alignment, reducing the complexity and cost of procedures, improving the accuracy of prosthetic placement, and facilitating soft tissue balancing and gap measurements, thereby enhancing surgical precision and patient outcomes.

Implementation Method 1

The system can include a first orientation device configured to be coupled with a tibia, the first orientation device comprising at least one inertial sensor. The system can include a second orientation device configured to be coupled with a femur, the second orientation device comprising at least one inertial sensor.

Methodology Applied

Scientific EffectInertial sensing: Accelerometer

Data Source

PatentUS20230059247A1Systems and methods for limb alignment

Publication Date: 2023.02.23 ORTHALIGN

AI summary

The present invention provides, in certain embodiments, a device for determining the tibial mechanical axis and the femoral mechanical axis. The present invention also provides a surgical orientation device, a reference device, and/or a module configured to track the mechanical axes during movement to facilitate limb alignment. The present invention further provides the surgical orientation device, the reference device, and/or the module configured to determine a gap measurement.