Bone Axis Determination via Rigid Camera and Marker

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Current medical navigation systems are costly and require significant surgical intervention to determine the mechanical axis of bones, which is crucial for surgical procedures like implanting artificial replacements.

Innovation Solution

An electronic device with a video camera and optional inertial sensors is rigidly attached to the bone to determine the mechanical axis by identifying key anatomical points and using marker detection systems, allowing for precise calculation of the axis with minimal surgical intervention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional medical navigation systems are used to determine the mechanical axis of a bone, then measurement precision is improved, but device complexity and cost increase significantly

Engineering Contradiction:
Improvemechanical axis determination accuracyVSAvoidnavigation system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of mechanical axis determination from complex medical navigation systems by using only a video camera and basic image processing. Instead of employing full navigation systems with multiple sensors and tracking devices, the invention isolates and implements only the necessary components (camera, marker detection, image processing) to achieve accurate mechanical axis determination with reduced complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces expensive, complex medical navigation systems with inexpensive, readily available video cameras and computers. The solution uses standard consumer-grade equipment rather than specialized medical devices, significantly reducing cost while maintaining measurement precision through clever use of image processing algorithms and marker-based tracking.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If traditional medical navigation systems are used to determine the mechanical axis of a bone, then measurement precision is improved, but surgical intervention increases

Engineering Contradiction:
Improvemechanical axis determination accuracyVSAvoidsurgical intervention requirement
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent attaches a marker to the bone before surgery begins, establishing a reference point that will be used throughout the procedure. This preliminary action simplifies subsequent steps by providing a fixed reference for mechanical axis determination, eliminating the need for complex intraoperative measurements and reducing overall surgical intervention requirements.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The video camera captures images that are automatically processed by computer algorithms to determine the mechanical axis. The system performs self-measurement and self-analysis without requiring manual anatomical landmark identification by surgeons, reducing surgical intervention while maintaining high measurement precision through automated image processing.

Inventive Principle:
Principle #25Self-service

3Device complexity

If a video camera is rigidly attached to the bone to determine the mechanical axis, then device complexity is reduced, but measurement precision may be compromised

Engineering Contradiction:
Improvedetermination device complexityVSAvoidmechanical axis determination accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces a marker as an intermediary between the video camera and the bone. The marker serves as a stable, easily detectable reference point that the camera can track accurately. This intermediary element allows the simple video camera system to achieve high measurement precision by providing clear, distinguishable features for image processing and coordinate system establishment.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent transforms the measurement problem from direct anatomical landmark identification to marker position detection. By changing the parameter being measured from complex anatomical features to simple, high-contrast marker positions, the system achieves higher precision with simpler equipment. The marker provides well-defined coordinates that are easily detected and processed by the video camera system.

Inventive Principle:
Principle #35Parameter changes

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 method allows for accurate determination of the mechanical axis with reduced costs and surgical intervention, enhancing the precision of surgical procedures by providing a cost-effective and minimally invasive means to align cutting planes and position implants.

Implementation Method 1

a video camera...captures a stationary marker

Methodology Applied
Scientific EffectImage capture and detection: Photography

Implementation Method 2

an output signal of the camera which captures a stationary marker...an inertial sensor system

Methodology Applied
Scientific EffectGravitation: Gravitation

Data Source

PatentEP2720634B1Device for determining the mechanical axis of a bone
Publication Date: 2023.05.03 BRAINLAB AG
  • EP2720634B1 patent drawingFigure 1A~1B
  • EP2720634B1 patent drawingFigure 2~3

AI summary

The present invention relates to a method for determining the mechanical axis of a bone using an electronic device which is rigidly attached to the bone and comprises a video camera, wherein: - the mechanical axis is determined from the positions of two points which define the mechanical axis; - the first of the two points is determined as the centre of rotation when the bone is pivoted about the first point, the centre of rotation being determined from an output signal of the camera which captures a stationary marker device; and - the second point is the exit point of the mechanical axis on the outer surface at the opposite end of the bone to the first point.