Surgical Alignment Using Patient-Specific Guides and References

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Solution Overview

Problem

Current methods for determining the alignment of instruments relative to joints during orthopaedic surgery lack precision and accuracy, particularly in procedures like hip arthroplasty, where aligning implants correctly is crucial for the success and longevity of the surgical outcome.

Innovation Solution

A system that includes a patient-specific guide with a defined axis, a first reference attached to the joint, and a positioning system using electromagnetic fields or infrared detection to determine the alignment of instruments relative to the joint, allowing for precise alignment of implants without physical contact with the guide during reaming and impaction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional alignment methods are used, then the procedure is simpler, but alignment precision and accuracy deteriorate

Engineering Contradiction:
Improvealignment precisionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

A guide is introduced as an intermediary component that couples to the joint and defines a reference axis. The guide includes a first reference that serves as a mediator between the joint anatomy and the positioning system, enabling precise alignment measurements without direct complex interaction between the positioning system and the joint itself

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional mechanical alignment methods with an optical/electromagnetic positioning system. Instead of relying on manual mechanical gauges and visual estimation, the system uses electromagnetic fields or infrared detection to measure positions and calculate alignment, significantly improving precision while reducing physical contact with the surgical site

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If physical contact with the guide is maintained during reaming and impaction, then alignment reference is available, but tissue trauma increases

Engineering Contradiction:
Improvetissue traumaVSAvoidalignment reference reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The alignment measurements are performed in advance while the guide is coupled to the joint. The system determines the position of the axis relative to the first reference before the guide is removed. This preliminary action captures the alignment data when the reference is most reliable, allowing the guide to be removed afterward without compromising alignment accuracy

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The positioning system creates a digital copy or representation of the alignment geometry by measuring the position of the axis relative to the first reference. This digital model allows alignment verification to continue after the physical guide is removed, eliminating the need for continuous physical contact during subsequent surgical steps

Inventive Principle:
Principle #26Copying

3Productivity

If conventional alignment methods are used, then equipment is simpler, but surgical time and efficiency are reduced

Engineering Contradiction:
Improvesurgical efficiencyVSAvoidpositioning system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The positioning system is designed to be multi-functional, capable of tracking multiple references (first reference on the joint, second reference on the instrument) and performing multiple measurement functions. This universal system can handle various alignment tasks throughout the procedure, improving efficiency despite the initial complexity investment

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system automatically calculates alignment information based on the measured positions of references. The control unit performs computations and generates alignment data without requiring manual calculation or intervention, allowing surgeons to focus on the procedure while the system self-manages the complex measurements and calculations

Inventive Principle:
Principle #25Self-service

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 system enables accurate and efficient alignment of instruments relative to the joint, ensuring proper positioning of implants, which enhances the surgical outcome by improving the precision and speed of the procedure while reducing tissue trauma and radiation exposure.

Implementation Method 1

using a positioning system to determine a position of the axis relative to the first reference, the position of the axis being determined based upon the position of the guide while the guide is coupled to the joint

Methodology Applied
Scientific EffectElectromagnetic field detection: Electromagnetic Induction

Implementation Method 2

The second reference includes an infrared detector, the first reference includes a fiducial, and using the positioning system to determine a position of the axis relative to the first reference includes using the positioning system such that the positioning system determines a relative position between the infrared detector and the fiducial

Methodology Applied
Scientific EffectInfrared radiation detection: Infrared Radiation

Data Source

PatentEP2720631B1Surgical alignment using references
Publication Date: 2022.01.26 SMITH & NEPHEW INC
  • EP2720631B1 patent drawingFigure 1
  • EP2720631B1 patent drawingFigure 2
  • EP2720631B1 patent drawingFigure 3A~3C

AI summary

Methods, systems, and apparatus, including computer-readable storage media, for surgical alignment using references. In one general aspect, a method includes coupling a guide to a joint, the guide defining an axis and having an outer contour formed to substantially conform to a portion of the joint. The first reference is attached at a fixed position relative to the joint. A positioning system is used to determine a position of the axis relative to the first reference, where the position of the axis is determined based upon the position of the guide while the guide is coupled to the joint. The guide is removed from the joint, and after the guide is removed from the joint, an instrument is positioned relative to the axis based on a position of a second reference relative to the first reference.