Integrated Sensor Measurement Arm for Hip Arthroplasty

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Solution Overview

Problem

Current devices for measuring femur displacement during total hip arthroplasty either interfere with the surgical field, increase procedure time, or require additional equipment, failing to provide an efficient and objective assessment of femur translation and offset.

Innovation Solution

A compact, sterile measurement arm with movable links and integrated sensors (accelerometers, magnetic field sensors, and gyroscopic sensors) that can be mounted to the pelvis and femur without obstructing the surgical field, allowing for intraoperative verification of leg length and offset changes without extending the procedure duration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a measurement device is used to measure femur displacement during total hip arthroplasty, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvefemur displacement measurement precisionVSAvoidmeasurement device complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple sensor types (accelerometers, magnetic field sensors, gyroscopic sensors) into an integrated sensor unit that is mounted on the measurement arm. This merging of sensing functions into a single compact unit provides comprehensive displacement measurement while avoiding the complexity of multiple separate measurement devices.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The measurement arm is designed to perform multiple functions: it measures displacement in three-dimensional space, tracks orientation changes, and provides real-time feedback during surgery. The same device structure supports various sensor types and can be applied to different measurement scenarios in hip arthroplasty, reducing the need for multiple specialized devices.

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

2Measurement precision

If a measurement device is mounted during surgery, then measurement precision is improved, but procedure time increases

Engineering Contradiction:
Improvefemur displacement measurement precisionVSAvoidsurgical procedure time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The measurement arm and sensor unit are pre-assembled and sterilized before surgery. The base element with mounting features is prepared in advance, allowing for quick attachment to the patient's anatomy during the surgical procedure without requiring complex setup or calibration steps that would extend operation time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex mechanical measurement systems with electronic sensors that provide direct digital readings. Accelerometers, magnetic field sensors, and gyroscopes electronically detect position and orientation changes, eliminating the need for manual measurement techniques and reducing the time required for data collection and processing.

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

3Measurement precision

If additional equipment is added to measure femur displacement, then measurement precision is improved, but the risk of contamination and bone damage increases

Engineering Contradiction:
Improvefemur displacement measurement precisionVSAvoidrisk of contamination and bone damage
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The measurement arm and sensor unit are designed as disposable or single-use components that can be sterilized and discarded after one surgical procedure. This eliminates the risk of cross-contamination between patients and removes the need for complex sterilization protocols, while the compact design minimizes the physical footprint and potential for interfering with the surgical field or causing bone damage.

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

Solution Approach 2:

The sensor unit is enclosed in a compact, sterile housing that can be easily disinfected or replaced. The measurement arm uses thin, flexible components that can navigate the surgical field without imposing excessive mechanical loads on the bone, reducing the risk of bone damage while maintaining measurement accuracy.

Inventive Principle:
Principle #30Flexible shells and thin films

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 precise, objective measurement of femur displacement without interfering with the surgical field or requiring additional equipment, reducing the risk of contamination and bone damage, and allowing for real-time assessment of prosthetic placement adjustments.

Implementation Method 1

The measurement arm includes at least two movable links, coupled serially to each other and to a support using rotational joints of at least one degree of freedom, and both movable links are fitted with an accelerometer and/or a magnetic field sensor and/or a gyroscopic sensor connected to the computing system unit.

Methodology Applied
Scientific EffectAccelerometer: Accelerometer

Implementation Method 2

The measurement arm includes at least two movable links, coupled serially to each other and to a support using rotational joints of at least one degree of freedom, and both movable links are fitted with an accelerometer and/or a magnetic field sensor and/or a gyroscopic sensor connected to the computing system unit.

Methodology Applied
Scientific EffectMagnetic field sensor: Magnetic Field

Implementation Method 3

The measurement arm includes at least two movable links, coupled serially to each other and to a support using rotational joints of at least one degree of freedom, and both movable links are fitted with an accelerometer and/or a magnetic field sensor and/or a gyroscopic sensor connected to the computing system unit.

Methodology Applied
Scientific EffectGyroscopic sensor: Gyroscope

Data Source

PatentEP3261586B1Device for measuring femur displacement during a surgical procedure to correct a damaged hip
Publication Date: 2021.03.24 POLITECHNA LODZKA
  • EP3261586B1 patent drawingFigure 1~2
  • EP3261586B1 patent drawingFigure 3~4
  • EP3261586B1 patent drawingFigure 5

AI summary

Device for measuring femur bone displacement during total hip arthroplasty includes a base element immovably mounted to the pelvis and a measurement arm, detachably mounted to said base element via a support, and the measurement arm is fitted with a microprocessor computing system with a display screen (5). The measurement arm includes at least two movable links I-4 and II-6, serially connected with each other and with support (2) by means of rotary joints with at least one (and preferably three) degrees of freedom, whereby both movable links are fitted with an accelerometer (preferably a three-axis accelerometer) and/or a magnetic field sensor and/or a gyroscope, preferably forming together an integrated acceleration, magnetic field and gyroscopic sensor unit (9).