Forefoot Mobility Evaluation Device With Pivot Plate Force Distribution

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Solution Overview

Problem

Existing methods for evaluating forefoot mobility lack objectivity, reliability, and practicality for clinical use, failing to provide standardized force application and inter-observer variability, and do not assess instability during the stance phase.

Innovation Solution

A device comprising an actuator, force sensor, transmission element, and displacement sensor, which equally distributes axial force to output shafts bearing against the first and lesser metatarsal heads, measuring relative displacement and angulation to quantify forefoot mobility objectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If manual examination methods are used with simple instruments, then the device complexity is reduced and ease of operation is improved, but measurement precision and reliability deteriorate due to lack of standardized force application

Engineering Contradiction:
Improveease of useVSAvoidmeasurement precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent replaces manual mechanical examination with an automated measurement system that uses a motorized actuator to apply standardized forces. The actuator systematically applies forces of 5N, 10N, 15N, and 20N to the first metatarsal head while sensors automatically record the displacement, eliminating the variability inherent in manual force application and providing precise, reproducible measurements.

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

2Reliability

If automated force application systems are implemented, then measurement reliability is improved through standardized force, but device complexity increases

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a pivot plate as an intermediary mechanical element that distributes the axial force from the actuator equally to both the first metatarsal head and the lesser metatarsal heads. This simple mechanical intermediary ensures force standardization and equal distribution without requiring complex control systems, thereby achieving reliability while keeping the device relatively simple.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The actuator serves multiple functions: it applies standardized forces to the forefoot, the pivot plate distributes this force equally to the first and lesser metatarsal heads, and the system simultaneously measures both the applied force (via force sensor) and the resulting displacement (via displacement sensor). This multi-functionality reduces the need for separate devices for each measurement task.

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

3Measurement precision

If existing instruments are used for research purposes, then measurement capability is provided, but practicality for daily clinical use deteriorates due to complexity

Engineering Contradiction:
Improvemeasurement capabilityVSAvoidpracticality for clinical use
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The device is designed to be self-contained and autonomous, with the actuator automatically applying the force sequence (5N, 10N, 15N, 20N) without requiring manual intervention. The force sensor and displacement sensor automatically record measurements, and the system computes relative mobility values independently, making the device ready for immediate clinical use without requiring complex setup or operation procedures.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4518752B1Evaluation of the forefoot relative mobility
Publication Date: 2025.10.29 FONDATION FORTE
  • EP4518752B1 patent drawingFigure 1
  • EP4518752B1 patent drawingFigure 2
  • EP4518752B1 patent drawingFigure 3

AI summary

The present relates to a device for evaluating the relative mobility of a forefoot (F) of a patient (P), the device (2) comprising an actuator (9), a force sensor (16), an housing (7), a transmission element (8) and two output shafts namely a first output shaft (10) and a second output shaft (11 ), the first output shaft (10) being configured for bearing against the first metatarsal head M1 of the forefoot whereas the second output shaft (11 ) being configured for bearing against the lesser metatarsal heads M2-M5 of the forefoot, the force sensor (16) is able to measure an axial force exerted by the actuator (9) to the two output shaft (10, 11) bearing to the forefoot, characterized in that the transmission element (8) comprises a pivot plate (14) connecting the housing (14) to the two output shafts (10, 11), the pivot plate (14) is able to equally distributes the axial force provided by the actuator (9) via the housing (7), to the first output shaft (10) and to the second output shaft (11), and wherein the device (2) comprises a displacement sensor (17) able to measure the angulation of the pivot plate (14).