Bone Expansion Activation Tool With Rotational Failure Detection

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Solution Overview

Problem

Existing bone expansion apparatuses, particularly plate distractors, face challenges in detecting failures during operation, which can lead to premature tearing due to mechanical stresses, especially when used on fragile attachments in young patients.

Innovation Solution

An activation tool with a drive member, first and second shafts, a coupling device, and detection means to easily detect rotational failures by switching between activation and failure modes, utilizing a coupling device that decouples shafts when rotational speeds differ, and visual and audible indicators for user feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the remote magnetic element is blocked in rotation to reduce mechanical stresses, then the reliability of the attachment is improved, but the ability to detect failure is worsened

Engineering Contradiction:

Improveattachment reliabilityVSAvoidfailure detection difficulty

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements feedback by using detection means (such as sensors or indicators) that provide real-time information about the rotational status of the remote magnetic element. When the element is blocked or fails to rotate properly, the detection means generates a signal that alerts the user or system, enabling immediate awareness of the failure condition without requiring manual inspection or creating additional mechanical stress on the fragile attachments.

Inventive Principle:

Principle #23Feedback

2Strength

If manual activation is used to minimize mechanical stress, then the strength of fragile attachments is preserved, but the ease of operation is worsened due to inability to detect failures

Engineering Contradiction:

Improveattachment strengthVSAvoidfailure detection ease

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The system performs self-monitoring through the detection means that automatically detects rotational failures of the remote magnetic element during manual activation. This eliminates the need for external monitoring or manual checking, allowing the operator to continue safe operation while the system independently tracks its own status and alerts when failures occur.

Inventive Principle:

Principle #25Self-service

3Device complexity

If simple magnetic coupling is used to activate the distractor, then the device complexity is reduced, but the measurement precision of rotational status is worsened

Engineering Contradiction:

Improveactivation tool complexityVSAvoidrotational status detection precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces complex mechanical sensing mechanisms with detection means that can be integrated into the magnetic coupling system. Instead of using elaborate mechanical linkages or contact-based sensors that would increase device complexity, the invention employs detection methods (such as magnetic sensors, optical indicators, or electronic detectors) that work within the existing magnetic field environment to precisely monitor the rotational status of the remote magnetic element.

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

Facilitates easy detection of rotational failures, reducing mechanical stress on fragile attachments and ensuring safe operation of bone expansion apparatuses, particularly plate distractors, by providing visual and audible feedback on mode changes.

Implementation Method 1

the rotation of the distractor magnet causes the distractor plates to separate by means of a worm screw mechanism. The worm screw converts the rotational movement of the distractor magnet into a translational movement

Methodology Applied

Scientific EffectMagnetic coupling: Magnetism

Implementation Method 2

a coupling device interposed between the first shaft and the second shaft, which is configured to couple the first shaft and the second shaft in a first mode, referred to as the activation mode, when the first shaft and the second shaft exhibit the same rotational speed, and is configured to angularly decouple the first shaft and the second shaft in a second mode, referred to as the failure mode, when a rotational speed of the second shaft is higher than the rotational speed of the first shaft

Methodology Applied

Scientific EffectMechanical coupling: Mechanical Force

Data Source

PatentUS12564424B2Activation tool for a bone expansion apparatus

Publication Date: 2026.03.03 ASSISTANCE PUBLIQUE HOPITAUX DE PARIS (APHP)

AI summary

The invention relates to an activation tool (3) comprising in particular:a coupling device (17) interposed between a first shaft (9) and a second shaft (15), which is configured to couple the first shaft (9) and the second shaft (15) in a first mode, referred to as the activation mode, when the first shaft (9) and the second shaft (15) exhibit the same rotational speed, and is configured to angularly decouple the first shaft (9) and the second shaft (15) in a second mode, referred to as the failure mode, when a rotational speed of the second shaft (15) is higher than the rotational speed of the first shaft (9),means (19) for detecting the switch from the first mode to the second mode.The invention also relates to a distraction assembly (1) having an activation tool (3) of the above-mentioned type, and a plate distractor (5).