Bidirectional Rotation Control for Mandibular Distractor

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Solution Overview

Problem

Existing mandibular distractors lack adequate adjustment control, leading to limitations in their implanted state and potential issues with unintended movement or overcorrection during distraction procedures.

Innovation Solution

The design incorporates a mechanism with recesses and holes on the drive rod and housing engaging portions, utilizing resilient members and protrusions to control bidirectional rotation, allowing precise adjustment and preventing unintended movement by requiring a predetermined force for rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a one-directional ratchet mechanism is used, then reverse distraction is prevented, but adjustment flexibility is reduced

Engineering Contradiction:

Improveprevention of reverse distractionVSAvoidadjustment flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The rotation control mechanism transitions from a static one-directional ratchet to a dynamic bidirectional system with可控 rotation control. The mechanism allows rotation in both directions when sufficient force is applied, enabling dynamic adjustment while maintaining stability during normal operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The mechanism changes the rotational parameters by allowing bidirectional rotation under sufficient force while maintaining unidirectional control under normal conditions. This parameter change enables both prevention of unintended reverse distraction and flexible adjustment when needed.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a locking screw is used, then distracted position is secured, but further distraction requires unlocking

Engineering Contradiction:

Improveposition stabilityVSAvoidadjustment convenience

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The rotation control mechanism provides self-service by automatically controlling rotation based on applied force. When sufficient force is applied during adjustment, rotation is permitted; when normal operational forces are applied, rotation is prevented. This eliminates the need for separate locking and unlocking operations.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces the mechanical locking screw system with a force-based rotation control mechanism. Instead of requiring manual locking and unlocking operations, the new system uses force-dependent rotational control to achieve both stability and adjustability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If inadequate adjustment control is provided, then device simplicity is maintained, but unintended movement or overcorrection occurs

Engineering Contradiction:

Improvemechanism simplicityVSAvoidmovement control accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The rotation control mechanism introduces dynamic force-dependent control to prevent unintended movement while maintaining relative simplicity. The mechanism remains compact and integrates into the existing distractor structure while providing reliable rotation control based on applied force thresholds.

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If bidirectional rotation is allowed without control, then adjustment flexibility is improved, but unintended movement increases

Engineering Contradiction:

Improvebidirectional adjustment capabilityVSAvoidrotation stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The mechanism changes the rotational parameter control by implementing force-dependent bidirectional rotation. Under normal conditions, rotation is controlled in both directions; when sufficient force is applied, rotation is permitted in either direction, enabling flexible adjustment while maintaining stability during normal operation.

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 solution enables better control over the relative movement of footplates, allowing for precise distraction and adjustment in both directions, reducing the risk of overcorrection and stress on bone attachment locations, especially beneficial in cases with poor or fragile bone quality.

Implementation Method 1

the protruding member comprises a spring or other elastically deformable member provided in the hole

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentEP3040038B1Distractor with bidirectional rotation control

Publication Date: 2017.03.22 STRYKER EUROPEAN HOLDINGS I LLC

Figure 1A~1B
Figure 2
Figure 3~4

AI summary

A distractor, such as a pediatric mandibular distractor, comprises a housing member (110) elongated along a longitudinal axis, at least one distal footplate (120) attached to the housing member; a drive rod (140); and at least one proximal footplate (130) configured to be driven by the drive rod. A housing engaging member (41) is configured to engage a drive rod engaging member (42) to prevent the housing from being rotated in either a first or second direction of rotation relative to the drive rod when a rotational force less than a predetermined force is applied to the housing or drive rod. The drive rod can be rotated relative to the housing in either the first or second rotational direction when a force greater than the predetermined force is applied to the drive rod or the housing.