Intramedullary Fixation Device for Hammertoe Correction

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Solution Overview

Problem

Current surgical methods for hammertoe correction using external K-wires face issues such as non-unions, K-wire migration, loss of fixation, and pin tract infections, necessitating the development of alternative fixation methods that provide stable and secure bone stabilization.

Innovation Solution

An intramedullary fixation device with an arrowhead design featuring barbed ends and a rigid body to resist rotational and axial movements, allowing for secure engagement with bone tissue and maintaining initial compression, thereby reducing the need for external fixation and minimizing tissue disruption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If external K-wires are used for fixation, then the procedure is simple to perform, but the reliability of fixation is poor due to non-unions, migration, and loss of fixation

Engineering Contradiction:

Improveease of procedureVSAvoidfixation stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The fixation device is divided into multiple arrowhead-shaped heads that can be independently inserted into different bone segments, with each head providing independent anchoring. This segmentation allows the device to address multiple fixation points simultaneously, improving overall fixation reliability while maintaining procedural simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The arrowhead-shaped heads feature asymmetric geometry with barbed edges that provide directional engagement with bone tissue. The asymmetric design creates mechanical interlocking that prevents migration and rotation, significantly improving fixation stability compared to symmetric cylindrical pins.

Inventive Principle:

Principle #4Asymmetry

2Ease of operation

If external K-wires are used for fixation, then the device is easy to insert, but harmful factors increase due to pin tract infections and tissue disruption

Engineering Contradiction:

Improveease of insertionVSAvoidinfection risk

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The invention extracts the problematic external portion of traditional pin fixation by creating an entirely intramedullary device. The arrowhead heads are inserted through small incisions and remain contained within the medullary canal, eliminating external pin tracts that are prone to infection while maintaining ease of insertion through the same minimally invasive approach.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The rigid body connecting the arrowhead heads acts as an intermediary element that transmits mechanical forces between bone segments without requiring external fixation. This internal mediator eliminates the need for external pins that create infection-prone pathways through the skin and soft tissues.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If smooth K-wires are used for fixation, then the procedure is minimally invasive, but the device fails to prevent rotational movement and bone migration

Engineering Contradiction:

Improvetissue disruptionVSAvoidfixation stability

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The arrowhead heads feature asymmetric geometry with barbed edges that provide directional engagement with bone tissue. The asymmetric design creates mechanical interlocking that prevents migration and rotation, significantly improving fixation stability compared to symmetric cylindrical pins.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The arrowhead heads incorporate curved, barbed surfaces that engage with the bone cortex in a interlocking manner. The curved geometry of the barbs allows for insertion in one direction while preventing removal or rotation, providing stable fixation with minimal tissue disruption.

Inventive Principle:

Principle #14Spheroidality (Curvature)

4Stability of the object's composition

If fixation devices with barbed ends are used, then rotational and axial movement is inhibited, but device complexity increases

Engineering Contradiction:

Improvefixation stabilityVSAvoiddevice structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple arrowhead heads and the rigid body are merged into a single integrated device that functions as one unified fixation system. This combining eliminates the need for separate insertion and fixation steps, reducing overall procedural complexity despite the enhanced stabilization capabilities of individual components.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9895179B2Intramedullary fixation devices

Publication Date: 2018.02.20 ARROWHEAD MEDICAL DEVICES TECHNOLOGIES LLC

AI summary

An internal intramedullary fixation device for the stabilization of bone in arthrodesis and fractures of the foot and hand is disclosed. During implantation in the medullary canal of each bone, the device grasps the edges of the canal, stabilizing the bone (internally) during the natural healing process.