Cannulated Bone Screw with Internal Threads for Charcot Arthropathy Fixation

Solution Overview

Problem

Current orthopedic implant devices for treating Charcot arthopathy, such as intramedullary nails and screws, face challenges with infection and wound closure due to surface prominence, increasing the risk of post-operative wound infections and dehiscence, which may lead to limb amputation.

Innovation Solution

A cannulated screw with spirally wound threads and transverse elements, such as staples or open-ended washers, is used to compress bones, along with instruments like reduction instruments and drill guides for precise alignment and fixation, reducing tissue tension and promoting stable bone fusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If plates or exposed screws are used for bone fixation, then bone fixation strength is improved, but wound closure difficulty increases and infection risk increases

Engineering Contradiction:

Improvebone fixation strengthVSAvoidinfection risk

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The invention extracts the fixation function from prominent external structures (plates and exposed screws) and relocates it to internal cannulated screws that engage bone through the medullary canal. This removes the source of surface prominence that causes wound closure difficulty and infection risk, while maintaining bone fixation strength through internal compression and compression elements.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The cannulated screw design nests the fixation mechanism within the bone's medullary canal structure. The compression elements are positioned within the cannulated shaft, creating a nested configuration that provides strong bone fixation without external prominence. This nested arrangement allows the fixation function to be embedded within the bone architecture itself.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Strength

If plates or exposed screws are used for bone fixation, then bone fixation strength is improved, but tissue tension increases and wound closure difficulty increases

Engineering Contradiction:

Improvebone fixation strengthVSAvoidwound closure difficulty

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The invention extracts the fixation function from prominent external structures (plates and exposed screws) and relocates it to internal cannulated screws that engage bone through the medullary canal. This removes the source of surface prominence that causes wound closure difficulty and infection risk, while maintaining bone fixation strength through internal compression and compression elements.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If intramedullary nails or screws are used for bone fixation, then bone fixation is achieved, but surface prominence increases and infection risk increases

Engineering Contradiction:

Improvebone fixationVSAvoidinfection risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The cannulated screw design nests the fixation mechanism within the bone's medullary canal structure. The compression elements are positioned within the cannulated shaft, creating a nested configuration that provides strong bone fixation without external prominence. This nested arrangement allows the fixation function to be embedded within the bone architecture itself.

Inventive Principle:

Principle #7Nested doll (Nesting)

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

The solution effectively reduces the risk of post-operative infections and dehiscence by minimizing tissue tension and promoting stable bone fusion, thereby reducing the likelihood of amputation in Charcot arthopathy treatments.

Implementation Method 1

the screw comprises a shaft having first and second ends with spirally wound screw threads beginning near the first end and extending along the shaft

Methodology Applied

Scientific EffectScrew mechanism: Screw

Implementation Method 2

The screw is then tightened causing the bones along the screw to be compressed

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

at least one transverse element is secured to the screw near its first or second end. By way of example but not limitation, the transverse elements may be staples, open-ended washers, or open-ended nuts

Methodology Applied

Scientific EffectMechanical fastening: Mechanical Fastener

Data Source

PatentUS12029456B2Devices and methods for bone fixation using axial implants

Publication Date: 2024.07.09 EXTREMITY MEDICAL LLC

AI summary

The invention comprises a method for fixating bones in the foot by aligning the bones in their desired position, inserting a screw in the aligned bones, inserting at least one transverse element near the head or tip of the screw, and tightening the screw to compress the bones. The screw comprises a shaft having first and second ends with spirally wound screw threads beginning near the first end and extending along the shaft. Advantageously, the screw is cannulated and screw threads are formed on an interior surface of the cannulation. Illustratively, the transverse elements may be staples, open-ended washers, or open-ended nuts. Reduction instruments and drill guides used in the invention are also disclosed.