Asymmetric Bone Screw for Torque and Migration Control

Solution Overview

Problem

Current bone stabilization devices, such as non-threaded metal nails, can migrate within the metacarpal bone, causing damage to surrounding tissue and requiring a second surgery for removal, while screws are lengthy and prone to breakage or incomplete insertion due to insufficient torque handling.

Innovation Solution

A screw with a larger proximal section and smaller distal section, featuring cutting structures for easier insertion and retention in the bone, allowing for sufficient torque application without deformation, eliminating the need for a second surgery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a non-threaded metal nail is used to stabilize the metacarpal bone, then the bone can be stabilized in position, but the nail can migrate through the bone and into surrounding tissue, causing damage and requiring a second surgery for removal

Engineering Contradiction:

Improvebone stabilizationVSAvoidnail migration risk

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The screw device is divided into two distinct sections: a proximal section with a larger diameter for engagement with the metacarpal head, and a distal section with a smaller diameter for engagement with the shaft portion. This segmentation allows each section to be optimized for its specific function, preventing migration while maintaining stability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the screw device have different diameters tailored to the specific anatomical regions they engage. The proximal section has a larger diameter suitable for the metacarpal head, while the distal section has a smaller diameter suitable for the shaft, providing localized optimization for stability and preventing migration.

Inventive Principle:

Principle #3Local quality

2Length of moving object

If a current screw design is lengthened to fit the metacarpal bone, then the screw can be inserted, but it lacks sufficient shaft and driving portion to handle the torque required, leading to breakage or incomplete insertion

Engineering Contradiction:

Improvescrew lengthVSAvoidtorque handling capability

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The screw is segmented into a proximal section and a distal section with different diameters. The proximal section includes a driving surface with larger diameter to handle torque, while the distal section has smaller diameter to fit within the bone. This segmentation allows the screw to achieve both sufficient length for insertion and adequate torque handling capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The screw device employs asymmetric diameter design where the proximal section has a larger diameter than the distal section. This asymmetry allows the proximal end to engage with the metacarpal head while the distal end fits within the shaft, providing both the necessary length for insertion and the torque handling capability through the larger proximal driving surface.

Inventive Principle:

Principle #4Asymmetry

3Ease of operation

If a screw with uniform diameter is used, then the insertion is straightforward, but the screw cannot generate sufficient torque to drive completely into the bone without breakage

Engineering Contradiction:

Improveinsertion easeVSAvoidtorque handling

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The screw device employs asymmetric diameter design where the proximal section has a larger diameter than the distal section. This asymmetry allows the proximal end to engage with the metacarpal head while the distal end fits within the shaft, providing both the necessary length for insertion and the torque handling capability through the larger proximal driving surface.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Different sections of the screw device have different diameters tailored to the specific anatomical regions they engage. The proximal section has a larger diameter suitable for the metacarpal head, while the distal section has a smaller diameter suitable for the shaft, providing localized optimization for stability and preventing migration.

Inventive Principle:

Principle #3Local quality

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 screw effectively stabilizes the metacarpal bone with reduced risk of tissue damage and eliminates the need for a second surgical procedure, providing stable fixation and minimizing complications like tendon irritation or infection.

Implementation Method 1

The distal end of the shaft has a cutting structure

Methodology Applied

Scientific EffectMechanical cutting:

Implementation Method 2

The shaft has an outer surface with threads that extend along a majority of the length of the shaft

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

The proximal end has a driving surface to receive and be turned by an appropriate driving tool

Methodology Applied

Scientific EffectTorque: Torque

Data Source

PatentUS20240315747A1Bone stabilization device

Publication Date: 2024.09.26 EXSOMED CORP

AI summary

A device and method for stabilizing a broken bone while it heals is disclosed. The device preferably has a (a) first (or proximal) section with a driving head, threads and a first diameter, and (b) second (or distal) section that is threaded and has a second diameter. The first section is preferably greater in diameter than the second section so that greater torque can be applied to tighten the device. The device may include one or more self-tapping structures to lessen the torque required to screw it into a bone.