Elastic Bar With Flexible Center for Gradual Pectus Excavatum Repair

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Solution Overview

Problem

Current treatments for pectus excavatum, such as the Nuss procedure, cause significant pain and require immediate correction, leading to potential opiate addiction and patient reluctance, while existing compliant mechanisms are not designed for gradual correction.

Innovation Solution

An elastic bar with flexible center portion and rigid end portions is designed to gradually correct pectus excavatum by leveraging the chest wall's de-stiffening phenomenon, using a biocompatible titanium alloy to minimize pain and facilitate a prolonged correction process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a stiff metal bar is used for immediate correction (Nuss procedure), then correction effectiveness is improved, but patient pain increases significantly

Engineering Contradiction:

Improvecorrection effectivenessVSAvoidpatient pain

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The bar transitions from a static, rigid structure to a dynamic, adaptable one. The compliant mechanism allows the bar to gradually adjust to the chest wall's natural de-stiffening process, enabling continuous adaptation rather than forcing immediate correction. This dynamic approach distributes the correction force over time, reducing peak pain while maintaining correction effectiveness.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the key parameter of bar stiffness from high (traditional Nuss bar) to variable/compliant. By modifying the mechanical properties of the bar to be compliant rather than rigid, the system can accommodate the chest wall's gradual de-stiffening phenomenon, thereby reducing pain during the correction process while still achieving the desired positional correction.

Inventive Principle:

Principle #35Parameter changes

2Speed

If immediate correction is achieved through stiff bar placement, then correction speed is improved, but pain medication dependency increases

Engineering Contradiction:

Improvecorrection speedVSAvoidpain medication

Core Design Contradiction:

SpeedVSQuantity of substance

Solution Approach 1:

The correction process is transformed from a single, immediate action to a periodic, progressive action. The compliant bar enables continuous, small adjustments that follow the chest wall's natural de-stiffening rhythm, replacing the one-time forceful correction with repeated, gentle corrections over time. This periodic approach achieves the same end result while minimizing the need for pain medication.

Inventive Principle:

Principle #19Periodic action

3Object-affected harmful factors

If a compliant mechanism is used for gradual correction, then patient pain is reduced, but correction duration is extended

Engineering Contradiction:

Improvepatient painVSAvoidcorrection duration

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The compliant bar mechanism is designed to automatically adapt to the chest wall's de-stiffening process without requiring external intervention or adjustment. The bar's compliance allows it to self-adjust as the chest wall naturally changes over time, eliminating the need for multiple surgical interventions or manual adjustments, thereby reducing overall time loss despite the extended correction duration.

Inventive Principle:

Principle #25Self-service

4Stability of the object's composition

If rigid bar fixation is used to prevent flipping, then bar stability is improved, but patient discomfort increases

Engineering Contradiction:

Improvebar stabilityVSAvoidpatient discomfort

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The invention replaces the rigid bar structure with a compliant, flexible bar that can adapt to the chest wall's contours and movements. This flexible bar maintains stability through its ability to conform to the anatomical structure rather than through rigid fixation, thereby preventing flipping and displacement while significantly reducing patient discomfort and pressure points.

Inventive Principle:

Principle #30Flexible shells and thin films

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 elastic bar provides gradual correction, reducing patient discomfort and the need for pain medication, ensuring effective and safe deformation adjustment over time.

Implementation Method 1

Compliant mechanisms have been favored over traditional rigid-link mechanisms in some engineering applications due to their low part count, stored strain energy, and simplicity/reliability

Methodology Applied

Scientific EffectStrain energy storage and release: Elasticity

Implementation Method 2

The phenomenon is observed once a constant force is applied to the chest wall by the brace; gradually and over time, the stiffness of the chest wall decreases, and the initial constant force then produces greater displacement. This phenomenon resembles stress relaxation in engineering materials.

Methodology Applied

Scientific EffectStress relaxation: Stress Relaxation

Data Source

PatentUS12458407B2Elastic bar for pectus excavatum repair

Publication Date: 2025.11.04 CHILDRENS HOSPITAL MEDICAL CENT CINCINNATI

AI summary

An implantable medical device, illustratively an elastic bar, for the gradual correction of pectus excavatum in patients.