Directional Hinged Rod Connector for Vertebral Growth Modulation

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Solution Overview

Problem

Current spinal fusion procedures for correcting spinal deformities in children eliminate spinal growth and motion, leading to high morbidity and unpredictable outcomes, as existing growth modulation techniques fail to effectively correct deformities in human spines due to differences in vertebral anatomy and biomechanics compared to animal models.

Innovation Solution

A spine growth modulation system using a non-compressible tether with a distraction hinge that applies distraction, rotation, and compression forces to modulate vertebral growth by moving the center of rotation outside the vertebral cortex, allowing for differential stress distribution across the endplate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If spinal fusion is performed to correct spinal deformities, then spinal alignment is improved, but spinal growth and motion are eliminated

Engineering Contradiction:

Improvespinal alignmentVSAvoidloss of spinal growth and motion

Core Design Contradiction:

ShapeVSObject-generated harmful factors

Solution Approach 1:

The spinal column is divided into instrumented and non-instrumented segments. The distraction hinge system is applied selectively to specific vertebral levels requiring growth modulation, while other segments maintain natural growth and motion capabilities. This segmentation allows correction of deformities at targeted levels without eliminating growth throughout the entire spine.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The distraction hinge mechanism provides dynamic force application to the vertebral growth plate, creating controlled distraction forces that modulate growth rates. The system transitions from static fusion to dynamic growth modulation, allowing the spine to adapt and grow while being guided toward proper alignment through controlled mechanical forces.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If early growth modulation techniques are used to maintain spinal motion, then motion is preserved, but deformity correction outcomes are unpredictable

Engineering Contradiction:

Improvespinal motionVSAvoiddeformity correction outcome

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The distraction hinge system applies predetermined distraction forces to the growth plate before significant deformity progression occurs. By initiating growth modulation early and maintaining controlled forces throughout growth, the system proactively guides spinal development toward correct alignment rather than attempting corrective action after deformity becomes severe.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system incorporates monitoring of spinal alignment progression and growth response to the distraction forces. Clinical evaluation of curve correction and growth rates allows adjustment of the distraction hinge parameters to optimize both motion preservation and reliable deformity correction outcomes.

Inventive Principle:

Principle #23Feedback

3Productivity

If distraction hinge applies forces to modulate vertebral growth, then growth modulation is achieved, but hardware failure risk increases

Engineering Contradiction:

Improvegrowth modulation effectivenessVSAvoidhardware failure rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The distraction hinge system allows adjustment of distraction force parameters to optimize the balance between growth modulation effectiveness and hardware reliability. By controlling the magnitude and direction of forces applied to the growth plate, the system achieves effective growth modulation while minimizing excessive stress that could lead to hardware failure.

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

The system effectively modulates vertebral growth to correct spinal deformities while maintaining motion, reducing hardware failure and individualizing force application for varying spinal curvatures, offering a safer and more predictable alternative to traditional fusion methods.

Implementation Method 1

A distraction hinge tip set screw may be screwed into the distraction hinge to compress a distraction hinge spring that pushes on the first end of the first spinal rod and the first end of the second spinal rod to cause a distraction force on the first spine vertebra and the second spine vertebra

Methodology Applied

Scientific EffectSpring: Spring

Data Source

PatentUS12471961B2Vertebral growth modulating directional hinged end-to-end rod connector

Publication Date: 2025.11.18 PHOENIX CHILDRENS HOSPITAL INC

AI summary

A first and second pedicle screw may be screwed into a first and second corresponding spine vertebra. A first end of a first spinal rod and a first end of a second spinal rod may be connected to a corresponding first and second opening in a distraction hinge. A rod-to-hinge connector may be positioned between the ends of the spinal rods and the openings in the distraction hinge if desired. A second end of the first spinal rod and a second end of the second spinal rod may be placed in a head of the corresponding first and second pedicle screws and attached using tip set screws. A tip set screw may be screwed into the distraction hinge to compress an internal spring that causes a distraction force that separates the first spine vertebra from the second spine vertebra and enables a center of rotation away from a vertebral cortex.