Spinal Elastic Constraint for Bending Stiffness

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Solution Overview

Problem

Current spinal implants that restrict flexion in patients with discogenic pain often face challenges such as high morbidity, irreversible nature, and lack of viable alternatives, with existing devices either being too large or failing to prevent excess flexion, leading to pain and increased stress.

Innovation Solution

The development of spinal implants that dynamically increase bending stiffness during flexion by coupling an elastic constraint between spinous processes, providing a preselected increase in stiffness and a 'hard' flexion limit to prevent over-flexion, while allowing unrestricted extension and minimal resistance to lateral bending or rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bone cerclage devices are applied with high tension to fix the segment in one position, then motion is effectively restricted and fusion likelihood is improved, but the device allows no motion which causes abnormal loading and motion at adjacent segments leading to adjacent segment morbidity

Engineering Contradiction:

Improvefusion likelihoodVSAvoidadjacent segment morbidity

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a dynamic elastic constraint that allows controlled motion rather than complete restriction. The elastic member permits the spinal segment to move within a physiological range while providing resistance to excessive flexion, thereby maintaining reliability for fusion support while preventing the harmful adjacent segment loading caused by complete immobilization.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of motion restriction from complete immobilization to controlled elastic resistance. By adjusting the elastic properties and pre-tension of the constraint, the system allows physiological motion while resisting pathological excessive flexion, thus improving adjacent segment health while maintaining fusion support.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If spinal fusion surgery is performed to treat discogenic pain, then pain relief is achieved, but the procedure is irreversible, costly, associated with high morbidity, and of questionable effectiveness

Engineering Contradiction:

Improvepain reliefVSAvoidhigh morbidity and irreversibility

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent employs a less invasive elastic constraint device that can be applied without complete spinal fusion. This approach provides a reversible, lower-morbidity alternative that addresses pain through controlled motion restriction rather than permanent fusion, allowing for adjustment or removal if needed.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent applies partial action by restricting only excessive pathological flexion while allowing normal physiological motion. This selective restriction provides pain relief for discogenic conditions without the complete immobilization and high morbidity associated with full spinal fusion surgery.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If existing elastic constraint devices are made robust with high fatigue strength, then they can withstand millions of cycles, but the implant size increases making it harder to implant and less tolerable for patients

Engineering Contradiction:

Improvefatigue strengthVSAvoidimplant size

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent optimizes the elastic parameter (stiffness) of the constraint device to achieve the right balance. By carefully selecting the elastic modulus and geometric parameters, the device provides sufficient fatigue strength for millions of cycles while maintaining a compact, implantable size that is well-tolerated by patients.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent may utilize composite material structures or optimized material selection to achieve high fatigue strength in a smaller, lighter form factor. This allows the elastic constraint to withstand cyclic loading while maintaining a patient-friendly implant size.

Inventive Principle:

Principle #40Composite materials

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

These implants effectively reduce flexion-related pain and instability by providing controlled resistance to flexion, reducing the risk of injury and maintaining a significant degree of spinal mobility, thus addressing the limitations of existing devices.

Implementation Method 1

coupling an elastic constraint between spinous processes, providing a preselected increase in stiffness

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS20230085446A1Methods and systems for increasing the bending stiffness of a spinal segment with elongation limit

Publication Date: 2023.03.16 EMPIRICAL SPINE INC

AI summary

A system for restricting spinal flexion includes a compliance member having a body and an elongation limit. The body typically comprises a spring or other tension element which provides elastic constraint to the spinal segment when the compliance member is attached to the spinous processes. The elongation limit prevents overextension of the compliance member, thus reducing the likelihood that the patient will experience over flexion of the spinal segment and reducing the risk of placing excessive mechanical load on the compliance member.