Flexible Interbody Cage Structure for Uniform Endplate Load Sharing

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Solution Overview

Problem

Existing interbody cages made of rigid materials do not ensure homogeneous load-sharing between the implant's surfaces and the vertebral endplates, leading to vertebral subsidence due to uneven anatomy, and existing flexible cages lack controlled flexibility and stability during compression.

Innovation Solution

Interbody cages with flexible structures such as 'S'-shaped or 'Z'-shaped springs, flexible strands, hoops, or convex mesh structures, restrained by a rigid frame, providing controlled flexibility and dampening of compression forces while engaging uneven vertebral endplates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid materials are used for interbody cages, then structural strength is improved, but load-sharing homogeneity deteriorates causing vertebral subsidence

Engineering Contradiction:

Improvestructural strengthVSAvoidload-sharing homogeneity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The cage structure is segmented into rigid peripheral walls and flexible internal elements (strands, springs, or lattice structures). This segmentation allows different regions to perform different functions: the rigid walls provide structural strength and containment, while the flexible internal elements distribute compression forces uniformly across the vertebral endplates, preventing subsidence.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cage combines rigid materials (for the peripheral frame and walls) with flexible materials (for the internal dampening structures). This composite construction enables the implant to simultaneously achieve high structural strength and homogeneous load distribution, as the rigid components maintain integrity while the flexible components adapt to vertebral surface irregularities.

Inventive Principle:

Principle #40Composite materials

2Reliability

If flexible materials are used for interbody cages, then load-sharing homogeneity is improved, but structural stability deteriorates

Engineering Contradiction:

Improveload-sharing homogeneityVSAvoidstructural stability

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

Different regions of the cage are assigned different mechanical properties: the peripheral walls and frame are made rigid to provide structural stability and prevent collapse, while the internal dampening elements are made flexible to ensure homogeneous load distribution. This local differentiation of material properties allows the cage to simultaneously achieve both stability and load-sharing homogeneity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Inventive Principle:

Principle #40Composite materials

3Reliability

If flexible structures are added to interbody cages, then dampening capability is improved, but device complexity increases

Engineering Contradiction:

Improvedampening capabilityVSAvoidstructural complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The cage incorporates flexible elements such as thin strands, spring structures, or lattice configurations that can bend and deform to absorb compression forces. These flexible components are integrated within the rigid cage framework, providing dampening capability while maintaining a relatively simple overall structure that is straightforward to implant.

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 solution ensures durable dampening of pressure on vertebral endplates, enhances bone growth, prevents subsidence, and maintains implant stability by controlled flexibility and reduced friction, facilitating effective bone fusion.

Implementation Method 1

The compression force exercised by the adjoining vertebrae are flexing the springs, strands, hoops, coils or convex mesh structures until the rigid borders of the chambers or lateral walls of the cage engage the vertebrae

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The hollowed-out rigid frame with its restraining feature, enables an effective control of the flexibility of the top and bottom surfaces of the interbody cage

Methodology Applied

Scientific EffectMechanical constraint:

Implementation Method 3

Where the vertebral endplates present depressed portions on their surfaces, the springs, strands, hoops, coils or convex mesh structures still fill those depressed cavities, although their flexion is more limited

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 4

The coating of the walls and sides of the mobile components of implants which are made of lattice or coiled structures also reduces the impact of friction generated by relative motions between several components of implants made with such structures

Methodology Applied

Scientific EffectFriction reduction: Lubrication

Data Source

PatentUS12575942B2Flexible interbody cage

Publication Date: 2026.03.17 CARATSCH ALEXANDER

AI summary

An intervertebral bone fusion implantable device configured with flexible structural elements on its top and bottom surfaces for controlled dampening of the compressive force exerted on the device by two vertebrae and for the maximization of the contact surface between the device and the uneven endplates of the vertebrae.