Dynamic Interbody Fusion Lattice for Controlled Graft Strain

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Solution Overview

Problem

Existing spinal implants used for interbody fusion often require stiff cages to prevent subsidence, which hinder the beneficial effects of vibrational waves and graft strain on bone growth, leading to non-union of adjacent vertebrae.

Innovation Solution

A dynamic spinal implant with a deformable structure that generates a modified strain tensor on bone grafts, incorporating lattice patterns and resonating elements to control and enhance mechanical load application, promoting bone growth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If stiff interbody cages are used to prevent subsidence, then structural stability is improved, but the beneficial effects of vibrational waves and graft strain on bone growth are negated

Engineering Contradiction:
Improvestructural stabilityVSAvoidbone growth promotion
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent applies the dynamics principle by transitioning from a static, stiff cage structure to a dynamic, adaptable structure. The interbody device incorporates a deformable lattice inner structure that can dynamically adjust its mechanical properties to transmit beneficial vibrational waves and strain to the bone graft while maintaining structural stability through controlled deformation rather than rigid resistance.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the mechanical properties of the cage structure. The inner structure uses a lattice pattern with controlled stiffness parameters that allow it to deform within specific ranges, transmitting vibrational energy and strain to the bone graft. The structure's elastic modulus and damping characteristics are optimized to balance stability with bone growth promotion.

Inventive Principle:
Principle #35Parameter changes

2Strength

If stiff interbody cages are used to prevent subsidence, then mechanical support is improved, but graft strain and vibrational wave effects are reduced

Engineering Contradiction:
Improvemechanical supportVSAvoidgraft strain
Core Design Contradiction:
StrengthVSForce

Solution Approach 1:

The patent employs flexible shell principles through the deformable lattice inner structure that acts as a flexible yet load-bearing component. This lattice structure can flex and deform under physiological loads, maintaining mechanical support while transmitting controlled strain and vibrational forces to the bone graft, unlike traditional rigid cages that absorb or dissipate these forces.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The patent utilizes composite material principles by combining the outer cage structure with an inner deformable lattice structure. This composite design allows the device to exhibit both the mechanical strength needed for initial stability and the flexibility required to transmit beneficial forces to the bone graft, achieving a dual-function material system.

Inventive Principle:
Principle #40Composite materials

3Reliability

If traditional rigid cages are used, then implant stability is maintained, but bone growth promotion through mechanical stimulation is hindered

Engineering Contradiction:
Improveimplant stabilityVSAvoidbone growth rate
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent directly applies mechanical vibration principles by designing the inner lattice structure to transmit and amplify vibrational waves to the bone graft. The lattice geometry and material properties are optimized to resonate at frequencies beneficial for bone growth, converting the device into an active bone stimulation system rather than a passive structural support.

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

The patent implements parameter changes by optimizing the lattice structure's geometric and material parameters to control its mechanical response. The structure's stiffness, damping, and resonant frequency parameters are tuned to maintain implant stability while maximizing bone growth promotion through controlled mechanical stimulation during the healing process.

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 dynamic spinal implant effectively promotes intervertebral bone growth by modulating mechanical loads, enhancing graft strain within a desired range, thereby improving fusion rates and reducing non-union complications.

Implementation Method 1

the inner structure is configured to generate a modified strain tensor on bone graft and/or bone substitute material disposed within the dynamic spinal implant

Methodology Applied
Scientific EffectStrain tensor modification: Deformation

Implementation Method 2

The stiff nature of these interbody cages generally negates any potentially beneficial effects of vibrational waves and/or graft strain on the bone growth process

Methodology Applied
Scientific EffectVibrational wave transmission: Vibration

Implementation Method 3

incorporating lattice patterns and resonating elements to control and enhance mechanical load application

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 4

The dynamic spinal implant effectively promotes intervertebral bone growth by modulating mechanical loads, enhancing graft strain within a desired range

Methodology Applied
Scientific EffectMechanical load modulation: Force

Implementation Method 5

require relatively stiff interbody cages to minimize stress shielding of ingrown bone

Methodology Applied
Scientific EffectStress shielding reduction: Stress Relaxation

Data Source

PatentEP4161450B1Dynamic interbody fusion devices
Publication Date: 2025.07.16 NUVASIVE INC
  • EP4161450B1 patent drawingFigure 1~2B
  • EP4161450B1 patent drawingFigure 3A~3C
  • EP4161450B1 patent drawingFigure 4~6

AI summary

The present disclosure provides dynamic interbody fusion devices and methods of making and using same.