Resilient Spiral Spring Ligament Assembly for Joint Kinematics

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Solution Overview

Problem

Conventional artificial ligaments fail to replicate the high strength, toughness, and resilience of natural ligaments, and struggle to replicate the natural kinematics of joints, especially in complex joints like the knee, which is highly dependent on ligament interactions with bone articulating areas.

Innovation Solution

A joint replacement system incorporating a prosthetic knee component connected to an artificial ligament via a resilient spiral spring element that resists loads through bending, mimicking the natural ligament's stiffness and providing tensioning and shock absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional artificial ligaments are used to replace damaged natural ligaments, then the joint can be stabilized and movement can be restored, but the artificial ligaments fail to replicate the high strength, toughness, and resilience of natural ligaments

Engineering Contradiction:
Improvestrength and resilience of ligamentVSAvoidstrength and toughness of artificial fibres
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention combines natural ligament tissue with an artificial resilient element (spring) to create a composite structure. The natural ligament provides biological compatibility and attachment, while the resilient element provides the missing strength, toughness, and resilience properties that artificial fibres alone cannot achieve.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention changes the mechanical parameters of the ligament system by introducing a spring element with specific elastic properties. The spring's stiffness, damping characteristics, and load-deflection behavior are designed to match and enhance the mechanical properties of natural ligaments, providing the required strength and resilience.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If prosthetic components are used to replace both ligament and bone tissue, then the joint can be stabilized, but it becomes extremely difficult to replicate the natural kinematics of the joint

Engineering Contradiction:
Improvestability of jointVSAvoidnatural kinematics of joint
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The resilient element acts as an intermediary between the prosthetic knee component and the artificial ligament, providing the necessary mechanical compliance and shock absorption. This intermediary component allows the system to maintain stability while accommodating the complex, natural movements of the knee joint that rigid prosthetic connections cannot achieve.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention introduces dynamic behavior to the joint replacement system through the spring element, which can deform, absorb energy, and return to its original shape. This dynamic response mimics the natural ligament's ability to adapt to varying loads and movements, enabling the prosthetic joint to replicate natural kinematics under different loading conditions.

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If artificial ligaments are made from uniform strands or bundles of artificial fibres, then the structure is simple to manufacture, but the ligament cannot match the high strength, toughness, and resilience of natural ligaments

Engineering Contradiction:
Improvesimplicity of artificial ligament constructionVSAvoidstrength, toughness and resilience of ligament
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The invention creates a composite structure combining simple-to-manufacture artificial fibres with a resilient spring element. The artificial fibre bundle provides the basic ligament structure and attachment points, while the spring element provides the enhanced mechanical properties, achieving both manufacturability and superior performance.

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

The system effectively replicates the natural kinematics of the knee joint, accommodating sudden loads and extreme articulations without overstressing the ligament, and can be adapted for various joints, offering a more stable and resilient alternative to conventional artificial ligaments.

Implementation Method 1

the resilient element configured to resist loads transmitted between the prosthetic knee component and the ligament by virtue of the resistance to bending of the resilient element

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

accommodating sudden loads and extreme articulations without overstressing the ligament

Methodology Applied
Scientific EffectShock absorption: Damping

Data Source

PatentEP3785666B1Ligament assembly
Publication Date: 2024.01.31 BIOMET UK HEALTHCARE
  • EP3785666B1 patent drawingFigure 1
  • EP3785666B1 patent drawingFigure 2
  • EP3785666B1 patent drawingFigure 3~5

AI summary

A ligament assembly (2) comprising a resilient element (20) connected to a bone anchor (4) and a ligament (18), the resilient element (20) acting m a cantilever and resisting toads transmitted between the bone anchor (4) and the ligament (18) by virtue of the resistance to bending of the resilient element. The ligament (18) may comprise an artificial ligament (18) which is adapted to replace a human or animal ligament. The resilient element (20) may comprise a spiral spring and may act as a biasing element/shock absorber operatively coupled to the artificial ligament (18) to control the effective stiffness of the artificial ligament (18). Consequently, the resilient element (20) enables an effective stiffness of the artificial ligament (18) to be achieved that more closely approximates the stiffness of a natural ligament.