Artificial Knee Ligament with Preformed Loops and Liners

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Solution Overview

Problem

Existing methods for implanting artificial knee ligaments often require excessive force and manipulation of the knee joint, risking damage to the ligament, and may result in instability due to loose or flexible ligaments, especially when preformed loops are not used.

Innovation Solution

An artificial knee ligament with fixed length and preformed loops, incorporating a loop liner made of a different material for enhanced durability and ease of attachment, allowing for secure coupling to prosthetic components without overflexing the knee joint or applying excessive force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the knee joint is overflexed to provide access to ligament fixings, then the ligament can be attached to both sides of the joint, but excessive force is required and there is a significant risk of damaging the artificial ligament

Engineering Contradiction:

Improveaccess to ligament fixingsVSAvoidrisk of damaging the artificial ligament

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The ligament is preformed with loops at both ends before implantation, allowing the surgeon to attach the ligament to the prosthetic components without requiring excessive manipulation or overflexing of the knee joint. This preliminary preparation of the ligament structure enables easier and safer attachment procedure.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If artificial ligaments are made flexible to allow articulation around the bollard, then the ligament can move with the knee joint, but the loops become worn over time

Engineering Contradiction:

Improvearticulation around the bollardVSAvoidwear of the loops

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The ligament incorporates a loop liner made of a different material (such as polyethylene or PTFE) at the loop region where contact with the bollard occurs. This local material differentiation provides a softer, more wear-resistant surface at the critical contact point while maintaining the overall flexibility and articulation capability of the ligament.

Inventive Principle:

Principle #3Local quality

3Stability of the object's composition

If the ligament is made stiff to maintain joint stability, then the joint remains stable, but the ligament cannot articulate around the bollard

Engineering Contradiction:

Improvejoint stabilityVSAvoidarticulation around the bollard

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The ligament is constructed with different material properties in different regions: the main body of the ligament is made stiff to maintain joint stability, while the loops are made flexible (and enhanced with loop liners) to allow articulation around the bollards. This local differentiation of material properties resolves the contradiction between stability and articulation.

Inventive Principle:

Principle #3Local quality

4Ease of operation

If preformed loops are used to avoid excessive manipulation, then the ligament can be attached without overflexing the knee, but the loops may become loose or fail after implantation

Engineering Contradiction:

Improveattachment without overflexingVSAvoidlooseness or failure of loops

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The loops are enhanced with loop liners made of wear-resistant materials such as polyethylene or PTFE. This local material enhancement at the loop region provides both the flexibility needed for easy attachment and the durability to prevent loosening or failure after implantation, while maintaining the overall stability of the ligament.

Inventive Principle:

Principle #3Local quality

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 provides a stable and durable artificial knee ligament that can be easily implanted without damaging the ligament, maintaining joint stability and reducing the risk of dislocation by using preformed loops and a resilient loop liner for secure attachment to prosthetic components.

Implementation Method 1

a loop liner made of a different material for enhanced durability and ease of attachment

Methodology Applied

Scientific EffectMaterial differentiation:

Implementation Method 2

a resilient loop liner for secure attachment to prosthetic components

Methodology Applied

Scientific EffectResilience: Elasticity

Data Source

PatentUS10959827B2Ligament fixing and a method of attaching a ligament

Publication Date: 2021.03.30 ZIMMER GMBH

AI summary

An artificial ligament is provided having an elongate body and two ends, with a loop being provided at least one of the ends and a loop liner being provided within the loop. A kit of artificial ligaments is also provided with each ligament in the kit having a different fixed length. Also provided are methods for determining a length of artificial ligament to be used within a prosthetic knee joint, selecting a ligament from a range or kit of ligaments, and implanting a prosthetic knee joint assembly comprising an artificial ligament.