Modular Unicompartmental Knee Prosthesis Adaptation

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Solution Overview

Problem

Current unicompartmental knee prostheses lack adaptability to individual patient anatomy, leading to suboptimal performance and higher revision rates, particularly in lateral procedures due to limited femoral component options and fixation methods.

Innovation Solution

A modular unicompartmental knee prosthesis system with interchangeable femoral and tibial components of varying sizes and materials, including a RES and 3CUT femoral component, AllPoly and MetalBack tibial components, and a fixed articular insert, allowing for greater flexibility and adaptability during surgery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a fixed design of femoral component is used, then the device complexity is reduced, but the adaptability to individual patient anatomy deteriorates

Engineering Contradiction:

Improvefemoral component designVSAvoidadaptability to patient anatomy

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The femoral component is divided into multiple interchangeable versions (first version with first thickness, second version with second thickness) that can be selected based on patient anatomy. This segmentation allows the system to maintain simplicity in each individual component while achieving high adaptability through combination choices.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Both femoral component versions are designed with the same basic structure and fixation mechanisms, allowing them to serve multiple anatomical requirements. The universal design pattern enables the same component architecture to adapt to different patient needs through variation in thickness.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If cemented fixation is used, then the ease of manufacture is improved, but the reliability of biological fixation deteriorates

Engineering Contradiction:

Improvefixation methodVSAvoidfixation stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The fixation method is changed from purely cemented to a combination of cemented and mechanical interlocking through protrusions and recesses. This parameter change in the fixation mechanism allows for both ease of manufacture and improved reliability by combining multiple fixation approaches.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The fixation system combines different fixation mechanisms (cemented and mechanical) into a composite approach. The protrusions and recesses create a hybrid fixation system that leverages both chemical bonding from cement and mechanical interlocking for enhanced reliability.

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If mobile articular inserts are used, then the adaptability to restore articular movement is improved, but the reliability deteriorates due to higher dislocation risk

Engineering Contradiction:

Improvearticular movement restorationVSAvoidinsert stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Instead of using mobile inserts that move freely to restore articular movement, the invention inverts the approach by using fixed inserts that provide stability. The articular movement is restored through the design of the fixed insert geometry and its interaction with the femoral component, rather than through mobility of the insert itself.

Inventive Principle:

Principle #13The other way round (Inversion)

4Adaptability or versatility

If lateral compartment UKA is performed, then the adaptability to treat lateral pathology is improved, but the device complexity and surgical difficulty increase

Engineering Contradiction:

Improvelateral compartment treatmentVSAvoidsurgical technique complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The prosthesis system is segmented into modular components (femoral component with specific geometry, tibial component, fixed insert) that can be independently selected and assembled. This modularity reduces the complexity of lateral compartment UKA by allowing standardized components to be combined in a systematic way.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The femoral component is designed with specific local geometric features (curved main body, convex outer side, inner side with fastening means) that are optimized for lateral compartment anatomy. This local quality customization allows the standardized prosthesis system to adapt to lateral pathology without increasing overall surgical complexity.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP4161448B1Unicompartimental knee prosthesis

Publication Date: 2024.07.10 GRUPPO BIOIMPIANTI

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AI summary

Prosthesis for knee arthroplasty comprising a femoral component with a minimum thickness and with two different systems for fastening to the femoral condyle and a tibial component with an upper surface which can have a double profile with a differentiated congruence profile. The tibial component can be made with a single body or in two parts of different materials.