Patellar Prosthesis With Compact Anchoring and Porous Interface

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Solution Overview

Problem

Existing patellar prostheses face challenges in ensuring effective interconnection of the polymer joint cap with the metallic support component, stability, and sufficient bone regrowth due to variability in polymer permeation and porous layer thickness, leading to potential detachment and instability.

Innovation Solution

A patellar prosthesis with a monolithic metallic support component and a polymeric joint cap, featuring a compact anchoring portion and a porous interface portion for osseointegration, along with connection pegs and recesses for stable anchoring, is manufactured via additive manufacturing, ensuring a seal without compromising bone integration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a porous osseointegration layer is used to enable bone regrowth, then bone integration is improved, but polymer material may intrude into the porous structure during manufacturing, compromising the bone regrowth capability

Engineering Contradiction:

Improvebone integrationVSAvoidpolymer intrusion into porous layer

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The support component is divided into two distinct portions: a compact anchoring portion for polymer attachment and a porous interface portion for bone integration. This segmentation prevents polymer material from intruding into the porous osseointegration layer while maintaining both functions effectively.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The compact anchoring portion acts as an intermediary barrier between the polymer joint cap and the porous osseointegration layer. It provides a sealing interface that prevents polymer intrusion while allowing the porous portion to maintain its bone regrowth capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the porous layer thickness is increased to ensure sufficient bone regrowth, then bone integration is improved, but the structural complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvebone regrowthVSAvoidporous layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Different portions of the support component have different structural qualities: the anchoring portion is compact for sealing, while the interface portion is porous for bone integration. This local differentiation optimizes each region's function without requiring the entire structure to be complex.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The compact anchoring portion and porous interface portion are merged into a single monolithic support component made by additive manufacturing. This integration simplifies manufacturing while maintaining the functional benefits of both structures.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If the porous layer thickness is reduced to simplify manufacturing, then device complexity is reduced, but bone regrowth capability is compromised

Engineering Contradiction:

Improveporous layer fabricationVSAvoidbone integration

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The interface portion maintains adequate porous thickness for bone regrowth while the anchoring portion remains compact. This local quality differentiation ensures sufficient bone integration capability without unnecessarily increasing overall manufacturing complexity.

Inventive Principle:

Principle #3Local quality

4Strength

If a monolithic metallic support component is used, then structural integrity is improved, but the ability to provide both sealing and osseointegration functions simultaneously is compromised

Engineering Contradiction:

Improvestructural integrityVSAvoiddual function capability

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The monolithic support component features local quality variations: a compact anchoring portion for sealing and a porous interface portion for osseointegration. This allows a single structurally integrated component to perform both sealing and bone integration functions simultaneously.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The support component combines different structural characteristics (compact and porous regions) within a single metallic material structure, enabling dual functionality while maintaining structural integrity through additive manufacturing.

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 solution provides stable anchoring and maximizes bone regrowth by preventing polymer intrusion into the osseointegration layer, enhancing the prosthesis's stability and integration with the natural patella.

Implementation Method 1

an interface portion (13) in direct continuity with said anchoring portion (14), said interface portion (13) consisting of a completely porous structure suitable for osseointegration

Methodology Applied

Scientific EffectOsseointegration: Adsorption

Implementation Method 2

said anchoring portion (14) being made in a compact material, lacking a porous structure and having an anchoring surface (17) for the polymeric material of the joint cap (12)

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Data Source

PatentUS20250318933A1Patellar prosthesis

Publication Date: 2025.10.16 LIMACORPORATE SPA

AI summary

A patellar prosthesis includes a support component in metallic material and a joint cap in polymeric material, anchored to an anchoring surface of said support component.