Modular Insert Hinged Knee Prosthesis Assembly

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Solution Overview

Problem

Existing hinge knee prosthesis designs face difficulties in adequate exposure for the hinge axle during femur implantation, especially when collateral ligaments are damaged, requiring either a dedicated hinge femoral component or challenging surgical access.

Innovation Solution

The orthopaedic prosthetic assembly features a femoral component with a pair of condyles defining an intercondylar notch, a modular insert with a bracket and elongated stem, and a hinge pin, allowing for a hinged knee prosthesis with improved assembly and stability, where the modular insert is pivotally coupled to the tibial component, enabling secure attachment and flexible movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a dedicated hinge femoral component is used, then the hinge axle can be properly positioned, but the device complexity increases

Engineering Contradiction:

Improvehinge axle positioningVSAvoidfemoral component design

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The modular insert is designed to be compatible with both standard and hinge femoral components, allowing the same insert to serve multiple functions. The bracket portion of the modular insert can accommodate either a standard femoral component or a hinge femoral component, eliminating the need for completely different component designs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The prosthesis is divided into separate modular components: the femoral component, the modular insert (with bracket and stem), and the tibial component. This segmentation allows the hinge mechanism to be added as a separate module rather than requiring a completely different femoral component design.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the hinge axle is inserted into the femur, then the hinge mechanism can be implemented, but the ease of operation decreases due to limited surgical access

Engineering Contradiction:

Improvehinge mechanism stabilityVSAvoidsurgical access

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The modular insert with its bracket serves as an intermediary component that connects the femoral component to the tibial component without requiring direct insertion of the hinge axle into the femur. The bracket is attached to the femoral component through the intercondylar notch, providing a stable attachment point that is more accessible surgically.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Instead of inserting the hinge axle vertically into the femur (requiring superior access), the bracket is positioned within the intercondylar notch and extends inferiorly, allowing the hinge mechanism to be assembled from a more accessible anterior or lateral surgical approach.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If a hinged knee prosthesis is used for damaged collateral ligaments, then the stability is improved, but the device complexity increases

Engineering Contradiction:

Improveknee stabilityVSAvoidprosthesis structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The hinge mechanism provides dynamic stability that adapts to the patient's needs. The hinge pin allows controlled rotation between the bracket and stem, enabling the prosthesis to transition from a fixed high-stability configuration to a more mobile configuration as the patient rehabilitates, rather than requiring a permanently complex rigid structure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The hinged configuration is implemented as a separate modular insert rather than being integrated into the basic femoral or tibial components. This allows the stability-enhancing hinge mechanism to be added only when needed (for patients with damaged collateral ligaments) while keeping the basic prosthesis design simple for patients with intact ligaments.

Inventive Principle:

Principle #1Segmentation

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

This design facilitates easier assembly and enhanced stability for the hinged knee prosthesis, accommodating varying anatomical conditions and providing secure attachment points for improved joint mobility and support.

Implementation Method 1

A hinge pin pivotally couples the elongated stem to the bracket. The platform is configured to pivot about a first axis extending in an inferior-superior direction and the elongated stem is configured to pivot about a second axis relative to the bracket and the femoral component.

Methodology Applied

Scientific EffectPivoting: Hinge

Implementation Method 2

A fastener is configured to secure the femoral component to the bracket of the modular insert.

Methodology Applied

Scientific EffectMechanical fastening: Mechanical Fastener

Data Source

PatentUS20240108471A1Orthopaedic prosthetic system for a hinged-knee prosthesis

Publication Date: 2024.04.04 DEPUY (IRELAND) LTD

AI summary

An orthopaedic prosthetic includes a femoral component including a pair of condyles spaced apart to define an intercondylar notch. A tibial component includes a tray and a platform pivotally coupled to the tray. A modular insert is configured to be selectively coupled to the femoral component to couple the femoral component to the tibial component.