Modular Knee Prosthesis Metaphyseal Sleeves for Joint Line Optimization

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Solution Overview

Problem

In knee revision surgeries, standard knee implants often fail to optimally seat metaphyseal sleeves due to differences in geometry, requiring additional bone preparation for larger sizes, which complicates joint line optimization and stability.

Innovation Solution

A modular knee prosthesis system with metaphyseal sleeves of varying lengths sharing a common geometry, allowing for efficient positioning without additional bone preparation, using tapered stems and stepped outer surfaces for frictional locking and optimal load transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If standard knee implants are used in revision surgeries, then the procedure can be performed with conventional components, but the metaphyseal sleeves cannot be optimally seated due to geometry differences requiring additional bone preparation

Engineering Contradiction:

Improveease of seating metaphyseal sleevesVSAvoidbone preparation complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent applies universality by designing metaphyseal sleeves with a standardized common geometry that can be used across multiple sleeve sizes. The common geometry includes a tapered stem and stepped outer surface that are identical across all sleeve variants, allowing the same bone preparation to accommodate different sleeve lengths. This eliminates the need for additional bone preparation when selecting larger sleeves, as they all share the same preparing interface geometry.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If larger sized metaphyseal sleeves are used, then joint line optimization is improved, but additional bone preparation is required which complicates the procedure

Engineering Contradiction:

Improvejoint line optimization flexibilityVSAvoidsurgical procedure simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent enables joint line optimization flexibility without increasing surgical complexity by making the bone preparation universal across all sleeve sizes. The common geometry of the tapered stem and stepped outer surface ensures that the same preparation works for all sleeve variants, allowing surgeons to select appropriate sleeve lengths for joint line optimization without requiring additional preparation steps.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent segments the sleeve into two distinct geometric portions: a common geometry portion (tapered stem and stepped outer surface) that remains identical across all sizes, and a variable geometry portion (distal portion) that differs to provide different lengths. This segmentation allows the standardized preparation to interface with the common portion while accommodating variable lengths in the distal portion.

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If multiple bone preparations are performed for different sleeve sizes, then the correct sleeve can be fitted, but the time required for the procedure increases

Engineering Contradiction:

Improvesleeve fitting precisionVSAvoidsurgical time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent eliminates the need for multiple bone preparations by establishing a universal preparation geometry that works for all sleeve sizes. The common geometry of the tapered stem and stepped outer surface serves as the standardized interface, allowing a single preparation to accommodate any sleeve length variant, thereby reducing surgical time while maintaining precise fitting.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables flexible optimization of the joint line and efficient seating of metaphyseal sleeves, enhancing the stability and performance of the knee prosthesis system without the need for further bone cavity preparation.

Implementation Method 1

tapered stems and stepped outer surfaces for frictional locking

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS11648127B2Method and system including sleeves and broaches for surgically preparing the patient's bone

Publication Date: 2023.05.16 DEPUY (IRELAND) LTD

AI summary

An orthopaedic surgical instrument system includes a first broach including a first end configured to be separately secured to a handle and a tapered body having a plurality of cutting teeth defined therein, and a second broach including a first end configured to be separately secured to the handle in place of the first broach, a first tapered body extending distally from a second end positioned opposite the first end, and a second tapered body extending distally from the first tapered body. The tapered body of the first broach and the first tapered body of the second broach have a first outer geometry and the second tapered body has a second outer geometry different from the first outer geometry.