Ultrasonic Bone Coating Embedding for Polymer Prosthetics

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Solution Overview

Problem

Traditional prosthetic acetabular cups with ceramic monoblock designs lack the necessary elastic modulus to match bone stiffness, leading to inadequate stress transfer and fixation, while semi-crystalline polymeric materials like UHMWPE are prone to property changes when heated, affecting strength and durability when coatings are applied.

Innovation Solution

A method and apparatus for applying a bone attachment coating using particles excited to increase their energy, allowing them to be embedded into a polymer surface without significantly heating the prosthetic component, using ultrasonic or electromagnetic energy, and applying pressure to ensure embedding without altering the polymer's properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermal spray methods are used to apply coating, then coating application is effective, but the polymer material is heated above melting point causing property changes

Engineering Contradiction:
Improvecoating application effectivenessVSAvoidpolymer material properties
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent replaces thermal spray methods with a mechanical particle delivery system where particles are accelerated through a nozzle using compressed gas or electromagnetic fields, eliminating thermal heating while maintaining effective coating application

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs ultrasonic vibration to excite particles before impact, enhancing their embedding capability into the polymer surface without requiring thermal heating, thus preserving material properties

Inventive Principle:
Principle #18Mechanical vibration

2Strength

If ceramic monoblock cups are used, then stress transfer is improved, but elastic modulus does not match bone stiffness

Engineering Contradiction:
Improvestress transfer capabilityVSAvoidelastic modulus match with bone
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent creates a composite structure by embedding osteoconductive particles (such as hydroxyapatite or titanium) into the polymer surface, combining the bone-matching elastic modulus of polymer with the osteointegration properties of ceramic particles

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies osteoconductive particles selectively to the bone-facing surface region where bone attachment is needed, while the bulk polymer material maintains its bone-matching elastic modulus and mechanical properties

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If particles are heated for embedding, then embedding effectiveness is improved, but polymer material undergoes permanent physical or chemical changes

Engineering Contradiction:
Improveparticle embedding effectivenessVSAvoidpolymer material integrity
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent uses ultrasonic vibration to excite particles to high velocities before impact, enabling effective embedding into the polymer surface through mechanical energy rather than thermal heating

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

The patent replaces thermal heating methods with mechanical particle acceleration and vibration, achieving embedding effectiveness through kinetic energy and ultrasonic excitation without thermal damage to the polymer

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 method effectively embeds osteoconductive particles into polymer surfaces of prosthetic components, enhancing bone attachment and fixation while maintaining the material's mechanical and chemical properties, enabling efficient mass production of cost-effective prosthetic cups with improved stress distribution and durability.

Implementation Method 1

exciting the particles so as to increase the energy, e.g. kinetic, vibrational and/or thermal energy, of the particles

Methodology Applied
Scientific EffectUltrasonic vibration: Ultrasonic Vibration

Implementation Method 2

the energy of the particles causes localised heating of the prosthetic component such that the particles may be embedded

Methodology Applied
Scientific EffectKinetic energy conversion to thermal energy: Viscous Heating

Data Source

PatentEP3280542B1A method and apparatus for applying a bone attachment coating
Publication Date: 2021.05.19 BIOMET UK HEALTHCARE
  • EP3280542B1 patent drawingFigure 1
  • EP3280542B1 patent drawingFigure 2(a)
  • EP3280542B1 patent drawingFigure 2(b)

AI summary

A method and apparatus for applying a bone attachment coating to a prosthetic component, the bone attachment coating being formed from a plurality of particles applied to a surface of the prosthetic component. The method comprising: locally exciting the particles so as to increase the kinetic and/or thermal energy of the particles; and applying pressure to the particles by virtue of a press arranged so as to press the particles against the surface of the prosthetic component at an interface between the press and the prosthetic component. The kinetic and/or thermal energy of the particles causes localised heating of the component such that the particles may be embedded into the surface of the prosthetic component.