Thermal Expansion Fixation for Prosthetic Hip Acetabulum

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing methods for manufacturing prosthetic hip acetabulums face challenges in achieving reliable and secure fixation of the insertion cup to the impactor, while minimizing the forces required and avoiding contamination risks, particularly with plastic components that can absorb condensate liquids contaminated with bacteria or microbes.

Innovation Solution

A manufacturing method involving an insertion cup with a concave inner receiving face and an outer annular receiving structure, where the installation and orientation insert is heated to expand, then cooled to engage radially around the receiving structure, providing a secure radial clamping that reduces the forces needed for fixation and minimizes contamination risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the installation and orientation insert is cooled to contract and permit its introduction into the insertion cup, then the insert can be introduced into the cup, but condensate liquids contaminated by bacteria or microbes can form and settle on the insert, causing deep-rooted contamination

Engineering Contradiction:

Improveintroduction of insert into cupVSAvoidbacterial contamination

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

Instead of cooling the insert to achieve contraction for introduction (which causes condensation and contamination), the patent inverts the approach by heating the insert to expand it for introduction, then allowing it to cool and contract for secure retention. This reversal eliminates the condensation problem while achieving the same mechanical effect.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent utilizes thermal expansion and contraction phase transitions of the plastic insert material. By heating the insert above its glass transition temperature, the material becomes more compliant and expands, allowing easy introduction. Subsequent cooling causes contraction and secure retention without condensation contamination.

Inventive Principle:

Principle #36Phase transitions

2Reliability

If the insertion cup is retained by an impactor with elastic tabs, then the cup can be held and manipulated, but the force required to spread the tabs apart increases with better hold, causing more effort for fixation

Engineering Contradiction:

Improvehold of cup by impactorVSAvoideffort to fix impactor to cup

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the physical parameters of the plastic insert by heating it above its glass transition temperature. This parameter change makes the material more compliant and reduces its mechanical strength temporarily, allowing easy fixation to the impactor. After cooling, the material returns to its original state providing reliable retention without requiring excessive fixation force.

Inventive Principle:

Principle #35Parameter changes

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 method ensures a reliable and secure fixation of the insertion cup to the impactor, reducing the risk of contamination and deformation during impaction, while allowing for easier handling and positioning of the articular insert, thus enhancing the stability and longevity of the prosthetic joint.

Implementation Method 1

heating the installation and orientation insert in order to increase the dimensions thereof

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

bringing the installation and orientation insert back to room temperature in order to reduce the dimensions thereof

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS9987139B2Method for manufacturing a prosthetic hip acetabulum

Publication Date: 2018.06.05 INVENTORIO

AI summary

A method for manufacturing a prosthetic hip acetabulum includes the following steps. First, one provides an insertion cup (1) having an inner concave receiving surface (3) having an opening surface (5) contained in an opening plane (P), and having an outer annular receiving structure (6). Next, one provides an installation and positioning insert (7) having a peripheral annular attachment structure (10) shaped to engage with the receiving surface (9) of the structure (6), fitting around that structure. Next, one heats the insert (7) in order to increase its size. Next, one fits the attachment structure (10) around the receiving surface (9) of the receiving structure (6). Finally, one cools the insert (7) to room temperature to reduce its size and achieve radial tightening of the attachment structure (10) on the outer annular receiving structure (6).