Modular Trial Heads for Hip Prostheses

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Solution Overview

Problem

Current hip replacement procedures face challenges in selecting prosthetic joint components that accurately match patient anatomy, as existing trial prostheses have limited diameter and offset combinations, restricting the ability to find a suitable fit for all patients.

Innovation Solution

A femoral trial system comprising multiple head and shell members with varying diameters and offsets, featuring barbed projections that securely engage stems, allowing for customizable fitting by ensuring precise mating with different stem components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If existing trial prostheses with limited diameter and offset combinations are used, then the device complexity is reduced, but the adaptability to different patient anatomies deteriorates

Engineering Contradiction:

Improveadaptability to patient anatomyVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The trial prosthesis is divided into separate modular components: a stem component and a head component that can be independently selected and combined. Multiple stem components with different geometries and multiple head components with varying diameters and offsets are provided, allowing customization without creating a single complex multi-functional device.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cavity in the head component is designed with universal engagement features (barbs at multiple depths) that can mate with various stem component types. This universal interface allows the same head component to work with multiple stem variations, increasing adaptability while maintaining reasonable device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple head and shell members with varying diameters and offsets are used, then the adaptability to patient anatomies is improved, but the device complexity increases

Engineering Contradiction:

Improveadaptability to patient anatomyVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system provides multiple head components that differ in specific parameters (diameter, offset, curvature) while maintaining the same basic structure and engagement interface. This allows customization through parameter variation rather than structural complexity, enabling anatomical matching without proportionally increasing device complexity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If barbed projections are used to securely engage stems, then the reliability of the trial prosthesis is improved, but the ease of manufacture deteriorates

Engineering Contradiction:

Improvereliability of trial prosthesisVSAvoidease of manufacture

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The barbed projections are pre-formed as integral features of the head component during manufacturing, rather than being added separately. This preliminary incorporation of the engagement mechanism simplifies the overall manufacturing process while ensuring reliable engagement with the stem component's exterior surface.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8840676B2Modular trial heads for a prosthetic

Publication Date: 2014.09.23 SMITH & NEPHEW INC

AI summary

A prosthesis trial system includes at least one head member having an outer surface and a cavity configured to mate with an exterior surface of a stem member. The prosthesis trial system further includes at least one shell member having an inner surface configured to mate with the outer surface of the at least one head member.