Multi-piece Prosthetic Joint with Rotational Expansion

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Solution Overview

Problem

Conventional hip prostheses face issues with dislocation due to impingement and component malposition, as they require rigid fixation and lack the ability to rotate completely around the femur's longitudinal axis, leading to potential dislocation and implant damage.

Innovation Solution

A multi-piece prosthetic joint component featuring an elongate outer sleeve with a stem-receiving cavity and a joint articulating member, allowing for selective longitudinal expansion through relative rotation between the stem and the sleeve, which changes the longitudinal relationship between the sleeve and the articulating member, providing variance and reducing the risk of dislocation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid fixation is used to secure the prosthetic joint components, then stability and strength are improved, but the ability to accommodate bone movement and adjust to malposition is reduced

Engineering Contradiction:

Improvefixation strengthVSAvoidadaptability to bone movement

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The prosthetic joint component is divided into multiple segments: a fixed outer sleeve portion anchored in bone and a movable inner portion containing the articulating member. This segmentation allows the distal portion to remain stable while the proximal portion can move independently to accommodate bone movement and correct malposition, resolving the contradiction between fixation strength and adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces dynamic movement capability between the outer sleeve and inner portion through controlled dislocation and relocation mechanisms. The articulating member can dislocate from its initial position and relocate to a corrected position, transforming the rigid static structure into a dynamic system that adapts to bone movement while maintaining overall stability.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If complete rotation around the femur's longitudinal axis is allowed, then adaptability and range of motion are improved, but the risk of dislocation and implant damage increases

Engineering Contradiction:

Improverange of motionVSAvoidrisk of dislocation

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The controlled dislocation and relocation mechanism enables dynamic adjustment of the articulating member's position. The system allows movement when needed (to accommodate malposition or bone movement) but maintains stability during normal function, reducing the risk of harmful dislocation while preserving necessary range of motion.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The design incorporates feedback through the interaction between the outer sleeve and inner portion, where the relative movement and positioning provide information about the state of the implant-bone interface. This feedback mechanism allows the system to respond appropriately to malposition or bone movement while preventing excessive movement that could cause damage.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If the femoral head is forced into aggressive orientations to achieve complete rotation, then range of motion is improved, but dislocation and implant damage occur

Engineering Contradiction:

Improverange of motionVSAvoidimplant damage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The controlled dislocation mechanism provides preliminary protection by allowing the articulating member to dislocate before aggressive forcing can occur. This preliminary movement absorbs the stress that would otherwise be transmitted to the implant components, preventing damage while still achieving the necessary range of motion.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The design incorporates cushioning through the controlled dislocation and relocation mechanism, which acts as a buffer between the articulating member and the bone-anchored outer sleeve. This cushioning effect protects the implant from damage during aggressive movements by allowing controlled movement before damage can occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS8268007B2Multi-piece prosthetic joint component

Publication Date: 2012.09.18 THE CLEVELAND CLINIC FOUND

AI summary

An elongate, longitudinally oriented outer sleeve includes an outer sleeve surface defining a radially oriented proximal sleeve border, a radially oriented proximal sleeve rim intersecting the outer sleeve surface at the proximal sleeve border, an outer sleeve body enclosed by the outer sleeve surface and the proximal sleeve rim, and an elongate, longitudinally oriented stem-receiving cavity formed in the outer sleeve body and intersecting the proximal sleeve rim to define a stem-receiving aperture. A joint articulating member includes an elongate, longitudinally oriented stem, an articulating surface, and an interface rim. When the stem is at least partially inserted into the stem-receiving cavity, the proximal sleeve rim and the interface rim interact to change a longitudinal relationship between the outer sleeve and the joint articulating member responsive to relative radially-oriented rotation between the stem and the stem-receiving cavity.