Modular Prosthesis Separation Tool Jack Mechanism

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Solution Overview

Problem

Current methods for removing modular prosthesis components, such as the neck and stem components from the sleeve in hip replacement surgeries, are cumbersome and risk damaging surrounding tissue due to the use of bone chisels and impaction tools, which can dislodge the sleeve from the femur.

Innovation Solution

A separation tool with an upper and lower body and a jack assembly that applies uniform pressure to gradually increase the gap between components, allowing controlled separation without the need for bone chisels or impaction tools, featuring a scissors jack mechanism driven by a threaded actuator rod for precise and controlled component disengagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If bone chisels and impaction tools are used to remove modular prosthesis components, then the components can be separated from the sleeve, but the sleeve may be dislodged from the femur and surrounding tissue may be damaged

Engineering Contradiction:

Improvecomponent separationVSAvoidtissue damage and sleeve dislodgement

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A specialized separation tool acts as an intermediary device between the surgeon and the prosthesis components. The tool includes a first component that engages the proximal component and a second component that engages the distal component, providing controlled separation forces without direct application of bone chisels or impaction tools that could damage tissue or dislodge the sleeve.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the traditional mechanical system of bone chisels and impaction tools with a controlled separation tool that uses a screw mechanism or hydraulic system to apply gradual, controlled forces. This substitution eliminates the harmful impulsive forces generated by traditional tools while maintaining the ability to separate components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If a one-piece prosthesis is used, then the structure is simpler, but flexibility in selecting prosthesis to fit varying patient anatomy is reduced

Engineering Contradiction:

Improveanatomy fitting flexibilityVSAvoidprosthesis structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The prosthesis is divided into modular components including a proximal component, a distal component, and an intermediate component. Each component can be independently selected and assembled to match the specific anatomical requirements of the patient, providing flexibility in stem length, curvature, and other geometric parameters while maintaining a relatively simple overall structure.

Inventive Principle:

Principle #1Segmentation

3Strength

If modular prosthesis components are designed for rigid engagement, then the prosthesis can bear functional loads, but the components become difficult to separate for revision procedures

Engineering Contradiction:

Improveload bearing capacityVSAvoidcomponent separation

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The separation tool incorporates a dynamic separation process that gradually increases the gap between components. The tool allows for controlled application of separation forces that can be adjusted during the procedure, transitioning from a tightly engaged state to a separated state without compromising the integrity of the implant-bone interface.

Inventive Principle:

Principle #15Dynamics

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 safe and controlled separation of modular prosthesis components in situ, minimizing tissue damage and maintaining the integrity of components within the bone, with a minimal profile that does not interfere with the prosthesis or surrounding tissue.

Implementation Method 1

featuring a scissors jack mechanism driven by a threaded actuator rod for precise and controlled component disengagement

Methodology Applied

Scientific EffectScrew mechanism: Screw

Implementation Method 2

a jack assembly that applies uniform pressure to gradually increase the gap between components

Methodology Applied

Scientific EffectMechanical advantage: Mechanical Advantage

Data Source

PatentUS8152814B2Separator tool for a modular prosthesis

Publication Date: 2012.04.10 DEPUY PROD INC

AI summary

A tool for separating components of a modular prosthesis includes an upper and lower body, each defining opposing bills at one end that are sized to fit in juxtaposed relation within an initial gap between the components. The upper body is provided with a handle so that the tool may be manually held by the surgeon with the opposing bills in position in the prosthesis. The tool includes a jack assembly disposed between the upper and lower bodies of the tool that is configured to be driven into an extended position, gradually separating the upper and lower bodies, and consequently exerting a separation force on the prosthesis components through the bills of the tool. The jack assembly is driven by a threaded actuator rod that bears against one element of the jack assembly as the actuator rod is rotated within a threaded bore in one of the bodies of the tool.