Osteotome Extractor With Segmented Cutting Elements

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Solution Overview

Problem

The challenge in removing a prosthesis from a bony implantation site is the difficulty in cutting and separating the strong bonding interface between the prosthesis and the bone, especially when the prosthesis has a porous surface, requiring precise and efficient tools to minimize bone material loss.

Innovation Solution

A surgical tool with elongate elements and a bayonet mechanism that includes a shaft with a handle and a head featuring cutting elements, which are inserted through apertures in the prosthesis to partially separate the bonding interface between the prosthesis and the bone, allowing for controlled extraction without excessive force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If osteotomes are used to cut the bonding interface between prosthesis and bone, then the bonding interface can be separated, but excessive bone material may be removed and the operation becomes time-consuming

Engineering Contradiction:

Improveextraction successVSAvoidbone material

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The tool divides the cutting function into multiple elongate elements (typically 3-6) arranged around the prosthesis, each element cutting a portion of the bonding interface simultaneously. This segmented approach distributes the cutting action across multiple points, enabling complete separation of the bonding interface while removing minimal bone material and reducing operation time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The elongate elements are designed to partially separate the bonding interface rather than completely cutting through it. This partial action is sufficient to break the bond between prosthesis and bone, allowing extraction without requiring excessive cutting of bone material, thus preserving bone stock while achieving successful removal.

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If multiple instruments are used for extraction, then the bonding interface can be separated, but the device complexity increases and the operation time increases

Engineering Contradiction:

Improveextraction successVSAvoidnumber of instruments

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The tool merges multiple functions into a single integrated instrument: the elongate elements perform cutting action, the bayonet mechanism provides secure engagement with the prosthesis flange, and the ratchet mechanism enables controlled extraction. This consolidation eliminates the need for multiple separate instruments (osteotomes, grasping tools, extraction devices), reducing device complexity and streamlining the extraction procedure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The extraction tool is designed as a universal device that can extract various types of prostheses (femoral stems, tibial trays, acetabular cups) with different geometries. The bayonet mechanism adapts to different flange configurations, and the elongate elements can be adjusted to match different aperture patterns, making the tool versatile across multiple prosthesis types without requiring instrument changes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If excessive force is applied to extract the prosthesis, then the prosthesis can be removed, but bone damage occurs and surgical precision is compromised

Engineering Contradiction:

Improveextraction speedVSAvoidbone damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The elongate elements perform preliminary cutting action on the bonding interface before extraction force is applied. By pre-severing the bond between prosthesis and bone through controlled cutting, the subsequent extraction requires minimal force, preventing bone damage while maintaining high extraction speed. This preliminary action eliminates the need for forceful extraction that would compromise bone integrity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The elongate elements act as intermediaries between the extraction tool and the bonding interface. Rather than applying force directly to the prosthesis-bone interface, the elements mediate the separation through controlled cutting action, distributing stress along the cutting edges and preventing concentrated forces that would damage bone tissue during extraction.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20220218497A1Osteotome extractor

Publication Date: 2022.07.14 HOWMEDICA OSTEONICS CORP

AI summary

A method for separating an implant from a bone, includes interfacing a tool with an implant including a flange, the flange including a proximal surface and a distal surface, the distal surface bearing on or facing the bone, the flange including an aperture defined through the flange; inserting an elongate element through the aperture from the proximal surface to the distal surface and into the bone; and partially separating a bonding interface between the implant and the bone using the elongate element.