Spherical-Arc Saw Blade for Acetabular Cup Extraction

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Solution Overview

Problem

Current methods for removing damaged acetabular cups during hip replacement surgery are time-consuming and can cause damage to the hipbone, especially in patients with osteoporosis, due to the manual and forceful nature of existing techniques.

Innovation Solution

A powered orthopedic tool featuring a hemispherical blade mounted on a drive shaft and linkage system that rotates and pivots to cut through the acetabular cup/bone interface, allowing for efficient removal of the cup with reduced manual force and increased precision.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If manual blade insertion and rotation technique is used, then the acetabular cup can be removed, but the procedure is time-consuming and can damage the hipbone

Engineering Contradiction:

Improveremoval speedVSAvoidhipbone damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the manual mechanical system with a powered mechanical system. A motor drives the blade rotation, and a powered actuation system controls the blade's longitudinal movement and pivoting, eliminating the need for manual force application and significantly reducing surgical time while maintaining control to prevent bone damage

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The blade assembly incorporates dynamic movement capabilities with multiple degrees of freedom: rotation about the longitudinal axis, longitudinal translation along the shaft, and pivoting motion. This dynamic system allows the blade to adapt to the curved interface between the acetabular cup and bone, enabling efficient cutting while following the natural geometry to minimize harmful forces

Inventive Principle:

Principle #15Dynamics

2Strength

If forceful manual rotation is applied, then the cup can be released, but the thin hipbone behind the cup is damaged

Engineering Contradiction:

Improvecup release forceVSAvoidbone damage

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The manual force application system is replaced with a powered actuation system that provides controlled, consistent force through a motor and transmission mechanism. This allows sufficient force to be applied to release the cup while maintaining precise control to prevent excessive forces that could damage the underlying bone

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The blade acts as an intermediary cutting tool between the powered actuation system and the cup-bone interface. The blade's spherical cutting surface distributes forces along the curved interface, allowing the cup to be released through controlled cutting rather than direct forceful manipulation that would transmit harmful loads to the bone

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If conventional manual technique is used, then the procedure can be completed, but it requires significant surgeon time and effort

Engineering Contradiction:

Improvesurgical simplicityVSAvoidremoval time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The manual operation system is replaced with an automated powered system that performs the complex multi-axis movements and force application. The surgeon simply guides the device and activates the motorized functions, dramatically reducing the time and physical effort required while maintaining operational simplicity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The powered blade system performs the cutting and cup release functions autonomously once positioned. The motor automatically rotates the blade and the actuation system automatically advances and pivots the blade along the cup-bone interface, eliminating the need for continuous manual manipulation and significantly reducing procedural time

Inventive Principle:

Principle #25Self-service

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

The tool significantly reduces the time required for acetabular cup removal and minimizes the risk of hipbone damage by using a motorized and pivoting blade system, enhancing surgical efficiency and patient safety.

Implementation Method 1

a drive shaft connected to a motor rotates the blade and head

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The blade's cutting surface is positioned at the acetabular cup/hipbone interface. Continued rotation of the drive shaft and blade cuts through the cup/bone interface to free the cup

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Data Source

PatentUS9724209B2Spherical-arc rotating saw blade power tool for acetabular cup extraction

Publication Date: 2017.08.08 INFINESSE CORP

AI summary

To remove a damaged acetabular cup attached to the hipbone, applicant positions the cutting surface of a curved cutting blade at the acetabular cup/hipbone interface. The blade mounts to a head. The powered drive shaft of a motor rotates the blade and head. A linkage, part of which may be around the drive shaft, moves longitudinally relative to the drive shaft under surgeon control. The linkage pivots the head and urges the blade into the interface. As the power tool rotates the curved blade and the linkage pivots the blade into the interface, the blade follows the hemispherical contour of the interface. Continued powered rotation of the drive shaft and blade and further pivoting of the blade cuts the cup from the hipbone.