Spring-Loaded Hard Liner Removal Instrument

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Solution Overview

Problem

Current methods for removing hard liners from acetabular cups during hip revision surgery are cumbersome, requiring strenuous and imprecise hammer-and-punch techniques, and existing pneumatic instruments are complex, costly, and inefficient, lacking a simple and accurate solution for disengaging the Morse taper friction-fit engagement.

Innovation Solution

A spring-activated hard liner removal instrument with a striking mass and axially aligned impactor generates an impulse to disrupt the Morse taper, allowing for precise and efficient removal of the hard liner, featuring a spring-loaded mechanism that accelerates the striking mass into contact with the impactor, minimizing tissue disruption and simplifying the surgical process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If hammer and punch are used to remove hard liner, then removal force is sufficient, but surgical time increases and precision decreases

Engineering Contradiction:

Improveremoval forceVSAvoidsurgical time

Core Design Contradiction:

ForceVSLoss of time

Solution Approach 1:

The spring mechanism is pre-loaded before the surgical procedure, storing elastic potential energy in advance. When triggered, this pre-stored energy is rapidly converted to kinetic energy, delivering the necessary impact force instantly without requiring repeated hammer strikes during surgery.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The instrument delivers a single periodic impact through the spring-loaded striking mass, replacing the repetitive periodic action of multiple hammer strikes. This single well-timed impact is sufficient to dislodge the hard liner, reducing surgical time while maintaining effective removal force.

Inventive Principle:

Principle #19Periodic action

2Force

If hammer and punch are used to remove hard liner, then removal capability is achieved, but surgical precision decreases

Engineering Contradiction:

Improveremoval capabilityVSAvoidsurgical precision

Core Design Contradiction:

ForceVSMeasurement precision

Solution Approach 1:

The manual hammer-and-punch mechanical system is replaced with a spring-loaded mechanical system that provides more controlled and precise force delivery. The spring mechanism allows for better positioning and more accurate application of force to the hard liner, improving surgical precision while maintaining removal capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of time

If pneumatic instrument is used to remove hard liner, then surgical time decreases, but device complexity increases

Engineering Contradiction:

Improvesurgical timeVSAvoiddevice complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The complex pneumatic system (gas source, valves, control mechanisms) is extracted and replaced with a simple spring-loaded mechanical system. The essential function of delivering rapid impact force is maintained through the spring mechanism, which is far simpler in construction and operation than a pneumatic system, thereby reducing device complexity while maintaining surgical efficiency.

Inventive Principle:

Principle #2Taking out (Extraction)

4Measurement precision

If pneumatic instrument is used to remove hard liner, then impact precision improves, but manufacturing cost increases

Engineering Contradiction:

Improveimpact precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The spring-loaded striking mass can be designed as a disposable or single-use component that is inexpensive to manufacture. Rather than investing in expensive pneumatic systems with precision control mechanisms, the invention uses simple, cheap mechanical components that achieve sufficient impact precision for the surgical application, thereby reducing manufacturing costs.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 instrument enables precise and efficient disengagement of the hard liner from the acetabular cup with reduced surgical effort and time, minimizing tissue impact and eliminating the need for complex pneumatic systems, thereby reducing surgical costs and improving procedural accuracy.

Implementation Method 1

A spring coupled to a portion of the striking mass at one end and coupled to a portion of the impactor at another end is selectively movable from a normal resting position to a loaded position

Methodology Applied

Scientific EffectSpring: Spring

Implementation Method 2

movement of the spring from the loaded position to the normal resting position accelerates the striking mass into contact with the impactor to generate an impulse

Methodology Applied

Scientific EffectImpulse: Impact Force

Data Source

PatentUS20240016626A1Hard liner removal instrument

Publication Date: 2024.01.18 JOINT DEVELOPMENT INC

AI summary

A hard liner removal instrument includes a barrel containing a striking mass in slidable relation therewith and a spring positioned between a first end of the barrel and the striking mass. The spring selectively moves between a normal resting position and a loaded position where the striking mass is positioned a greater distance from a second end of the barrel opposite the first end than when the spring is in the normal resting position. As such, movement of the spring from the loaded position to the normal resting position accelerates the striking mass into the second end of the barrel to generate an impulse sufficient to interrupt a Morse taper to remove one orthopedic component from another, e.g., during revision surgery.