Telescoping Bone Cement Plunger for Lower Dispensing Force

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Solution Overview

Problem

Dispensing high-viscosity bone cement is challenging due to the high force required to transfer it from mixing devices to dispensing tools like syringes, making it difficult to handle and apply effectively in medical procedures.

Innovation Solution

A dispensing system with a two-stage plunger mechanism, comprising a first outer plunger with a smaller inner diameter and a second inner plunger with a check valve, reduces the force needed by amplifying pressure through a telescoping design, allowing easier transfer and dispensing of bone cement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional syringes or simple dispensing devices are used to transfer high-viscosity bone cement, then the device structure remains simple, but a great amount of force is required to transfer the cement, making it difficult to operate

Engineering Contradiction:

Improveease of transferring bone cementVSAvoidforce required to transfer cement

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The dispensing system employs a nested plunger structure where an inner plunger is positioned within an outer plunger. The inner plunger has a smaller diameter than the outer plunger, creating a telescoping arrangement. This nested configuration allows the plungers to work together to reduce the force needed to dispense high-viscosity bone cement by distributing the pressure more effectively through the cement volume.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Ease of operation

If a single-stage plunger is used, then the device complexity remains low, but the pressure amplification effect is insufficient to easily dispense high-viscosity cement

Engineering Contradiction:

Improveease of dispensing bone cementVSAvoidcomplexity of plunger mechanism

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The system uses a nested plunger configuration where the inner plunger fits within the outer plunger. This nested arrangement creates a telescoping mechanism that amplifies pressure during cement dispensing. The inner plunger's movement within the outer plunger's lumen creates a mechanical advantage that multiplies the dispensing force, making it easier to handle high-viscosity bone cement while maintaining reasonable device complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If high-viscosity bone cement is used to effectively fill small gaps and hold bone fragments, then the bonding effectiveness is improved, but the cement becomes difficult to load into dispensing devices due to its viscosity

Engineering Contradiction:

Improveeffectiveness of bone fragment bondingVSAvoidease of loading cement into device

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The nested plunger system with inner and outer plungers creates a telescoping mechanism that reduces the force required to load and dispense high-viscosity bone cement. The concentric arrangement of plungers allows for efficient force distribution and pressure amplification, enabling the cement to be loaded into the dispensing device without excessive force while maintaining its high-viscosity properties for effective bonding.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The dispensing system incorporates a dynamic plunger mechanism where the inner plunger can move independently within the outer plunger's lumen. This dynamic arrangement allows the system to adapt to the viscosity of the bone cement during loading and dispensing operations, providing variable pressure application that facilitates easier loading of high-viscosity material while maintaining control during dispensing.

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

The system significantly reduces the force required to dispense bone cement by up to 2.5 times, making it easier to handle and apply, while maintaining compatibility with existing mixing and dispensing devices.

Implementation Method 1

reduces the force needed by amplifying pressure through a telescoping design

Methodology Applied

Scientific EffectPressure amplification: Hydraulic Press

Data Source

PatentUS12508061B2Dispensing system and methods of use

Publication Date: 2025.12.30 MEDTRONIC EUROPE SÀRL

AI summary

A dispensing system includes a main body having a base and an extension extending from the base. The extension includes an inner surface defining a passageway. The main body includes an opening that extends through the extension. The opening is in communication with the passageway. A first plunger is configured to be positioned within the passageway. The first plunger includes a lumen extending through and between opposite proximal and distal end surfaces of the first plunger. A second plunger is configured to be positioned within the lumen. Kits and methods are disclosed.