Bone Cement Mixing Device with Volume Compensation
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Solution Overview
Problem
Conventional devices for mixing polymethyl methacrylate bone cement are complex and expensive, requiring high-pressure pneumatic or mechanical squeezing devices, and are not suitable for paste-like components, leading to potential air contamination and leakage issues, which compromise the quality and strength of the cement.
Innovation Solution
A device with a first container for a paste-like component and a second container for another component, featuring a movable mixing device and a volume compensation element to prevent air entry and leakage, allowing for manual mixing and use of inexpensive cement guns, suitable for volume ratios up to 1:50.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high-pressure pneumatic or mechanical squeezing devices are used to press cement pastes through static mixers, then mixing is achieved, but device complexity and cost increase significantly
Solution Approach 1:
The device separates the squeezing function (performed by a simple manual pistol) from the mixing function (performed by a separate mixing element), eliminating the need for complex high-pressure squeezing devices while maintaining effective mixing capability
Solution Approach 2:
A mixing element is introduced as an intermediary component that facilitates mixing without requiring high squeezing forces, acting as a mediator between the simple manual pistol and the cement paste
2Device complexity
If manual squeezing guns are used for paste-like bone cements, then device cost is reduced, but sufficient squeezing force and mixing capability are not achieved
Solution Approach 1:
The device divides the mixing function from the squeezing function, allowing a simple manual pistol to provide squeezing force while a dedicated mixing element performs the mixing, achieving both low cost and effective mixing
Solution Approach 2:
The mixing element serves as an intermediary that enables effective mixing with low squeezing forces, allowing manual pistols to be used without sacrificing mixing capability
3Manufacturing precision
If static mixers with multiple mixing spirals are used for unequal volume ratios, then homogeneous mixing is achieved, but pressure drop increases requiring higher squeezing forces
Solution Approach 1:
The mixing element acts as an intermediary that achieves homogeneous mixing with minimal pressure drop, eliminating the need for multiple mixing spirals and high squeezing forces
4Productivity
If conventional two-component cartridges with static mixers are used, then mixing occurs during discharge, but air contamination and leakage issues compromise cement quality
Solution Approach 1:
The device separates the mixing operation from the discharge operation, allowing mixing to occur in a controlled environment before discharge, thereby preventing air contamination while maintaining productivity
Solution Approach 2:
The mixing is performed as a preliminary action before discharge, ensuring the cement paste is thoroughly mixed and sealed before being discharged, preventing air contamination during the process
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
Ensures a homogeneous cement dough without air contamination, maintaining sterility and mechanical strength, while reducing costs and complexity by separating the squeezing and mixing processes and using a movable volume compensation element to manage volume fluctuations.
Implementation Method 1
at least one volume compensation element, in particular in the form of a volume compensation piston, which can be moved axially in the first container
Implementation Method 2
a mixing device for mixing the content of the first container, wherein the mixing device can be moved from the outside in the first container for mixing
Implementation Method 3
a discharge plunger arranged to be displaceable in the first container for pressing out the contents of the first container through a discharge opening
Implementation Method 4
Radical formation only occurs when all components of the redox initiator systems work together... the components of the redox initiator system previously stored separately in the two pastes react, with radicals being formed which trigger the radical polymerization of the at least one monomer
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a device for storing, mixing, and applying polymethyl methacrylate bone cement, comprising a first container (1) for a first paste-like component of the bone cement, a discharge piston (4) slidably arranged in the first container (1) for squeezing out the contents of the first container (1) through a discharge opening, a mixing device (22) for mixing the contents of the first container (1), wherein the mixing device (22) is arranged in the first container (1) and the mixing device (22) is movable from the outside in the first container (1) for mixing, and at least one second container (18) for at least one second component of the bone cement is arranged in or on the first container (1), wherein the second container (18) can be opened so that the contents of the first container (1) and the second container (18) can be mixed together in the first container (1).wherein at least one boundary surface of the first container (1) is formed by a movable volume compensation element (4, 6). The invention also relates to a method for producing a polymethyl methacrylate bone cement with such a device, comprising the steps of: A) providing the device, wherein the first container (1) is filled with a first paste-like component of the PMMA bone cement and the second container (18) is filled with a second, preferably liquid, component of the PMMA bone cement; B) opening the second container; C) mixing the two components by moving the mixing device (22), wherein, during the movement of the mixing device (22), a rod or tube connected to the mixing device (22) is repeatedly pushed into and withdrawn from the first container (1).wherein the volume change of the contents of the first container (1) caused by pushing in and pulling out is compensated by a movement of at least one volume compensation element (6); and D) application of the mixed bone cement by advancing the discharge piston (4) in the first container (1).