PMMA Bone Cement Mixing Cartridge Using Gravity Monomer Transfer
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Solution Overview
Problem
Existing mixing systems for polymethylmethacrylate (PMMA) bone cement require external vacuum sources, which are costly, complex, and prone to errors, and often introduce air inclusions that affect the mechanical properties of the cement, making them inconvenient and unreliable for surgical use.
Innovation Solution
A closed, full-prepacked mixing system where the PMMA bone cement powder and monomer liquid are stored in separate compartments within a cartridge, allowing for mixing without external vacuum pumps, using gravity to transfer the monomer liquid into the powder compartment, ensuring air-free mixing and adjustable monomer-to-powder ratios for consistent cement production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external vacuum pumps are used for mixing, then air inclusions can be removed, but the device complexity and cost increase
Solution Approach 1:
The patent removes the external vacuum pump from the mixing system and extracts only the essential function of air removal. Instead of using a complex external vacuum source, the system relies on the natural density difference between air and monomer liquid, allowing air to rise and escape automatically during the mixing process, thereby simplifying the device while maintaining cement quality.
Solution Approach 2:
The mixing system performs air removal autonomously without external assistance. The monomer liquid naturally displaces air from the powder during mixing, and the air bubbles rise to the surface and escape on their own due to buoyancy, eliminating the need for external vacuum equipment and making the system self-sufficient.
2Productivity
If external vacuum sources are used, then mixing can be performed, but the system becomes prone to errors and requires more energy
Solution Approach 1:
The system utilizes the inherent physical properties of the materials involved - the monomer liquid naturally flows into the powder and air bubbles automatically rise and escape due to density differences. This self-driven mixing process eliminates the need for external energy sources, making the system energy-efficient and more reliable.
Solution Approach 2:
The patent replaces the mechanical vacuum pump system with a passive mixing mechanism based on fluid dynamics and buoyancy. Instead of using mechanical force to remove air, the system relies on the natural behavior of fluids and gases during mixing, substituting complex mechanical systems with simpler physical phenomena.
3Device complexity
If manual mixing with spatulas is used, then the system is simple, but air inclusions are introduced that affect mechanical properties
Solution Approach 1:
The patent employs hydraulic principles by using the monomer liquid to flow through and around the powder particles during mixing. This fluid-based mixing method naturally displaces air from the interstices of the powder and ensures complete wetting, producing a homogeneous mixture without air inclusions while maintaining simple device architecture.
4Reliability
If vacuum cementing systems are used, then air inclusions are prevented, but the ease of operation decreases due to setup requirements
Solution Approach 1:
The patent extracts the air removal function from the complex vacuum cementing system and implements it through the natural density-based separation that occurs during mixing. This eliminates the need for vacuum pump setup and operation, making the surgical procedure more convenient while maintaining cement quality.
Solution Approach 2:
The system automatically handles air removal during the mixing process without requiring surgical staff to operate vacuum equipment. The air bubbles self-naturally rise and escape during mixing, making the operation simpler and more user-friendly while ensuring reliable cement quality.
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 enables reliable, air-free mixing of PMMA bone cement without external energy sources, simplifying surgical procedures, reducing costs, and ensuring consistent cement quality, while being easy to operate and less prone to errors.
Implementation Method 1
allowing for mixing without external vacuum pumps, using gravity to transfer the monomer liquid into the powder compartment
Data Source
AI summary
Device for the mixing of polymethylmethacrylate bone cement and for storing a monomer liquid and a cement powder as starting components of the bone cement, comprisinga cartridge having an internal space closed on one side by a mobile dispensing plunger;a monomer container for a monomer liquid and/or a connector for attachment of a monomer container which can be opened in the device so that the monomer liquid flows from the monomer container into the device; anda connecting conduit through which the monomer liquid can be guided into the internal space of the cartridge; having a pumping plunger that can be shifted axially in the hollow cylinder arranged in the hollow cylinder, which can be used to push monomer liquid from the hollow cylinder through the connecting conduit into the internal space of the cartridge by actuating the pumping plunger.