PMMA Bone Cement Mixing With Puncture Transfer and Pumping
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Solution Overview
Problem
Existing prepackaged mixing systems for PMMA bone cement face challenges such as air inclusion, conduit blockage, and uncontrolled mixing, necessitating a device that ensures safe and reliable transfer and mixing of monomer liquid with powder components.
Innovation Solution
A device comprising a base part with a container, hollow mandrel, and piston, along with a cartridge, allows for controlled transfer of monomer liquid into the cartridge using a self-sealing septum and a movable piston, preventing leakage and contamination while ensuring complete mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If monomer liquid is transferred through a conduit into the powder component, then mixing is achieved, but the conduit can become blocked by swollen and sticky bone cement
Solution Approach 1:
The device is divided into separate functional modules: a base unit with monomer storage and a cartridge with powder, connected by a removable conduit. The conduit can be detached and replaced if blocked, preventing complete system failure and maintaining reliability while allowing continued operation.
Solution Approach 2:
The conduit material and internal diameter are specifically selected to resist swelling bone cement adhesion. The conduit dimensions and surface properties are optimized to maintain fluid flow characteristics while preventing blockage, addressing the reliability issue without compromising transfer efficiency.
2Productivity
If vacuum is applied to transfer monomer liquid, then transfer speed increases, but air bubbles may be drawn into the cement paste
Solution Approach 1:
The conduit is pre-filled with monomer liquid before connection to the powder cartridge. This creates a liquid seal that prevents air from being drawn into the cement paste during vacuum transfer, eliminating air inclusion while maintaining high transfer speed through vacuum application.
Solution Approach 2:
The pre-filled conduit acts as an intermediary medium between the vacuum source and the mixing chamber. It provides a liquid barrier that mediates the vacuum effect, allowing rapid monomer transfer while blocking air from entering the cement paste and causing defects.
3Device complexity
If manual mixing is performed with spatulas, then simplicity is maintained, but air bubbles are included in the bone cement paste
Solution Approach 1:
The manual spatula mixing operation is replaced by an automated vacuum-driven transfer system. The vacuum mechanism automatically draws monomer liquid through the conduit into the powder, performing the mixing function without manual intervention and eliminating air bubble inclusion that occurs with spatula mixing.
4Ease of manufacture
If cement powder penetrates the monomer liquid transfer conduit during storage, then no special protection is needed, but the conduit becomes blocked due to swelling and sticking
Solution Approach 1:
The conduit is extracted as a separate, removable component from the main system. It can be detached from either the base unit or cartridge and stored separately, preventing cement powder from penetrating and blocking it during storage while maintaining system simplicity through modular design.
Solution Approach 2:
The conduit is designed with pre-filled monomer liquid that creates a protective barrier against cement powder penetration during storage. This preliminary protective action prevents swelling and sticking before they can occur, maintaining reliability without requiring complex protection mechanisms.
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 device facilitates simple, reliable, and safe mixing of PMMA bone cement components, preventing conduit blockage and ensuring consistent mixing ratios, thereby improving the mechanical properties of the cured cement.
Implementation Method 1
the hollow mandrel is configured to pierce the self-sealing septum in order to transfer a monomer liquid from the collection area into the cartridge
Implementation Method 2
the piston is configured to pump a monomer liquid from the collection area through the hollow mandrel into the cartridge
Implementation Method 3
the hollow mandrel is configured to pierce the self-sealing septum
Data Source
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AI summary
The present invention relates to a device for producing bone cement, comprising a base part (100) which has a container (101) with a carrier (118) for receiving a vessel with monomer liquid, a bottom part (103) with a collection area (104), a hollow mandrel (105) with a tip (106) and a piston (107) with a passage (108) for receiving the hollow mandrel (105), and a cartridge (200) for receiving a PMMA bone cement powder (201), wherein the cartridge has a septum (202) which delimits the cartridge to the outside; wherein the piston is configured to pump a monomer liquid from the collection area through the hollow mandrel into the cartridge.