Bone Cement Kit Vacuum Mixing via Pyrogenic Silica
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Solution Overview
Problem
Existing bone cement mixing systems require manual mixing, leading to potential air pockets and inhomogeneities in the cement dough, and previous solutions involving vacuum mixing systems are limited by quickly swelling cement powders that hinder monomer liquid penetration.
Innovation Solution
A bone cement kit comprising a cement powder with particulate or fibrous additives like pyrogenic silicon dioxide, which enhances monomer liquid penetration and absorption, allowing for a tack-free, plastically deformable dough formation without manual or technical mixing, using a monomer solution containing methyl methacrylate and an activator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual mixing of cement powder and monomer liquid is used, then the mixing process is simple and requires no complex equipment, but air bubbles are included in the bone cement mixture which negatively affects mechanical properties
Solution Approach 1:
The invention extracts the harmful air bubbles from the mixing process by introducing the monomer liquid through a vacuum port at the bottom of the cartridge, drawing the liquid through the cement powder and displacing trapped air. This eliminates air inclusions without requiring complex mixing equipment.
Solution Approach 2:
The invention uses vacuum pressure to introduce monomer liquid into the cement powder cartridge. The vacuum applied via a vacuum port at the bottom draws the liquid through the cement powder, creating homogeneous mixing while removing air bubbles through pneumatic pressure differential.
2Reliability
If vacuum mixing systems are used to avoid air inclusions, then air bubbles are removed from the mixture, but the systems require complex equipment and special conditions
Solution Approach 1:
The invention merges the vacuum mixing function directly into the cartridge design by incorporating a vacuum port at the bottom of the cartridge. This integrates the complex vacuum system functionality into the simple cartridge structure, eliminating the need for separate complex mixing equipment.
Solution Approach 2:
The cartridge is designed to be self-mixing through vacuum application. The monomer liquid automatically draws through the cement powder via the vacuum port, creating homogeneous mixing and removing air bubbles without requiring external mixing devices or special operational procedures.
3Productivity
If cement powder particles quickly swell upon contact with monomer liquid, then the cement paste forms rapidly, but the swelling particles form a gel-like barrier that hinders further monomer liquid penetration
Solution Approach 1:
The invention applies vacuum before complete mixing occurs, drawing monomer liquid through the cement powder from the bottom up. This preliminary vacuum action ensures thorough penetration and homogeneous distribution of monomer throughout the powder before swelling can create barriers, preventing inhomogeneities in the final paste.
Solution Approach 2:
Instead of introducing monomer from the top where swelling particles create barriers, the invention introduces monomer from the bottom through the vacuum port. This inverted approach allows liquid to penetrate through less resistant paths and be drawn through the entire powder mass, ensuring homogeneous mixing despite rapid swelling.
4Reliability
If conventional cement powders are used with vacuum mixing, then air can be removed from the mixture, but the powder particles are poorly wetted by methyl methacrylate due to differing surface energies
Solution Approach 1:
The vacuum pressure differential created by applying vacuum at the bottom port forces monomer liquid through the cement powder matrix. This pneumatic driving force overcomes the poor wettability caused by surface energy differences, ensuring complete penetration and uniform distribution of monomer throughout the powder.
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 solution enables reproducible and quick production of a homogeneous bone cement that hardens independently through radical polymerization, overcoming issues of air pockets and inhomogeneities, and allowing for easy processing and application.
Implementation Method 1
the additive is a pyrogenic silicon dioxide and has an absorption capacity greater than or equal to 9.4 g of methyl methacrylate per gram of additive at room temperature
Implementation Method 2
enhances monomer liquid penetration and absorption
Implementation Method 3
the activator N,N-dimethyl-p-toluidine reacts with dibenzoyl peroxide to form radicals. These radicals initiate the radical polymerization of the methyl methacrylate
Implementation Method 4
the activator N,N-dimethyl-p-toluidine reacts with dibenzoyl peroxide to form radicals
Implementation Method 5
the polymers of the powder component swell in the methyl methacrylate, forming a plastically deformable paste
Implementation Method 6
a vacuum introduces the monomer liquid into the cartridge from above. The vacuum, applied via a vacuum port at the bottom of the cartridge, draws the liquid through the cement powder, displacing the air trapped between the cement particles
Data Source
AI summary
The invention relates to a polymethyl methacrylate bone cement. The process comprises the steps of providing a cement powder containing at least one particulate polymethyl methacrylate or polymethyl methacrylate copolymer of the sieve fraction less than 100 µm, an initiator, and at least one particulate or fibrous additive insoluble in methyl methacrylate, wherein the additive has an absorption capacity greater than or equal to 0.6 g of methyl methacrylate per gram of additive at room temperature; furthermore, providing a monomer solution containing at least one methyl methacrylate and an activator; and bringing the cement powder and the monomer solution into contact, wherein the mixing is carried out without the application of shear forces. The invention also relates to a bone cement kit for use in such a process and to a bone cement producible by such a process.