Nested Cartridge Bone Cement Mixing System
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Solution Overview
Problem
Conventional systems for mixing and dispensing polymethyl methacrylate bone cements face challenges with highly viscous paste-like components, requiring excessive manual force and often resulting in inefficient use, residue issues, and difficulties in maintaining precise mixing ratios, especially in surgical settings where sterility and ease of use are critical.
Innovation Solution
A storage and mixing system featuring a first tubular cartridge with a cylindrical interior for one starting component and a second tubular cartridge nested inside, where both cartridges have axially movable discharge pistons, and a pressing device with a clamping edge that deforms the inner cartridge to advance both pistons synchronously, allowing for efficient manual operation and precise mixing without residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional discharge pistons with large diameter (30-40 mm) are used to dispense highly viscous paste-like bone cement, then the cement can be dispensed, but excessive manual force is required that cannot be exerted by medical users
Solution Approach 1:
The patent employs a nested cartridge structure where an inner cartridge containing the second starting component is placed inside an outer cartridge containing the first starting component. Both cartridges have their own discharge pistons, and the pressing device is nested within the outer cartridge to compress both cartridges simultaneously. This nested arrangement allows for reduced piston diameters while maintaining effective dispensing of highly viscous materials through coordinated compression of both cartridges.
2Adaptability or versatility
If two separate cartridges with two separate dispensing pistons are used for two-component bone cements, then both pastes can be pressed into a static mixer, but the system complexity increases
Solution Approach 1:
The patent merges the two separate cartridge systems into a single integrated cartridge assembly where both cartridges are positioned side-by-side within one housing. The pressing device combines the functions of compressing both cartridges into a single mechanical unit with one plunger that acts on both discharge pistons simultaneously. This merging approach maintains the capability to mix two paste-like components while significantly reducing system complexity compared to using two completely separate cartridges and dispensing systems.
3Manufacturing precision
If a single pressing device acts on both discharge pistons simultaneously, then synchronous advancement is achieved, but the pressing device structure becomes more complex
Solution Approach 1:
The patent employs asymmetric design in the pressing device where the single plunger has different acting areas on the two discharge pistons. The first discharge piston has a larger diameter and requires less force, while the second discharge piston has a smaller diameter and requires more force to achieve the same displacement. By designing the pressing device with asymmetric force distribution through different plunger contact areas, synchronous advancement of both pistons is achieved while maintaining a relatively simple single-plunger structure rather than requiring a complex dual-plunger system with precise synchronization 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
Enables efficient, residue-free mixing and dispensing of polymethyl methacrylate bone cement with minimal manual effort, ensuring reproducible mixing ratios and reducing the complexity of assembly and operation, suitable for surgical applications.
Implementation Method 1
a pressing device which can be advanced axially in the interior of the first cartridge and has a clamping edge for pressing the inner second cartridge against the inner wall of the outer first cartridge, wherein the pressing device can be advanced in the direction of the cartridge head in such a way that during the movement of the pressing device the inner second cartridge is continuously compressed axially
Implementation Method 2
a pressing device which can be advanced axially in the interior of the first cartridge and has a clamping edge for pressing the inner second cartridge against the inner wall of the outer first cartridge
Data Source
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AI summary
Storage and mixing system for paste-like multi-component PMMA bone cements comprising a first tubular cartridge (1) with a first cylindrical interior containing a first output component (3), a first dispensing piston (5), a second tubular cartridge (2) arranged inside the first tubular cartridge (1), wherein the second cartridge (2) bears against the inner wall of the first cartridge (1) with its outer wall and is attached to the inner wall of the first cartridge (1), wherein the second cartridge (2) contains a second output component (4) and a second dispensing piston (6), wherein, viewed from the cartridge head (9), behind the first dispensing piston (5) and the second dispensing piston (6), a pressing device (7) axially propellable in the interior of the first cartridge (1) with a clamping edge (8) for compressing the second cartridge (2) is arranged.wherein the pressing device (7) can be advanced in the direction of the cartridge head (9) such that during the movement of the pressing device (7) the second cartridge (2) is continuously compressed axially and the first discharge piston (5) and the second discharge piston (6) are advanced in the direction of the cartridge head (9).